Self-Powered, Paper-Based Electrochemical Devices for Sensitive Point-of-Care Testing

This work describes the fabrication of self-powered, paper-based electrochemical devices (SPEDs) designed for sensitive diagnostics in low-resource settings and at the point of care. SPEDs are inexpensive, lightweight, mechanically flexible, easy to use, and disposable by burning. The top layer of the SPED is fabricated using cellulose paper with patterned hydrophobic domains that delineate hydrophilic, wicking-based microfluidic channels for accurate colorimetric assays, and self-pipetting test zones for electrochemical detection. The bottom layer of the SPED is a triboelectric generator (TEG) fabricated on hydrophobic paper and capable of harvesting electric energy from the user's interaction with the SPED. An inexpensive and rechargeable handheld potentiostat is fabricated to interface with the SPED, enabling the accurate quantitative electrochemical detection of glucose, uric acid, and l-lactate. The battery powering the potentiostat can be recharged by the user, using the sequential discharge of a capacitor previously charged with the TEG built into the SPED. A machine-vision diagnostic application is created to automatically identify and quantify each of the colorimetric tests from a digital image of the SPED, taken under a wide range of ambient light conditions, in order to provide fast diagnostic results to the user as well as to facilitate remote expert consultation.