A microdroplet-based capacitive sensing matrix for tactile applications

In this paper, we present a highly sensitive microdroplet-based interfacial capacitive sensor matrix device, achieving ultrahigh sensitivity of 0.4nF/kPa and minimal detectable pressure of 33Pa at a 3×3×0.2mm³ packaging. The microdroplet-based sensor is comprised of an array of nanoliter ionic droplets sandwiched between two flexible substrates with patterned transparent electrodes. The sensing principle primarily relies on high elasticity of the sensing droplet and large capacitance presented at the electrode-electrolyte interface. Theoretical analyses and experimental investigations on several design parameters are thoroughly conducted to characterize. Finally, the microdroplet-based pressure sensor is successfully utilized for tactile sensing applications, such as Braille characters scanning and non-invasive cardiovascular pressure recording.