Research On Bio-inspired Water Strider Robot Based On Superhydrophobic Surface

Aquatic micro-robots which can walk freely on water like water striders have attracted considerable interests among scientists in biomimetic area,these biomimetic robot showed a potential prospect in the fields of water quality monitoring,aquatic exploration,and other surveillance missions.The supporting legs were obtained on Al substrates by the process of chemical etching,boiling-water immersion and surface energy reduction.This robot is driven by four mini-type digital servos and controlled by control panel which integrated a Bluetooth 4.0 module.(1)Analyze the important part surface tension play when water strider floating or sliding on water surface;Analyze the water strider floating mechanism and establish the mechanics analysis model;Deduce the two-dimensional contour curve equation of water –air when water strider les contacting with the surface water based on Young-Laplace equation.(2)Taking into consideration the shortage of preparation of superhydrophobic surface,chemical etching,boiling-water immersion and fluorination was adopted.The wettability of obtained samples was researched;the micro-morphology,crystal structures,and chemical composition of the prepared superhydrophobic surfaces on Al substrate were analyzed to explore the formation mechanism of special morphology on the surface.Results show that,the micrometer-scale rectangular-shaped plateaus and step-like structures and nanometer-scale needle-like structures are formed on the Al surface after chemical etching and boiling-water immersion,which has a superhydrophilic property while after modified by FAS,it transforms into a superhydrophobic surface with a water contact angle of 168° and sliding angle of 2°.(3)Fabricate the supporting leg using the above chemical etching,boiling-water immersion and fluorination method.The micro digital servos are used as the driving mechanism of the bionic water strider robot,and the program control board is written in Arduino to complete the assembly of the bionic water strider robot and carry out the water test.Comparing the loading capacity of the supporting leg of different processing methods and the results showed that the above processing method made the support leg better loading capacity.On the premise of ensuring that the support leg is not into the water,the maximum compression depth is 5.05 mm,and the volume of drainage water is increased and the maximum loading is 42.5 g compared with the support leg that is not treated.The loading capacity is doubled as compared with the support leg that is not treated..(4)The force analysis model is established and the force analysis and calculation are carried out based on the model.The results of theoretical calculation are compared with the actual measurement results.The results show that the maximum error between the theoretical loading and the actual loading is less than 7%,which shows that the force analysis model is suitable for the load calculation of the bionic water robot.