Advancements in artificial or electronic skin are fundamental to the creation of humanoid robots, as skin provides us humans with the sense of touch, the ability to detect temperature and pain, and many other important aspects of life. The human body has tactile receptors located in the skin, which is what allows us to convert temperature or mechanical stimuli into electrical signals for the brain.
It is extremely difficult to replicate these abilities in electronic skin, and today’s versions are only capable of detecting movement or temperature separately. There has yet to be any that can do both simultaneously like human skin, until now.
Multimodal Ion-Electronic Skin
A research team at Stanford University has developed a new, multimodal ion-electronic skin that is able to do just that. By applying special properties of the ion conductors, the team was able to create simple structures which allow the electronic skin to measure temperature and mechanical stimulation at the same time.
The team included POSTECH professor Unyong Jeong and Dr. Insang You of the Department of Materials Science and Engineering, as well as Professor Zhenan Bao. The findings were published in Scienceon Nov. 20.
Prior to this development, electronic skin often suffered from large errors in measuring temperature when mechanical stimuli were applied to it. The team looked toward the human skin as inspiration and created the sensor with electrolytes, as they are responsible for giving human skin the ability to stretch freely without breaking. The ion conductor material that contains electrolytes can have different measurable properties depending on its measurement frequency.
Through all of this, the team developed a multifunctional artificial receptor capable of measuring a tactile sensation and temperature simultaneously. The team was able to derive the charge relaxation time and the normalized capacitance, which are two variables that can measure temperature and movements without responding to the other.
The newly developed artificial receptor has many potential commercial uses, as it can accurately measure the temperature of the applied object and the strain profile upon external stimuli.
As for the multimodal ion-electronic skin, it could be applied to wearable temperature sensors or robot skins to make them more humanoid.
Dr. Insang You is first author of the research.
“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,” You said. “I suspect that this mechanism is one of the ways that the actual human skin recognizes different stimuli like temperature and movement.”
Jeong was the corresponding author.
“This study is the first step in opening the door for multimodal electronic skin research using electrolytes,” Jeong said. “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.”