Revolutionary Super-Adhesive Patches Boost Skin Contact

Abstract

Skin-interfaced electronics have emerged as a promising frontier in personalized healthcare. However, existing skin-interfaced patches often struggle to simultaneously achieve robust skin adhesion, adaptability to dynamic body motions, seamless integration of bulky devices, and on-demand, damage-free detachment. Here, a hybrid strategy that synergistically combines these critical features within a thin, flexible patch platform is introduced. This design leverages shape memory polymers (SMPs) arranged in a tessellated array, comprising both rigid and compliant SMPs. This configuration enables exceptional deformability, motion adaptability, and ultra-strong, repeatable skin adhesion while offering on-demand adhesion control. Furthermore, the design facilitates the seamless integration of bulky electronics without compromising skin adhesion. By incorporating sizeable electronics including signal acquisition circuits, sensors, and a battery, it is demonstrated that the proposed tessellated patch can be securely mounted on the skin, accommodate dynamic body motions, precisely detect physiological signals with an outstanding signal-to-noise ratio (SNR), wirelessly transmit data, and be effortlessly released from the skin.

A research team, affiliated with UNIST has unveiled an ultra-strong adhesive patch platform that adheres effectively to rough skin surfaces and shows remarkable motion adaptiveness during dynamic body movements, all while offering irritation-free removal on demand. The key to this technology lies in the surface adaptability inspired by barnacles and armadillo carapaces, which feature a tessellated structure that balances rigidity and flexibility.

Led by Professor Hoon Eui Jeong from the Department of Mechanical Engineering and Professor Jae Joon Kim from the Department of Electrical Engineering at UNIST, along with researchers from the National Institute of Ecology (NIE), the team has introduced a highly adhesive, detachable, and stretchable skin patch, known as the Motion Adaptive Tessellation Patch. This innovative technology is garnering attention for its potential to facilitate the commercialization of wearable electronic devices, such as healthcare monitoring systems and transdermal drug delivery systems.

The team designed this attachment patch by arranging shape memory polymers that mimic the characteristics of barnacle adhesive proteins and the structure of armadillo armor. This innovative approach enables the adhesive component to adjust its stiffness, allowing it to conform to uneven surfaces, such as those found in nature. The mechanism resembles the way soft adhesive proteins fill the contours of rough rocks before hardening to create a strong bond.

The shape memory polymer mimics this natural principle, allowing it to adhere to the skin's irregularities while enabling easy, irritation-free removal through temperature control. Additionally, this mechanism allows for multiple attachments and detachments by merely adjusting the temperature.

The design is further enhanced by the incorporation of an armadillo-inspired structure, which promotes flexibility and resilience to ensure that the patch remains securely attached during intense movements. The armadillo's armor features a "tessellation" structure where soft collagen fills the spaces between hard bony fragments, providing significant strength while still allowing for movement. By emulating this structure, the research team maximized adhesion by integrating elastic polymers with the shape memory polymer.

"Existing body-attached devices often fall short in terms of durability against deformation and repetitive stress induced by movement, frequently leading to skin irritation and discomfort during prolonged use," stated Professor Jeong. "Through this study, we have developed an innovative adhesive technology capable of addressing these challenges."

These attachable electronic devices not only maintain adhesion while running or navigating stairs but are also capable of measuring vital signs such as heart rate and blood pressure.

Professor Kim emphasized, "To effectively embed batteries and sensors in these devices while acquiring high-quality bio-signals, it is crucial to maintain adhesion during vigorous movements. Our research seeks to overcome the limitations of existing technologies that restrict usability due to motion constraints." He also mentioned, "We aim to leverage these findings to facilitate technology transfer and initiate a startup."

Their findings were published online on October 20 in Advanced Materials, a prestigious journal in the field of materials science, and will be featured in an upcoming print issue. This research was supported by the Ministry of Science and ICT (MSIT), the Ministry of Trade, Industry and Energy (MOTIE), and the National Institute of Ecology (NIE).

Journal Reference

Geonjun Choi, Jaeil Kim, Hyunjoong Kim, et al., "Motion-Adaptive Tessellated Skin Patches With Switchable Adhesion for Wearable Electronics," Adv. Mater., (2024).