Speaker
Description
Flexible capacitive pressure sensors are critical for wearable technologies, but traditional designs struggle with low sensitivity in low-pressure ranges, making the choice of electrode materials a crucial factor for achieving optimal electrical performance. This work presents a comparative study on the characterization of silver (Ag) and titanium/gold (Ti/Au) electrodes for the implementation of a zinc oxide (ZnO)-based flexible pressure sensor. The electrode–semiconductor interface plays a critical role in determining charge transport behavior, sensitivity, and stability of pressure sensors, particularly in low-pressure wearable applications. Fabricated on flexible Polyvinyl Chloride (PVC) substrates within a Metal-Insulator-Metal (MIM) architecture, the design utilizes ZnO interlayers to significantly amplify capacitance changes through inherent piezoelectric and polarization effects. Morphological evaluations confirmed that drop-casted Ag electrodes exhibit a granular structure that increases effective surface area, whereas sputtered Ti/Au electrodes present a highly uniform and smooth surface. Electrical characterization revealed that Ag electrodes exhibited linear current–voltage characteristics, indicating natural Ohmic contact behavior. Conversely, unoptimized Ti/Au electrodes demonstrated nonlinear responses associated with Schottky-type interfaces, impeding initial charge flow. A subsequent annealing treatment significantly reduced these interface barriers and improved the linearity and charge transport of the Ti/Au contacts. Ultimately, the findings highlight the profound influence of electrode material selection on the electrical performance and suitability of ZnO-based pressure sensors, guiding future developments in reliable wearable electronics.
