A Multi-legged Soft Millirobot With Light And Magnetic Actuation And Humidity Sensing

Intelligent soft robots are one of the important manifestations of human civilization.The development of robotics technology can bring various conveniences,especially in the fields of medical treatment and military affairs.Among them,soft micro-robots have attracted widespread attention in the development of intelligent soft robots.The soft micro-robots have strong adaptability to external shocks and can complete complex tasks in narrow spaces and unstructured environments.In recent years,the soft micro-robot systems have the following characteristics:i)a single-type driving mode;ii)involving less research related to the"leg"structure;iii)lack of a sensing system;vi)not yet combined with triboelectric generators.It is acknowledgement that the soft micro-robots driven by a single mode and lacking a sensing system will be limited in practical applications.In addition,a robot with a"leg"structure can reduce movement resistance and achieve the goal of reducing energy consumption.In order to accelerate the progress and development of the soft micro-robot systems,we use acetylene black(AB)as the photothermal conversion material,and adopt spin coating and magnetic field processing technology to obtain a multi-legged soft robot.The soft robot that can move,climb a slope,swim and sense humidity by near-infrared irradiation(NIR)or magnetic field dual actuation.The specific work is as follows:(1)The preparation of the AB-PDMS/Kapton bilayer polymer composite film with infrared response and the study of its photo-thermo-mechanical properties.Attribute to AB’s strong absorption characteristics of near-infrared light,the composite film has excellent photothermal mechanical conversion performance under 808 nm NIR irradiation.By comparing and analyzing the performance of actuators with different AB mass ratio,we concluded that the optimal thickness ratio of the photothermal layer to the inert layer is about 2.88;Combined with the real-time temperature change curve under NIR irradiation with an incident light intensity of 90 m W/cm~2,it is determined that the induced AB mass ratio should be controlled at about 4 wt%to prevent irreversible plastic deformation.(2)The manufacture of multi-legged soft robot and the exploration of its basic motion performance.Based on the bilayer photothermal actuator,we have prepared a multi-legged soft robot(Millirobot)that responds to NIR light and magnetic field stimulation by introducing magnetic particles and magnetic field processing technology.Under the stimulation of light and magnetic field,Millirobot can complete a series of tasks,such as walking,climbing,swimming and transporting cargos.Furthermore,we analyzed the movement mechanism of the robot under different stimuli,that is,it is a movement pattern similar to frog jumping in the light-driven mode,and a movement pattern similar to human walking in the magnetic-induced mode.(3)Taking into account the structural characteristics of the multi-legged robot,we combined the theory of triboelectric nanogenerator to design a robot-based triboelectric nanogenerator system(Millirobot-TENG)with humidity sensing function.It is worth to note that there is no need for complex sensor system integration,just make Millirobot perform the specified action under the stimulation of light or magnetic field,so that Millirobot-TENG can realize the monitoring of humidity in a narrow space.The Millirobot-TENG has excellent cycle characteristics,and it can not only complete the humidity sensing task,but also complete the sensing of temperature,air pressure,PH value,and special gases in a confined space.