Wearable aptamer-field-effect transistor sensing system for noninvasive cortisol monitoring

Abstract

Wearable technologies for personalized monitoring require sensors that track biomarkers often present at low levels. Cortisol-a key stress biomarker-is present in sweat at low nanomolar concentrations. Previous wearable sensing systems are limited to analytes in the micromolar-millimolar ranges. To overcome this and other limitations, we developed a flexible field-effect transistor (FET) biosensor array that exploits a previously unreported cortisol aptamer coupled to nanometer-thin-film In 2 O 3 FETs. Cortisol levels were determined via molecular recognition by aptamers where binding was transduced to electrical signals on FETs. The physiological relevance of cortisol as a stress biomarker was demonstrated by tracking salivary cortisol levels in participants in a Trier Social Stress Test and establishing correlations between cortisol in diurnal saliva and sweat samples. These correlations motivated the development and on-body validation of an aptamer-FET array-based smartwatch equipped with a custom, multichannel, self-referencing, and autonomous source measurement unit enabling seamless, real-time cortisol sweat sensing.

Pre-equilibrium biosensors: A new approach towards rapid and continuous molecular measurements

“…Figure 6b. Even for the demanding sensing requirements chosen for this example, we find that the kinetic parameters are within the expected range of typical antibodies 30,31 and that the noise requirement is tractable, based on the sensing performance of published biosensors [32][33][34][35][36][37][38][39] .This supports the idea that antibodies should be viable receptors for use in a real-time insulin sensor.…”

Cushing’s Disease Management: Glimpse Into 2051

“…In terms of development, several independent researchers across the globe are working on systems which can be used to measure cortisol concentrations in body fluids and can thus be estimated on a superficial patch or wearable. A cortisol sensor has been formulated using extended gate-field-effect transistor ( 13 – 17 ). This has been developed as wearable contact lenses which can detect cortisol concentration in tears ( 13 ).…”

“…This cortisol sensor is integrated with transparent antennas and wireless communication circuits to link with the smartphone ( 14 ). A similar sensing system applied on the wrist with capability to measure sweat cortisol levels has been developed and tested which shows promise ( 14 – 17 ) ( Table 3 ). It is very likely that such a device will be developed and integrated into the traditional wearable watch as cortisol levels have applications in measurement of daily stress or allostatic load.…”

Battery-free, tuning circuit–inspired wireless sensor systems for detection of multiple biomarkers in bodily fluids

“…In recent years, studies on developing novel biochemical sensors and/or integrated systems with supporting wireless modules have received considerable attention and are progressing rapidly (8,(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). The great success and breakthroughs of pioneering works in this field have set the stage for next-generation health care.…”