Development And Application Of Soft Actuator Based On Ni-Ti Alloy And Polylactic Acid

Soft actuators with the capability for stable and delicate grasping of soft objects without mechanical damage have attracted increasing attention.At present,soft actuators have been widely used in bionic muscles,soft robots,objects picking,biomedicine and other fields.However,the soft actuator still has the following limitations: it is difficult to drive remotely due to the limitation of tethered power supply,the continuous energy consumption is needed in the working process,and low response force.Therefore,it has important theoretical significance and application value to explore new materials and preparation methods to optimize the performance of soft actuators.In view of the shortcomings of current soft actuators,this paper proposes to use the phase transition temperature difference characteristics of different materials to fabricate untethered soft actuators with holding force.Focusing on the untethered soft actuator,this paper mainly carries out the following three aspects of work:(1)A kind of untethered soft actuator model with holding force is proposed by using the phase transition temperature difference characteristics of different materials.Based on the principle of this model,a light response soft actuator with holding force is fabricated when the energy supply is stopped,the bending angle and response time of the soft actuator under different power infrared light are tested.In addition,its performance is optimized by improving the photothermal conversion efficiency of the soft actuator.(2)On the basis of the existing soft actuator model,using the two-way memory characteristics of shape memory alloy,the soft actuator can achieve multi-morphological response,and the soft actuator has the holding force in the lower temperature range,when it is in the higher temperature range,the soft actuator has two-way response characteristics.Finally,the thermal response force,response time and repeatability of the multi-morphological soft actuator under different power infrared light are tested.In addition,based on this model,the multi-morphological response of the soft actuator is also realized by using the two-way memory characteristics of the shape memory film.(3)This part of the work builds and perfects the corresponding application system for the fabricated soft actuator and conducts functional verification.The soft actuator is assembled into a gripper,which can still keep grasping the target after the energy supply is stopped;secondly,based on the different resistance characteristics of Ni-Ti alloy at different temperatures,a design that can judge the metal phase transition temperature,the application potential of this soft actuator in the field of signal continuous monitoring is also demonstrated.Then,a multi-functional gripper is fabricated based on the multimorphological soft actuator,which can continuously grasp or grasp-release the target in different temperature ranges;According to the bending stiffness characteristics of various materials of multi-shape soft actuators in different temperature ranges,a temperature alarm system is designed,which can be used to monitor the temperature.When the temperature exceeds the range,the system can sound an alarm.Finally,a bending sensor is fabricated on the basis of soft film to improve the operation accuracy of the actuator.To sum up,the untethered soft actuator model with holding force based on the temperature difference of phase transition of different materials proposed in this paper is helpful to develop soft actuators for different scenes.This kind of soft actuator has the characteristics of large response force and no continuous energy consumption,so it has great application potential in biomedical and other fields.