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  • 1.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Svängande sensorer hittar prostatacancer2010Ingår i: medtechinfo.comArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 2.
    Andersson, Britt M.
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Easterling, Kenneth E.
    Guo, Shi-ju
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Electrical resistivity and critical temperature of Bi-based high-Tc superconductors to 1 GPa1990Ingår i: High Pressure Research, volumes 3 to 5: High Pressure Science and Technology: Proceedings of the 12. AIRAPT and 27. EHPRG Conference, University Paderborn 1989, London: Gordon and Breach , 1990, s. 120-122Konferensbidrag (Refereegranskat)
    Abstract [en]

    We have measured the electrical resistance R of a sintered, two-phase, high-TC superconductor with the nominal composition BiSrCaCu2Ox, as a function of T and p. We find d(lnR)/dp ≃ -0.06 GPa-1 at 295 K, while dTC/dp is 2.5 K/GPa for the phase with Tc ≃ 76 and 2 K/GPa for that with TC ≃ 106 K.

  • 3.
    Andersson, Britt M.
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Easterling, Kenneth E.
    Loberg, Bengt
    Niska, John
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    High-pressure properties of high-Tc superconductor samples produced by hot isostatic pressing1990Ingår i: High Pressure Research, volumes 3 to 5: High Pressure Science and Technology: Proceedings of the 12. AIRAPT and 27. EHPRG Conference, University Paderborn 1989, London: Gordon and Breach , 1990, s. 123-126Konferensbidrag (Refereegranskat)
    Abstract [en]

    The electrical resistance of dense YBa2Cu3Ox and YBa2Cu4Oy produced by hot isostatic pressing has been measured vs. T and p. At 295 K we find d (ln R)/dp ≃ -0.12 and -0.09 GPa-1, respectively, with no systematic dependence on initial density. For 1-2-4, dTC/dp ≃ 5.1 K/GPa, which is ten times that of 1-2-3.

  • 4.
    Andersson, Britt M.
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Defects and the thermal conductivity of YBa2Cu3O7-d and YBa2Cu4O81993Ingår i: Journal of Alloys and Compounds, volume 195: Proceedings of Symposium A on High Tc Superconductors of the 1992 E-MRS Fall Conference, Strasbourg 1992, Elsevier Sequoia S.A. , 1993, s. 655-658Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present below the first measured data for the thermal diffusivity and the thermal conductivity, λ, of dense, sintered ceramic YBa2Cu4O8 (1-2-4) as a function of temperature T between 40 and 310 K. At 300 K, λ is 6.3 Wm−1K−1, increasing with decreasing T to about 9.5 Wm−1K−1 near Tc. This T dependence is much stronger than in YBa2Cu3O7−δ (1-2-3). Only a very small enhancement is observed in λ below Tc. As in 1-2-3, λ is mainly limited by phonon scattering by defects.

  • 5.
    Andersson, Britt M.
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Thermal conductivity and thermal diffusivity of dense, bulk YBa2Cu4O81994Ingår i: High Temperatures - High Pressures volume 26, issue 1: Proceedings of the 13th European Conference on Thermophysical Properties (13 ECTP), Lisboa 1993, London: Pion Press , 1994, s. 53-57Konferensbidrag (Refereegranskat)
    Abstract [en]

    We have measured the thermal conductivity, lambda, and the thermal diffusivity, a, of dense bulk ceramic YBa2Cu4O8 (1-2-4) between 30 and 300 K. For this material lambda is about 10 W/Km near 100 K, comparable with the in-plane thermal conductivity for single crystals of the more common high-Tc material YBa2Cu3O7 (1-2-3). Also, lambda has a much stronger T dependence in 1-2-4 than in 1-2-3. We find that, for 1-2-4, lambda can be very well described by a semiclassical phonon theory, which includes phonon, electron, and boundary scattering. The difference between the present results and those for 1-2-3 can be explained mainly in terms of a smaller amount of point-defect scattering in 1-2-4 because of the stable oxygen stoichiometry of this material.

  • 6.
    Andersson, Britt M.
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Thermal conductivity of YBa2Cu4O8 dominated by phonon-phonon interactions1993Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 48, nr 5, s. 3575-3578Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The thermal conductivity κ of dense sintered ceramic YBa2Cu4O8 in the range 30–310 K has been measured. At 100 K, κ is 10 W m-1 K-1, approaching the in-plane κ of single crystals of other high-Tc materials. κ decreases rapidly with increasing T to 7.4 W m-1 K-1 at 300 K. Fitting standard models for κ(T) to the data we find that κ is limited mainly by phonon-phonon interactions. Depending on the model used, the best fit is found for effective values of FTHETADebye between 155 and 185 K, characteristic for the acoustic phonon branches, indicating that such phonons carry most of the heat. Finally, we suggest a possible way to test the electron-phonon model for the electrical and thermal conductivities in high-Tc materials.

  • 7.
    Andersson, Britt M.
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Thermal conductivity of YBa2Cu4O8 under high pressure1993Ingår i: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 216, nr 1-2, s. 187-194Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The thermal diffusivity a of YBa2Cu4O8 (1-2-4) has been measured as a function of pressure p and temperature T over the range 85<T<310 K and up to 1 GPa (10 kbar). From the data obtained we have calculated the pressure dependence of the thermal conductivity κ as a function of T. κ increases slowly with increasing p above 150 K but decreases below this value. Most of the high-T increase with p is caused by an increase in the electronic thermal conductivity κe. For the phonon thermal conductivity, which dominates κ in 1-2-4, we find that charge transfer with p causes a strong increase in electron-phonon scattering with p, while the p dependence of the boundary scattering and phonon-phonon scattering is in reasonable agreement with the behaviour predicted by simple models.

