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Abstract
Thermoresponsive hydrogels such as poly(N-isopropylacrylamide) (pNIPAM) are highly interesting materials for generating soft actuator systems. Whereas the material has so far mostly been used in macroscopic systems, we here demonstrate that pNIPAM is an excellent material for generating actuator systems at the micrometer scale. Two-Photon Direct Laser Writing was used to precisely structure thermoresponsive pNIPAM hydrogels at the micrometer scale based on a photosensitive resist. We systematically show that the surface- to-volume ratio of the microactuators is decisive to their actuation efficiency. The phase transition of the pNIPAM was also demonstrated by nanoindentation experiments. We observed that the mechanical properties of the material can easily be adjusted by the writing process. Finally, we found that not only the total size and surface structure of the microactuator plays an important role, but also the crosslinking of the polymer itself. Our results demonstrate for the first time a systematic study of pNIPAM-based microactuators, which can easily be extended to systems of microactuators that act cooperatively, e.g., in microvalves.
Document type: | Preprint |
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Publisher: | Universität |
Place of Publication: | Heidelberg |
Date Deposited: | 22 Dec 2022 10:55 |
Date: | 2022 |
Faculties / Institutes: | Fakultät für Ingenieurwissenschaften > Institute for Molecular Systems Engineering and Advanced Materials |
DDC-classification: | 000 Generalities, Science 500 Natural sciences and mathematics 530 Physics 540 Chemistry and allied sciences 620 Engineering and allied operations |
Uncontrolled Keywords: | soft microactuators, direct laser writing, two-photon-polymerization, responsive 23 materials, thermoresponsive hydrogels |
Additional Information: | This is the pre-peer reviewed version of the following article: Spratte, T., Geiger, S., 1 Colombo, F., Mishra, A., Taale, M., Hsu, L.-Y., Blasco, E., Selhuber-Unkel, C., Increasing the Efficiency of Thermoresponsive Actuation at the Microscale by Direct Laser Writing of pNIPAM. Adv. Mater. Technol. 2022, 2200714., which has been published in final form at https://doi.org/10.1002/admt.202200714. |