Professor Changkyu Jeong's team (College of Engineering, Division of Advanced Materials Engineering) has developed a self-powered patch with very high adhesion by integrating a piezoelectric composite material with an octopus-sucker structure.

This research, conducted in collaboration with Professor Chang-Hyun Bang's team in the Department of Chemical Engineering at Sungkyunkwan University, was published in the May issue of the world-leading energy and chemistry journal ACS Energy Letters (IF = 23.101) and was selected as the cover article. (Article title: Conformably Skin-Adherent Piezoelectric Patch with Bioinspired Hierarchically Arrayed Microsuckers Enables Physical Energy Amplification) The paper lists Hyunseung Kim, a PhD candidate at Jeonbuk National University (JBNU), and Dr. Dawan Kim of Sungkyunkwan University as co-first authors.

Piezoelectric materials convert external mechanical forces into voltage, and vice versa. They are used in many applications such as sensors and transducers, but they are typically rigid ceramic materials.

Piezoelectric composite materials are made by mixing piezoelectric ceramic particles with soft polymers. They have been developed for application to wearable formats and healthcare electronic devices and have recently been widely researched in sensors and energy harvesting. Nevertheless, piezoelectric composite films have the limitation of easily detaching when applied to the body and failing to adhere in moist conditions.

To overcome these limitations, the research team developed a method for integrating an octopus-sucker structure. Octopus suckers contain unique papillae inside. When the sucker adheres to a wet surface under external force, it displaces surface moisture, and the remaining fluid gathers around the spherical papillae and their surroundings by capillary action. At this point, the interior of the sucker becomes a vacuum and a strong negative pressure is generated, causing it to adhere firmly to the surface. This is analogous to naturally formed cupping. Professor Chang-Hyun Bang's team first reported this phenomenon in Nature in 2017.

Because this biomimetic octopus-sucker fabrication technique also uses soft polymers, the researchers were able to produce it together with the soft polymer matrix of the piezoelectric composite material and develop a piezoelectric energy composite device incorporating the octopus-sucker structure. They confirmed that the resulting bioinspired piezoelectric composite not only delivers output comparable to existing piezoelectric composite energy harvesters but also remains attached and functions as an energy patch when affixed to joints during free movement or when attached underwater.

Professor Changkyu Jeong said, "Although there has been extensive research on flexible piezoelectric composite energy harvesting, studies on effective adhesion to the body have always had limitations. This research makes it possible to create efficient piezoelectric healthcare sensors."

Professor Chang-Hyun Bang of Sungkyunkwan University commented, "Since reporting the octopus-sucker structure in the previous Nature paper, we have devoted significant attention to developing skin-adherent healthcare monitoring devices. This study marks the starting signal for initiating full-scale convergent research in the piezoelectric device field."

This research was carried out through close collaboration between JBNU, Sungkyunkwan University, and Professor Sungwoo Cheon of the Department of Electronics and Information Engineering at Korea University Sejong Campus, representing close cooperation between the capital region and regional institutions. It was supported by the Ministry of Science and ICT (Minister Hye-Sook Lim) and conducted under the National Research Foundation of Korea's Mid-Career Research Program, Young Researcher Program, and Basic Research Program.