Robots Get "Skin" Too!... National Pukyong University Develops Ultra-Flexible Gelatin Electronic Skin

Research Team Led by Kim Yonghyun and Park Myungki
Paving the Way for AI-Powered Wearable Platforms

What if robots were given skin? The futuristic concept often seen in science fiction movies is now becoming a reality.

A gelatin-based hydrogel sensor has been developed that is as soft and stretchable as human skin, while maintaining stable electrical signals even after being stretched and released.

A research team led by Professor Kim Yonghyun of the Department of Display and Semiconductor Engineering and Professor Park Myungki of the Department of Chemistry at National Pukyong University (President Bae Sanghoon) has developed this material, which can reliably detect everything from subtle human movements to large joint motions.

Kim Yonghyun, Park Myungki Professor. Provided by Pukyong National University

This material can be attached to the skin to collect signals, which are then processed by artificial intelligence (AI) to accurately distinguish human motions. As a result, it is attracting attention as a next-generation wearable electronic skin (e-skin) platform.

The research team created a soft and elastic base structure by adding glycerol and polyethylene glycol to gelatin derived from pig skin collagen.

They then applied a hybrid conductive network combining silver nanowires (AgNWs) and the conductive polymer PEDOT:PSS, achieving both high electrical conductivity and durability. A glutaraldehyde crosslinking process was used to tightly bind the molecular structure, ensuring that the material maintains its form and performance even after prolonged use.

The most notable feature of the developed hydrogel sensor is its exceptionally low electrical hysteresis (signal distortion). Conventional sensors often suffer from signal mismatches and measurement fluctuations when stretched and released, but this material exhibits signal distortion of less than 3.5% even when stretched up to 200%, providing stable and consistent signals for identical movements. It also demonstrated durability by maintaining performance after more than 1,000 cycles of repeated deformation.

In particular, when attached to real skin, this hydrogel sensor was able to precisely detect not only large movements such as finger bending, arm and knee joint motions, walking, and jumping, but also subtle biosignals such as pulse, respiration, and facial expression changes. The research team connected the sensor to a wireless system for real-time data transmission, enabling AI analysis that successfully classified 13 different motions with an accuracy of approximately 97.7%.

The research findings were published in the world-renowned chemical engineering journal (IF=13.2) under the title 'Exceptionally low electrical hysteresis, soft, skin-mimicking gelatin-based conductive hydrogels for machine learning-assisted wireless wearable sensors.'

By fundamentally reducing the signal instability issues that have plagued conventional hydrogels, the research team believes this material could be expanded as an 'intelligent electronic skin' for AI-based human-machine interfaces (HMI) and digital healthcare applications.

Research image of Professor Kim Yonghyun.

Professor Kim Yonghyun stated, "Gelatin hydrogels are as soft as skin, but their signal instability has always been a major limitation for sensor applications. Through this research, we have achieved softness, reliability, and AI compatibility all at once. We expect this material to be used in a wide range of fields, including precise biosignal monitoring, rehabilitation and smart exercise coaching, next-generation wearable devices, and robotic electronic skin."

This content was produced with the assistance of AI translation services.