In Situ Reversible and Repeatable Actuation of the 3D-Printed Micro-Scale Cantilever Covered With a Light-Heat Converting Film as a New Approach Toward 4D Printing

We present a new approach for in situ actuating of a microscale 3D-printed polymer cantilever utilizing a laser beam. To enable the polymer cantilever deflection, a light-heat converting film consisted of carbon nanotubes (CNT) or nitrocellulose lacquer was applied to the surface of the cantilever. This film causes IR absorption and its efficient conversion into heat that induces local change in the phase of the structural material and, therefore, the cantilever deflection and hence actuation. To our knowledge, this solution has not been previously presented in the literature. The research was conducted on the cantilevers printed using the inkjet technique. The results demonstrated a direct correlation between the laser power supply current and the deflection of the cantilevers tip; with adjusting the current, the beam tip achieved a significant deflection ranging from tens to hundreds of micrometers. Additionally, for 100 cycles, where in one cycle the laser beam was ON-OFF, the cantilever retained its mechanical properties; meanwhile, the film endured. These findings open new possibilities for the practical application of this remote actuation method across various fields of engineering, in micro- and microscale, and beyond, such as 4D printing structuring components and further for advanced actuators and sensors. [2025-0010]