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Published December 10, 2013 | Supplemental Material
Journal Article Open

A handheld magnetic sensing platform for antigen and nucleic acid detection


The core requirements for point-of-care (POC) diagnostics necessitate low-cost, portability, easily integrated sample preparation, and quick measurement time. Frequency-shift based magnetic sensing is a measurement technique utilizing a complementary metal-oxide-semiconductor (CMOS) integrated-circuit (IC) chip for magnetic label detection. The sensing scheme leverages the low-cost manufacturing of IC chips while demonstrating the potential for multiplexing capabilities. In this article, we present modifications to this scheme for POC viability. We introduce a handheld reusable reader and a disposable open-well cartridge for the detection of nucleic acids and antigens. The diagnostic system utilizes a novel "magnetic freezing" technique to reduce measurement time, obviates baseline measurement before or during biological assay, and reduces sensor noise. We utilize these enhancements for the room temperature, amplification-free detection of a 31 base-pair DNA oligomer and the interferon-γ (IFN-γ) protein. We have demonstrated reliable measurements down to 100 pM for the DNA assay and 1 pM for the protein.

Additional Information

© 2014 The Royal Society of Chemistry. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Received 16th October 2013, Accepted 10th December 2013. First published online 10 Dec 2013. This research was supported by the Caltech CI2 and City of Hope grants. The authors would like to acknowledge Stephanie Johnson and Rob Phillips for their help in aiding DNA attachment chemistry; Habib Ahmad, Alex Sutherland and James Heath for guidance and tools in developing surface chemistry; and Derek Rinderknecht and Morteza Gharib for providing high power microscopes.

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August 19, 2023
August 19, 2023