Low-Power Wearable Enabled by Extended Gate Field-Effect Transistors to Advance Vigilant Biochemical Sensing

Biochemical monitoring of sweat through vigilant wearable systems offers new opportunities for improved stress management. A low-power biochemical sensing platform has been developed to perform potentiometric sensing using extended gate field-effect transistors (EGFET) for wearable biochemical monitoring. In vitro validation of the EGFET-enabled electrochemistry was achieved by testing pH and electrolyte concentrations. As a model biochemical analyte and important stress biomarker, neuropeptide Y (NPY) detection was demonstrated with this sensing platform by using an anti-NPY aptamer. The sensor and system operation were optimized to meet the sensitivity requirements to monitor NPY in sweat in a range of 100 fM to 100 nM by comparing different gate drive voltages. The sensing electronics power was optimized to enable longer term operation allowing 11 days of continuous monitoring on a single charge using a 3.8 g 150 mAh lithium polymer battery. The sensitivity of this custom designed electronics system was found to be similar to a commercial benchtop system when the same NPY aptamer-based sensor was tested in artificial sweat. The results indicated the largest current signal change of 34.3% for 100 nM NPY compared to the baseline current. Selectivity was measured against the stress biomarker cortisol. The measurements were achieved with a resolution of 13.59 μA/decade concentration change of NPY. These initial results pave the way towards vigilant sensing of stress biomarkers in sweat using a wearable system.