Electronic Control System For Scanning Electrochemical Microscopy Study

Scanning electrochemical microscope (SECM) is a new scanning probe microscope, which is proposed in 1986 and has a rapid development. According to electrochemical principle, SECM drives little tip close to sample, measures the electrochemical current which is produced by redox, and acquires the information about sample. The resolution of SECM is up to 100 nanometer. For SECM has chemical sensitivity, it is used not only to detect surface of conductor or nonconductor but also to distinguish electrochemical character of non-uniformility surface and to fabricate in micron.Presently commodity of SECM has been produced abroad, and it is very expensive. There isn't apparatus of SECM in China. The paper mainly designs the electronic control system of SECM, which includes power supply of piezoelectric ceramic and micro-current detection. The paper is to provide technical preparation for the research and design of SECM..SECM chooses piezoelectric ceramic as micro-positioning stage, which has a super-high resolution in nanometers. The power supply is the key components of piezoelectric ceramic actuators. There are a lot of researches about its power supply, most of which has a complex circuit. After analyzing demands of power supply, the paper designed a new power supply based on voltage-controlled with high voltage amplifier PA69. Thus the integration of circuit is improved, and input offset voltage is compensated. Test proves that the power supply can achieve demands of probe positioning of SECM, and power supply has high precision, simply circuit, and high reliability.There are two work electrodes in cell of SECM. The current signal of work electrode is so weak in nanoampere that it is difficult to be distinguished from the noise. The paper proposes a biopotentiostat with reference electrode of virtual ground. The voltage of two work electrode is controlled dependently by a complete symmetry circuit, which makes design simply and improves anti-jamming. On micro-current detecting, the paper collects signals by a feedback resistor, and amplifies the voltage on resistor by an instrument amplifier AD620. Test proves that the circuit can detect micro-current very well, and overcome disadvantages of some instruments.The control part is designed based on the embedded, 32 bit RISC microcontroller ARM LPC2138. Design a D/A circuit to control power supply of piezoelectric ceramic and Biopotentiostat, a A/D circuit to sample micro-current. Also design an USB circuit of CP2102 to communicate with PC. In software programming , the paper selects C as programming language to realize each functions.In the end, some advice is put forward to improve the performance of SECM, which provides favorable foundation for future research.