Fig. 5. Fabrication of modular multicomponent soft microrobots with multiple transformations.

(A) Stripe-shaped microstructures fabricated by applying droplets with fluorescent green, red, and blue nanoparticles to different parts of the microelectrode. After the shape transformation under pH or ionic stimuli, the stripe microstructure transformed into helical and coiled microstructures with two and three separated modules. Scale bars, 500 μm. (B) Modularized fabrication of two-fingered microrobot with customized components including fluorescent nanoparticles, cells, and MNPs and execution of bidirectional bending on horizontal module and twisting on vertical module. Scale bars, 500 μm. (C) The two-, three-, and four-fingered microrobots with modular design can respond to ionic and pH stimuli. The white dashed line indicates the position of the section view of the current density simulation results. The FEA simulation revealed the shape-morphing process of the two-, three-, and four-fingered microrobots. Scale bars, 600 μm.