Abstract:

This paper presents an electrochemical sensing platform for point-of-care diagnostic applications. The platform uses the electrochemical impedance spectroscopy (EIS) technique for affinity sensing applications. The platform includes sensor front end, stimulus generation, analog sensor data acquisition and conditioning, digital-to-analog conversion, back-end digital signal processing, wireless interface and a user app. The platform is powered by a USB based rechargeable battery at 3.3V. Signal generation, digital data acquisition/processing are managed by an on-board microcontroller. Automatic gain control and noise reduction filter are implemented to meet the signal-to-noise ratio (SNR) requirements of the applications. The gain for the transimpedance amplifier (TIA) can be varied from 50 ohms to 100 kOhms. The frequency range for the EIS is from 0.16 Hz to 15 kHz with 96 data points. An average error of 2.6% was achieved. The circuit occupies a board area of 28.16cm² at the cost of less than $50. Whole system was validated with redox couple to measure its EIS response.