Magnetic Supersense Could Inspire Ultrasensitive Prosthetic Limbs

Robots that are capable of "feeling" their way around the world, thanks to hairy electronic skin, could be one step closer to reality, according to a new study.

Teensy electronic hairs, which sense minute vibrations through changes in their magnetic field, not only give robots a supersense of touch, but could also give people with prosthetic limbs a better feel for their surroundings, the researchers said.

"We are interested in integrating the sensor into robotic arms for people with disabilities to give them the capability to feel a complex environment and handle things more easily," said study co-author Lifeng Hao, a researcher at the Harbin Institute of Technology in China. [Bionic Humans: Top 10 Technologies]

Hairy skin

In recent years, many research groups around the globe have made great strides in developing bionic arms and legs that could help patients replace lost limbs.  Sscientists are also developing "electronic skin" — thin, stretchy material that is packed with electronics that aim to replicate the sensory capabilities of real skin.

The tactile sensation that electronic skins have imparted has been limited however, so Hao was looking for ways to improve the technology.

Hao was inspired to make electronic skin "hairy" when he was playing with his daughter, "who tried to gently touch my arm," he saild Live Science. "I realized that hairy skin was just what I was looking for."

That’s because human skin relies on hair for its exquisite sense of touch. For instance, fine hair, which covers 95 percent of the human body, helps people feel the slightest breeze, Hao said.

Magnetic microwires

To mimic the human sense of touch, the team built artificial hairs using magnetic cobalt-based microwires — commonly used, durable filaments that are as flexible as human hairs — the researchers wrote in the study, which was published online Nov. 25 in the journal ACS Applied Materials & Interfaces.

The researchers found that minute pressure changes altered the orientation of magnetic particles in the microwires, influencing the electrical fields in nearby sensors. AS such, the sensors could detect tiny physical disturbances.

The researchers used commercially available magnetic cobalt-based microwires, which were each about 50 micrometers in diameter. To protect them from their surroundings, the researchers coated the microwires in glass layers that were about 5 micrometers thick. (In comparison, the average human hair is about 100 micrometers across.)

The scientists embedded their artificial hairs in silicone rubber. In experiments, this synthetic, hairy skin could detect pressures that were induced by a 5.6-lb. (2.55 kilogram) weight and a fly that only weighed about 0.0005 ounces (0.015 grams). The hairs also detected light breezes that had a wind speed of just 6.7 mph (10.8 km/h).

The researchers noted that the ability of robotic or prosthetic hands to detect slip and friction is key to ensuring that these artificial limbs can hold items without dropping them. They noted that a two-finger robotic gripper that's equipped with the synthetic hairy skin could feel when something tugged away objects it was clamped onto. [Body Beautiful: The 5 Strangest Prosthetic Limbs]

In addition, the magnetic microwires could reveal whether materials touching the electronic skin were magnetic or were electrically insulating or conducting. The electronic skin also proved to be durable, showing no signs of wear even after 10,000 cycles of having a 2.2-lb. (1 kg) weight applied on it.

Original article on Live Science.