4D Printing and mechanical characterization of a thermo-responsive hydrogel at the microscale

4D Printing and mechanical characterization of a thermo-responsive hydrogel at the microscale

Cussen, Kai (TU Delft Mechanical Engineering)

Mirzaali, Mohammad J. (mentor)
Accardo, A. (mentor)
Yarali, E. (mentor)

Delft University of Technology

Mechanical Engineering | BioMechanical Design

2024-06-24

Thermo-responsive hydrogels are a class of smart material that show increasing promise and applications in the biomedical engineering industry. This thesis investigated a thermo-responsive hydrogel for 4D printing applications. A poly(N-isopropylacrylamide) (>97%) (pNIPAM) based hydrogel was developed and the concentration of NIPAM, as well as the molar ratio of crosslinker, N,N-methylenebis (acrylamide) (>99%) (Mbis), to monomer was investigated to determine an optimal resin composition, which was determined from the thermo-response of the hydrogel at the microscale.
The resins were used to print several bilayer beams with varying laser power, scanning speed and hatching angles. Once the optimal composition and printing parameters were determined, mechanical characterization of the hydrogel was performed to measure the Young’s modulus at various loading rates via nanoindentation.
The thermal expansion coefficient (TEC) of the hydrogel was measured in three orthogonal directions at different temperatures. Finally, based on the shape morphing behaviour of the bilayer beams, we developed shape morphing applications at the microscale including a thermo-responsive micro-gripper and thermo-responsive drug delivery valve. The purpose of this work was, therefore, to explore possible applications of such a hydrogel and the ability to print with it in the microscale via two photon polymerization.

4D Printing
Biomaterials
microscale
Two photon polymerization
Hydrogel

http://resolver.tudelft.nl/uuid:790e1ff8-d0bd-418a-a595-d32c19d29dc0

2026-06-24

Campus only

Student theses

master thesis

© 2024 Kai Cussen