Fig. 1. Schematics of intelligent micro-nano device.(a) Original state of intelligent micro-machine before pH stimulation; (b) in response to the stimulus of pH, the intelligent micro-machine “grasps” micro-nano particle

Fig. 2. pH-response properties of BSA structures. (a)Optical microscope images of BSA block structure (15 μm×15 μm×5 μm) processed at three scanning step lengths (100, 150, and 200 nm) in solvent with different pH values; (b) variation of swelling rate of BSA structure processed at three step lengths with pH value; (c) relationship between response time and swelling ratio; (d) relationship between swelling to 100 cycles of stimulation and the swelling ratio in a solvent with pH of 13

Fig. 3. Fabrication and characterization of BSA-based block structure with non-uniform scanning step lengths. (a) 3DMAX model of BSA block structure;(b) SEM images of BSA block structure;(c) three-dimensional laser confocal microscopy image of BSA-based block structure;(d) cross-sectional profile of BSA-based block structure

Fig. 4. Dynamic response of BSA-based lilayer cantilever structure. (a)3DMAX model of lilayer cantilever structure; (b) relationship between cantilever bending angle and double-layer scanning step length; (c) SEM image of BSA-based cantilever structure;(d) SEM image of BSA-based cantilever structure tilted at 30°

Fig. 5. pH-driven intelligent micro-machine. (a) Responses of micro-machine to pH stimulus; (b) repeated reversible actions of “grasping”, “releasing”, and “grasping tightly” by the intelligent micro-machine; (c) distance between the micro-mechanical cantilever versus response time; (d) micro-mechanical cantilever enables 100 cycles switching in a solvent with pH values of 5 to 13