Pressure and temperature sensing via ZnO-PDMS based membrane for wearable electronic applications

In this work, we have grown vertically oriented ZnO microstructures via low-temperature hydrothermal method using microsphere photolithography and followed by etching to prepare the growth substrate and establish ZnO nucleation  areas. The synthesized structures were rod-shaped ZnO microcrystals with a height of 5 μm and a diameter of about 400 nm. Such structures were encapsulated in polydimethylsiloxane (PDMS) for ZnO-PDMS membrane  formation. Based on this membrane, flexible and solid pressure sensors were fabricated. All sensors have been studied using electrical impedance spectroscopy in terms of the change in resistance and electrical capacitance when  pressure is applied. A correlation between the electrical characteristics of such sensors and an applied mechanical pressure was demonstrated. One of such sensors shows the possibility of synchronous measurement of pressure  and temperatures in the range of 25 °C – 100 °C was demonstrated. Fabricated sensors can find their application in the field of personalized healthcare and for the advancement of electronic skin (E-skin).