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Quantitative, high-sensitivity measurement of liquid analytes using a smartphone compass

Published

Author(s)

Mark Ferris, Gary Zabow

Abstract

Smartphone ubiquity has led to rapid developments in portable diagnostics. While successful, such platforms are predominantly optics-based, using the smartphone camera as the sensing interface. By contrast, magnetics-based modalities exploiting the smartphone compass (magnetometer) remain unexplored, despite inherent advantages in optically opaque, scattering or auto-fluorescing samples. Here we report smartphone analyte sensing utilizing the built-in magnetometer for signal transduction via analyte-responsive magnetic-hydrogel composites. As these hydrogels dilate in response to targeted stimuli, they displace attached magnetic material relative to the phone's magnetometer. Using a bilayer hydrogel geometry to amplify this motion allows for sensitive, optics-free, quantitative liquid-based analyte measurements that require neither any electronics nor power beyond that contained within the smartphone itself. We demonstrate this concept with glucose-specific and pH-responsive hydrogels, including glucose detection down to single-digit micromolar concentrations with potential for extension to nanomolar sensitivities. The platform is adaptable to numerous measurands, opening a path towards portable, inexpensive sensing of multiple analytes or biomarkers of interest.
Citation
Nature Communications
Volume
15

Keywords

Smartphone, hydrogel, smart materials, magnetic sensing, diagnostics

Citation

Ferris, M. and Zabow, G. (2024), Quantitative, high-sensitivity measurement of liquid analytes using a smartphone compass, Nature Communications, [online], https://doi.org/10.1038/s41467-024-47073-2, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956278 (Accessed April 14, 2024)
Created April 2, 2024, Updated April 1, 2024