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Publications (5 of 5) Show all publications
Valijam, S., Nilsson, D., Öberg, R., Albertsdóttir Jonsmoen, U. L., Porch, A., Andersson, M. & Malyshev, D. (2023). A lab-on-a-chip utilizing microwaves for bacterial spore disruption and detection. Biosensors & bioelectronics, 231, Article ID 115284.
Open this publication in new window or tab >>A lab-on-a-chip utilizing microwaves for bacterial spore disruption and detection
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2023 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 231, article id 115284Article in journal (Refereed) Published
Abstract [en]

Bacterial spores are problematic in agriculture, the food industry, and healthcare, with the fallout costs from spore-related contamination being very high. Spores are difficult to detect since they are resistant to many of the bacterial disruption techniques used to bring out the biomarkers necessary for detection. Because of this, effective and practical spore disruption methods are desirable. In this study, we demonstrate the efficiency of a compact microfluidic lab-on-chip built around a coplanar waveguide (CPW) operating at 2.45 GHz. We show that the CPW generates an electric field hotspot of ∼10 kV/m, comparable to that of a commercial microwave oven, while using only 1.2 W of input power and thus resulting in negligible sample heating. Spores passing through the microfluidic channel are disrupted by the electric field and release calcium dipicolic acid (CaDPA), a biomarker molecule present alongside DNA in the spore core. We show that it is possible to detect this disruption in a bulk spore suspension using fluorescence spectroscopy. We then use laser tweezers Raman spectroscopy (LTRS) to show the loss of CaDPA on an individual spore level and that the loss increases with irradiation power. Only 22% of the spores contain CaDPA after exposure to 1.2 W input power, compared to 71% of the untreated control spores. Additionally, spores exposed to microwaves appear visibly disrupted when imaged using scanning electron microscopy (SEM). Overall, this study shows the advantages of using a CPW for disrupting spores for biomarker release and detection.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Raman spectroscopy, Fluorescence sep CaDPA, Waveguide, Biomarker, Bacillus
National Category
Other Physics Topics Other Electrical Engineering, Electronic Engineering, Information Engineering Biophysics
Identifiers
urn:nbn:se:umu:diva-206257 (URN)10.1016/j.bios.2023.115284 (DOI)000980707400001 ()37031508 (PubMedID)2-s2.0-85151660389 (Scopus ID)
Funder
Swedish Research Council, 2019-04016Swedish Foundation for Strategic ResearchThe Kempe Foundations, JCK-1916.2Swedish Armed Forces, 470-A400821
Available from: 2023-04-01 Created: 2023-04-01 Last updated: 2023-09-05Bibliographically approved
Valijam, S., Nilsson, D. P. G., Malyshev, D., Öberg, R., Salehi, A. & Andersson, M. (2023). Fabricating a dielectrophoretic microfluidic device using 3D-printed moulds and silver conductive paint. Scientific Reports, 13(1), Article ID 9560.
Open this publication in new window or tab >>Fabricating a dielectrophoretic microfluidic device using 3D-printed moulds and silver conductive paint
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2023 (English)In: Scientific Reports, E-ISSN 2045-2322, Vol. 13, no 1, article id 9560Article in journal (Refereed) Published
Abstract [en]

Dielectrophoresis is an electric field-based technique for moving neutral particles through a fluid. When used for particle separation, dielectrophoresis has many advantages compared to other methods, like providing label-free operation with greater control of the separation forces. In this paper, we design, build, and test a low-voltage dielectrophoretic device using a 3D printing approach. This lab-on-a-chip device fits on a microscope glass slide and incorporates microfluidic channels for particle separation. First, we use multiphysics simulations to evaluate the separation efficiency of the prospective device and guide the design process. Second, we fabricate the device in PDMS (polydimethylsiloxane) by using 3D-printed moulds that contain patterns of the channels and electrodes. The imprint of the electrodes is then filled with silver conductive paint, making a 9-pole comb electrode. Lastly, we evaluate the separation efficiency of our device by introducing a mixture of 3 μm and 10 μm polystyrene particles and tracking their progression. Our device is able to efficiently separate these particles when the electrodes are energized with ±12 V at 75 kHz. Overall, our method allows the fabrication of cheap and effective dielectrophoretic microfluidic devices using commercial off-the-shelf equipment.

Place, publisher, year, edition, pages
Springer Nature, 2023
National Category
Fluid Mechanics and Acoustics Analytical Chemistry Other Physics Topics
Identifiers
urn:nbn:se:umu:diva-209721 (URN)10.1038/s41598-023-36502-9 (DOI)37308526 (PubMedID)2-s2.0-85161909317 (Scopus ID)
Funder
Swedish Research Council, 2019-04016Swedish Foundation for Strategic ResearchThe Kempe Foundations, JCK-1916.2
Available from: 2023-06-13 Created: 2023-06-13 Last updated: 2023-06-26Bibliographically approved
Nilsson, D. P. .., Jonsmoen, U. L., Malyshev, D., Öberg, R., Wiklund, K. & Andersson, M. (2023). Physico-chemical characterization of single bacteria and spores using optical tweezers. Research in Microbiology, 174(6), Article ID 104060.
Open this publication in new window or tab >>Physico-chemical characterization of single bacteria and spores using optical tweezers
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2023 (English)In: Research in Microbiology, ISSN 0923-2508, E-ISSN 1769-7123, Vol. 174, no 6, article id 104060Article in journal (Refereed) Published
Abstract [en]

