Newly-Developed Electronic Artificial Skin Can Sense Touch, Pain and Heat

A team of researchers at RMIT University has developed electronic artificial skin that mimics the human body’s near-instant feedback response and can react to painful sensations with the same lighting speed that nerve signals travel to the brain.

Skin is the largest human sensory organ covering the entire body.

Every region of the skin is full of sensors, which detect external stimuli and actively measure the level of such stimuli.

Sensory skin feedback is indicative of health. For instance, pin pricks are used to study the response of a nervous system to evaluate degree of paralysis from nerve damage.

Artificial skin receptors that demonstrate such feedback ability are integral to advancements in healthcare and intelligent robotics.

Such receptors can replace damaged receptors, augment sensation of specific stimuli, or serve as the feedback mechanism for human-machine or machine-machine interfaces.

“Our pain-sensing prototype is a significant advance towards next-generation biomedical technologies and intelligent robotics,” said co-lead author Professor Madhu Bhaskaran, a researcher in the Functional Materials and Microsystems Research Group and the Micro Nano Research Facility at RMIT University.

“Skin is our body’s largest sensory organ, with complex features designed to send rapid-fire warning signals when anything hurts.”

“We’re sensing things all the time through the skin but our pain response only kicks in at a certain point, like when we touch something too hot or too sharp.”

“No electronic technologies have been able to realistically mimic that very human feeling of pain — until now.”

“Our artificial skin reacts instantly when pressure, heat or cold reach a painful threshold.”

“It’s a critical step forward in the future development of the sophisticated feedback systems that we need to deliver truly smart prosthetics and intelligent robotics.”

Professor Bhaskaran and her colleagues used three technologies in their research:

(i) stretchable electronics: combining oxide materials with biocompatible silicone to deliver transparent, unbreakable and wearable electronics as thin as a sticker;

(ii) temperature-reactive coatings: self-modifying coatings 1,000 times thinner than a human hair based on a material that transforms in response to heat;

(iii) brain-mimicking memory: electronic memory cells that imitate the way the brain uses long-term memory to recall and retain previous information.

The pressure sensor prototype combines stretchable electronics and long-term memory cells, the heat sensor brings together temperature-reactive coatings and memory, while the pain sensor integrates all three technologies.

“The memory cells in each prototype were responsible for triggering a response when the pressure, heat or pain reached a set threshold,” said first author Md. Ataur Rahman, also from the Functional Materials and Microsystems Research Group and the Micro Nano Research Facility at RMIT University.

“We’ve essentially created the first electronic somatosensors — replicating the key features of the body’s complex system of neurons, neural pathways and receptors that drive our perception of sensory stimuli.”

“While some existing technologies have used electrical signals to mimic different levels of pain, these new devices can react to real mechanical pressure, temperature and pain, and deliver the right electronic response.”

“It means our artificial skin knows the difference between gently touching a pin with your finger or accidentally stabbing yourself with it — a critical distinction that has never been achieved before electronically.”

The team’s paper was published in the journal Advanced Intelligent Systems.