  • 8.
    Andersson, Britt M.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Thermal diffusivity and thermal conductivity of YBa2Cu3O7-d and YBa2Cu4O8 between 20 and 300 K1992Ingår i: Proceedings of the Joint Nordic Spring Meeting '92 / [ed] Per-Anker Lindgård, Roskilde: Risö National Laboratory/Grafisk Service, Risö , 1992, s. 251-Konferensbidrag (Övrigt vetenskapligt)
  • 9.
    Andersson, Britt M.
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Niska, John
    Loberg, Bengt
    Thermal conductivity of polycrystalline YBa2Cu4O81994Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 49, nr 6, s. 4189-4198Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have measured the thermal conductivity κ and the thermal diffusivity a of a dense bulk ceramic polycrystalline sample of YBa2Cu4O8 (1:2:4) in the temperature range 30–300 K. We find κ≊10 W m-1 K-1 at 100 K, significantly higher than in ceramic YBa2Cu3O7-δ (1:2:3) and approaching the in-plane value for single-crystal 1:2:3, and decreasing to 7.6 W m-1 K-1 at 300 K. The data for this sample can be described by standard theories for phonon thermal conductivity of crystalline materials with boundary, phonon, and electron scattering. The higher κ in 1:2:4 as compared to 1:2:3 is, in this model, due to the smaller point defect scattering in the former. The fitted parameters for the three scattering mechanisms all agree with independent estimates based on simple models; inserting data for electric resistivity, grain size, carrier density, and lattice properties we can predict κ and its T dependence to within about 20%. We also discuss models for the phonon and electron thermal conductivities in some detail, including some second-order effects such as inelastic electron scattering and a T-dependent carrier density.

  • 10.
    Andersson, Britt M.
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Niska, John
    Loberg, Bengt
    Easterling, Kenneth
    Electrical transport in dense, bulk YBa2Cu4O8 produced by hot isostatic pressing1990Ingår i: Physica B Volumes 165 & 166, Part 2: LT-19 Part II: Contributed Papers, Proceedings of the 19th International Conference on Low Temperature Physics, Brighton 1990, Elsevier B.V. , 1990, s. 1699-1700Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dense (98.5%) bulk sintered specimens of YBa2Cu4O8 have been produced by hot isostatic pressing. Data for the electrical resistivity π versus temperature T and pressure p in the range 70–300 K and 0–0.7 GPa are reported and discussed. The critical current density of the material studied exceeds 100 Acm−2 below 60 K.

  • 11.
    Andersson, Britt M.
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Niska, John
    Loberg, Bengt
    Easterling, Kenneth
    Electrical transport properties of dense bulk YBa2Cu4O8 produced by hot isostatic pressing1990Ingår i: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 170, nr 5-6, s. 521-531Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Highly dense sintered YBa2Cu4O8 has been produced by hot isostatic pressing (HIP). The electrical resistivity varrho of this material has been measured as a function of temperature T and pressure varrho in the range 40–650 K and 0–0.7 GPa. Both the temperature dependence and the pressure dependence of varrho are found to be well described by a model based on the standard Bloch-Grüneisen theory. It is pointed out that varrho is liner in T only under isobaric conditions, while varrho is strongly nonlinear in all high-Tc superconductors under isochoric (constant volume) conditions. The critical current density of the material is 900 A/cm2 at 4 K, while the resistivity is 630 μΩ cm at 294 K.

  • 12.
    Eklund, Anders
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Lindén, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap.
    Bäcklund, Tomas
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Evaluation of applanation resonator sensors for intra-ocular pressure measurement: results from clinical and in vitro studies.2003Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 41, nr 2, s. 190-197Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Glaucoma is an eye disease that, in its most common form, is characterised by high intra-ocular pressure (IOP), reduced visual field and optic nerve damage. For diagnostic purposes and for follow-up after treatment, it is important to have simple and reliable methods for measuring IOP. Recently, an applanation resonator sensor (ARS) for measuring IOP was introduced and evaluated using an in vitro pig-eye model. In the present study, the first clinical evaluation of the same probe has been carried out, with experiments in vivo on human eyes. There was a low but significant correlation between IOP(ARS) and the IOP measured with a Goldmann applanation tonometer (r = 0.40, p = 0.001, n = 72). However, off-centre positioning of the sensor against the cornea caused a non-negligible source of error. The sensor probe was redesigned to have a spherical, instead of flat, contact surface against the eye and was evaluated in the in vitro model. The new probe showed reduced sensitivity to off-centre positioning, with a decrease in relative deviation from 89% to 11% (1 mm radius). For normalised data, linear regression between IOP(ARS) and direct IOP measurement in the vitreous chamber showed a correlation of r = 0.97 (p < 0.001, n = 108) and a standard deviation for the residuals of SD < or = 2.18 mm Hg (n = 108). It was concluded that a spherical contact surface should be preferred and that further development towards a clinical instrument should focus on probe design and signal analysis.

