Fabrication of solid state electrodes for use in noninvasive sweat sensor

Abstract

Healthcare for a wide variety of illnesses ultimately requires some form of bloodwork, which can often be painful or stressful. Conversely, human sweat contains biomarkers that can indicate a patient’s current glucose levels and pH, making it a potential tool in monitoring many illnesses that previously could not be studied noninvasively. Developing an affordable sensor that can effectively measure human sweat for these biomarkers begins with finding a way to develop a Solid State Electrode (SSE) pairing that can compete with commercially available electrodes. Pairs of silver and platinum wires were used to construct an Ag/AgCl reference electrode (RE) and Pt/IrOx working electrode (WE), through a series of coatings and/or electroplating. Each pair was then submerged in varying pH solutions (pH 4-10) at 2 minute intervals, while being measured for voltage over time. A commercially available sensor was used as the control trial. Following these initial tests, the RE was subjected to a salt bridge coating to increase the stability of the electrode’s voltage, as well as its longevity. These new RE’s were placed in a pH 7 solution for 24 hours to measure their stability and longevity, before a second wave of pH tests were performed alongside a new batch of WE’s. The results collected thus far indicate that the fabrication of accurate SSE’s that function for an adequate amount of time at affordable costs is possible. Notably, the trials that featured the salt-bridge RE’s were more in-line with the commercial sensor’s results, indicating a greater degree of accuracy. A larger facility with better equipment should be able to produce the same quality of work at higher quantities, where they can begin to integrate the SSE’s into a full sensory device.