For development of artificial skin, the key challenge is to monitor both human motion, as well as simultaneously sensing touch with both pressure and strain sensing functionalities. Several independent strain and pressure sensors for human motion monitoring and touch have been reported, but they involve the use of sophisticated cleanroom processes that are expensive and energy inefficient.

Addressing these issues, a new type of electronic, recoverable skin-like pressure and strain sensor on a flexible, bio-degradable pencil eraser substrate has been developed using a novel rolling-pin process and pre-compaction mechanical press – both solvent-free, low-cost and energy-efficient techniques.

The eraser serves as a substrate for strain sensing as well as acting as a dielectric for capacitive pressure sensing, thereby eliminating the steps of dielectric deposition, which is crucial in capacitive-based pressure sensors. A multiwalled-carbon-nanotube (MWCNT) film acts as the strain sensing element as well as the metal contacts for capacitive pressure sensing, which further eliminates the need for metal deposition. Moreover, since the strain sensing is resistive and the pressure sensing is capacitive, there is no need for front-end processing of data, which would have otherwise included extra hardware and complicated data analysis. Unlike, many facile approaches that are not scalable, this fabrication procedure is robust as it restricts the slippage of MWCNTs on the eraser, ensures scalability and can be integrated onto large areas.

This low-cost fabrication process holds tremendous potential in flexible electronics and healthcare for developing organic skin like devices with multiple functionalities.