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A lab-on-a-chip utilizing microwaves for bacterial spore disruption and detection

Valijam, Shayan, Nilsson, Daniel P.G., Öberg, Rasmus, Albertsdóttir Jonsmoen, Unni Lise, Porch, Adrian ORCID:, Andersson, Magnus and Malyshev, Dmitry 2023. A lab-on-a-chip utilizing microwaves for bacterial spore disruption and detection. Biosensors and Bioelectronics 231 , 115284. 10.1016/j.bios.2023.115284

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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.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Engineering
Additional Information: License information from Publisher: LICENSE 1: URL:, Start Date: 2023-04-02
Publisher: Elsevier
ISSN: 0956-5663
Date of First Compliant Deposit: 3 April 2023
Date of Acceptance: 28 March 2023
Last Modified: 04 May 2023 07:25

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