Development and Field Validation of an End-User Photo-Thermal Device for Accurate Detection and Quantification of Analytes in Fluidic Samples

While paper-based rapid tests are abundantly used in medicine, their performance is limited by the poor limit of detection and binary response of the test. We have previously shown that interpreting rapid tests based on laser-induced photothermal responses can offer over an order magnitude improvement in test performance. This work reports on miniaturization of our photothermal sensing paradigm in a low-cost handheld device and its field validations. The hand-held device excites assay gold nanoparticles with a modulated, low-power LED while recording their thermal wave responses with low-cost single-element sensors. An Arduino-based processor demodulates thermal wave responses while offering internet-of-things capability. Results from a human study on detection and quantification of Cannabis consumption will also be presented and discussed.