  • 13. Ekstrand-Hammarström, Barbro
    et al.
    Magnusson, Roger
    Österlund, Camilla
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Lungmedicin.
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Bucht, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Lungmedicin.
    Wingfors, Håkan
    Oxidative stress and cytokine expression in respiratory epithelial cells exposed to well-characterized aerosols from Kabul, Afghanistan2013Ingår i: Toxicology in Vitro, ISSN 0887-2333, E-ISSN 1879-3177, Vol. 27, nr 2, s. 825-833Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study aerosol samples collected in an Asian mega-city (Kabul, Afghanistan) were compared to PM samples collected in a European location with traffic (Umea, Sweden) and a reference urban dust material (SRM 1649b). The toxicity of each sample towards normal human bronchial epithelial (NHBE) cells and a human bronchial epithelial cell line (BEAS-2B) was tested along with their ability to induce reactive oxygen species (ROS) formation and inflammatory responses. The extracts' morphology and elemental composition was studied by SEM-EDXRF, and filter samples were analyzed for metals and organic compounds. The PM from Kabul contained a larger fraction of fine particles, 19 times more polyaromatic hydrocarbons (PAH) and 37 times more oxygenated PAH (oxy-PAH) compared to samples from timed. The PM-samples from Kabul and the reference material (SRM 1649b) induced significantly stronger oxidative stress responses than the samples from Umea. Furthermore, samples collected in Kabul induced significantly higher secretion of the cytokines IL-6, IL-8 and GM-CSF while SRM1649b induced a cytokine pattern more similar to samples collected in Umea. Several properties of the particles could potentially explain these differences, including differences in their size distribution and contents of PAH and oxy-PAH, possibly in combination with their relative transition metal contents. 

  • 14.
    Golriz, Mohammad R
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Matida, E A
    Carleton university, Ottawa, Canada.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Production of Nano/Micro Beclomethasone Dipropionate particles Using Supercritical Carbon Dioxide2005Ingår i: Nordic Baltic Conference on Biomedical Engineering and Medical Physics, IFMBE , 2005, s. 156-157Konferensbidrag (Refereegranskat)
  • 15.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Bergh, Anders
    Umeå universitet, Medicinsk fakultet, Medicinsk biovetenskap. Umeå universitet, Medicinsk fakultet, Medicinsk biovetenskap, Patologi.
    Ljungberg, Börje
    Umeå universitet, Medicinsk fakultet, Kirurgisk och perioperativ vetenskap. Umeå universitet, Medicinsk fakultet, Kirurgisk och perioperativ vetenskap, Urologi och andrologi.
    Lindahl, Olof
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Detection of prostate cancer with a resonance sensor2005Ingår i: IFMBE Proccedings: NBC'05 Umeå 13th Nordic Baltic Conferenceon Biomedical Engineering and Medical Physics, Umeå, 2005, s. 130-131Konferensbidrag (Refereegranskat)
  • 16.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Patologi.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Urologi och andrologi.
    Lindahl, Olof
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Indentation loading response of a resonance sensor: discriminating prostate cancer and normal tissue2013Ingår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 37, nr 7, s. 416-423Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Prostate cancer is the most common type of cancer among men worldwide. Mechanical properties of prostate tissue are promising for distinguishing prostate cancer from healthy prostate tissue. The aim was to investigate the indentation loading response of a resonance sensor for discriminating prostate cancer tissue from normal tissue. Indentation measurements were done on prostate tissue specimens ex vivo from 10 patients from radical prostatectomy. The measurement areas were analysed using standard histological methods. The stiffness parameter was linearly dependent on the loading force (average R2 = 0.90) and an increased loading force caused a greater stiffness contrast of prostate cancer vs normal tissue. The accuracy of the stiffness contrast was assessed by the ROC curve with the area under the curve being 0.941 for a loading force of 12.8 mN. The results are promising for the development of a resonance sensor instrument for detecting prostate cancer.

  • 17.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Eklund, Anders
    Medicinsk teknik och informatik, Biomedical Engineering and Informatics, Umeå University Hospital.
    Lindahl, Olof
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    A resonance sensor technique to detect cancer in prostate - Model experiments in silicone2002Ingår i: IFMBE Proceedings: The 12th Nordic Baltic Conference on Biomedical Engineering and Medical Physics, Reykjavik, 2002, s. 33-34Konferensbidrag (Refereegranskat)
  • 18.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof
    Dept of Computer Science and Electrical Engineering, Luleå University of Technology.
    Instrument towards faster diagnosis and treatment of prostate cancer: Resonance sensor stiffness measurements on human prostate tissue in vitro2009Ingår i: IFMBE Proceedings of the World Congress on Medical Physics and Biomedical Engineering, Heidelberg: Springer , 2009, s. 145-148Konferensbidrag (Refereegranskat)
    Abstract [en]

    Prostate cancer is the most common cancer among men and the methods used to detect and diagnose prostate cancer are not sufficiently accurate. Radical prostatectomy is a surgical treatment of prostate cancer where the whole prostate is removed from the patient. Prostate tissue stiffness can be measured with a stiffness sensitive resonance sensor. The aim of this study was to measure the stiffness on the anterior and posterior side of fresh human prostate tissue in vitro and compare these two groups with each other and relate the findings with the prostate tissue histology.  In a prostate tissue slice with mostly normal healthy tissue, the anterior side was significantly harder (p-value < 0.05) as expected. In a prostate tissue slice with areas of cancer tumors, no difference was found between the anterior and posterior sides. However, large stiffness variations were found within groups with measurements points on cancer tissue (coefficient of variation, CV = 42 and 85%), as opposed to groups without cancer tissue (CV = 27 and 28%).  The large stiffness variations could be used as a sign for the presence of cancer. The results are promising for the development of an instrument and method for faster diagnosis on radical prostatectomy samples.

