A Multi-Technique Reconfigurable Electrochemical Biosensor: Enabling Personal Health Monitoring in Mobile Devices

This paper describes the design and characterization of a reconfigurable, multi-technique electrochemical biosensor designed for direct integration into smartphone and wearable technologies to enable remote and accurate personal health monitoring. By repurposing components from one mode to the next, the biosensor's potentiostat is able reconfigure itself into three different measurements modes to perform amperometric, potentiometric, and impedance spectroscopic tests all with minimal redundant devices. A 3.9 × 1.65 cm2 PCB prototype of the module was developed with discrete components and tested using Google's Project Ara modular smartphone. The amperometric mode has a ±1 nA to ±200 μA measurement range. When used to detect pH, the potentiometric mode achieves a resolution of <; 0.08 pH units. In impedance measurement mode, the device can measure 50 Ω-10 MΩ and has been shown to have <; 6° of phase error. This prototype was used to perform several point-of-care health tracking assays suitable for use with mobile devices: 1) Blood glucose tests were conducted and shown to cover the diagnostic range for Diabetic patients (~200 mg/dL). 2) Lactoferrin, a biomarker for urinary tract infections, was detected with a limit of detection of approximately 1 ng/mL. 3) pH tests of sweat were conducted to track dehydration during exercise. 4) EIS was used to determine the concentration of NeutrAvidin via a label-free assay.