The Detecting Device Design Of Micro Current Based On Tunneling Effect

A detecting device of micro current signal is introduced in this paper, the purpose of the thesis isresearch detecting device used for SPM. In the scheme, piezoelectric stack is used for micro-driveactuator, and piezoelectric lifting platform is used for the macro-drive actuator for Z-axis. Thismicro-drive and macro-drive combination with the piezoelectricity platform of two dimensionalaccurate displacement, the probe, amplifying circuit, manual displacement, platform, manual slopedplatform and other instruments, make up the three dimensional precision drive system—the SPMsystem(Scanning Probe Microscopy system). The research of the micro current signal detectingdevice is aimed at detecting the micro current produced by SPM system based on tunnel effect. Apractical and high-integration micro current signal detection technology is achieved which can detectthe micro current. This will promote the further research development of SPM system.The hardware, software and the mechanical design of the system were determined based on therequired function of the system. After the circuit design and PCB board system, the hardwaredebugging was completed. After the software architecture design and program, the software andhardware circuit joint debugging was completed. After the design and manufacture of the mechanicaldevice, integrated debugging of mechanical devices, circuits and software was completed. The systemexperiment realized the designed function of the system. Through the test and optimization of thevarious subsystems of SPM system, the stability and reliability of the SPM system was improved.In order to realize the micro current detecting device design based on the tunnel effect, STMprobe, the design of micro current detection circuit, and the design of the signal processing hardwarewere completed. After using Multisim software to simulate and verify the designed circuit, usedAltium Designer to draw the schematics, completed the debugging of hardware circuit. The subjectcompleted the digital signal processing, realized the PID control, and completed the program forZ-axis and precision drive control using MATLAB combined with the C language in dSPACEenvironment. The design and debugging of SPM system was completed, and related experiments werecarried out. The experimental results showed that the micro current of the micro current wassuccessfully detected, the micro current detecting device design based on tunnel effect was achieved.