  • 19.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof
    Dept. of Computer Science and Electrical Engineering (Systemteknik), Luleå University of Technology.
    Stiffness of a small tissue phantom measured by a tactile resonance sensor2010Ingår i: IFMBE Proceedings of XII Mediterranean Conference on Medical and Biological Engineering and Computing, Heidelberg: Springer , 2010, s. 395-398Konferensbidrag (Refereegranskat)
  • 20.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Bergh, Anders
    Umeå universitet, Medicinsk fakultet, Medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinsk fakultet, Kirurgisk och perioperativ vetenskap.
    Lindahl, Olof
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Resonance sensor for prostate tissue stiffness measurements – detecting prostate cancer2006Ingår i: World Congress on Biomedical Engineering and Medical Physics, August 27 - September 1, 2006, Seoul, Korea, IFMBE , 2006Konferensbidrag (Refereegranskat)
  • 21.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Patologi.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Urologi och andrologi.
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Explanatory models for a tactile resonance sensor system-elastic and density-related variations of prostate tissue in vitro2008Ingår i: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 29, nr 7, s. 729-745Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tactile sensors based on piezoelectric resonance have been adopted for medical applications. The sensor consists of an oscillating piezoelectric sensor–circuit system, and a change in resonance frequency is observed when the sensor tip contacts a measured object such as tissue. The frequency change at a constant applied force or mass load is used as a stiffness-sensitive parameter in many applications. Differential relations between force and frequency have also been used for monitoring intraocular pressure and stiffness variations in prostate tissue in vitro. The aim of this study was to relate the frequency change (Δf), measured force (F) and the material properties, density and elasticity to an explanatory model for the resonance sensor measurement principle and thereby to give explanatory models for the stiffness parameters used previously. Simulations of theoretical equations were performed to investigate the relation between frequency change and contact impedance. Measurements with a resonance sensor system on prostate tissue in vitro were used for experimental validation of the theory. Tissue content was quantified with a microscopic-based morphometrical method. Simulation results showed that the frequency change was dependent upon density (ρ) and contact area (S) according to Δf ∝ ρS3/2. The experiments followed the simulated theory at small impression depths. The measured contact force followed a theoretical model with the dependence of the elastic modulus (E) and contact area, FES3/2. Measured density variations related to histological variations were statistically weak or non-significant. Elastic variations were statistically significant with contributions from stroma and cancer relative to normal glandular tissue. The theoretical models of frequency change and force were related through the contact area, and a material-dependent explanatory model was found as Δf ∝ ρE−1F. It explains the measurement principle and the previously established stiffness parameters from the material properties point of view.

  • 22.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Bergh, Anders
    Umeå universitet, Medicinsk fakultet, Medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinsk fakultet, Kirurgisk och perioperativ vetenskap.
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Prostate tissue stiffness as measured with a resonance sensor system: a study on silicone and human prostate tissue in vitro.2006Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 44, nr 7, s. 593-603Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Prostate cancer is the most common form of cancer in men in Europe and in the USA. Some prostate tumours are stiffer than the surrounding normal tissue, and it could therefore be of interest to measure prostate tissue stiffness. Resonance sensor technology based on piezoelectric resonance detects variations in tissue stiffness due to a change in the resonance frequency. An impression-controlled resonance sensor system was used to detect stiffness in silicone rubber and in human prostate tissue in vitro using two parameters, both combinations of frequency change and force. Variations in silicone rubber stiffness due to the mixing ratio of the two components could be detected (p<0.05) using both parameters. Measurements on prostate tissue showed that there existed a statistically significant (MANOVA test, p<0.001) reproducible difference between tumour tissue (n=13) and normal healthy tissue (n=98) when studying a multivariate parameter set. Both the tumour tissue and normal tissue groups had variations within them, which were assumed to be related to differences in tissue composition. Other sources of error could be uneven surfaces and different levels of dehydration for the prostates. Our results indicated that the resonance sensor could be used to detect stiffness variations in silicone and in human prostate tissue in vitro. This is promising for the development of a future diagnostic tool for prostate cancer.

