Femtosecond Laser Preparation Of Smart Soft Micro And Nano Actuators

As technology advances and society develops,miniaturised and intelligent products are widely sought after and enjoyed.Nowadays,new technological terms such as 3D printing,4D morphing and micro-nano robotics are well-known and are playing their unique role in various fields.Traditional actuators are mostly mechatronic systems made of rigid materials(e.g.metal,silicon and silica)and therefore have a range of problems such as poor biocompatibility,flexibility and biodegradability,which limit their application in the biomedical field.The emergence of intelligent soft materials that are soft and adaptive has therefore given rise to endless visions of the future.Smart materials are generally composed of hydrogels with high biocompatibility,excellent physico-chemical properties and a moderate elasticity,which are generally driven by non-passive environmental stimuli.The translation of this drive into mechanical response behavior is significant for the development of,for instance,smart microactuators and micro-electromechanical systems.The development of ultrafast lasers and in particular femtosecond laser direct writing technology has been a great boon for micro and nano robotics as well as MEMS technology.In comparison with traditional processing technologies,femtosecond laser nanofabrication technology has the advantages of true 3D,high spatial resolution,high precision and universal applicability of materials,which brings a lot of practical efficiency and vision in the fields of biomedicine,tissue engineering,analytical chemistry,optics,etc.This thesis focuses on soft and smart micro-nano actuators,using femtosecond laser two-photon micro-nano processing to prepare smart material-based structures and to explore and optimise parameters for the further design of functional micro-nano actuators.The major research accomplishments are as follows:1.The theoretical basis and application of the different mechanical response of the internal network density of the material under the external environmental stimulus is proposed.Firstly,PBMA,a smart material with chemical solvent response,was processed by femtosecond laser,and PBMA-based smart 4D deformable soft micronano actuator was prepared in one step by specifically studying the relationship between different laser scan steps and expansion ratio of the processed micro-nano structure,and the angle of bending and oscillation under different laser scan steps and stimulation response of the double layer.The BSA protein material is highly biocompatible and flexible,and has the characteristics of p H stimulation response,which can provide important help for single cell manipulation and target delivery.In this paper,by taking the swelling of BSA in different p H aqueous solutions as the starting point of research,we specifically explore the swelling ratio of different internal network densities and stimulus response,and design a soft intelligent micro-mechanical arm with different network densities of the same material,and the combination of soft and hard can finally realize the grasping and releasing of micro-nano rods.Through the exploration and research of this paper,it can provide certain reference value and help in the domains of medical treatment,bioengineering,nano optics,and micro and nano deformation robots.2.A tunable artificial intelligent compound eye system is proposed.Unlike the mammalian monocular eye,the natural compound eye structure does not have the function of focal length adjustment.In this study,an artificial compound eye system based on BSA(bovine serum albumin)smart material was prepared by combining the large visual field angle of the compound eye with the advantage of adjustable focal length of the monocular eye by means of femtosecond laser two-photon polymerisation.In the experiment,the focal length of the artificial compound eye system was adjusted by changing the p H value of the solution to obtain a large field of view with intelligent tunable imaging.Furthermore,to enhance the stability of the artificial compound eye system,a high intensity compound eye with excellent imaging was obtained by coupling the rigid material SU-8 as a microlens with BSA using a femtosecond laser with two photons.