Size-Change Behavior of Free-Form Microstructures During Ultrafast Laser Direct Writing Within Pure-Protein Precursors

Ultrafast laser direct writing (LDW) is a versatile 3D microfabrication technology with a high spatial resolution, reduced heat accumulation, and a diverse range of applications usually tied to the applied precursor material. When using a protein precursor, it is possible to fabricate proteinaceous microstructures with the native protein function retained for use in cell cultures, lab-on-a-chip, and soft robotics. It is common to fabricate such proteinaceous microstructures by adhering them to glass. However, when we perform so-called free-form fabrication, without any substrate adhesion, we observe size changes during the fabrication process. This study quantified the in-precursor size changes to increase predictability. We also evaluated a potential mechanism for these changes by examining the role of protein hydration shells. These findings are expected to contribute to the fabrication of desired designs and promote the use of this technology.