  • 23.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Bergh, Anders
    Umeå universitet, Medicinsk fakultet, Medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinsk fakultet, Kirurgisk och perioperativ vetenskap.
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Resonance sensor measurements of stiffness variations in prostate tissue in vitro: a weighted tissue proportion model2006Ingår i: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 27, nr 12, s. 1373-86Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Prostate cancer is the most common type of cancer in men in Europe and the US. The methods to detect prostate cancer are still precarious and new techniques are needed. A piezoelectric transducer element in a feedback system is set to vibrate with its resonance frequency. When the sensor element contacts an object a change in the resonance frequency is observed, and this feature has been utilized in sensor systems to describe physical properties of different objects. For medical applications it has been used to measure stiffness variations due to various patho-physiological conditions. In this study the sensor's ability to measure the stiffness of prostate tissue, from two excised prostatectomy specimens in vitro, was analysed. The specimens were also subjected to morphometric measurements, and the sensor parameter was compared with the morphology of the tissue with linear regression. In the probe impression interval 0.5-1.7 mm, the maximum R(2) > or = 0.60 (p < 0.05, n = 75). An increase in the proportion of prostate stones (corpora amylacea), stroma, or cancer in relation to healthy glandular tissue increased the measured stiffness. Cancer and stroma had the greatest effect on the measured stiffness. The deeper the sensor was pressed, the greater, i.e., deeper, volume it sensed. Tissue sections deeper in the tissue were assigned a lower mathematical weighting than sections closer to the sensor probe. It is concluded that cancer increases the measured stiffness as compared with healthy glandular tissue, but areas with predominantly stroma or many stones could be more difficult to differ from cancer.

  • 24.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Urologi och andrologi.
    Lindahl, Olof A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Resonanssensorteknik för detektering av prostatacancer2010Ingår i: Medicinteknikdagarna 2010 / [ed] Ronnie Lundström, Umeå: Svensk förening för medicinsk teknik och fysik , 2010, s. 193-193Konferensbidrag (Refereegranskat)
  • 25.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Bergh, Anders
    Umeå universitet, Medicinsk fakultet, Medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinsk fakultet, Kirurgisk och perioperativ vetenskap.
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Spatial variations in prostate tissue histology as measured by a tactile resonance sensor2007Ingår i: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 28, nr 10, s. 1267-81Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In recent years, tactile sensors based on piezoelectric resonance sensor technology have been used for medical diagnosis where the sensor's stiffness-measuring properties can reflect tissue pathology. The change in the frequency of the resonating system and the change in force when contact is made with tissue are used as a stiffness parameter. Earlier stiffness measurements of prostate tissue in vitro demonstrate variations related to tissue composition. In this study, measured stiffness from two human prostate specimens was compared to histological composition of prostate tissue below and around the measurement points. Tissue stiffness was measured with the resonance sensor system. Tissue composition was measured at four different depths in the tissue specimen using a microscopic-image-based morphometrical method. With this method, the proportion of tissue types was determined at the points of intersections in a circular grid on the images representing each measurement point. Numerical values were used for weighting the tissue proportions at different depths in the tissue specimen. For an impression depth of 1.0 mm, the sensing depth in this study was estimated to be 3.5-5.5 mm. Stiffness variations due to horizontal tissue variations were investigated by studying the dependence of the size of the circular grid area relative to the contact area of the sensor tip. The sensing area (grid radius) was estimated to be larger than the contact area (contact radius) between the sensor tip and the tissue. Thus, the sensor tip registers spatial variations in prostate tissue histology, both directly below and lateral to the tip itself. These findings indicate that tumours around the sensor tip could be detected, which in turn supports the idea of a future resonance-sensor-based clinical device for detecting tumours and for guiding biopsies.

  • 26.
    Jonsson, Ulf G.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    A FEM-Based Method Using Harmonic Overtones to Determine the Effective Elastic, Dielectric, and Piezoelectric Parameters of Freely Vibrating Thick Piezoelectric Disks2013Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 60, nr 1, s. 243-255Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To gain an understanding of the electroelasticproperties of tactile piezoelectric sensors used in the characterizationof soft tissue, the frequency-dependent electric impedanceresponse of thick piezoelectric disks has been calculatedusing finite element modeling. To fit the calculated to the measuredresponse, a new method was developed using harmonicovertones for tuning of the calculated effective elastic, piezoelectric,and dielectric parameters. To validate the results, theimpedance responses of 10 piezoelectric disks with diameterto-thickness ratios of 20, 6, and 2 have been measured from10 kHz to 5 MHz. A two-dimensional, general purpose finiteelement partial differential equation solver with adaptive meshingcapability run in the frequency-stepped mode, was used.The equations and boundary conditions used by the solver arepresented. Calculated and measured impedance responses arepresented, and resonance frequencies have been compared indetail. The comparison shows excellent agreement, with averagerelative differences in frequency of 0.27%, 0.19%, and0.54% for the samples with diameter-to-thickness ratios of 20,6, and 2, respectively. The method of tuning the effective elastic,piezoelectric, and dielectric parameters is an importantstep toward a finite element model that describes the propertiesof tactile sensors in detail.

