RESEARCH

Biofluiddynamics    Drops    Bubbles    Soft Matter & Robots    Emergence    Nanofabrication   



Soft Matter

Botanical movements

Related publications
1. W. Jung, W. Kim, and H.-Y. Kim, “Self-burial mechanics of hygroscopically responsive awns,” Integrative and Comparative Biology 54, 1034–1042 (2014)
2. W. Jung, S. M. Choi, W. Kim, and H.-Y. Kim, “Reduction of granular drag inspired by self-burrowing rotary seeds,” Physics of Fluids 29, 041702 (2017)
3. B. Shin, J. Ha, M. Lee, K. Park, G. H. Park, T. H. Choi, K.-J. Cho, and H.-Y. Kim, “Hygrobot: A self-locomotive ratcheted actuator powered by environmental humidity,” Science Robotics 3, eaar2629 (2018)
4. J. Ha, S. M. Choi, B. Shin, M. Lee, W. Jung, and H.-Y. Kim, “Hygroresponsive coiling of seed awns and soft actuators,” Extreme Mechanics Letters 38, 100746 (2020)
5. H. Na, Y.-W. Kang, C. S. Park, S. Jung, H.-Y. Kim, and J.-Y. Sun, “Hydrogel-based strong and fast actuators by electroosmotic turgor pressure,” Science 376, 301-307 (2022)
6. B. Shin, Y. Jung, M. Choi, and H.-Y. Kim, “Thermodynamics of hygroresponsive soft engines: cycle analysis and work ratio,” Physical Review Applied 18, 044061 (2022)
7. K. Park, J. Ha, B. Shin, and H.-Y. Kim, “Hygroresponsive movements of plants and soft actuators,” Soft Matter in Plants: From Biophysics to Biomimetics. Royal Society of Chemistry., pp. 227-240 (2023)
8. C. J. Park, J. Ha, H.-R. Lee, K. Park, J.-Y. Sun, and H.-Y. Kim, “Plant cell-like tip-growing polymer precipitate with structurally embedded multistimuli sensing ability,” Proceedings of the National Academy of Sciences 120, e2211416120 (2023)
9. T. Cano, H. Na, J.-Y. Sun*, and H.-Y. Kim*, “Swelling kinetics of constrained hydrogel spheres,” Soft Robotics 10, 1171-1180 (2023)
10. M. Choi, B. Shin, and H.-Y. Kim*, “Hygromachines: humidity-powered wheels, seesaws, and vehicles,” Proceedings of the National Academy of Sciences 120, e2211416120 (2023)
11. B. Shin, S. Jung, M. Choi, K. Park*, and H.-Y. Kim*, “Plant-inspired soft actuators powered by water,” MRS Bulletin 49, 1-14 (2024)
12. Z. Chen, J. Chen, S. Jung, H.-Y. Kim, M. L. Preti, C. Laschi, Z. Ren, M. Sitti, R. J. Full, and G.-Z. Yang*, “Bioinspired and biohybrid soft robots: Principles and emerging technologies,” Matter 8, 102045 (2025)
13. C. J. Park, H. Jeon, Y. K. Choi, J. S. Kim, Y. W. Lim, and H.-Y. Kim*, “Perpendicular growth of a tip-growing polymer precipitate on parallel line-patterned surfaces,” Physical Review Research 8, L012005 (2026)
14. C. Kim, J. Won, D. Kim, S. Jung*, H.-Y. Kim*, and Y. Hyun*, “Viola seed pod architecture shapes sequential, force-augmented pinching,” Science 392, 1302-1307 (2026)



Hygrobot, a self-locomotive actuator powered by environmental humidity: Ref. 3



Elastocapillary coalescence of plates and pillars

When a paintbrush is dipped into a bucket of paint and pulled out, surface tension forces cause the individual hairs in the brush to coalesce which simultaneously becomes impregnated with paint. We study such elastocapillary interactions by conducting simple experiments and solving free-boundary problems.


Related publications
1. D. Vella, H.-Y. Kim, and L. Mahadevan, "The wall-induced motion of a floating flexible train," Journal of Fluid Mechanics 502, 89-98 (2004)
2. H.-Y. Kim and L. Mahadevan, "Capillary rise between elastic sheets," Journal of Fluid Mechanics 548, 141-150 (2006)
3. H.-M. Kwon, H.-Y. Kim, J. Puell, and L. Mahadevan, "Equilibrium of an elastically confined liquid drop," Journal of Applied Physics 103, 093519 (2008)
4. K. J. Park and H.-Y. Kim, "Bending of floating flexible legs," Journal of Fluid Mechanics 610, 381-390 (2008)
5. Z. Wei, T. M. Schneider, J. Kim, H.-Y. Kim, J. Aizenberg, and L. Mahadevan, "Elastocapillary coalescence of plates and pillars," Proceedings of the Royal Society A 471, 20140593 (2015)
6. T.-H. Kim, J. Kim, and H.-Y. Kim, "Evaporation-driven clustering of microscale pillars and lamellae," Physics of Fluids 28, 022003 (2016)


