Research

My research interest lies in understanding the fundamental transport and dynamics of polymeric materials in flow processing, and developing advanced additive manufacturing methods to progress the microfabrication landscape. I use experimental tools from fluorescence microscopy, microrheology to high-resolution 3D printing platforms to probe and design new materials. In tandem I develop theoretical frameworks to analyze my findings in the context of non-Newtonian fluid mechanics and non-equilibrium statistical mechanics.

High-resolution Continuous Liquid Interface Production (CLIP)

I focused on designing and modeling advanced AM concepts to increase print speed and print resolution simultaneously to push the current technological boundary of additive manufacturing technology. A single-digit micron resolution Continuous Liquid Interface Production (CLIP) printer is developed, along with first-principles model (optics, fluid mechanics, and reaction kinetics to guide the soft-ware controlled 3D printing process. The high-resolution CLIP printer has enabled multiple applications in directions ranging from novel drug delivery platforms, 2.5D microelectronics packaging strategies and miniature capacitive pressure sensor systems.

B. J. Lee*, K. Hsiao*, G. Lipkowitz, T. Samuelsen, J. M. DeSimone “Characterization of a 30 micron pixel size CLIP-based 3D printer and its enhancement through dynamic printing optimization”, Additive Manufacturing, 55, 102800, (2022). *equal contribution [doi]
K. Hsiao*, B. J. Lee*, T. Samuelsen, G. Lipkowitz, D. Ilyn, A. Shih, M. T. Dulay, L. Tate, E. S. Shaqfeh, *Joseph M. DeSimone “Single-digit-micrometer-resolution continuous liquid interface production 3D printer”, in print at Science Advances (2022). *equal contribution [doi]

Passive microrheology measurement of extensional viscosity

I studied the microscopic origin of macroscopic stress development in semi-dilute polymer solutions using a passive micro-rheology platform. I investigated the stress-induced particle migration trajectories in semi-dilute polymer solutions and employed a second order fluid model to further estimate the normal stress and solution transient extensional viscosity.

K. Hsiao, J. Dinic, Y. Ren, V. Sharma, C. M Schroeder. “Passive non-linear microrheology for determining extensional viscosity” Physics of Fluids, 29(12), pp 121603 (2017). [doi]

Single molecule dynamics of architecturally complex polymers in non-dilute solutions

I used linear DNA solutions as model system to study the dynamics of semi-dilute polymer solutions. I investigated the dynamics of ring polymers and revealed for the first time their single molecule dynamics under strong extensional flow. Simulation further elucidated the topological constraints in ring polymers that led to strong hydrodynamic coupling of ring’s double strands. (Collaboration with Prof. Charles Sing at UIUC)

K. Hsiao, C. M. Schroeder, C. E. Sing “Ring polymer dynamics are governed by a coupling between architecture and hydrodynamic interactions” Macromolecules, 49(5), pp1961-1971 (2016). [doi]
Y. Li, K. Hsiao, C. A. Brockman, D. Y. Yates, G. B. McKenna, C. M. Schroeder, M. J. San Francisco, J. A. Kornfeld, R. M. Anderson. “When Ends Meet: Circular DNA Stretches Differently in Elongational Flows” Macromolecules, 48(16), pp 5997-6001, (2015). [doi]
Y. Zhou, K. Hsiao, K. E. Regan, D. Kong, G. B. Mckenna, R. M. Robertson-Anderson, C. M. Schroeder “Effect of molecular architecture on ring polymer dynamics in semidilute linear polymer solutions”, Nature Communications, 10(1), pp 1753, (2019). [doi]

This work revealed the role of local intermolecular interactions on non-dilute polymer solutions stretching dynamics. Under near equilibrium flow condition, I found the longest relaxation time of semi-dilute polymer solutions followed the blob theory’s power-law scaling: $\tau \sim (c/c^* )^{0.48}$. Under strong extensional flow, the transient stretching dynamics showed a significant decrease in molecular extension compared to the ultra-dilute solutions due to intermolecular interaction.

F. Latinwo, K. Hsiao, C. M Schroeder “Nonequilibrium thermodynamics of dilute polymer solutions in flow” The Journal of chemical physics, 141(17), pp 174903 (2014). [doi]
K. Hsiao, C. Sasmal, R. Prakash, C. M. Schroeder. “Direct observation of DNA dynamics in semidilute solutions in extensional flow”, Journal of Rheology, 61, pp 151-167 (2017).[doi]
C. Sasmal, K. Hsiao, C. M. Schroeder, R. Prakash. “Parameter-free prediction of DNA dynamics in planar extensional ow of semidilute solutions”, Journal of Rheology, 61, pp 169-186 (2017). [doi]