  • 27.
    Jonsson, Ulf
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lindahl, Olof
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Resonanssensorer för biologiska mätningar: Simulering av resonansspektra från en ansatt FEM-modell och motsvarande mätning av spektra hos piezoelektriska diskar - en jämförelse2010Konferensbidrag (Refereegranskat)
  • 28.
    Jonsson, Ulf G
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lindahl, Olof
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    A finite element model of soft tissue used in the investigation of the properties of piezoelectric tactile sensors2012Ingår i: Medicinteknikdagarna 2012, 2012Konferensbidrag (Refereegranskat)
  • 29.
    Jonsson, Ulf G
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Dept. of Engineering Sciences and Mathematics, Luleå University of Technology, Sweden.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Modeling the high-frequency complex modulus of a silicone rubber using standing lamb waves and an inverse finite element method2014Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 61, nr 12, s. 2106-2120Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To gain an understanding of the high-frequency elastic properties of silicone rubber, a finite element model of a cylindrical piezoelectric element, in contact with a silicone rubber disk, was constructed. The frequency dependent elastic modulus of the silicone rubber was modeled by a four parameter fractional derivative viscoelastic model in the 100 kHz to 250 kHz frequency range. The calculations were carried out in the range of the first radial resonance frequency of the sensor. At the resonance, the hyperelastic effect of the silicone rubber was modeled by a hyperelastic compensating function. The calculated response was matched to the measured response by using the transitional peaks in the impedance spectrum that originates from the switching of standing Lamb wave modes in the silicone rubber. To validate the results, the impedance responses of three 5 mm thick silicone rubber disks, with different radial lengths, were measured. The calculated and measured transitional frequencies have been compared in detail. The comparison showed very good agreement, with average relative differences of 0.7 %, 0.6 %, and 0.7 % for the silicone rubber samples with radial lengths of 38.0 mm, 21.4 mm, and 11.0 mm, respectively. The average, complex, elastic modulus of the samples were: (0.97 + 0.009i) GPa at 100 kHz and (0.97 + 0.005i) GPa at 250 kHz.

  • 30.
    Lindahl, Olof
    et al.
    Luleå tekniska universitet.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Karlsson, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Lundström, Ronnie
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Ramser, Kerstin
    Luleå tekniska universitet.
    Från forskningside till kommersiell produkt på marknaden: CMTF, ett framgångsexempel2009Ingår i: Medicinteknikdagarna 2009, Svensk förening för medicinsk teknik och fysik , 2009, s. 17-Konferensbidrag (Refereegranskat)
  • 31.
    Lindahl, Olof
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Luleå tekniska universitet.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lundström, Ronnie
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Hallberg, Josef
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Luleå tekniska universitet.
    A Triple-Helix model for refining biomedical engineering research into spin-off companies for the health care market2013Ingår i: World Congress on Medical Physics and Biomedical Engineering May 26-31, 2012, Beijing, China / [ed] Mian Long, Springer, 2013, s. 2088-2090Konferensbidrag (Refereegranskat)
    Abstract [en]

    Triple-Helix activities at the centre for biomedical engineering and physics (CMTF) have generated growth both in academia at the universities and in the industry in Northern Sweden. Cooperation was built up between the 26 research projects and about 15 established companies in the field of biomedical engineering. The established researcher - owned company for business development of the research results from the CMTF, CMTF Business Development Co Ltd, has so far launched one spin-off company and has 15 new business leads to business develop. The activities have also increased the interest for commercial and entrepreneurship questions among the scientists in the centre. So far a total of seven spin-off companies have resulted from the CMTF-research since the year 2000.

  • 32.
    Lindahl, Olof
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lundström, Ronnie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Hallberg, Josef
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    A tripple-helix model for refining biomedical engineering research into innovations and spin-off companies2012Ingår i: Medicinteknikdagarna 2012, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Triple-Helix activities within the center for biomedical engineering and physics (CMTF) have generated growth in academic research as well as industry in Northern Sweden in the field of biomedical engineering. Currently CMTF holds 26 ongoing research projects involving more than 150 researchers. So far a total of eight spin-off companies have resulted from research in CMTF since the year 2000. A researcher-owned company, CMTF Business Development Co Ltd, has been established for business development of the research results from the CMTF, which so far have launched two spin-off companies and 15 new business leads for business development. The activities have also increased the interest for innovations and entrepreneurship among the scientists in the center.

  • 33.
    Lindahl, Olof
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lundström, Ronnie
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Hallberg, Josef
    Luleå tekniska universitet.
    CMTF en forskningsorganisation med slutmålet att förädla resultaten till produkter på hälso- och sjukvårdsmarknaden2011Konferensbidrag (Refereegranskat)
  • 34.
    Lindahl, Olof
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lundström, Ronnie
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Hallberg, Josef
    Luleå tekniska universitet.
    Development of spin-off companies for health care from biomedical research results2011Ingår i: European Conference of the International Federation for Medical and Biological Engineering, 14-18 sept, 2011: vol. 5, Budapest, Ungern, 2011Konferensbidrag (Refereegranskat)
  • 35.
    Lindahl, Olof
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lundström, Ronnie
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Ramser, Kerstin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    From biomedical research to spin-off companies for the health care market2010Ingår i: The XII Mediterranean Conference on Medical and Biological Engineering and Computing: vol. 29, part 4, Springer, 2010, s. 624-626Konferensbidrag (Refereegranskat)
    Abstract [en]

    Through research at the centre for biomedical engineering and physics (CMTF) seven new companies have been established in Northern Sweden. The activities have generated growth both in academia at the universities and in the industry in Northern Sweden. Cooperation was built up between the 23 research projects and more than 20 established companies in the field of biomedical engineering. A researcher-owned company for business development of the research results from the CMTF has been established, CMTF Business Development Co Ltd, and has launched its first spin-off company in the autumn 2009. It has also increased the interest for commercial and entrepreneurship questions among the scientists in the centre. So far seven spin-off companies have resulted from the CMTF-research.

