Iridium and Ruthenium oxide miniature pH sensors: Long-term performance

Screen-printed sensing electrodes attract much attention for water pollution monitoring due to their small size, physical and chemical durability, and low cost. This paper presents the fabrication and broad potentiometric characterization of RuO2 pH sensing electrodes deposited by screen printing on alumina substrates and sintered in the 800–900 °C temperature range. All the fabricated electrodes showed close to Nernstian sensitivity, good linearity, fast response, small drift, low hysteresis, and low cross-sensitivity toward various interfering cations and anions. Furthermore, decreasing the sintering temperature led to better adhesion of the RuO2 layer and a negligible response to interfering ions. The measurements in real-life samples from different water sources showed that the fabricated electrodes are on par with conventional glass electrodes with a maximum deviation of 0.11 pH units, thus indicating their potential for application in water quality monitoring.

Section: Resultsmentioning

confidence: 99%

Fabrication, Potentiometric Characterization, and Application of Screen-Printed RuO2 pH Electrodes for Water Quality Testing

Uppuluri

Lazouskaya

Szwagierczak

et al. 2021

“…For instance, many works have shown different electrochemical modes of ruthenium oxide (RuOx) electrodes and their applications in in vitro studies. The electrode has been reported as a potentiometric pH electrode [ 7 , 8 ], an amperometric oxygen electrode [ 9 ], an amperometric nitric oxide electrode [ 10 , 11 ], as well as an electrophyiosology electrode [ 12 ]. This work presents another mode of operation, using the thin film RuOx electrode to observe the contractile activities of a human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) monolayer through electrical impedance spectroscopy (EIS), demonstrating the versatility of the presented RuOx electrode.…”

Section: Introductionmentioning

confidence: 99%

Monitoring Contractile Cardiomyocytes via Impedance Using Multipurpose Thin Film Ruthenium Oxide Electrodes

Tanumihardja

Bruijn

Slaats

et al. 2021

A ruthenium oxide (RuOx) electrode was used to monitor contractile events of human pluripotent stem cells-derived cardiomyocytes (hPSC-CMs) through electrical impedance spectroscopy (EIS). Using RuOx electrodes presents an advantage over standard thin film Pt electrodes because the RuOx electrodes can also be used as electrochemical sensor for pH, O2, and nitric oxide, providing multisensory functionality with the same electrode. First, the EIS signal was validated in an optically transparent well-plate setup using Pt wire electrodes. This way, visual data could be recorded simultaneously. Frequency analyses of both EIS and the visual data revealed almost identical frequency components. This suggests both the EIS and visual data captured the similar events of the beating of (an area of) hPSC-CMs. Similar EIS measurement was then performed using the RuOx electrode, which yielded comparable signal and periodicity. This mode of operation adds to the versatility of the RuOx electrode’s use in in vitro studies.

“…In recent years, researchers have been working on the development of novel pH microsensors, in the context of which metal/metal oxide electrodes have received more and more attention. Among these metal oxide electrode materials, iridium and its oxides have attracted the most attention because they have advantages in processing, micromanipulation, wide test range, rapid response time, and good biocompatibility [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. These characteristics make it suitable for extreme environments and in vivo pH measurement.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Characterization of Iridium Oxide pH Microelectrodes Based on Sputter Deposition Method

Guo

Wang

et al. 2021

pH value plays an important role in many fields such as chemistry and biology; therefore, rapid and accurate pH measurement is very important. Because of its advantages in preparation, wide test range, rapid response, and good biocompatibility, iridium oxide material has received more and more attention. In this paper, we present a method for preparing iridium oxide pH microelectrodes based on the sputter deposition method. The sputtering parameters of iridium oxide are also studied and optimized. Open-circuit potential tests show that microelectrodes exhibit near-Nernstian pH response with good linearity (about 60 mV/pH), fast response, high stability (a slight periodic fluctuation of potential change <2.5 mV in 24 h), and good reversibility in the pH range of 1.00–13.00.