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Dahlberg, Tobias
Alternative names
Publications (5 of 5) Show all publications
Dahlberg, T., Malyshev, D., Andersson, P. O. & Andersson, M. (2020). Biophysical Fingerprinting of Single Bacterial Spores using Laser Raman Optical Tweezers. In: Proceedings Volume 11416, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XXI, 2020: . Paper presented at SPIE Defense + Commercial Sensing, 2020, Online Only, California, United States, April 27, 2020.. SPIE - International Society for Optical Engineering, Article ID 1141601.
Open this publication in new window or tab >>Biophysical Fingerprinting of Single Bacterial Spores using Laser Raman Optical Tweezers
2020 (English)In: Proceedings Volume 11416, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XXI, 2020, SPIE - International Society for Optical Engineering, 2020, article id 1141601Conference paper, Published paper (Refereed)
Abstract [en]

Spore-forming bacteria that cause diseases pose a danger in our society. When in spore form, bacteria can survive high temperatures and resist a plethora of disinfection chemicals. Effective disinfection approaches are thus critical. Since a population of bacterial spores is heterogeneous in many aspects, single spore analyzing methods are suitable when heterogeneous information cannot be neglected. We present in this work a highresolution Laser Raman optical tweezers that can trap single spores and characterize their Raman spectra. We first evaluate our system by measuring Raman spectra of spores, and purified DNA and DPA. Thereafter, we expose Bacillus thuringiensis spores to peracetic acid, chlorine dioxide, and sodium hypochlorite, which are common disinfection chemicals. The data reveals how these agents change the constitutes of a spore over time, thus improving on the mode of action of these disinfection chemicals.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2020
National Category
Atom and Molecular Physics and Optics Biophysics
Identifiers
urn:nbn:se:umu:diva-170121 (URN)10.1117/12.2558102 (DOI)
Conference
SPIE Defense + Commercial Sensing, 2020, Online Only, California, United States, April 27, 2020.
Available from: 2020-04-27 Created: 2020-04-27 Last updated: 2020-04-29Bibliographically approved
Dahlberg, T., Stangner, T., Hanqing, Z., Wiklund, K., Lundberg, P., Edman, L. & Andersson, M. (2018). 3D printed water-soluble scaffolds for rapid production of PDMS micro-fluidic flow chambers. Scientific Reports, 8(1), Article ID 3372.
Open this publication in new window or tab >>3D printed water-soluble scaffolds for rapid production of PDMS micro-fluidic flow chambers
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2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, no 1, article id 3372Article in journal (Refereed) Published
Abstract [en]

We report a novel method for fabrication of three-dimensional (3D) biocompatible micro-fluidic flow chambers in polydimethylsiloxane (PDMS) by 3D-printing water-soluble polyvinyl alcohol (PVA) filaments as master scaffolds. The scaffolds are first embedded in the PDMS and later residue-free dissolved in water leaving an inscription of the scaffolds in the hardened PDMS. We demonstrate the strength of our method using a regular, cheap 3D printer, and evaluate the inscription process and the channels micro-fluidic properties using image analysis and digital holographic microscopy. Furthermore, we provide a protocol that allows for direct printing on coverslips and we show that flow chambers with a channel cross section down to 40 x 300 μm can be realized within 60 min. These flow channels are perfectly transparent, biocompatible and can be used for microscopic applications without further treatment. Our proposed protocols facilitate an easy, fast and adaptable production of micro-fluidic channel designs that are cost-effective, do not require specialized training and can be used for a variety of cell and bacterial assays. To help readers reproduce our micro-fluidic devices, we provide: full preparation protocols, 3D-printing CAD files for channel scaffolds and our custom-made molding device, 3D printer build-plate leveling instructions, and G-code.

