Figure 4.6.

A thin-film, wearable diabetes monitoring and therapeutic delivery system. The system monitors the pH and glucose levels in sweat, and enables transcutaneous drug delivery using a bioabsorbable, thermoresponsive microneedle patch. (a, b) The skin-mounted graphene-hybrid electrochemical device array is connected to a portable electrochemical analyzer via Bluetooth. (c) Relative humidity measurement data from the device. (d) Example pH variation between two human subjects, and (e) consistent glucose concentrations of sweat vs. blood. (f, g) Before and after correction using the measured pH, and sensitivity after multiple reuses. (h) Microneedle illustration. (i) Drug release via microneedle patch as a function of temperature and (j) stepwise drug release. (k) Photograph illustrating the stepwise microneedle dissolution. (l) Heater integrated with microneedles, laminated on the skin near the mouse abdomen. (m) Mouse skin stained to visualize the micro-sized holes made by the penetration of the microneedles. (n) Images of the patch with the thermal actuation. (o) Blood glucose concentrations of mice between the treated (red) and the non-treated group (blue and green). Adapted by permission from (433) published by Springer Nature.