Elastocapillary coalescence of lamellae due to evaporation: Ref. 6



Poro-elasto-capillarity

Related publications
1. M. Lee, S. Kim, H.-Y. Kim, and L. Mahadevan, "Bending and buckling of wet paper," Physics of Fluids 28, 042101 (2016)
2. J. Kim, J. Ha, and H.-Y. Kim, "Capillary rise of non-aqueous liquids in cellulose sponges," Journal of Fluid Mechanics 818, R2 (2017)
3. J. Ha, J. Kim, Y. Jung, G. Yun, D.-N. Kim, and H.-Y. Kim, "Poro-elasto-capillary wicking of cellulose sponges," Science Advances 4, eaao7051 (2018)
4. J. Ha and H.-Y. Kim, "Capillarity in soft porous solids," Annual Review of Fluid Mechanics 52, 263-284 (2020)
5. J. Kim, M.-W. Moon, and H.-Y. Kim, "Capillary rise in superhydrophilic rough channels," Physics of Fluids 32, 032105 (2020)
6. J. Choi, W. Kim, and H.-Y. Kim, "Crack density in bloodstains," Soft Matter 16, 5571-5576 (2020)
7. S. Jung, W. Kim, and H.-Y. Kim, "Dynamics of directional soluble wicking," Journal of Fluid Mechanics 915, A58 (2021)


Poro-elasto-capillary wicking of cellulose sponges: Ref. 2




Soft robots, sensors & actuators

Related publications
1. Y. Lee, W. J. Song, Y. Jung, H. Yoo, M.-Y. Kim, H.-Y. Kim, and J.-Y. Sun, "Ionic spiderwebs," Science Robotics 15, eeez5405 (2020)
2. S. Ku, J. Myeong, H.-Y. Kim, and Y.-L. Park, "Delicate fabric handling using a soft robotic gripper with embedded microneedles," IEEE Robotics and Automation Letters 5, 4852-4858 (2020)
3. W. J. Song, Y. Lee, Y. Jung, Y.-W. Kang, J. Kim, J.-M. Park, Y.-L. Park, H.-Y. Kim, and J.-Y. Sun, "Soft artificial electroreceptors for noncontact spatial perception," Science Advances 7, eabg9203 (2021)
4. J.-S. Park, J. Kim, A. Lee, and H.-Y. Kim*, "Snap-through inversion of elastic shells swelling via solvent diffusion," Soft Matter 19, 8213-8220 (2023)
5. H. B. Jeong, C. Kim, A. Lee*, and H.-Y. Kim*, "Sequential multimodal morphing of single-input pneu-nets," Soft Robotics 10, 1137-1145 (2023)
6. J.-S. Park, K. Ki, A. Lee*, J.-Y. Sun*, and H.-Y. Kim*, "Snap inflatable modular metastructures for multipath, multimode morphing machines," Cell Reports Physical Science 6, 102448 (2025)
7. S. Lee, Y. E. Cho, H.-Y. Kim*, and J.-Y. Sun*, "Photo-tunable elastomers enabling reversible, broad-range modulation of mechanical properties via dynamic covalent crosslinkers," Small 21, 2412657 (2025)
8. G. Lee, and H.-Y. Kim*, "Fold-cut structures with tunable stiffness for multimorphing soft robots," Advanced Intelligent Systems 7, 2500229 (2025)
9. S.-Y. Choi, J.-S. Park, W. J. Song, M. Kim, Y. H. Lee, Y. E. Cho, H. Lee, H.-Y. Kim*, and J.-Y. Sun*, "Elasto-magnetic instabilities for amplified actuation and mechanical memory," Nature Communications 17, 1511 (2026)
10. Y. H. Lee, S. W. Moon, M.-G. Lee, W. J. Song, S.-Y. Choi, G. Sung, Y. E. Cho, J. Choi, B. I. Park, Y. Lee, H.-Y. Kim*, and J.-Y. Sun*, "A reconfigurable dielectric elastomer actuator via phase-transitional ferrofluid enables sustainable operation," Science Advances 12, eaeb7409 (2026)


Cover of the July issue of Science Robotics (2020): Ref. 1



Granular materials

Related publications
1. Y. Jung, S. Jung, S.-I. Lee, W. Kim, and H.-Y. Kim, "Avian mud nest architecture by self-secreted saliva," Proceedings of the National Academy of Sciences of the United States of America 118, e2018509118 (2021)
2. K. Son, J.-Y. Sun, and H.-Y. Kim, "Agile reversible shape-morphing of particle rafts," Soft Matter 17, 7554-7564 (2021)
3. K. Son, Y. Choi, E. Kwon, L. G. Rigon, Y. Baek*, and H.-Y. Kim*, "Dynamics of self-propelled particles in vibrated dense granular media," Soft Matter 20, 2777-2788 (2024)
4. H. Jeon, K. Park*, J.-Y. Sun*, and H.-Y. Kim*, "Particle-armored liquid robots," Science Advances 11, eadt5888 (2025)


Back Scatter, March issue of Physics Today (2022): Ref. 2