Many pH sensors on the market today have specific limitations, such as the large and fragile construction of glass electrodes, or the complicated manufacturing processes of silicon-based devices including ion-sensitive field-effect transistors (ISFETs). Furthermore, most pH sensors require a stable reference electrode, which is difficult to miniaturize. In applications where the solution properties are largely understood, the use of an impedimetric sensor without a reference electrode may be sufficient, thereby simplifying the manufacturing of such sensors. In this work, inkjet printed and flash lamp annealed Ta₂O₅ on interdigitated electrodes, with an approximate sensor area of 4 mm × 4 mm, is investigated as a capacitive pH sensing layer in 0.5 M alkali chloride buffer solutions. By using the equivalent circuit of the insulator-electrolyte interface, the double layer capacitance is shown to decrease with an increase in pH within the range of pH 2 to pH 9, and agrees with prior results for anodic Ta₂O₅. When using the device as a sensor in both 0.5 M NaCl and 0.5 M LiCl aqueous solutions, the change in capacitance at 100 Hz is approximately − 110 nF/pH. Apart from pH sensing, these results may also prove informative in other applications, such as electrolytic capacitors, electrophysiology, and battery anodes in aqueous electrolyte. Moreover, the use of flexible, gold metallized polyethylene terephthalate (PET) foils as the sensor substrate potentially allows for large-scale production via roll-to-roll manufacturing, and further permits for use of the sensor in flexible applications such as goods packaging.

当今市场上的许多 pH 传感器具有特定的局限性，例如玻璃电极的大而易碎的结构，或者包括离子敏感场效应晶体管 (ISFET) 在内的硅基器件的复杂制造工艺。此外，大多数 pH 传感器需要稳定的参比电极，这很难小型化。在很大程度上了解溶液特性的应用中，使用没有参考电极的阻抗传感器可能就足够了，从而简化了这种传感器的制造。在这项工作中，喷墨打印和闪光灯对 Ta ₂ O _{5进行了退火处理}在叉指电极上，大约传感器面积为 4 mm × 4 mm，作为 0.5 M 碱金属氯化物缓冲溶液中的电容式 pH 传感层进行研究。通过使用绝缘体-电解质界面的等效电路，表明在 pH 2 至 pH 9 范围内，双电层电容随着 pH 值的增加而减小，并且与阳极 Ta ₂ O _{5的先前结果一致}. 当将该器件用作 0.5 M NaCl 和 0.5 M LiCl 水溶液中的传感器时，100 Hz 时的电容变化约为 - 110 nF/pH。除了 pH 值传感之外，这些结果还可能在其他应用中提供信息，例如电解电容器、电生理学和水性电解质中的电池阳极。此外，使用柔性镀金聚对苯二甲酸乙二醇酯 (PET) 箔作为传感器基板可能允许通过卷对卷制造进行大规模生产，并进一步允许将传感器用于诸如商品包装等柔性应用中。