New Electronic Skin Is Paving the Way for Better Prosthetics
By: Sritan Motati
Tags: Science, Medicine, Biomedical Engineering, Electronics, Technology

How It’s Made

In their research, the team at RMIT developed three, functioning prototypes that can detect and respond to either pain, temperature, or pressure (each one detected a unique stimulus). Each prototype’s goal was to imitate a specific component in our skin’s sensing system: the Pacinian corpuscle for pressure, thermoreceptor for temperature, and nociceptor for pain.

Someone wearing the electronic skin prototype (Picture Credit: RMIT University)

To make this skin, the researchers utilized three technologies that they had previously pioneered, as said in their research published in Advanced Intelligent Systems:

Oxide thin films: transparent, unbreakable, and extremely slim electronics that combine oxide materials with biocompatible silicone.

transparent, unbreakable, and extremely slim electronics that combine oxide materials with biocompatible silicone. Temperature-sensing coatings: coatings exponentially thinner than a human hair that modify themselves when heat is detected.

coatings exponentially thinner than a human hair that modify themselves when heat is detected. Memristors: electronic memory elements that mimic the human brain by using long-term memory to store information and make decisions.

Md Ataur Rahman, another researcher in this study, said that the three sensors used these technologies to replicate a biological nervous system and react when pressure, heat, or pain reached a chosen threshold.

“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.”

A memristor computer (Picture Credit: IEEE Spectrum)

Let’s take a closer look at each of the prototypes they developed.

Pressure Sensor

A typical Pacinian corpuscle, our skin’s natural pressure sensor, sends electrical impulses via the nervous system when pressure is exerted on the skin, which leads to a motor response. To emulate this, the researchers at RMIT used the oxide thin films and memristors to build their electronic pressure sensors. In these sensors, when pressure is applied to them, they allow current to flow through the memristors, which leads to the initiation of a motor response. When pressure isn’t applied, an insufficient amount of current flows through the memristors, which means no response.

Temperature Sensor

When thermoreceptors in human skin detect temperatures above 30 °C, they start firing action potentials, which results in an electric current being sent in the nervous system and a motor response. The artificial thermoreceptors use the memristors and temperature-sensing coatings to measure the temperature and initiate a response. Like in the pressure sensor, when the artificial temperature sensors detect high temperatures, they send electrical impulses, with higher currents being sent at higher temperatures.

Electronic skin prototype made with oxide thin films (Picture Credit: RMIT University)

Pain Sensor

Human nociceptors are one of the most important receptors in our bodies because they’re responsible for detecting pain and responding to it. The researchers at RMIT focused on mimicking thermal nociceptors, which are best at detecting noxious heat and burns (start firing at temperatures around 45 °C). When these stimuli are detected, the nociceptor activates an appropriate response to prevent further damage. The electronic nociceptors, which use all three technologies, function similarly, as when it detects pressure and temperatures above 68 °C, current flows through the circuit, with the response intensity proportional to the severity of the stimulus.