Technology capable of replicating the sense of touch — also known as haptic feedback — can greatly enhance human-computer and human-robot interfaces for applications such as medical rehabilitation and virtual reality. A soft artificial skin was developed that provides haptic feedback and, using a self-sensing mechanism, has the potential to instantaneously adapt to a wearer's movements.
The skin's system of soft sensors and actuators enables the artificial skin to conform to the exact shape of a wearer's wrist, for example, and provide haptic feedback in the form of pressure and vibration. Strain sensors continuously measure the skin's deformation so that the haptic feedback can be adjusted in real time to produce a sense of touch that's as realistic as possible.
The artificial skin contains soft pneumatic actuators that form a membrane layer, which can be inflated by pumping air into it. The actuators can be tuned to varying pressures and frequencies (up to 100 Hz). The skin vibrates when the membrane layer is inflated and deflated rapidly. A sensor layer sits on top of the membrane layer and contains soft electrodes made of a liquid-solid gallium mixture. These electrodes measure the skin's deformation continuously and sends the data to a microcontroller that uses this feedback to fine-tune the sensation transmitted to the wearer in response to the wearer's movements and changes in external factors.
The artificial skin can be stretched up to four times its original length for up to a million cycles. The skin has been tested on users’ fingers; the next step will be to develop a fully wearable prototype for applications in rehabilitation and virtual and augmented reality.