Fig. 5. Heat-assisted magnetic programming of soft materials at the microscale.

(A) Scanning a focused laser spot on a magnetic soft elastomer (MSE), which creates a precisely controlled local heating, in a desired pattern is used to program the magnetization profile on that material. (B and C) An example soft structure with six petals (150-μm width, 500-μm length, and 30-μm thickness) is placed on a micropost. Red arrows indicate the magnetization directions of the petals. Magnetic actuation (60 mT) resulted in deformation of petals in reverse directions. (D) A collimated laser can heat a desired shape on a target magnetic soft elastomer in one shot through a mask containing the micropattern of this desired shape. (E and F) Magnetic flux density measurements of example magnetically programmed samples by this micropatterned laser heating. The smallest magnetic pattern is 80 μm in width. Scale bars, 250 μm. (G) Contact transfer of desired magnetic profiles in one shot via global heating. The magnetic soft elastomer is placed in direct contact with NdFeB magnets, with a greater Curie temperature, arranged in different configurations and heated above the Curie temperature of the CrO₂. Magnetization directions of the NdFeB magnets are transferred to the magnetic soft elastomer during cooling. (H and I) Magnetic flux density measurements of the NdFeB masters of different example shapes and configurations and the magnetic soft elastomer slaves. Scale bars, 500 μm and 1 mm, respectively. (J) Contact transfer of a complex magnetization profile in the geometric pattern of Minerva. Insets show close up views of the magnetic flux density profile of the magnetic soft elastomer slave. The smallest magnetic pattern is 38 μm in width. Color bars indicate magnetic flux density strength. Scale bars, 1 mm and 250 μm, respectively.