Additive manufacturing and characterization of microstructures using two-photon polymerization for use in cryogenic applications

Fabricating polymer structures for use at cryogenic temperatures is a non-trivial task due to coefficient of thermal expansion mismatches and stresses that are induced because of this mismatch. This work demonstrates a viable process to additively fabricate polymer microstructures using two-photon polymerization (TPP) on silicon substrates with tetraethylorthosilicate oxide for use at cryogenic temperatures. The process of creating the polymerized structures using resins SR368 and SR499, as well as its application onto the target substrate is detailed. The importance of pre-fabrication adhesion layer processing is discussed and post-polymerization procedures are described. Cryogenic thermal cycling was performed by direct submersion into liquid nitrogen to assess worst-case degradation due to thermal shock and exhibited encouraging shear load failure performance after thermal cycling. The reliability of the test structures demonstrated in this work shows promise for implementing more complex structures using TPP for use at cryogenic temperatures. Graphical abstract