Lab on skin™: 3D monolithically integrated zero-energy microanofludics and FD SOI ion sensitive FETs for wearable multi-sensing sweat applications

摘要

This paper reports a novel fully integrated low power multi-sensing smart system, which, by wafer-level 3D heterogeneous integration of Ion Sensitive Fully Depleted (FD) FETs and SU-8 microanofludics, achieves the first of its kind wearable multi-sensing system, called Lab on Skin^{TM, capable to detect biomarkers in human sweat. In the reported configuration, the multi-sensing system exploits arrays of functionalized sensors capable to simultaneously detect pH, Na+ and K+ concentrations in sweat in real time. We present a detailed electrical DC and dynamic characterization, showing excellent sensitivities (52mV/dec for pH and -37mV/dec for Na+sensors) with ultra-low power consumption (less than 50 nWatts/sensor). We report ion cross-sensitivities and a differential measurement approach that allows calibrated measurements. Overall, the paper reports significant advances in the design and fabrication of microanofludics channels, inlets compatible with human skin pore size and density, and outlet passive pumps with flow rates of tens of pl/s; all capable of exploiting capillary forces in order to provide a zero energy pumping of sweat into sensing channels. Moreover, we report the first integration of a miniaturized Ag/AgCl Quasi-Reference Electrodes (QRE) into the sensing system, with long term stability, paving the way for fully wearable electronic chips in flexible patches or as plug-in modules in wrist based devices.}