Interfacial Controlled Fabrication Of Bionic Skin And Their Flexible Sensing/Actuation Applications

Skin is the largest organ of organisms,which bridges the gap between the outside world and the body’s integumentary system.It can actively sense the physical or chemical strimuli from the environment and further behave like deformation or changing body colors to survive and adapt itself.Inspired by these specific capabilities,a variety of flexible E-skin,soft actuators and their integration devices havebeen developed,demonstrating significant potentials in boosting the field of soft robtics and artificial intelligence.Specifically,the interface structure and interactions of functional components have played crucial rules in the realization of high-efficient and reliable device performance.However,there are still lack of effective strategies to refinedly control the interface structures and their effect on the achieved functions.In the bionic skin system,it is significantly important to effectively adjust the interface structure between conductive layer and flexible/stretchable layer,illustrate the mechanism of multifunctional composition,achieve sensitive and stable sensing function and further develop an integrated bionic device with synergetic sensing and actuating behaviors.In this thesis,the biomimetic skin was developed by in-situ modified of carbon nanomaterials and polymer elastomers at the water-air interface.The main work are as follows:(1).The self-assembly behavior of different carbon nanomaterials at the water-air interface was studied.It is proved that the interfacial self-assembly behavior of carbon nanomaterials is of great significance for the stability of water-air and water-oil interfaces.Furthermore,in situ asymmetric modification of CNTs films at the wateroil interface and in situ composite with polymer elastomers at the water-air interface were achieved.It provides a theoretical guidance for the subsequent asymmetric interfacial composites of carbon nanomaterials to prepare biomimetic skin.(2).A self-adhesive CNTs/TPE epidermis electronics with embedded interlocking structure were prepared at the water-air interface,which effectively improves the interface stability between carbon nanotubes and TPE substrate.Moreover,it has good sensing performance and durability even after 1000 times of cyclic stretching.Due to the ultra-thin(1.8μm)properties,the CNTs/TPE film can be conformally attached to the skin surface for real-time human physiological behaviour detection.Additionally,the free-standing hybrid film can be employed for the effective detection of tiny airflow changes and even acoustic vibration.(3).Swimming bladder inspired underwater self-sensing soft actuator was constructed by a sandwiched assembly of the water-air interfacial prepared PDMS and CNTs/PDMS films.Due to the excellent flexibility and elasticity of the PDMS film,the controllable vertical motion of the actuator is realized under the reversible elastic deformation driven by external air pressure.In addition,the neural-like function of biological skin was achieved by integrating CNTs film,enabling it to real-time track the motion process and sense the surrounding environment.As a proof of concept,an artificial swim bladder is designed to perceive the external vibration stimuli and further navigate its directional underwater motion,demonstrating significant potentials in intelligent bionic applications.(4).A skin-inspired negative strain sensor based on wrinkled interfacial graphene/PDMS film is fabricated.The resultant sensors exhibit large detection range(up to 180%),high sensitivity(-1.17)and fast response time(< 0.1s)and high durability with over 5000 cycles under the maximum test range(70% for E100P5G).The negative sensor shows good performance for detecting human activites.It’s similiar the sensory properties of the skin,which produces stronger nerve signals under strong stimuli.Meanwhile,the negative sensor has a good ability to distinguish the strain and compress deformation.In conclusion,a skin-inspired hybrid film was prepared through a simple,efficient and low-cost method by in-situ water-air interface modification,which effectively solved the drawback of traditional film preparation on solid substrate.The resultant film can be used as a self-adhesive epidermal electronic with excellent stability.Moreover,the seamless integration of sensing and actuation performance of the film was realized as the function of biological skin,which demonstrates the great potential applications in artificial intelligence and wearable electronics.