Next gen haptics: A soft, artificial skin with tactile feedback

Roboticists have developed the first soft, wearable interface with high-fidelity tactile feedback.

A pair of robotics labs at a Swiss university have developed a soft, wearable skin that provides high-fidelity tactile feedback. Potential uses are wide-ranging and include rehabilitation and virtual reality.

We take our sense of touch for granted. Oenologists have devoted dictionaries to describing the tastes and smells of wine, and sight and hearing have long been the vectors of choice for mass media. The bias extends to technology, where touch is an afterthought, not largely catered to by developers outside the odd vibrating gaming controller or occasional keyboard that doesn't feel mushy.

That's a shame, since touch is such a big part of how we perceive and interact with the physical world. But new efforts underway to measure and simulate the sense of touch could fundamentally alter human-machine interactions in the years ahead. I've written about SynTouch, a California company whose technology enables the accurate measurement of the sensation of touch for consumer products brands and maybe one day for robots.

The Reconfigurable Robotics Lab (RRL) led by Prof. Jamie Paik and the Laboratory for Soft Bioelectronics Interfaces (LSBI) led by Prof. Stéphanie Lacour build on that legacy with a soft skin made out of silicone that's capable of providing vibratory feedback for a range of frequencies. That could solve a big problem with the current generation of haptic-equipped electronics controllers. Because of a lack of sensors on such control interfaces, there is currently no way to make sure that the user gets a consistent feedback while they're moving or interacting with the environment around them.

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"The SPA skin comprises a membrane that can be inflated by pumping air into it and a sensor layer based on a mix of liquid and solid gallium that can be used to convert mechanical stress into change in electrical resistance," according to a spokesperson. "The device is based on Soft Pneumatic Actuators (SPAs), made out of light and flexible materials that can be precisely controlled by adjusting their internal air pressure."

Both laboratories belong to NCCR Robotics, a Swiss research consortium that specializes in human-oriented robotics, including soft robots. The haptic skin could have applications in the robotics field, giving users direct access to tactile feedback felt by robots.

"For the first time, we have an entirely soft wearable interface consisting of integrated sensors and actuators, that produces a consistent tactile feedback with high fidelity" explains Harshal Sonar, a researcher in Paik's lab and the first author of a recent paper on the soft skin in the journal Soft Robotics. "This opens the door for various applications and new research, from bidirectional communication with humans or machines to more precise, quantitative experiments on somatosensory feedback in humans."

During testing the researchers sought to demonstrate that the device was capable of tuneable and reliable tactile feedback regardless of how the actuator might be positioned on a human subject. To do this, the researchers applied the actuator to a silicone cube, simulating contact with the human skin. 

"They then tuned the actuator to varying pressures and frequencies (up to 100 impulses per second) and used the sensors to measure how the deformation of the material varied in response to the actuator impulses and to contact with the silicone cube," according to the NCCR Robotics spokesperson. "Next, they were able to select a desired target deformation and use information coming from the sensors to adjust the pressure in the actuator. This way, a real user wearing the device would be sure to get the right feeling regardless of how the actuator is positioned and of which external factors my affect it."

The research team is now working on a fully wearable prototype, which could be useful in neuroscientific studies for rehabilitation and in virtual reality, where haptics are enjoying renewed attention.