Screen Printed Thick Film Reference Electrodes for Electrochemical Sensing

Abstract

This paper presents printed thick film Ag|AgCl|KCl reference electrodes (RE) for electrochemical sensors. The screenprinted REs with 10-µm thick glass-KCl salt matrix layer exhibit a stable potential of 5 mV. Cyclic voltammetric analysis shows that the anodic and cathodic peak current of the RE increases with the scan rate in the range of 25-150 mVs −1. The analytical performance of the REs shows a stable open circuit potential for the NaCl concentrations in the range of 30-100 mM. Testing the presented REs for electrochemical pH sensor application (with RuO 2-based sensitive electrode) the sensitivity of 55 mV/pH was noted in the pH range of 4.5-9. Evaluating the effect of temperature on the performance of REs, a potential variation of −3.8 mV/°C was observed. Finally, a LabVIEW interface was developed to store, analyze, and calculate the sensitivity of the sensor under different temperature conditions. The LabVIEW interface can also be used to calculate the pH-value/temperature of unknown solutions under known temperature/pH conditions.

Flexible potentiometric pH sensors for wearable systems

“…A standard potentiometric sensor consists of a combination of two electrodes, a sensitive (working) electrode and a reference electrode (RE). 152,[167][168][169][170] To determine pH, potentiometric sensors measure the potential difference between two electrodes immersed in a solution of unknown pH (according to Nernstian equation). In this section, we discus different materials which are used for the fabrication of sensitive and reference electrodes for wearable potentiometric pH sensors.…”

“…7a) could have different shapes or use an array of electrodes. 152,[167][168][169][170] Considering the requirements of wearble systems, integrated sensing technologies should be ultra exible and/or stretchable. In addition, wearable devices for clinical diagnostics, such as those used for remote or real-time healthcare monitoring require the following features: (i) reduced measurement errors and testing time (ii) lack of interference from other analytes (iii) high performance under bending conditions (iv) adequate availability of bio uids (e.g.…”

Flexible Printed Reference Electrodes for Electrochemical Applications

“…[26] The fabrication steps of the proposed FRE are shown in Figure 7a. For testing the performance of FRE, commercial GRE (Sigma Aldrich, UK) thick film rigid RE (RRE) [28] fabricated on alumina substrate and RuO 2 -based pH-sensing electrode were used. Initially, one end of the Ag electrode was converted into AgCl layer by chloridization during dip coating.…”

“…The surface morphology of thick film glass-KCl composite was observed with scanning electron microscopy (FEI Nova NanoSEM) and the electrochemical measurements were carried out for two-and threeelectrode systems with Metrohm Autolab (PGSTAT302N, Netherland). For testing the performance of FRE, commercial GRE (Sigma Aldrich, UK) thick film rigid RE (RRE) [28] fabricated on alumina substrate and RuO 2 -based pH-sensing electrode were used. [22] The FRE was characterized to measure their OCP response against a commercial GRE (Autolab, Netherland) and RuO 2 -based pH SE in a buffer solution of pH value 7.…”

“…However, the glass-KCl composite used ethyl cellulose as a binder for the paste formation, which has lower value of the potential against GRE (≈10 mV). [11,28] Currently, we have used a copolymer-based binder paste. Generally, the binder materials are known to influence the hydration time and stability.…”