  • 36.
    Lindahl, Olof
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Ramser, Kerstin
    Luleå tekniska universitet.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    CMTF: en 10-årig triple-helix modell för medicinteknisk innovationsutveckling2010Konferensbidrag (Övrigt vetenskapligt)
  • 37.
    Lindberg, Peter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap.
    Lindahl, Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    An improved resonance sensor system for detecting cancerous tissue in the prostate2005Ingår i: Proceedings of 13th Nordic Baltic Conference on Biomedical Engineering and Medical Physics / [ed] Ronnie Lundström, Britt Andersson, Helena Grip, Swedish Society for Medical Engineering and Medical Physics , 2005, s. 132-133Konferensbidrag (Refereegranskat)
  • 38.
    Lindberg, Peter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap.
    Lindahl, Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Hardness measurements on prostate with an improved resonance sensor system2006Ingår i: World Congress on Biomedical Engineering and Medical Physics, August 27 - September 1, 2006, Seoul, Korea, IFMBE , 2006Konferensbidrag (Refereegranskat)
  • 39.
    Lindberg, Peter L
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Patologi.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Urologi och andrologi.
    Lindahl, Olof A
    Luleå tekniska Universitet.
    An image analysis method for prostate tissue classification: preliminary validation with resonance sensor data2009Ingår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 33, nr 1, s. 18-24Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Resonance sensor systems have been shown to be able to distinguish between cancerous and normal prostate tissue, in vitro. The aim of this study was to improve the accuracy of the tissue determination, to simplify the tissue classification process with computerized morphometrical analysis, to decrease the risk of human errors, and to reduce the processing time. In this article we present our newly developed computerized classification method based on image analysis. In relation to earlier resonance sensor studies we increased the number of normal prostate tissue classes into stroma, epithelial tissue, lumen and stones. The linearity between the impression depth and tissue classes was calculated using multiple linear regression (R(2) = 0.68, n = 109, p < 0.001) and partial least squares (R(2) = 0.55, n = 109, p < 0.001). Thus it can be concluded that there existed a linear relationship between the impression depth and the tissue classes. The new image analysis method was easy to handle and decreased the classification time by 80%.

  • 40. Niska, John
    et al.
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Easterling, Kenneth
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Loberg, Bengt
    Formation of the 124 phase superconductor (YBa2Cu4O8) by retaining oxygen in a reaction HIP sintering process1990Ingår i: Journal of materials science letters, ISSN 0261-8028, E-ISSN 1573-4811, Vol. 9, nr 7, s. 770-771Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ceramic superconductor YBa2Cu4O8 has been produced by high temperature sintering of a mixture of CuO and YBa2Cu3O7 in a glass capsule under high hydrostatic argon pressure. The resulting highly dense material is investigated by X-ray diffraction, optical and electron microscopy, resistance measurements and hardness measurements, and shown to be a homogeneous High transition temperature superconductor.

  • 41.
    Nitze, Florian
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ammonia assisted growth of multiwalled carbon nanotubes2009Ingår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 246, nr 11-12, s. 2440-2443Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bamboo structured nitrogen-containing carbon nanotubes are grown on e-beam deposited thin metal films (cobalt/iron) by chemical vapor deposition. The approach uses ammonia as supporting gas to form nano catalyst particles in the pretreatment phase. Ammonia is also used as nitrogen source. The effect of ammonia on the grown structures at different temperatures (720 and 810 °C) is investigated by SEM, TEM and Raman spectroscopy. We show that ammonia promotes growth of vertically aligned CNT carpets on thicker metal films (5 nm) than usually used. At the same time ammonia is inducing a high amount of defects but this effect changes significantly with temperature. At 720 °C defects are clearly ammonia induced while at 810 °C the defects seem to be induced by a different mechanism. Furthermore, the presence of ammonia in both pretreatment phase and growth phase reduces the outer diameter of the grown nanotubes.

  • 42.
    Nitze, Florian
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ammonia Induced CNT Growth on Metal Films2009Ingår i: Symposium K: Nanotubes and Related Nanostructures, 2009Konferensbidrag (Övrigt vetenskapligt)
  • 43.
    Norén, Niklas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap.
    Lindahl, Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Spring-damper model for prostate tissue2005Ingår i: 13th Nordic-Baltic conference on biomedical engineering and medical physics, IFMBE , 2005, s. 281-282Konferensbidrag (Refereegranskat)
  • 44.
    Ramstedt, Madeleine
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sjöberg, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Surface properties of hydrous manganite (-MnOOH): A potentiometric, electroacoustic, and x-ray photoelectron spectroscopy study2004Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 20, nr 19, s. 8224-8229Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The acid-base characteristics of the manganite (-MnOOH) surface have been studied at pH above 6, where dissolution is negligible. Synthetic microcrystalline particles of manganite were used in the experiments. From potentiometric titrations, electrophoretic mobility measurements, and X-ray photoelectron spectroscopy (XPS), a one pKa model was constructed that describes the observed behavior. The data show no ionic strength effect at pH < 8.2, which is the pH at the isoelectric point (pHiep), but ionic strength effects were visible above this pH. To explain these observations, Na+ ions were suggested to form a surface complex. The following equilibria were established: =MnOH2+1/2 =MnOH-1/2 + H+, log 0 (intr.) = -8.20; =MnOH2+1/2 + Na+ =MnOHNa+1/2 + H+, log 0 (intr.) = -9.64. The excess of Na+ at the surface was supported by XPS measurements of manganite suspensions containing 10 mM NaCl. The dielectric constant of synthetic manganite powder was also determined in this study.

