Professor Inkyu Park‘s research group of the department of mechanical engineering at KAIST has developed an irregular microdome structure-based sensitive pressure sensor using internal popping of microspheres.

 The development of flexible pressure sensors has attracted significant attention owing to their various potential applications in wearable devices, human-machine interfaces, and health monitoring systems. An effective approach for fabricating a soft pressure sensor structure with high sensitivity is to construct microstructures such as pyramids, domes, and pillars. These approaches can be used to manufacture various types of microstructures for high-sensitivity pressure sensor applications. 

In general, a typical approach for fabricating a pressure sensor structure with a 3D surface morphology is the microfabrication of molds followed by elastomer casting processes. However, microfabrication processes require several iterative steps to fabricate micro-patterned molds such as photolithography and etching, which have limitations in the on-demand design and manufacturing flexibility. 

In this work, to overcome these limitations, we propose a novel strategy for generating 3D and irregular micro-dome structures for flexible pressure sensors by internal popping of microspheres. When heat is applied to a composite film composed of microspheres and an elastomer matrix, the microspheres expand and irregular micro-dome structures are generated on the surface. Notably, our fabrication method allows controllable microscale 3D surface morphology without micro-patterned mold and fabricating highly sensitive pressure sensor owing to the irregular micro-dome structures. Using this fabrication method, we demonstrated practical applications, such as a fingertip-shaped pressure sensor to detect the blood pulse on the index finger and to recognize soft objects. Finally, a large-area and multi-pixel sensor array pad was demonstrated to realize various functions such as drawing, multi-touch, and deep learning-based motion controller.

 Dr. Young Jung and Mr. Jungrak Choi are the co-first authors, Professor Inkyu Park and Dr. Hanchul Cho are the co-corresponding authors of this paper, and it was published in Advanced Functional Materials on July 4 as a back cover article. (Journal title: “Irregular Microdome Structure-Based Sensitive Pressure Sensor Using Internal Popping of Microspheres”)

[Reference] Y. Jung. et al., (2022) “Irregular Microdome Structure-Based Sensitive Pressure Sensor Using Internal Popping of Microspheres.” Advanced Functional Materials

[Main Author] Young Jung (Korea Advanced Institute of Science & Technology), Jungrak Choi (Korea Advanced Institute of Science & Technology), Inkyu Park (Korea Advanced Institute of Science & Technology), Hanchul Cho (Korea Institute of Industrial Technology)

* Contact : Inkyu@kaist.ac.kr, hc.cho@kitech.ac.kr