Asymmetric microstructure of hydrogel: two-photon microfabrication and stimuli-responsive behavior

Abstract

We propose an asymmetric three-dimensional (3D) multiphoton polymerization microfabrication method, and successfully demonstrate it through fabricating the size- and shape-controlled stimuli-responsive asymmetric hydrogel microcantilevers. The reversible ion-responsive hydrogel microcantilevers exhibit attractive and controllable bending behavior due to their asymmetric deformation to external ions. The reversible bending direction of microcantilevers completed within only 0.133 s when the surrounding environment was alternated from water to 1 M NaCl solution. Furthermore, the microcantilevers exhibited large total bending angles θ_T up to 32.9°. The bending behavior can be also strongly influenced by increasing the length of the microcantilevers. The 3D stimuli-responsive hydrogels were demonstrated to be promising for the application of microactuators and micromanipulators. This designable microfabrication technique and the stimuli-responsive behavior of asymmetric microstructure of hydrogel with versatility in the shape would be prospective for developing biomedical microdevices.