POSTECH-Stanford joint research team develops multimodal ion-electronic skin that distinguishes
temperature from mechanical stimuli.
This skin can detect various movements and is applicable in fields including humanoid
skin and temperature sensors.
What if we didn’t have skin?
We would have no sense of touch, no detection of coldness or pain, leaving us inept to respond
to any situation.
The skin is not just a protective shell for organs, but rather a signaling system for
survival that provides information on the external stimuli or temperature, or a meteorological
observatory that reports the weather.
Tactile receptors, tightly packed throughout the skin, feel the temperature or mechanical
stimuli – such as touching or pinching – and convert them into electrical signals to the
brain.
The challenge for electronic skin, being developed for use in artificial skins or humanlike robots
like the humanoids, is to make it feel the temperatures and movements like how human
skin feels them as much as possible.
So far, there are electronic skins that can detect movement or temperature separately,
but none are able to recognize both simultaneously like the human skin.
A joint research team consisting of POSTECH researchers and researchers of Stanford University
have together developed the multimodal ion-electronic skin that can measure the temperature and
mechanical stimulation at the same time.
The research findings, published in the journal Science, are characterized by making very
simple structures through applying special properties of the ion conductors.
There are various tactile receptors in the human skin that can detect hot or cold temperatures
as well as other tactile sensations such as pinching, twisting or pushing.
Through these receptors, humans can distinguish between the mechanical stimuli and temperature.
The conventional electronic skin fabricated so far had the issue of having large errors
in measuring temperature if mechanical stimuli were applied to the skin.
Human skin is freely stretchable yet unbreakable because it is full of electrolytes, so the
joint research team made the sensor using them.
They also took advantage of the fact that the ion conductor material containing electrolyte
can have different measurable properties according to its measurement frequency.
On the basis of the new finding, a multifunctional artificial receptor was created that can measure
a tactile sensation and temperature at the same time.
This artificial receptor with a simple electrode-electrolyte-electrode structure has great commercialization potential
and accurately measures the temperature of the object applied as well as the direction
or strain profile upon external stimuli such as squeezing, pinching, spreading and twisting.
The multimodal ion-electronic skin, which can be freely stretched or modified but can
also detect temperature, is anticipated to be applicable in wearable temperature sensors
or in robot skins for humanlike robots like humanoids.
When an index finger touches an electronic skin, the electronic skin detects contact
as a temperature change, and when a finger pushes the skin, the back part of the contact
area stretches and recognizes it as movement.
This mechanism is one of the ways that the actual human skin recognizes different stimuli
like temperature and movement.
This study is the first step in opening the door for multimodal electronic skin research
using electrolytes.
The ultimate goal of this research is to create artificial ion-electronic skin that simulates
human tactile receptors and neurotransmitters, which will help restore the sense of touch
in patients who have lost their tactile sensation due to illness or accidents.