Recently, benefiting from the rapid advances in the design of various flexible sensors, flexible wearable electronic devices have gained increasing attention for potential applications in individual medical care, health assessment, sports monitoring, etc. For example, Professor Ting Zhang' group, at Suzhou Institute of Nanotech and Nanobionics of Chinese Academy of Sciences (SINANO.CAS), have made great research progress in flexible/stretchable sensing electronics and their applications in wearable smart systems, such as concluding high-quality carbon film based flexible sensor, silk-molded flexible electronic skin, and porous ionic membrane based multifunctional flexible humidity sensor, etc.
Among various flexible sensors, the flexible tactile sensors, which can be integrated in the curved surfaces such as touchscreen, flexible displays and even human body, have received considerable attention, however, most of those were not widely adopted because of certain drawbacks such as wide detection range but suffering from slow response time; great sensitivity but limited by complicated preparation method. Hence, it is still a challenge to develop a high-sensitivity flexible tactile sensor using a low-cost, facile but efficient prepared strategy, especially for the micro-structured/patterned dielectric layer. An effective approach towards improving the performances of tactile sensors is the judicious selection of patterned electrode.
Inspired from the bionic inspired fabrication strategy, the micro/nanostructures of natural plants can be used as an effective soft mould to fabricate the micro-patterned electrodes. Professor Zhang Ting's group have proposed and achieved significant progress of demonstrating the utilization of bionic microstructures on natural lotus leaves to design and fabricate new-type of high-performance flexible capacitive tactile sensors. The novel flexible capacitive tactile sensor is constructed by the micro-patterned top and bottom Polydimethylsiloxane (PDMS)/Au electrodes coupled with polystyrene (PS) microspheres as the dielectric thin layer. Inspired by the bionic micro/nanostructures of natural plants, we found the lotus leaf can be used as an effective soft mould to fabricate the micro-patterned PDMS/Au electrodes, due to its uniform surface microstructures. The flexible capacitive sensors demonstrated stable and high sensing performance, such as high sensitivity (0.815 kPa-1), wide dynamic response range (from 0 to 50 N), and fast response time (~38 ms). Remarkably, the flexible capacitive sensors show the distinct pattern responses to different type of forces (bending, stretching, and pressure touching by a single hair). Such high sensing performance makes the flexible capacitive tactile sensor the promising candidate for various applications such as in artificial electronic-skins and wearable electronics.
Source and top image: Ting Zhang Suzhou Institute of Nano-tech and Nano-bionics