No abstract

The applicability of electrochemically deposited polyaniline (PANI) layer in the design of optical pH sensors has been evaluated in this research. PANI layer was electrochemically deposited by potential cycling on the surface of the indium tin oxide (ITO)-modified transparent electrode. The dependence of UV/Vis absorbance spectra of PANI layer on the pH has been evaluated. Significant pH dependence in optical absorbance at three peak maxima (at 455 nm, 630 nm and 855 nm) as well as the wavelength of maximum absorbance (λ max ) has been discussed. Taking into account an optical absorbance at different wavelengths and pH-dependent variation of absorbance peak maxima, the advantages and some limitations in pH determination by glass/ITO/PANI structure have been revealed and outlined. The sensitivity of PANI structure to the changes of pH by using different optical absorbance evaluation methods have been assessed and discussed. The applicability of combination of simultaneous determination of several here evaluated analytical signals has been foreseen.

Organic electrochemical transistors (OECTs) based on Poly (3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) are a benchmark system in organic bioelectronics. In particular, the superior mechanical properties and the ionic-electronic transduction yield excellent potential for the field of implantable or wearable sensing technology. However, depletion-mode operation PEDOT:PSS-based OECTs cause high static power dissipation in electronic circuits, limiting their application in electronic systems. Hence, having control over the threshold voltage is of utmost technological importance. Here we demonstrate PEDOT:PSS-based dual-gate OECTs with solid-state electrolyte where the threshold voltage is seamlessly adjustable during operation. We show that the degree of threshold voltage tuning linearly depends on the gate capacitance, which is a straightforward approach for circuit designers to adjust the threshold voltage only by the device dimensions. The PEDOT:PSS-based dual-gate OECTs show excellent device performance and can be pushed to accumulation-mode operation, resulting in a simplified and relaxed design of complementary inverters.