It’s fair to say that we take our skin for granted, but as Zhenan Bao, PhD, points out, it’s actually “a complex sensing, signaling and decision-making system.”
Bao, a Stanford chemical engineer, has been working for decades to develop an artificial skin that can mimic the organ’s ability to stretch, repair itself and function as a sensory network.
Her latest milestone, with other researchers from Stanford and Seoul National University, is the construction of an artificial nerve circuit that imitates human reflexes and ability to sense touch. A Stanford Engineering news release about the new Science paper explains the three components of the artificial network:
The first is a touch sensor that can detect even minuscule forces. This sensor sends signals through the second component — a flexible electronic neuron. The touch sensor and electronic neuron are improved versions of inventions previously reported by the Bao lab.
Sensory signals from these components stimulate the third component, an artificial synaptic transistor modeled after human synapses.
The artificial synaptic transistor, the brainchild of Tae-Woo Lee , PhD, of Seoul National University, was engineered to recognize and react to sensory inputs. To test the system’s ability to generate reflexes, the researchers hooked it up to an insect leg and applied various increments of pressure to the touch sensor. The release describes what happened next:
The electronic neuron converted the sensor signal into digital signals and relayed them through the synaptic transistor, causing the leg to twitch more or less vigorously as the pressure on the touch sensor increased or decreased.
Tests of the artificial nerve circuit didn’t stop here. Bao and her colleagues also found that the system could differentiate Braille letters and detect the direction of motion when a cylinder was rolled over the sensor.
As advanced as all of this sounds, however, there’s still much work to do before artificial skin can fully emulate the biological original. As the news release notes:
The researchers say artificial nerve technology remains in its infancy. For instance, creating artificial skin coverings for prosthetic devices will require new devices to detect heat and other sensations, the ability to embed them into flexible circuits and then a way to interface all of this to the brain.
Image by Kevin Craft courtesy of the Stanford School of Engineering