Experimental Validation on the Industrial Panel-Level Process for Producing Solid-State EGFET Sensor Chips

Abstract

This article presents the experimental validations on an industrial panel-level produced solid-state multisensor for simultaneously pH, electrical conductivity (EC), and temperature detection of solution. Indium tin oxide (ITO) is adopted as the sensing material of the sensor chip due to its good ion selectivity, EC, and linear temperature coefficient of resistance (TCR) characteristics. Meanwhile, thin film deposited Ag/AgCl reference electrode is produced surrounding the sensing electrode to enhance the sensing performance. The sensing chip is produced in the glass substrate and is directly connected to the integrated circuit via a commercial USB-C flexible wire. The experimental results prove that the developed integrated sensor exhibits a high acidity response of 0.1 V/pH ranging from pH 2 to 13. The measured sensitivity is 0.9/°C for temperature detection with a high linearity of 0.9999 and 0.07 V/mS for solution conductivity with the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}$ </tex-math></inline-formula> -squared value of 0.9993. The sensing performance of the developed chips is also evaluated by measuring the urine samples of the five volunteers after drinking water, coffee, and beer, respectively. The measured results are also compared with commercial sensors. The developed integrated sensor has shown its potential for rapid and high performance for detecting the pH, ionic strength, and temperature in solution samples.