Dr. Samya Sen is a Postdoc in the Appel Lab at Materials Science and Engineering. He earned his doctorate in mechanical engineering from University of Illinois Urbana-Champaign with Prof. Randy H. Ewoldt. His main research interests are soft materials, rheology, and non-Newtonian fluid mechanics. His current focus is studying the rheology of and developing novel hydrogels for biomedical applications.

Stanford Advisors

Current Research and Scholarly Interests

Samya's research interests are primarily soft materials and complex fluids. He uses experimental techniques of fundamental rheology in conjunction with non-Newtonian fluid mechanics to model, characterize, design, and understand soft material behavior. The applications of his research range from yield-stress fluid design in consumer products, industrial materials, and wildfire suppression. His current research projects as a postdoctoral researcher with Prof. Appel is in the rheological of novel hydrogels for biomedical applications, including improved drug delivery. His focus is on developing transient, stimuli-responsive materials with tunable mechanical and mass transport properties which can be tuned in situ and in vitro for controlled drug-release profiles. He also works on mathematical modeling of mass transport, structural evolution, and constitutive behavior of polymeric and colloidal materials in the context of soft biomaterials.

Lab Affiliations

All Publications

  • Soft glassy materials with tunable extensibility. Soft matter Sen, S., Fernandes, R. R., Ewoldt, R. H. 2023


    Extensibility is beyond the paradigm of classical soft glassy materials, and more broadly, yield-stress fluids. Recently, model yield-stress fluids with significant extensibility have been designed by adding polymeric phases to classically viscoplastic dispersions [Nelson et al., J. Rheol., 2018, 62, 357; Nelson et al., Curr. Opin. Solid State Mater. Sci., 2019, 23, 100758; Dekker et al., J. Non-Newtonian Fluid Mech., 2022, 310, 104938]. However, fundamental questions remain about the design of and coupling between the shear and extensional rheology of such systems. In this work, we propose a model material, a mixture of soft glassy microgels and solutions of high molecular weight linear polymers. We establish systematic criteria for the design and thorough rheological characterization of such systems, in both shear and extension. Using our material, we show that it is possible to dramatically change the behavior in extension with minimal change in the shear yield stress and elastic modulus, thus enabling applications that exploit orthogonal modulation of shear and extensional material properties.

    View details for DOI 10.1039/d3sm01150j

    View details for PubMedID 38078477

  • Thixotropic spectra and Ashby-style charts for thixotropy JOURNAL OF RHEOLOGY Sen, S., Ewoldt, R. H. 2022; 66 (5): 1041-1053

    View details for DOI 10.1122/8.0000446

    View details for Web of Science ID 000848363100002

  • Thixotropy in viscoplastic drop impact on thin films PHYSICAL REVIEW FLUIDS Sen, S., Morales, A. G., Ewoldt, R. H. 2021; 6 (4)
  • Rheology of fibre suspension flows in the pipeline hydro-transport of biomass feedstock BIOSYSTEMS ENGINEERING Faghani, A., Sen, S., Vaezi, M., Kumar, A. 2020; 200: 284-297
  • Viscoplastic drop impact on thin films JOURNAL OF FLUID MECHANICS Sen, S., Morales, A. G., Ewoldt, R. H. 2020; 891
  • Base-triggered self-amplifying degradable polyurethanes with the ability to translate local stimulation to continuous long-range degradation CHEMICAL SCIENCE Xu, Y., Sen, S., Wu, Q., Zhong, X., Ewoldt, R. H., Zimmerman, S. C. 2020; 11 (12): 3326-3331


    A new type of base-triggered self-amplifying degradable polyurethane is reported that degrades under mild conditions, with the release of increasing amounts of amine product leading to self-amplified degradation. The polymer incorporates a base-sensitive Fmoc-derivative into every repeating unit to enable highly sensitive amine amplified degradation. A sigmoidal degradation curve for the linear polymer was observed consistent with a self-amplifying degradation mechanism. An analogous cross-linked polyurethane gel was prepared and also found to undergo amplified breakdown. In this case, a trace amount of localized base initiates the degradation, which in turn propagates through the material in an amplified manner. The results demonstrate the potential utility of these new generation polyurethanes in enhanced disposability and as stimuli responsive materials.

    View details for DOI 10.1039/c9sc06582b

    View details for Web of Science ID 000528663000021

    View details for PubMedID 34122840

    View details for PubMedCentralID PMC8152679

  • Acid-Triggered, Acid-Generating, and Self-Amplifying Degradable Polymers JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Miller, K. A., Morado, E. G., Samanta, S. R., Walker, B. A., Nelson, A. Z., Sen, S., Tran, D. T., Whitaker, D. J., Ewoldt, R. H., Braun, P. V., Zimmerman, S. C. 2019; 141 (7): 2838-2842


    We describe the 3-iodopropyl acetal moiety as a simple cleavable unit that undergoes acid catalyzed hydrolysis to liberate HI (p Ka ∼ -10) and acrolein stoichiometrically. Integrating this unit into linear and network polymers gives a class of macromolecules that undergo a new mechanism of degradation with an acid amplified, sigmoidal rate. This trigger-responsive self-amplified degradable polymer undergoes accelerated rate of degradation and agent release.

    View details for DOI 10.1021/jacs.8b07705

    View details for Web of Science ID 000459642000009

    View details for PubMedID 30698426