Paper Number
AM5                         My Program 

Session
Additive and Advanced Manufacturing

Title
Stabilizing liquid threads in embedded 3D printing

Presentation Date and Time
October 21, 2025 (Tuesday) 2:50

Track / Room
Track 5 / O’Keeffe + Milagro

Authors (Click on name to view author profile)

  1. Hossain, Mohammad Tanver (University Of Illinois Urbana-champaign, Mechanical Science and Engineering)
  2. Eom, Wonsik (University Of Illinois Urbana-champaign, Mechanical Science and Engineering)
  3. Tawfick, Sameh H. (University Of Illinois Urbana-champaign, Mechanical Science and Engineering)
  4. Ewoldt, Randy H. (University Of Illinois Urbana-champaign, Mechanical Science and Engineering)

Author and Affiliation Lines (in printed abstract book)
Mohammad Tanver Hossain, Wonsik Eom, Sameh H. Tawfick and Randy H. Ewoldt
Mechanical Science and Engineering, University Of Illinois Urbana-champaign, Urbana, IL 61801

Speaker / Presenter 
Hossain, Mohammad Tanver

Keywords
additve manufacturing; advanced manufacturing; applied rheology; non-Newtonian fluids; rheometry

Text of Abstract
The stability of a liquid filament embedded within a yield-stress medium is governed by a balance between interfacial tension and the resistance of the supporting matrix. We asked a fundamental question: What is the smallest stable filament diameter achievable in embedded 3D printing, given a supporting matrix with a known yield stress? We found that the minimum diameter is governed by a previously unidentified critical plastocapillary number (yield-capillary number) [1], which captures the competition between capillary forces and the yield stress of the surrounding viscoplastic medium. When the plastocapillary number falls below a critical threshold, filaments break up due to capillary-driven instabilities. We were also motivated by another question: how can we push beyond this limit? To do so, we created a new embedded printing technique that rapidly solidifies the liquid filament upon deposition using a solvent exchange mechanism [2]. This strategy enables the formation of stable, ultra-thin filaments far below the predicted critical diameter, expanding the resolution frontier of embedded 3D printing additive manufacturing.

[1] Hossain M. T., W. Eom, A. Shah, A. Lowe, D. Fudge, S. H. Tawfick and R. H. Ewoldt, “The critical plastocapillary number for a Newtonian liquid filament embedded into a viscoplastic fluid,” Journal of Non-Newtonian Fluid Mechanics, in revision. DOI: 10.2139/ssrn.5120697
[2] Eom, W., M. T. Hossain, V. Parasramka, J. Kim, R. W. Y. Siu, K. A. Sanders, D. Piorkowski, A. Lowe, H. G. Koh, M. F. L. De Volder, D. S. Fudge, R. H. Ewoldt and S. H. Tawfick, “Fast 3D printing of fine, continuous, and soft fibers via embedded solvent exchange,” Nature Communications, 16, 842 (2025). DOI: 10.1038/s41467-025-55972-1