The Fabrication And Magnetic Actuation Characteristics Of Biomimetic Microrobot Based On PDMS&Fe₃O₄ Film

With the increasing demand for precision operations in tiny regions,the application of microrobots have embraced promising prospects,and the widespread demand has motivated its rapid development.Although advanced micro-nano processing technology has promoted the development of microrobots of various configurations,the material composition and manufacturing of microrobots are still relatively single limited by the processing characteristics of materials,so it is significant to study multi-mode fabrication schemes.This paper proposes a method for fabricating a magnetic microrobot based on a PDMS&Fe₃O₄ bilayer.A flexible flagellar microrobot and a helical microrobot can be simultaneously fabricated using bilayer structure,which are actuated by a uniformly oscillating magnetic field and rotating magnetic field,respectively.The experimental actuation was performed in the self-built magnetic field actuation system.In the fabrication scheme of helical microrobots,a bilayer structure composed of a magnetic layer and a non-magnetic was proposed.The prestrain of the non-magnetic layer induced self-scrolling of a bilayer,and the bilayer was patterned according to a corresponding cutting scheme to obtain a helical structure,and the effect of the fabrication parameters on the helical parameter was studied.By studying the multipatterned prestrain schemes,the corresponding self-scrolling structures were obtained,and the container structure can be integrated on helical structure.Through the additional use of the bilayer structure and a corresponding cutting scheme,a flexible flagellar microrobot consisted of a magnetic head and a non-magnetic tail was fabricated.According to the actuation type of the prepared microrobot,a uniform magnetic field actuation system was built.The parameter design of the coil was completed through theoretical calculation,and a two-axis Helmholtz coil was manufactured.By designing the excitation module of the coils and integrating the generation algorithm of rotating and oscillating magnetic fields in the control software,a real-time controllable excitation current can be generated,so that the coil system can generate the required actuation magnetic field.In the detection of the magnetic field in coil,the accurate measurement of the alternating magnetic field was implemented by using a linear Hall sensor,which verified that the magnetic field can meet the experimental requirements.In the aqueous medium,the actuation experiment of helical microrobots with different parameters were actuated in a rotating magnetic field to study frequency response,and analyze relationship between helical parameters and swimming speeds.To study the effect of medium viscosity on the swimming performance of microrobot,the experiments were implemented on glycerin solutions with different concentrations.Due to the loading capacity of the helical structure with container,the magnetization effect on swimming stability was analyzed,and the positive effect of radial magnetization on swimming stability was demonstrated.The flexible flagellar microrobot was actuated in water using an oscillating magnetic field,and a dynamic model was established to study its oscillation characteristics.For these torque-actuated microrobots,the mechanism of step-out was demonstrated by studying their frequency response characteristics.