At the NWO Biophysics 2025 Conference, PhD candidate Ana Sofia Oliveira Nogueira presented innovative work on understanding how hydrogels—materials commonly used as skin surrogates—respond to high-speed liquid microjets. This research supports the development of needle-free injection systems, an emerging technology offering a less painful and more sustainable alternative to traditional needles.

Needle-free injections rely on ultra-fast liquid jets to deliver medication through the skin. To optimize these systems, researchers must understand how skin-like materials deform and recover during impact. However, hydrogels often behave inconsistently at small scales, making precise analysis essential.

The study uses ultrafast high-speed imaging combined with Particle Image Velocimetry (PIV) to capture and analyze the deformation of agarose and alginate hydrogels as they are struck by microjets. By tracking microscopic particles within the gels, this method reveals how the material moves, stretches, and absorbs mechanical energy during impact.

From these measurements, the team estimated key mechanical properties of the hydrogels. The agarose samples showed mechanical behavior consistent with previous studies, confirming the reliability of the method. Alginate hydrogels showed much softer characteristics, indicating that the preparation protocol may require further refinement for needle-free injection research.

Overall, the work demonstrates that ultrafast PIV-based imaging is a powerful tool for evaluating hydrogel performance and understanding cavity formation during microjet impact. These insights contribute to the ongoing development of safer, more efficient, and more sustainable needle-free injection technologies.