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A Thermally Powered ISFET Array for On-Body pH Measurement
IEEE Transactions on Biomedical Circuits and Systems
|September 1, 2017
Summary
This study presents a wearable, battery-less system for analyzing body fluid pH using thermoelectric generators. This innovation enables continuous on-body electrochemical sensing for sports science and healthcare.
Area of Science:
- Wearable electronics
- Electrochemical sensing
- Biomedical engineering
Background:
- Next-generation wearables detect biofluid analytes using electrochemical sensors.
- Ion-sensitive field-effect transistors (ISFETs) offer advantages over ion-selective electrodes (ISEs) for integration and low power.
Purpose of the Study:
- To develop a wearable, thermoelectrically powered system for on-body perspiration analysis.
- To demonstrate the feasibility of battery-less electrochemical sensing using body heat.
Main Methods:
- Fabrication of an application-specific integrated circuit (ASIC) in 0.35 μm CMOS technology.
- Integration of an ISFET array, signal processing module, and transmitter.
- Utilization of commercial thermoelectric generators (TEGs) for power harvesting.
Main Results:
- The system achieved a pH sensitivity of 6–8 kHz/pH over a range of 7–5.
- The sensing array and processing module consumed only 6 μW, enabling full power from body heat.
- Array averaging reduced input-referred integrated noise to 104 μV, achieving a minimum detectable limit of 0.008 pH units.
Conclusions:
- The developed system is a feasible foundation for battery-less, on-body electrochemical sensing.
- This technology has potential applications in sports science and healthcare for continuous perspiration analysis.
