Fig. 1. Direct writing of micro-nano structure of smart materials. (a) Chemical molecular structure of the composition of the photoresist and a photo of an actual sample; (b) schematic diagram of femtosecond two-photon polymerization system used to 3D processing; (c) schematic of double-layer mesh structure with different line spacing and its shape transformation; (d) SEM image of the double-layer six-petal structure; (e) shape transformation diagram of the self-bending six-petal structure in water

Fig. 2. Dependence of the width and height of suspension beam model on laser power and scanning speed. (a) Diagram of line width with respective to the laser power and scanning speed, in which the inset shows the SEM image of the suspended cantilever fabricated under the laser power of 20mW and scanning speed of 1000μm·s^-1; (b) diagram of line height with respective to the laser power and scanning speed, in which the inset shows the 45° titled SEM image of the suspended cantilever

Fig. 3. Swelling degree test of hydrogel materials under different direct writing parameters. (a) Three-dimensional network diagram of the monomer material formed by chain polymerization and the chemical structural formula of the stimulus responsive group existing in the monomer material; (b) schematic diagram of football swelling; (c) optical microscope image of football model during swelling and de-swelling process under laser power of 15mW and scanning speed of 500μm·s^-1; (d) swelling degr

Fig. 4. Variation of mechanical modulus of hydrogel materials under different laser direct-writing parameters. (a) Stress-strain curves of hydrogel materials formed under different laser powers at a scanning direct writing speed of 250μm·s^-1(the solid line represents the loading curve of the head and the dotted line represents the unloading curve), and a scanning electron microscope image of the test block; (b) test results of mechanical modulus of hydrogel materials under different laser dir

Fig. 5. Design, manufacturing and testing of the double-layer actuation microstructure. (a)(b) Self-bending and self-curling topography of the double-layer ribbon microstructure based on finite element simulation calculations and corresponding experimental results; (c) different self-bending effects obtained using different laser direct writing parameters; (d) microstructure design of bionic mimosa and the effect of laser direct writing manufacturing, and the upper left corner is the undeveloped and dev