CAREER: Multiscale Understanding of Laser-Induced Bubble Dynamics and the Mechanism of Resultant Jet Flow in Thin-Shearing Hydrogels

Hydrogels possess promising properties, such as biocompatibility and mechanical flexibility. This makes them ideal for various biomedical and energy applications. Currently, hydrogel fabrication relies on laser-assisted printing.

In this process hydrogel jet formation is driven by the generation, expansion, and collapse of laser-induced bubbles. Although there is extensive research on laser interactions with liquids, the fundamental dynamics of laser-induced bubbles in hydrogels is not well understood. This research aims to combine modeling, simulation, and experimentation to deepen understanding of laser-induced bubble dynamics and the fluid mechanics of hydrogel jet flow in laser-assisted printing processes.

Additionally, the project includes a comprehensive educational framework to promote broadening participation in STEM and foster partnerships with local K-12 schools and the University of Houston’s STEM Zone program. It will also introduce new technical elective courses through an inter-college educational collaboration.

The goal of this research is to integrate experimental and numerical methods to elucidate the complex, multiscale dynamics of laser-induced bubbles in shear-thinning hydrogels and the mechanisms driving hydrogel jet formation. To capture initial bubble formation from laser interactions, the researcher will perform first-principles molecular dynamics simulations at the nanoscale.

At the microscale, a discrete Boltzmann model will be developed to investigate bubble behavior within the hydrogel layer, accounting for viscoelastic effects. A computational fluid dynamics model will also be created, incorporating critical bubble size and hydrogel viscoelastic properties to explore the multi-physics mechanisms of jet formation, growth, and collapse.

Experimentally, a customized high-resolution, time-resolved imaging system with 100-picosecond resolution will be built to observe bubble dynamics and jet formation in the hydrogel. These images and videos will serve to validate the numerical models across scales. The findings from this research will address key knowledge gaps in bubble formation and jet flow mechanisms, laying a theoretical foundation for advancing next-generation 3-dimensional printing technology for multifunctional soft materials.

Additionally, this project has potential applications in diverse fields, such as drug delivery, soft robotics, sensors, and supercapacitors for energy harvesting and storage.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.