  • 45.
    Shirdel, Mariam
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Liljelind, Ingrid
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Nilsson Sommar, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Håkan, Wingfors
    Totalförsvarets forskningsinstitut, FOI.
    Bergdahl, Ingvar A
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Should one really use wind tunnel experiments for a passive sampler?2017Konferensbidrag (Övrigt vetenskapligt)
  • 46.
    Shirdel, Mariam
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Bergdahl, Ingvar
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Sommar, Johan N.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Wingfors, Håkan
    CBRN Defence & Security Division, Swedish Defence Research Agency, Umeå, Sweden.
    Liljelind, Ingrid E.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Improving the UNC passive aerosol sampler model based on comparison with commonly used aerosol sampling methods2018Ingår i: Annals of Work Exposures and Health, ISSN 2398-7308, Vol. 62, nr 3, s. 328-338Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objectives: In an occupational environment, passive sampling could be an alternative to active sampling with pumps for sampling of dust. One passive sampler is the University of North Carolina passive aerosol sampler (UNC sampler). It is often analysed by microscopic imaging. Promising results have been shown for particles above 2.5 µm, but indicate large underestimations for PM2.5. The aim of this study was to evaluate, and possibly improve, the UNC sampler for stationary sampling in a working environment.

    Methods: Sampling was carried out at 8-h intervals during 24 h in four locations in an open pit mine with UNC samplers, respirable cyclones, PM10 and PM2.5 impactors, and an aerodynamic particle sizer (APS). The wind was minimal. For quantification, two modifications of the UNC sampler analysis model, UNC sampler with hybrid model and UNC sampler with area factor, were compared with the original one, UNC sampler with mesh factor derived from wind tunnel experiments. The effect of increased resolution for the microscopic imaging was examined.

    Results: Use of the area factor and a higher resolution eliminated the underestimation for PM10 and PM2.5. The model with area factor had the overall lowest deviation versus the impactor and the cyclone. The intraclass correlation (ICC) showed that the UNC sampler had a higher precision and better ability to distinguish between different exposure levels compared to the cyclone (ICC: 0.51 versus 0.24), but lower precision compared to the impactor (PM10: 0.79 versus 0.99; PM2.5: 0.30 versus 0.45). The particle size distributions as calculated from the different UNC sampler analysis models were visually compared with the distributions determined by APS. The distributions were obviously different when the UNC sampler with mesh factor was used but came to a reasonable agreement when the area factor was used.

    Conclusions: High resolution combined with a factor based on area only, results in no underestimation of small particles compared to impactors and cyclones and a better agreement with the APS’s particle size distributions. The UNC sampler had lower precision than the impactors, but higher than the respirable cyclone. The UNC sampler with area factor could be used for PM2.5, PM10 and respirable fraction measurements in this working environment without wind.

  • 47.
    Shirdel, Mariam
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Bergdahl A., Ingvar
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Wingfors, Håkan
    Swedish Defence Research Agency, CBRN Defence & Security Division, Umeå, Sweden.
    Sommar, Johan N.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Liljelind, Ingrid E.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Passive personal air sampling of dust in a working environment: A pilot study2019Ingår i: Journal of Occupational and Environmental Hygiene, ISSN 1545-9624, E-ISSN 1545-9632, Vol. 16, nr 10, s. 675-684Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study was to make a preliminary evaluation of the University of North Carolina passive aerosol sampler (UNC sampler) for personal air sampling of particles. Nine personal air samplings of respirable fraction were conducted in an open-pit mine, with pairwise UNC samplers and a respirable cyclone mounted on the chest of workers. UNC samples were analyzed with scanning electron microscopy (SEM) and to some extent energy dispersive X-ray spectroscopy (EDS). Respirable cyclone filter samples were weighed. Correlations and particle elemental compositions were described. Microscopic imaging of the collection surface showed that the particles were heterogeneously deposited across the surface of the UNC sampler. Collected particles were shaped as gravel particles and the resulting particle size distribution in air showed a peak at ca. 3 µm aerodynamic diameter, similarly to what has previously been reported from the same mine. The elemental composition indicated mineral origin. All correlations between the airborne mass concentrations from UNC samplers and respirable cyclones (Pearson = 0.54 and Spearman = 0.43) and between pairs of parallel UNC samplers (Pearson = 0.55 and Spearman = 0.67) were weak. The UNC sampler mass concentrations were approximately 30 times higher than those measured with the respirable cyclone. In conclusion, the UNC sampler, when used for personal sampling in a mine, provides a reasonable particle size distribution and the deposited particles appeared to be of mineral origin and not from textile or skin but the approximately 30-fold overestimation of mass concentrations when comparing with respirable cyclone sampling indicates that further improvements are necessary. Positioning of the sampler may be critical and moving the UNC sampler from the chest to e.g. the top of a helmet might be an improvement. Grounding of the sampler in order to avoid static electricity might also be useful. The UNC sampler should continue to be researched for personal sampling, as passive sampling might become a useful alternative to more laborious sampling techniques.

  • 48.
    Shirdel, Mariam
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Bergdahl, Ingvar A.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Wingfors, Håkan
    Sommar, Johan N.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Liljelind, Ingrid E.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Passive personal sampling of dust in a working environment: a first studyManuskript (preprint) (Övrigt vetenskapligt)
  • 49.
    Shirdel, Mariam
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Håkan, Wingfors
    Totalförsvarets forskningsinstitut, FOI.
    Andersson, Britt