An implementation of an electronic tongue system based on a multi-sensor potentiometric readout circuit with embedded calibration and temperature compensation

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• 作者：Wen-Yaw Chung^a ; ^{eldanny@cycu.edu.tw" class="auth_mail" title="E-mail the corresponding author} ; Angelito A. Silverio^a ; Vincent F.S. Tsai^b ; ^c ; Cheanyeh Cheng^d ; Shu-Yu Chang^a ; Zhou Ming-Ying^a ; Chi-Ying Kao^d ; Si-Yuan Chen^e ; Dorota G. Pijanowska^f ; Dan Rustia^a ; Yi-Wen Lo^a
• 关键词：Electronic Tongue ; ISFET ; Enzyme Extended Gate Field Effect Transistor ; pH ; Ionized Calcium ; Potentiometric Sensor Analog Front- End
• 刊名：Microelectronics Journal
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：57
• 期：Complete
• 页码：1-12
• 全文大小：5797 K

文摘

We present an electronic tongue system composed of an analog front-end (AFE) with embedded calibration and temperature compensation for interfacing with an array of Ion-Sensitive FETs (ISFETs) or Enzyme – Extended Gate FETs (EEGFET). The AFE consists of a floating bridge type constant voltage constant current (CVCC) structure, and transmission gates as sensor enable. It also includes a temperature readout circuit and an instrumentation amplifier for temperature compensation. The calibration algorithm is synthesized into a Field Programmable Gate Array (FPGA) and implemented onto an Application Specific Integrated Circuit (ASIC). The system shall be used to measure the pH and the concentration of calcium ions in a solution alongside a conductometric sensor system. The ISFETs used are from ITE-Poland and shall be utilized to measure pH; meanwhile, to measure the Ca²⁺ concentration, EEGFETs with calcium ionophore on polyvinyl chloride (PVC) on SnO₂/ITO/Glass thin film have been fabricated. The performance of the system using pH buffer solutions of pH 4–10, and CaCl₂ buffer concentrations of 0.001–1 M has been verified. The sensors and the AFE readout exhibited a Nernstian response (~50 mV/pH) with a very stable output having a relative standard deviation of just ~−0.4%, and a Ca²⁺ sensitivity of 25.02 mV/pCa, with a drift of −6.82 mV/M-s. An on-chip version of the AFE using TSMC 0.35 µm CMOS 2P4M Technology is also presented as well as the ASIC implemented on TSMC 0.18 µm CMOS 1P6M technology.