Skin-Inspired Tactile Sensor on Cellulose Fiber Substrates with Interfacial Microstructure for Health Monitoring and Guitar Posture Feedback

Abstract

Skin-inspired flexible tactile sensors, with interfacial microstructure, are developed on cellulose fiber substrates for subtle pressure applications. Our device is made of two cellulose fiber substrates with conductive microscale structures, which emulate the randomly distributed spinosum in between the dermis and epidermis layers of the human skin. The microstructures not only permit a higher stress concentration at the tips but also generate electrical contact points and change contact resistance between the top and bottom substrates when the pressure is applied. Meanwhile, cellulose fibers possessing viscoelastic and biocompatible properties are utilized as substrates to mimic the dermis and epidermis layers of the skin. The electrical contact resistances (ECR) are then measured to quantify the tactile information. The microstructures and the substrate properties are studied to enhance the sensors’ sensitivity. A very high sensitivity (14.4 kPa−1) and fast recovery time (approx. 2.5 ms) are achieved in the subtle pressure range (approx. 0–0.05 kPa). The device can detect subtle pressures from the human body due to breathing patterns and voice activity showing its potential for healthcare. Further, the guitar strumming and chord progression of the players with different skill levels are assessed to monitor the muscle strain during guitar playing, showing its potential for posture feedback in playing guitar or another musical instrument.

Origami-Inspired Conductive Paper-Based Folded Pressure Sensor with Interconnection Scaling at the Crease for Novel Wearable Applications

“…The sensing mechanism for the sensor is electrical contact resistance (ECR) variation mechanism which has been previously reported. − ECR is represented by the resistance between two conductive surfaces. The electrical current can pass through the contact points at the interface, as shown in Figure b.…”

“…Previous research has explored the use of origami structures in tactile sensors but has not delved into the implications of folds and creases. − This current work employs origami-inspired folding to amplify sensor performance by expanding the effective area and pressure-sensing range. Adjustments on rigid substrates enhance sensitivity, delivering results 3.4 times more sensitive than conventional photocopy paper sensors . Although employing a folding technique slightly prolongs the recovery time to 1.4 ms, it adequately accommodates real-time applications.…”

“…Adjustments on rigid substrates enhance sensitivity, delivering results 3.4 times more sensitive than conventional photocopy paper sensors. 53 Although employing a folding technique slightly prolongs the recovery time to 1.4 ms, it adequately accommodates real-time applications.…”