Heterogeneous integration of low power pH FinFET sensors with passive capillary microfluidics and miniaturized Ag/AgCl quasi-Reference Electrode

This work presents one of the first low power pH sensing microfluidic chip based on the heterogeneous integration of: (i) high-k FinFET sensors with liquid gate, (ii) miniaturized Ag/AgCl quasi-Reference Electrode and (iii) passive microfluidic. The integration of these three components provides a fully integrated and compact platform that could be exploited for ionic monitoring in biofluids for healthcare applications. We describe the full fabrication process for the microfluidic system with the embedded reference electrode. The electrical characterization of heterogeneously integrated pH FinFET sensor with the integrated reference electrode shows I
_d
-V
_g
characteristics with subthreshold swing SS~141mV/dec, low Ioff current and I
_ON
/I
_OFF
> 10
⁵
. When applying a constant current operation scheme, a sensitivity of 8mV/pH of the output drain voltage is reported. Due to the biocompatibility of the selected materials and small size, the resulting microsystem-on-chip could be used as a noninvasive wearable sensor for continuous monitoring of pH in sweat.