Nanochannel Templated Iridium Oxide Nanostructures for Wide-Range pH Sensing from Solutions to Human Skin Surface

Abstract

Herein we report the fabrication of highly sensitive solid-state pH sensors based on iridium oxide nanowires (IONWs) for a wide-range of pH measurements. IONWs were confined electrodeposits on the indium tin oxide (ITO) electrode using a highly ordered silica nanochannel membrane as the template. Subsequently removing the template produced amorphous IONWs consisting of hydrated iridium oxyhydroxides. The IONW/ITO sensor can rapidly respond to the pH of the aqueous solutions in a wide range (from 0 to 13), avoiding the acid and alkaline errors encountered by conventional pH electrodes and exhibiting a super-Nernst analytical sensitivity as high as 235.5 mV/pH in the very acidic range of ∼0–2.5 and 90.1 mV/pH beyond (pH = ∼2.5–13). The sensitivity was associated with the interconversion of oxidation states of iridium oxyhydroxides. While in the very acidic range, intercalation of Cl– was proved to be responsible for the exceptionally high pH sensitivity. Moreover, the sensor was also demonstrated to work in organic solutions too. Finally, the flexible IONW/ITO electrode was prepared and interfaced to a wireless electrochemical device for real-time epidermal pH analysis with smartphones.

Identification of bacteria strains using the Recombinase Polymerase Amplification assay on a miniaturized solid-state pH sensor

“…The electrodes were calibrated in pH 7.0 solution (Aldrich Sigma, USA) for 2 days to stabilize the potential readings. The pH values are calculated by Nernst equation which is extensively reported in previous papers [9, 10, 14]. In ISFET sensor, pH values are displayed directly through the computer-connected interface electronics to drive the sensor and read the sensor output, provided by Microsens.…”

“…The sensing H + on ion-sensitive field-effect transistors (ISFET) has become the standard indicator for rapid detection [6], quantification [2], and DNA sequencing [7], which means that H + from NA amplification is a reliable indicator to detect pathogens. While the metal oxide pH sensors have been used to detect pH of blood [8], skin [9], and urine [10], the sensors have not been explored as a reliable platform to detect H + from NA amplification. Recently, a label-free and electrochemical detection of NA based on primer-generation rolling circle amplification were developed on the iridium oxide pH sensor [11].…”

Iridium oxide nanoparticles modified carbon fiber microelectrodes for pH detection

“…其中, 玻璃电极被 广泛应用于水溶液的pH检测, 但是, 玻璃电极存在体 积较大、质子敏感玻璃膜易损坏等缺点, 不适用于食 品、植物组织内的pH检测 [10,11] . 近年来, 离子敏感的 金属/金属氧化物, 例如二氧化钌(RuO 2 ) [12] 、五氧化二 钽(Ta 2 O 5 ) [13] 、氧化锡(SnO 2 ) [14] 、二氧化钛(TiO 2 ) [15] 、 氧化铱(IrO x ) [16,17] 等在pH检测领域得到了广泛的关注.…”

“…传感器. 固态pH传感器无需内充电解液、体积灵活可 控、可微型化和柔性化 [8,16] , 在食品安全、疾病诊断 及环境保护等领域受到广泛关注 [9] . 例如, Cao等 氧化铱修饰在柔性基底表面, 结合无线数据传输技术, 构建的可植入式pH传感器用于胃食管反流患者病情 监测.…”

In Vivo Molecular Insights into Syntrophic Geobacter Aggregates

“…Among the above-mentioned methods for preparing iridium electrode, the traditional electrodeposition method requires complex deposition solution with strict ratio. 32,33 Thermal oxidation and thermal sputtering require high-temperature oxidation instruments, 34,35 which are generally expensive, further limiting the application of iridium-based electrodes. In this study, the bulk iridium electrode using simple self-electrodeposition approach was prepared by cyclic voltammetry (CV) technology, which has the advantages of cost effectiveness, simple preparation, and good response performance.…”