Spore-forming pathogenic bacteria are adapted for adhering to surfaces, and their endospores can tolerate strong chemicals making decontamination difficult. Understanding the physico-chemical properties of bacteria and spores is therefore essential in developing antiadhesive surfaces and disinfection techniques. However, measuring physico-chemical properties in bulk does not show the heterogeneity between cells. Characterizing bacteria on a single-cell level can thereby provide mechanistic clues usually hidden in bulk measurements. This paper shows how optical tweezers can be applied to characterize single bacteria and spores, and how physico-chemical properties related to adhesion, fluid dynamics, biochemistry, and metabolic activity can be assessed.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
endospores, Raman spectroscopy, metabolic activity, adhesion, pili, CaDPA
National Category
Biophysics Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-208300 (URN)10.1016/j.resmic.2023.104060 (DOI)37068697 (PubMedID)2-s2.0-85166663908 (Scopus ID)
Available from: 2023-05-17 Created: 2023-05-17 Last updated: 2023-08-16Bibliographically approved
Nilsson, D., Holmgren, M., Holmlund, P., Wåhlin, A., Eklund, A., Dahlberg, T., . . . Andersson, M. (2022). Patient-specific brain arteries molded as a flexible phantom model using 3D printed water-soluble resin. Scientific Reports, 12, Article ID 10172.
Open this publication in new window or tab >>Patient-specific brain arteries molded as a flexible phantom model using 3D printed water-soluble resin
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2022 (English)In: Scientific Reports, E-ISSN 2045-2322, Vol. 12, article id 10172Article in journal (Refereed) Published
Abstract [en]

Visualizing medical images from patients as physical 3D models (phantom models) have many roles in the medical field, from education to preclinical preparation and clinical research. However, current phantom models are generally generic, expensive, and time-consuming to fabricate. Thus, there is a need for a cost- and time-efficient pipeline from medical imaging to patient-specific phantom models. In this work, we present a method for creating complex 3D sacrificial molds using an off-the-shelf water-soluble resin and a low-cost desktop 3D printer. This enables us to recreate parts of the cerebral arterial tree as a full-scale phantom model (10×6×410×6×4 cm) in transparent silicone rubber (polydimethylsiloxane, PDMS) from computed tomography angiography images (CTA). We analyzed the model with magnetic resonance imaging (MRI) and compared it with the patient data. The results show good agreement and smooth surfaces for the arteries. We also evaluate our method by looking at its capability to reproduce 1 mm channels and sharp corners. We found that round shapes are well reproduced, whereas sharp features show some divergence. Our method can fabricate a patient-specific phantom model with less than 2 h of total labor time and at a low fabrication cost.

Place, publisher, year, edition, pages
Nature Publishing Group, 2022
National Category
Orthopaedics Other Physics Topics Medical Image Processing Other Medical Engineering
Identifiers
urn:nbn:se:umu:diva-195731 (URN)10.1038/s41598-022-14279-7 (DOI)000812565400068 ()2-s2.0-85132118240 (Scopus ID)
Funder
Swedish Research Council, 2019-04016
Available from: 2022-06-03 Created: 2022-06-03 Last updated: 2023-09-05Bibliographically approved
Nilsson, D. P. G., Dahlberg, T. & Andersson, M. (2021). Step-by-Step Guide to 3D Print Motorized Rotation Mounts for Optical Applications. Applied Optics, 60(13), 3764-3771
Open this publication in new window or tab >>Step-by-Step Guide to 3D Print Motorized Rotation Mounts for Optical Applications
2021 (English)In: Applied Optics, ISSN 0003-6935, E-ISSN 1539-4522, Vol. 60, no 13, p. 3764-3771Article in journal (Refereed) Published
Abstract [en]

Motorized rotation mounts and stages are versatile instruments that introduce computer control to optical systems, enabling automation and scanning actions. They can be used for intensity control and position adjustments, etc. However, these rotation mounts come with a hefty price tag, and this limits their use. This work shows how to build two different types of motorized rotation mounts for 1" optics, using a 3D printer and off-the-shelf components. The first is intended for reflective elements, like mirrors and gratings, and the second for transmissive elements, like polarizers and retarders. We evaluate and compare their performance to commercial systems based on velocity, resolution, precision, backlash, and axis wobble. Also, we investigate the angular stability using Allan variance analysis. The results show that our mounts perform similar to systems costing more than 2000 Euro, while also being quick to build and costing less than 200 Euro. As a proof of concept, we show how to control lasers used in an optical tweezers and Raman spectroscopy setup. When used for this, the 3D printed motorized rotational mounts provide intensity control with a resolution of 0.03 percentage points or better.

Place, publisher, year, edition, pages
Optical Society of America, 2021
National Category
Other Physics Topics Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:umu:diva-181868 (URN)10.1364/AO.422695 (DOI)000645865100027 ()2-s2.0-85105102116 (Scopus ID)
Available from: 2021-03-30 Created: 2021-03-30 Last updated: 2023-09-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1303-0327

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