Place, publisher, year, edition, pages
Nature Publishing Group, 2018
National Category
Other Materials Engineering Other Engineering and Technologies not elsewhere specified Other Physics Topics
Identifiers
urn:nbn:se:umu:diva-144631 (URN)10.1038/s41598-018-21638-w (DOI)000425500300044 ()
Funder
Swedish Research Council, 2013-5379The Kempe Foundations, JCK-1622
Available from: 2018-02-08 Created: 2018-02-08 Last updated: 2018-08-16Bibliographically approved
Stangner, T., Dahlberg, T., Svenmarker, P., Zakrisson, J., Wiklund, K., Oddershede, L. B. & Andersson, M. (2018). Cooke-Triplet-Tweezers: More compact, robust and efficient optical tweezers. Optics Letters, 43(9), 1990-1993
Open this publication in new window or tab >>Cooke-Triplet-Tweezers: More compact, robust and efficient optical tweezers
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2018 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 43, no 9, p. 1990-1993Article in journal (Refereed) Published
Abstract [en]

We present a versatile three-lens optical design to improve the overall compactness, efficiency, and robustness for optical tweezers based applications. The design, inspired by the Cooke–Triplet configuration, allows for continuous beam magnifications of 2–10× , and axial as well as lateral focal shifts can be realized without switching lenses or introducing optical aberrations. We quantify the beam quality and trapping stiffness and compare the Cooke–Triplet design with the commonly used double Kepler design through simulations and direct experiments. Optical trapping of 1 and 2 μm beads shows that the Cooke–Triplet possesses an equally strong optical trap stiffness compared to the double Kepler lens design but reduces its lens system length by a factor of 2.6. Finally, we demonstrate how a Twyman–Green interferometer integrated in the Cooke–Triplet optical tweezers setup provides a fast and simple method to characterize the wavefront aberrations in the lens system and how it can help in aligning the optical components perfectly.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-145899 (URN)10.1364/OL.43.001990 (DOI)000431179400013 ()29714728 (PubMedID)
Available from: 2018-03-21 Created: 2018-03-21 Last updated: 2018-06-09Bibliographically approved
Stangner, T., Hanqing, Z., Tobias, D., Krister, W. & Andersson, M. (2017). Step-by-step guide to reduce spatial coherence of laser light using a rotating ground glass diffuser. Applied Optics, 56(19), 5427-5435
Open this publication in new window or tab >>Step-by-step guide to reduce spatial coherence of laser light using a rotating ground glass diffuser
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2017 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 56, no 19, p. 5427-5435Article in journal (Refereed) Published
Abstract [en]

Wide field-of-view imaging of fast processes in a microscope requires high light intensities motivating the use of lasers as light sources. However, due to their long spatial coherence length, lasers are inappropriate for such applications, as they produce coherent noise and parasitic reflections, such as speckle, degrading image quality. Therefore, we provide a step-by-step guide for constructing a speckle-free and high-contrast laser illumination setup using a rotating ground glass diffuser driven by a stepper motor. The setup is easy to build, cheap, and allows a significant light throughput of 48%, which is 40% higher in comparison to a single lens collector commonly used in reported setups. This is achieved by using only one objective to collect the scattered light from the ground glass diffuser. We validate our setup in terms of image quality, speckle contrast, motor-induced vibrations, and light throughput. To highlight the latter, we record Brownian motion of micro-particles using a 100x oil immersion objective and a high-speed camera operating at 2000 Hz with a laser output power of only 22 mW. Moreover, by reducing the objective magnification to 50x, sampling rates up to 10,000 Hz are realized. To help readers with basic or advanced optics knowledge realize this setup, we provide a full component list, 3D-printing CAD files, setup protocol, and the code for running the stepper motor.

Place, publisher, year, edition, pages
Optical Society of America, 2017
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-135625 (URN)10.1364/AO.56.005427 (DOI)000404745800041 ()
Available from: 2017-06-01 Created: 2017-06-01 Last updated: 2018-08-15Bibliographically approved
Enevold, J., Dahlberg, T., Stangner, T., Tang, S., Lindh, E. M., Gracia-Espino, E., . . . Edman, L.Tunable two-dimensional patterning of a semiconducting C60 fullerene film using a spatial light modulator.
Open this publication in new window or tab >>Tunable two-dimensional patterning of a semiconducting C60 fullerene film using a spatial light modulator
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(English)Manuscript (preprint) (Other academic)
National Category
Other Physics Topics
Identifiers
urn:nbn:se:umu:diva-166406 (URN)
Available from: 2019-12-16 Created: 2019-12-16 Last updated: 2019-12-18
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