Design and Fabrication of Low Cost Thick Film pH Sensor using Silver Chlorinated Reference Electrodes with Integrated Temperature Sensor

Goib Wiranto,Yuyu Rachmat Tayubi,Dimas Sukma Batara,Novrita Idayanti,G.A Chang,G Chen,S Arumuga Perumal,M Ma

doi:10.1051/matecconf/20164001001

Abstract

This paper describes the design and fabrication of thick film pH sensor, in which the reference electrode has been formed by chlorination of Ag using FeCl 3 . The process was aimed to replace Ag/AgCl paste commonly used as reference electrodes. Fabricated using thick film screen printing technology on Al 2 O 3 substrate, the pH sensor showed a measured sensitivity of -52.97, -53.17 and -53.68 mV/pH at 25°C, 45°C, and 65°C, respectively. The measured values were close to the theoretical Nernstian slope of -59 mV/pH 25°C.The sensor was also designed with an integrated Ruthenium based temperature sensor for future temperature compensation. The measured resistance temperature characteristics showed a linear reasponse over the range of 25 – 80°C. This miniaturised planar sensor should find wide application, especially in field water quality monitoring, replacing their glass type counterparts.

Highlights

Nowadays, water quality monitoring requires real time data in which mesurement must be performed in situ/online from a remote location
Materials used for reference electrodes are Ag/AgCl, due to their stability, performance, and safety against environmental issues [7]
The use of Ruthenium as an active layer for pH sensor has been demonstrated [19] in the previous work

Summary

Introduction

Water quality monitoring requires real time data in which mesurement must be performed in situ/online from a remote location. Marine, aquaculture, agriculture, and mining are among the areas where online water quality monitoring have been widely implemented [1,2,3,4]. Sensors employed in such application need to be compact, rugged and robust to withstand harse environmental condition. In today’s pH electrochemical sensors, the relatively high cost of Ag/AgCl reference electrode material [8] has become a problem that needs to be solved either by replacing with different material, or by finding an alternative method for its preparation. This paper will describe the design, fabrication, and the results of characterisation of the sensor

Design and fabrication

Device characterisation

Ruthenium based temperature sensor

The pH sensor

Conclusion