Studies On Intelligent Sensing Devices Based On Pressure Sensors And Actuators

Sensors and actuators with sensing function are a type of devices which are closely related to people's life.Their common characteristics are that they can detect pressure and electrical stimulus signals and realize force-electricity conversion.In our actual life and industrial production,electrical signals are the easiest to detect and force is ubiquitous,thus it is necessary to study the relationship between signals of force and electricity.This paper takes flexible intelligent sensors and actuators as research objects,and discusses some problems existing in the manufacturing methods and applications.The main research contents and innovations are as follows:1.By changing the internal structure of the active material,a force electric sensor is constructed.Sensor devices were fabricated using a commercial,lightweight,low-cost,compressible manufacturing material and a convenient manufacturing technique.The commercial melamine foam was transformed into a graphitized elastic carbon foam with partially fractured internal fibers by simple carbonization treatment.Compared with the three-dimensional structural sensors that have emerged in recent years,it not only avoids the problem of complex process and expensive material,but also overcomes the shortcoming of dull,unstable,and work with difficulty at pressures below 10 kPa.The obtained piezoresistive sensor exhibits an excellent sensitivity of 100.29 kPa^-1 and a good stability during 11000 repeated press-release cycles.It is worth mentioning that a small mass of 30.4 mg corresponding to 3 Pa can be detected clearly.2.By changing the contact between active materials and electrodes,a force electric sensor is constructed.The performance of the sensor was improved by using wrinkled graphene film as conductive material and water-soluble polyvinyl alcohol nanowire as a spacer.Starting from the active material and structure design,which are the two main factors affecting the piezoresistive sensor performance,the wrinkled graphene film as the conductive material was obtained through PDMS template with rough surface,and the polyvinyl alcohol nanowire as the isolation layer to regulate the sensor structure was obtained by electrostatic spinning preparation technology.This not only avoids the disadvantages of complexity,high cost,time-consuming and long photolithography caused by traditional lithography process,but also overcomes the shortcoming that the general isolation layer is easily saturated due to its uniform microstructure.The device shows an amazing high sensitivity of 28.34 kPa^-1 with the ability to identify lightweight rice weighing about 22.4 mg?2.24 Pa?.It also demonstrates good cycling stability during 6000repeated pressure and release cycles.Meanwhile,it is capable of detecting subtle pulse beat and monitor various human movement behaviors.3.By constructing MXene and LDPE bilayer structure,the actuator of electric-force conversion is realized.High performance actuators were made of two materials,MXene and low density polyethylene?LDPE?,which have large thermal expansion coefficient.MXene,as a member of novel two-dimensional materials,has the merit of good surface hydrophilicity,excellent conductivity,and good chemical stability.Many achievements about MXene have been made in various fields.However,the adoption of MXene in actuator is rarely mentioned.The actuators of MXene and LDPE bilayer structures were obtained by simple coating method.It can response quickly under low voltage,lift 6.4times of its own weight under thermal stimulation,and carry weight forward under light stimulation.It overcomes the disadvantage that the voltage or temperature of general actuator is too high,which leads to the waste of resources.The actuator can be easily integrated into the circuit with other devices,and has a great application prospect in the future integrated devices.