Can This Skin Sensor Give Robotics and Prosthetics a Delicate Touch?

October 28, 2017 by Tim Youngblood

Researchers at the University of Washington have designed a 'skin' sensor to give robots and prosthetics more sensitivity for precision tasks.

Researchers at the University of Washington have designed a 'skin' sensor to give robots and prosthetics more sensitivity for precision tasks.

Artificial intelligence is now capable of performing tasks and calculations with incredible precision. While programming for robotics continues to get more and more sophisticated, the progress of robotics has been held back by a lack of sensors that give them a human-like touch. Researchers from the University of Washington and UCLA have teamed up to design a sensor they hope will make robots more suited for precision tasks.

Not much information has been divulged about how cost-effective the design is or what kind of software is used, so they probably won't be available to public anytime soon, but the research shows encouraging signs for the technology as a whole. 


“If a robot is going to dismantle an improvised explosive device, it needs to know whether its hand is sliding along a wire or pulling on it. To hold on to a medical instrument, it needs to know if the object is slipping. This all requires the ability to sense shear force, which no other sensor skin has been able to do well,” -Jonathan Posner, UW professor and co-author of the paper.

The team's work has been successful so far. Robots outfitted with the skin have been successful at sensitive tasks such as opening doors, using a phone, picking up packages, and shaking hands. According to UW, the skin is even more sensitive than human fingers and can sense small vibrations at 800 per second. 


The sensors are placed on the ends of appendages and function as sensitive fingertips. Image courtesy of UCLA Engineering.

How Do the Skin Sensors Work?

The sensors are made possible by a stretchable electronics skin that was manufactured at the Washington Nanofabrication Facility. The skin itself is made of the same silicone rubber used to make swimming goggles. The rubber is embedded with serpentine channels that are only about half the width of a human hair. These serpentine channels are filled with electrically conductive liquid metal. The liquid metal is resistant to cracking and fatigue when stretched, giving them much more flexibility than solid wires.

When a surface is touched, the metal on one side of a finger stretches and the other side is compressed. This changes the amount of electricity that can flow through the channels, which gives measurements for shear force and vibration. This process recreates the effect of sliding one's finger across a surface to distinguish subtle differences in tension so a robot or prosthetic limb would be able to do something like slide a finger along a wire without pulling it.



The tension and compression generated by placing a robotic finger on a surface are used to calculate shear force. Credit: Reprinted from Sensors and Actuators A: Physical with permission from Elsevier via U. Washington.

Robotics Inspired By Biology

The inspiration for the skin sensor was human biology. Like a human fingertip, it bulges on one side of the nailbed (on a robot, the points where each side of the skin is attached act as the nailbed) and the tension where the skin meets the nailbed can determine shear force. 

Many researchers these days are looking to human and animal biology to tack design challenges for robotics. Millions of years of evolution serve as helpful trial and error for designers. This has always been a subject of fascination for me, so I added some other robotic designs inspired by biology below.


Featured image courtesy of UCLA Engineering.

1 Comment
  • A
    albsure November 03, 2017

    The irony here is itself, palpable.  Mankind strives with great effort to design a sensing system which is modeled after the human body, the greatest design known in our experience. Yet evolution is cited as the source of the human body’s capabilities, arrived at by chance and through scientifically un-provable means. Imitation is the highest form of flattery.

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