Design Framework and Sensing System for Noninvasive Wearable Electroactive Drug Monitoring

Wearable drug monitoring targeting epidermally retrievable biofluids (e.g., sweat) can enable a variety of applications, including drug compliance/abuse monitoring and personalized therapeutic drug dosing. In that regard, voltammetry-based approaches are suitable because they uniquely leverage the electroactive nature of target drug molecules for quantification, eliminating the reliance on the availability of recognition elements. However, to adapt such approaches for the envisioned application, three main challenges must be addressed: (1) constructing a sensitive voltammetric sensing interface with high signal-to-background ratio, (2) decoupling the confounding effect of endogenous electroactive species (naturally present in complex biofluid matrices) and baseline variation, and (3) realizing wireless voltammetric excitation and signal acquisition/transmission. To this end, first, a framework for the quantification of electroactive drugs is presented, which centers on the evaluation and determination of suitable sensing electrodes and characterization of the interference from a panel of physiologically relevant electroactive species. This framework was utilized to establish the design space and operational settings for the development of a coupled sensing system and analytical framework to render sample-to-answer drug readouts in complex biofluid matrices. The presented design framework and sensing system can serve as a basis for future wearable sensor development efforts aiming to monitor electroactive species such as pharmaceutical molecules.