Browsing by Author "Park, Chanho"

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    3D touchless multiorder reflection structural color sensing display
    (American Association for the Advancement of Science, 2020) Kang, Han Sol; Han, Sang Won; Park, Chanho; Lee, Seung Won; Eoh, Hongkyu; Baek, Jonghyeok; Shin, Dong-Gap; Park, Tae Hyun; Huh, June; Lee, Hyungsuk; Kim, Dae-Eun; Ryu, Du Yeol; Thomas, Edwin L.; Koh, Won-Gun; Park, Cheolmin
    The development of a lightweight, low-power, user-interactive three-dimensional (3D) touchless display in which a human stimulus can be detected and simultaneously visualized in noncontact mode is of great interest. Here, we present a user-interactive 3D touchless sensing display based on multiorder reflection structural colors (SCs) of a thin, solid-state block copolymer (BCP) photonic crystal (PC). Full-visible-range SCs are developed in a BCP PC consisting of alternating lamellae, one of which contains a chemically cross-linked, interpenetrated hydrogel network. The absorption of a nonvolatile ionic liquid into the domains of the interpenetrated network allows for further manipulation of SC by using multiple-order photonic reflections, giving rise to unprecedented visible SCs arising from reflective color mixing. Furthermore, by using a hygroscopic ionic liquid ink, a printable 3D touchless interactive display is created where 3D position of a human finger is efficiently visualized in different SCs as a function of finger-to-display distance.
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    A wirelessly programmable, skin-integrated thermo-haptic stimulator system for virtual reality
    (National Academy of Sciences, 2024) Kim, Jae-Hwan; Vázquez-Guardado, Abraham; Luan, Haiwen; Kim, Jin-Tae; Yang, Da Som; Zhang, Haohui; Chang, Jan-Kai; Yoo, Seonggwang; Park, Chanho; Wei, Yuanting; Christiansen, Zach; Kim, Seungyeob; Avila, Raudel; Kim, Jong Uk; Lee, Young Joong; Shin, Hee-Sup; Zhou, Mingyu; Jeon, Sung Woo; Baek, Janice Mihyun; Lee, Yujin; Kim, So Young; Lim, Jaeman; Park, Minsu; Jeong, Hyoyoung; Won, Sang Min; Chen, Renkun; Huang, Yonggang; Jung, Yei Hwan; Yoo, Jae-Young; Rogers, John A.
    Sensations of heat and touch produced by receptors in the skin are of essential importance for perceptions of the physical environment, with a particularly powerful role in interpersonal interactions. Advances in technologies for replicating these sensations in a programmable manner have the potential not only to enhance virtual/augmented reality environments but they also hold promise in medical applications for individuals with amputations or impaired sensory function. Engineering challenges are in achieving interfaces with precise spatial resolution, power-efficient operation, wide dynamic range, and fast temporal responses in both thermal and in physical modulation, with forms that can extend over large regions of the body. This paper introduces a wireless, skin-compatible interface for thermo-haptic modulation designed to address some of these challenges, with the ability to deliver programmable patterns of enhanced vibrational displacement and high-speed thermal stimulation. Experimental and computational investigations quantify the thermal and mechanical efficiency of a vertically stacked design layout in the thermo-haptic stimulators that also supports real-time, closed-loop control mechanisms. The platform is effective in conveying thermal and physical information through the skin, as demonstrated in the control of robotic prosthetics and in interactions with pressure/temperature-sensitive touch displays.