Researchers from Stanford and Seoul National University have developed an artificial nerve system able to sense touch, and to communicate with the body’s real, biological nerve system. In the future, such a system could even be able to detect changes in texture, position, and pressure. The research suggests that prosthetics could eventually offer such capabilities, vastly improving quality of life for people with artificial limbs. Furthermore, the technology could also eventually be used to grant robots similar abilities.
The research was reported yesterday in the journal Science.
The system was able to stimulate a twitching reflex in a cockroach and read Braille letters.
According to Stanford chemist Zhenan Bao, who led the effort:
“We take skin for granted but it’s a complex sensing, signaling and decision-making system. This artificial sensory nerve system is a step toward making skin-like sensory neural networks for all sorts of applications.”
The nerve system uses flexible, inexpensive, organic materials, and consists of three separate components.
First, dozens of sensors react to pressure inputs, increasing voltage between a pair of electrodes. The sensors are able to detect even very small amounts of pressure.
Next, a “ring oscillator” converts these changes in voltage to a series of electrical pulses, in an electronic neuron that, as with the pressure sensor, is an improved version of an earlier invention from Bao’s lab.
Combined with pulses from other pressure sensors connected to their own ring oscillators, the pulses then feed into what’s called a synaptic transistor, which is modeled off of biological human synapses. This device outputs patterns of electrical pulses that match the pulses created by biological neurons.
This third component was created by Tae-Woo Lee of Seoul National University, another author of the new paper. Lee explained:
“Biological synapses can relay signals, and also store information to make simple decisions. The synaptic transistor performs these functions in the artificial nerve circuit.”
Ultimately, the system was able to discern the motion of a rod moving across the sensors, and was able to successfully identify Braille characters. When connected to the detached leg of a cockroach, with an electrode from the artificial neuron attached to the roach neuron, signals from the artificial neuron were able to stimulate a reflex, making the leg contract.
The device could someday be embedded in a thin covering for neuro-prosthetics that would resemble skin, although this would require new innovations to detect heat and other sensations, a way to build these devices into flexible circuits, and a way for the device to communicate with the brain.
Such technology could eventually make it easier for wearers to control prosthetics, and could even allow robots to handle more complex tasks.