Artificial skin developed to help rehabilitation and enhance VR
Image credit: EPFL
Scientists at Ecole Polytechnique Federale de Lausanne (EPFL), France, have developed a soft, flexible artificial skin made of silicone and electrodes.
The skin was created by EPFL's Reconfigurable Robotics Lab (RRL), headed by Jamie Paik, and Laboratory for Soft Bioelectronic Interfaces (LSBI), headed by Stéphanie Lacour, at the School of Engineering. Both labs are part of the NCCR Robotics program.
The flexible skin's system, comprised of silicone, electrodes, soft sensors and actuators, enable the artificial skin to conform to the exact shape of a wearer's finger or wrist 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 as realistic as possible.
The human sense of touch plays an important role in how we perceive and interact with the world around us and technology capable of replicating our sense of touch - known as haptic feedback - can greatly enhance human-computer and human-robot interfaces for applications such as medical rehabilitation and virtual reality.
"This is the first time we have developed an entirely soft artificial skin where both sensors and actuators are integrated," said Harshal Sonar, the study's lead author. "This gives us closed-loop control, which means we can accurately and reliably modulate the vibratory stimulation felt by the user. This is ideal for wearable applications, such as for testing a patient's proprioception in medical applications."
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 100Hz or 100 impulses per second). 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 send the data to a microcontroller, which 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. That makes it particularly attractive for a number of real-world applications. For now the scientists have tested it on users' fingers and are still making improvements to the technology.
"The next step will be to develop a fully wearable prototype for applications in rehabilitation and virtual and augmented reality," says Sonar. "The prototype will also be tested in neuroscientific studies, where it can be used to stimulate the human body while researchers study dynamic brain activity in magnetic resonance experiments."
The study was published in the journal Soft Robotics.
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