Advances in robotics and prosthetics have given people who have lost a limb greater mobility. New research in electronic skin, or e-skin, could soon give them the sense of touch.

E-skin (or tactile skin) is a multisensory patch with a set of sensors and associated electronics either integrated on flexible substrates or embedded into soft substrates. The types of sensors included depend on the target application. In the case of a prosthetic limb, for example, force, temperature, and pain sensors would be used to mimic human tactile feelings.

A team at the University of Glasgow is studying 3D printing for e-skin production, how it can operate with various technologies, and the best opportunities for future e-skin evolutions.

“E-skin’s ability to detect subtle pressure and temperature changes makes it vital to robotic and artificial limb advancements, especially if human interactions with robotics are going to be kept safe,” said Ravinder Dahiya, Professor of Electronics and Nanoengineering at the University of Glasgow.

An illustration of the e-skin concept can be found below in Figure 1.

Figure 1: E-Skin Concept Illustration

The earliest exploration of tactile sensing began in the 1970’s with a focus on transduction mechanisms, and eventually the research made its way into robotics with the creation of multi-finger robotic hands and prosthetics. However, sensory technology and e-skin didn’t truly become relevant until the medical field took notice – perhaps due to the fact that the medical field holds the largest potential for e-skin.

In healthcare applications, e-skin could also have sensors to measure variations in the analytes or bio-markers present in bodily fluids (sweat or tears), as well as physiological parameters (pulse or blood pressure) in real time. While additional requirements, like disposable substrates, need to be considered, e-skin could enable advancements in mobile health, wearables, and self-health management. A variety of medical scenarios where e-skin can be incorporated are pictured below in Figure 2.

Figure 2: Potential E-Skin Uses in Medical Field

Advances in off-the-shelf and 3D-printed components, ultrathin flexible chips, energy autonomy, and neural data computation are still needed for e-skin to be a common component of prosthetics and medical wearables. Additionally, the complexity of copying skin morphology with sensors and substrates is a massive challenge.

Still, the research team believes a more holistic approach to e-skin development could be the path forward. Multidisciplinary teams, including neuroscientists, clinicians, engineers, and technologists, could unlock the numerous roadblocks of e-skin production. On the one side, neuroscientists and clinicians would analyze the tactile encoding, or clinical validity of sensors on e-skin. On the other side, engineers and technologists could synthesize the artificial systems.

“An effective e-skin, particularly on large areas is still many years away,” said Professor Dahiya. “However, in bits and pieces, the e-skin is already making an impact. In commercial terms I see IoT, wearables and health monitoring as the areas for large scale adoption in near to mid-terms. In the long term, we will see adoption in robotics and prosthetics.”

Moving forward, the team will continue to study how e-skin can handle the large volume of tactile data and will develop neuromorphic tactile skin to effectively handle that data.

For more information on electronic skin, visit the IEEE Xplore Digital Library.