(Invited) Electrochemically Tunable Sensors for Passive Sweat Analytics and Its Applications for Wearable Technologies

Wearable electronic monitors hold great promise in helping people to reach their health goals. These increasingly sophisticated devices help the wearers improve their wellness by constantly monitoring their activities and bodily responses. While consumer wearables could be more useful for patients with conditions like diabetes or cardiac problems, current solutions are still in the early stages of development. Wearable devices hold the potential to transform some industries most importantly the health care industry. This talk will focus on designing the sensor building block towards achieving passive eccrine diagnostics. In this talk I will present a device for monitoring cortisol levels in a non-invasive manner from passively expressed human sweat. Noninvasive biosensing is achieved through the modulation of the sweat/electrode interface through a combination of inorganic and organic surface engineering towards achieving electrochemical double layer modulated sensors. There is currently a small selection of portable or point-of-care diagnostic tools for detection of cortisol. Electroanalytical techniques are desired over other transduction methods due to increased accuracy and sensitivity with minimal instrumentation that utilize low power sources. The resulting electrochemical signal can be easily and reliably analyzed lending itself to a wearable form factor that is relevant for the presented applications. The use of portable electroanalytical techniques in sweat-based wearables ranging from amperometry, cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy (EIS) has been investigated with increased interest in recent years. Outside of our group, most efforts have been to monitor the general physiology of the user through measuring analytes such as sodium, zinc, ammonium, lactate, glucose, ethanol, or pH. For this work, non-faradaic EIS was targeted for its ability as a label-free method for rapid and highly specific affinity-based detection of target molecules. This can be accomplished by measuring effective changes in the resistive and capacitive behaviors of the sensor due to specific binding events of the specific biomarker, in this case; cortisol onto a transduction element to quantify cortisol levels present in low volumes of human sweat. Figure 1