Electronic skin brings robots one step closer to human touch

The ability to feel touch is something most people take for granted. Yet for robots, prosthetic limbs, and many wearable technologies, accurately detecting physical contact remains a major technical challenge. Researchers in South Korea have now reported a significant advance that could help machines develop a more human-like sense of touch, potentially improving applications ranging from healthcare robotics to advanced prosthetics. A team led by Associate Professor Jaekyun Kim from Hanyang University ERICA has developed a new type of electronic skin built around a vertically integrated dual-gated tribotronic transistor.

The technology, described in the journal Nano Energy, can detect touch, pressure, and even the proximity of nearby objects while allowing engineers to adjust sensor sensitivity electronically. The development addresses longstanding limitations associated with electronic skin systems and could ultimately create safer, more intuitive interactions between humans and machines. This development could help robots, prosthetic devices, and wearable electronics perceive touch, pressure, and proximity with greater precision, supporting safer and more reliable interactions between people and machines.

Why robots need a sense of touch

Vision systems and artificial intelligence have dramatically improved robotic capabilities over the past decade. However, physical interaction remains an area where machines lag behind humans. Humans continuously process information about pressure, texture, movement, and proximity through millions of receptors embedded within the skin. This sensory feedback enables us to pick up fragile objects, shake hands, or react instantly to unexpected contact.

For robots and prosthetic devices, reproducing this capability remains difficult. Many existing tactile sensors can detect contact, but often have fixed sensitivity, limited sensing range, or are challenging to integrate into large-area sensing surfaces. As robots increasingly enter healthcare environments, manufacturing facilities, homes, and care settings, researchers are seeking technologies that support more natural and safer human-machine interactions.

The Hanyang University team’s approach relies on a technology known as a tribotronic transistor. Tribotronic devices exploit the triboelectric effect, a phenomenon that occurs when two materials come into contact and then separate, generating an electrical charge. This effect is familiar to anyone who has experienced a static electric shock after walking across a carpet. In sensing applications, triboelectric nanogenerators (TENGs) convert mechanical actions such as touch, movement, or pressure into measurable electrical signals. Because they generate signals directly from physical interaction, they are particularly attractive for self-powered wearable electronics and advanced sensing systems.

However, conventional tribotronic devices typically suffer from two limitations. Their sensitivity is often fixed once manufactured, and integrating large numbers of sensors into dense arrays can be difficult. The new design was specifically created to overcome both obstacles.

At the heart of the system is a vertically stacked architecture that combines several advanced materials. The device incorporates a polydimethylsiloxane (PDMS) sensing layer positioned above a gate insulator and an indium-tin-zinc-oxide (ITZO) thin-film transistor. This arrangement effectively creates two controllable gates within a compact structure. The lower gate establishes the baseline electrical current flowing through the transistor. The upper gate responds to triboelectric charges generated when a conductive object makes contact with the PDMS surface and then separates.

As an object approaches or touches the surface, these electrical conditions change, producing a measurable alteration in transistor current. Because the lower gate can be adjusted electronically, researchers can tune the sensor’s sensitivity to suit different applications. According to the research team, this combination of tuneable amplification and compact design enables far denser sensor arrays than previously possible.

Detecting both touch and proximity

One particularly interesting feature of the technology is its ability to detect not only direct contact but also nearby objects. The researchers demonstrated proximity sensing at distances up to 500 micrometres. As a charged object approaches the electronic skin, the triboelectric potential changes gradually, causing the transistor current to recover in a predictable manner. This produces an analogue signal that reflects how close the object is to the sensing surface.

The system can also respond to varying levels of pressure. Increasing force expands the contact area between the PDMS layer and an object, generating additional triboelectric charge and producing a stronger sensor response. This combination of pressure detection, touch sensing, and proximity awareness could prove valuable for robotic systems operating around humans.

To move beyond individual test devices, the researchers fabricated a 10 × 10 active sensor array using their new architecture. The array successfully detected finger touches at individual pixel locations and demonstrated reliable proximity sensing using a stainless-steel probe. The results suggest the design can scale beyond laboratory prototypes toward more practical electronic skin systems. Durability was also encouraging. The sensors maintained stable performance through 1,000 operating cycles without noticeable degradation. Response and recovery times were measured at approximately 127 milliseconds and 212 milliseconds respectively, supporting reliable operation during repeated use.

While the breakthrough originated in South Korea, the implications are highly relevant for Canada. Canada is increasingly investing in robotics, artificial intelligence, advanced manufacturing, and healthcare technology. Research centres such as Mila in Montréal, the Vector Institute in Toronto, and the Alberta Machine Intelligence Institute are helping position the country as a global leader in intelligent systems. A key challenge for next-generation robotics is enabling machines to interact safely with humans. Electronic skin technologies like the Hanyang system could become important components of healthcare robots deployed in hospitals, long-term care facilities, and assisted living environments.

The technology may also benefit Canada’s growing medical device sector. Advanced prosthetic limbs capable of more accurately sensing touch and pressure could improve user experience and functionality for amputees. Beyond healthcare, wearable monitoring systems incorporating sensitive electronic skin could support wellness tracking, rehabilitation programmes, sports science, and remote patient monitoring applications.