“Electronic Skin” Stretches and Senses Biological Data in Real-Time

durable electronic skin with high sensitivity to touch may finally be within reach

By Jonny Lupsha, Wondrium Staff Writer

The emerging tech of e-skin has just reached a potentially major milestone, Science Mint reported. Previous hurdles for the technology have included developing a skin that is sensitive to touch yet durable. The sense of touch is a complex system.

Hand touching a tree
In the “tree bark test,” when running your fingers along the bark of a tree, you feel the bark as you move your hand across the surface, feeling individual details, but, overall, you experience a feeling of texture. Photo By Ronnachai Palas / Shutterstock

According to Science Mint, scientists may have made a breakthrough in the recent technological field of electronic skin. “Electronic skin, or e-skin, may play an important role in upcoming next-generation personalized medicine, prosthetics, AI, and soft robotics,” the article said. “However, making reasonably flexible electronics that can perform such delicate tasks while also enduring the bumps and scrapes of everyday life is challenging, and every material involved must be carefully engineered.

“A team led by [KAUST postdoc Yichen] Cai and colleague Jie Shen has now developed a durable e-skin using a hydrogel reinforced with silica nanoparticles as a strong and stretchy substrate and a 2-D titanium carbide MXene as the sensing layer, bound together with highly conductive nanowires.”

The article said their e-skin can sense objects from 20 cm away, respond to stimuli in less than one-tenth of a second, and record biological data in real-time, which can tell users vital information like when their blood pressure changes. Our biological sense of touch is an involved system of cells and receptors.

Skin Deep

The process by which energy in the world is converted to neural impulses is called transduction, and it plays a major part in our sense of touch.

“The transduction process for touch is accomplished by many different types of receptors located at different locations below the surface of the skin,” said Dr. Peter M. Vishton, Associate Professor of Psychology at William & Mary. “In addition to having different locations in depth, the cells’ structure gives them different receptive properties. We only experience one conscious perception of touch, but it’s derived from many different types of information capture.”

One type of receptor, the Merkel receptor, lives very close to the surface of the skin. Dr. Vishton said Merkel receptors are small and in some cases very densely packed together, making it so we can detect differences in patterns of pressure when something is pressed against our skin. He gave the example of being able to differentiate between feeling the bark of an oak tree and the bark of a maple tree to illustrate the work Merkel receptors do.

Getting under Your Skin

Another vital receptor for the sense of touch is Meissner’s corpuscle. It performs a different but equally important task than the Merkel receptor.

“Meissner’s corpuscles are located at about the same depth within the skin,” Dr. Vishton said. “These cells are substantially larger than Merkel cells and thus can’t decode fine details very well. What they can encode is vibration.”

Dr. Vishton said that if you press on a Meissner’s corpuscle, it would respond for just a few milliseconds and then shut off. Releasing that pressure does the same. In other words, the Meissner’s corpuscle measures changes in pressure. Therefore, since they respond for such a brief amount of time, the best thing to stimulate them is vibration, which is a rapid, continuous increase and decrease of pressure. The tree bark test returns to explain this.

“If you were to run your fingers along those oak and maple trees, feeling their bark as you move your hands across the surfaces, you would feel the individual details to some extent, but your primary experience would be that of an overall texture,” he said. “That emergent perception of texture is derived from the patterns of vibration sensed by these Meissner’s corpuscles.”

Maintaining sensation after wear-and-tear has been one of the biggest hurdles in e-skin, but that problem may soon be solved.

Edited by Angela Shoemaker, Wondrium Daily

Dr. Vishton is Associate Professor of Psychology at William & Mary.

Dr. Peter M. Vishton contributed to this article. Dr. Vishton is Associate Professor of Psychology at William & Mary. He earned his PhD in Psychology and Cognitive Science from Cornell University.