Real-Time Telemetry System for Amperometric and Potentiometric Electrochemical Sensors

Author： Wang Wei-Song Huang Hong-Yi Chen Shu-Chun Ho Kuo-Chuan Lin Chia-Yu Chou Tse-Chuan Hu Chih-Hsien Wang Wen-Fong Wu Cheng-Feng Luo Ching-Hsing

Publisher： MDPI

E-ISSN： 1424-8220|11|9|8593-8610

ISSN： 1424-8220

Source： Sensors, Vol.11, Iss.9, 2011-09, pp. : 8593-8610

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Abstract

A real-time telemetry system, which consists of readout circuits, an analog-to-digital converter (ADC), a microcontroller unit (MCU), a graphical user interface (GUI), and a radio frequency (RF) transceiver, is proposed for amperometric and potentiometric electrochemical sensors. By integrating the proposed system with the electrochemical sensors, analyte detection can be conveniently performed. The data is displayed in real-time on a GUI and optionally uploaded to a database via the Internet, allowing it to be accessed remotely. An MCU was implemented using a field programmable gate array (FPGA) to filter noise, transmit data, and provide control over peripheral devices to reduce power consumption, which in sleep mode is 70 mW lower than in operating mode. The readout circuits, which were implemented in the TSMC 0.18-μm CMOS process, include a potentiostat and an instrumentation amplifier (IA). The measurement results show that the proposed potentiostat has a detectable current range of 1 nA to 100 μA, and linearity with an R² value of 0.99998 in each measured current range. The proposed IA has a common-mode rejection ratio (CMRR) greater than 90 dB. The proposed system was integrated with a potentiometric pH sensor and an amperometric nitrite sensor for in vitro experiments. The proposed system has high linearity (an R² value greater than 0.99 was obtained in each experiment), a small size of 5.6 cm × 8.7 cm, high portability, and high integration.