Education & Certifications


  • M.S., Stanford University, Chemical Engineering (2018)
  • B.S., Seoul National University, Chemical and Biological Engineering (2015)

Stanford Advisors


All Publications


  • An Ultrastretchable and Self-Healable Nanocomposite Conductor Enabled by Autonomously Percolative Electrical Pathways. ACS nano Kim, S. H., Seo, H., Kang, J., Hong, J., Seong, D., Kim, H., Kim, J., Mun, J., Youn, I., Kim, J., Kim, Y., Seok, H., Lee, C., Tok, J. B., Bao, Z., Son, D. 2019

    Abstract

    Both self-healable conductors and stretchable conductors have been previously reported. However, it is still difficult to simultaneously achieve high stretchability, high conductivity, and self-healability. Here, we observed an intriguing phenomenon, termed "electrical self-boosting", which enables reconstructing of electrically percolative pathways in an ultrastretchable and self-healable nanocomposite conductor (over 1700% strain). The autonomously reconstructed percolative pathways were directly verified by using microcomputed tomography and in situ scanning electron microscopy. The encapsulated nanocomposite conductor shows exceptional conductivity (average value: 2578 S cm-1; highest value: 3086 S cm-1) at 3500% tensile strain by virtue of efficient strain energy dissipation of the self-healing polymer and self-alignment and rearrangement of silver flakes surrounded by spontaneously formed silver nanoparticles and their self-assembly in the strained self-healing polymer matrix. In addition, the conductor maintains high conductivity and stretchability even after recovered from a complete cut. Besides, a design of double-layered conductor enabled by the self-bonding assembly allowed a conducting interface to be located on the neutral mechanical plane, showing extremely durable operations in a cyclic stretching test. Finally, we successfully demonstrated that electromyogram signals can be monitored by our self-healable interconnects. Such information was transmitted to a prosthetic robot to control various hand motions for robust interactive human-robot interfaces.

    View details for PubMedID 31072094

  • Polyimide-PEG Segmented Block Copolymer Membranes with High Proton Conductivity by Improving Bicontinuous Nanostructure of Ionic Liquid-Doped Films MACROMOLECULAR CHEMISTRY AND PHYSICS Woo, E., Coletta, E., Holm, A., Mun, J., Toney, M. F., Yoon, D. Y., Frank, C. W. 2019; 220 (9)
  • Modular and Reconfigurable Stretchable Electronic Systems ADVANCED MATERIALS TECHNOLOGIES Kang, J., Son, D., Vardoulis, O., Mun, J., Matsuhisa, N., Kim, Y., Kim, J., Tok, J., Bao, Z. 2019; 4 (3)
  • Effect of Nonconjugated Spacers on Mechanical Properties of Semiconducting Polymers for Stretchable Transistors ADVANCED FUNCTIONAL MATERIALS Mun, J., Wang, G., Oh, J., Katsumata, T., Lee, F. L., Kang, J., Wu, H., Lissel, F., Rondeau-Gagne, S., Tok, J., Bao, Z. 2018; 28 (43)
  • An integrated self-healable electronic skin system fabricated via dynamic reconstruction of a nanostructured conducting network. Nature nanotechnology Son, D., Kang, J., Vardoulis, O., Kim, Y., Matsuhisa, N., Oh, J. Y., To, J. W., Mun, J., Katsumata, T., Liu, Y., McGuire, A. F., Krason, M., Molina-Lopez, F., Ham, J., Kraft, U., Lee, Y., Yun, Y., Tok, J. B., Bao, Z. 2018

    Abstract

    Electronic skin devices capable of monitoring physiological signals and displaying feedback information through closed-loop communication between the user and electronics are being considered for next-generation wearables and the 'Internet of Things'. Such devices need to be ultrathin to achieve seamless and conformal contact with the human body, to accommodate strains from repeated movement and to be comfortable to wear. Recently, self-healing chemistry has driven important advances in deformable and reconfigurable electronics, particularly with self-healable electrodes as the key enabler. Unlike polymer substrates with self-healable dynamic nature, the disrupted conducting network is unable to recover its stretchability after damage. Here, we report the observation of self-reconstruction of conducting nanostructures when in contact with a dynamically crosslinked polymer network. This, combined with the self-bonding property of self-healing polymer, allowed subsequent heterogeneous multi-component device integration of interconnects, sensors and light-emitting devices into a single multi-functional system. This first autonomous self-healable and stretchable multi-component electronic skin paves the way for future robust electronics.

    View details for PubMedID 30127474

  • Nonhalogenated Solvent Processable and Printable High-Performance Polymer Semiconductor Enabled by Isomeric Nonconjugated Flexible Linkers MACROMOLECULES Wang, G., Molina-Lopez, F., Zhang, H., Xu, J., Wu, H., Lopez, J., Shaw, L., Mun, J., Zhang, Q., Wang, S., Ehrlich, A., Bao, Z. 2018; 51 (13): 4976–85
  • Tough and Water-Insensitive Self-Healing Elastomer for Robust Electronic Skin ADVANCED MATERIALS Kang, J., Son, D., Wang, G., Liu, Y., Lopez, J., Kim, Y., Oh, J., Katsumata, T., Mun, J., Lee, Y., Jin, L., Tok, J., Bao, Z. 2018; 30 (13): e1706846

    Abstract

    An electronic (e-) skin is expected to experience significant wear and tear over time. Therefore, self-healing stretchable materials that are simultaneously soft and with high fracture energy, that is high tolerance of damage or small cracks without propagating, are essential requirements for the realization of robust e-skin. However, previously reported elastomers and especially self-healing polymers are mostly viscoelastic and lack high mechanical toughness. Here, a new class of polymeric material crosslinked through rationally designed multistrength hydrogen bonding interactions is reported. The resultant supramolecular network in polymer film realizes exceptional mechanical properties such as notch-insensitive high stretchability (1200%), high toughness of 12 000 J m-2 , and autonomous self-healing even in artificial sweat. The tough self-healing materials enable the wafer-scale fabrication of robust and stretchable self-healing e-skin devices, which will provide new directions for future soft robotics and skin prosthetics.

    View details for PubMedID 29424026

  • Taming Charge Transport in Semiconducting Polymers with Branched Alkyl Side Chains ADVANCED FUNCTIONAL MATERIALS Schroeder, B. C., Kurosawa, T., Fu, T., Chiu, Y., Mun, J., Wang, G., Gu, X., Shaw, L., Kneller, J. E., Kreouzis, T., Toney, M. F., Bao, Z. 2017; 27 (34)
  • Phase transition of block copolymer/homopolymer binary blends under 2D confinement MACROMOLECULAR RESEARCH Kim, Y., Mun, J., Yu, G., Char, K. 2017; 25 (6): 656–61