HMN 2026: How the epidermal electrode is Rigid on insertion, soft once inside

A research team at POSTECH (Pohang University of Science and Technology) has developed a novel electrode that the human body does not reject. This advance addresses a fundamental limitation of current wearable technology and is attracting significant attention from the academic community.

A team led by Professor Geunbae Lim of the Department of Mechanical Engineering, together with Dr. Jungho Lee and Dr. Gaeun Yun, in collaboration with Professor Sung-Min Park and Professor Chulhong Kim, has developed a “Dermal Bioelectrode (Dermal Electronics)” that minimizes pain and inflammation while enabling stably biosignal measurement unaffected by external environmental factors.

The study has been published in Advanced Materials.

The challenge: Comfort vs. accuracy

As smartwatches measure heart rates and adhesive patches monitor blood glucose levels, wearable devices have become integral tools for everyday health management. However, the electrode technology that enables these devices still faces structural limitations.

Epidermal electrodes attached to the skin surface are convenient to use but produce unstable signals due to sweat, dryness, and body movement.

In contrast, microneedle electrodes inserted into the skin offer greater signal accuracy but can cause tissue irritation and inflammatory responses because of their rigid structure. As a result, users have long been forced to choose between convenience and reliability.

The innovation: A structure-transforming electrode

The team’s electrode is rigid like a needle at the moment of insertion—stiff enough to penetrate the stratum corneum—but transforms into a soft, compliant structure once it reaches the dermal layer.

The concept draws on the same principle by which aluminum serves as a strong alloy in aircraft yet becomes a thin, pliable foil in the kitchen: identical materials can exhibit entirely different mechanical properties depending on their structural design.

The key enabling technologies are ultra-precision micro-fabrication of highly flexible biomaterials and an effervescent structural transformation mechanism. An effervescent sacrificial layer allows the electrode to pass through the stratum corneum within seconds, after which it settles stably into the dermis.

Once in the dermal layer, the electrode becomes inherently flexible, minimizing the mechanical stress imposed on surrounding cells and tissues. In effect, the body recognizes the electrode not as a foreign object but as a structure capable of being coexistent.

Validated performance

Through experiments on both animal models and human subjects, the team confirmed that virtually no tissue damage or immune response occurs even during prolonged implantation. Moreover, the electrode’s stable positioning within the dermal layer renders it immune to changes in the external environment: signal accuracy remained consistent under conditions of perspiration, dehydration, and extended wear.

Broader significance

This research goes beyond incremental improvements in wearable electrodes; it expands the signal acquisition zone from the skin surface to the dermal layer—a significant shift in biosignal measurement.

“This technology can extend beyond medical diagnostic devices to next-generation ‘Physical AI‘ systems that precisely collect biometric data and integrate it with artificial intelligence,” said Professor Lim. “It marks the starting point for a new class of data-driven technologies that continuously understand and leverage human biometric information.”

Expected impact

The rapid advancement of artificial intelligence is bringing humanoid robots and virtual reality closer to everyday life. Controlling a robot’s precise movements and driving virtual avatars requires high-dimensional, accurate interpretation of biosignals. In medical and industrial settings, acquiring reliable biometric data is considered a core requirement for robot actuation.

This study elevates the depth and reproducibility of biosignal collection and interpretation, strengthening the connection between software and hardware—an advancement expected to play a pivotal role in the development of next-generation interface technologies.

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