Controller and control method of fpga-based scanning ion conductance microscope

Abstract

The invention provides a controller and a control method based on a FPGA (Field Programmable Gate Array) of a scanning ionic conductivity microscope. The controller comprises a communication unit and a clock unit, wherein the communication unit is respectively connected to an upper computer and a PID (Proportion Integration Differentiation) solving unit; the PID solving unit is respectively connected to a signal acquisition unit, a PWM (Pulse-Width Modulation) output unit and a DA (Destination Address) unit; the clock unit is used for unifying time sequential routines. The control method comprises the steps that after parameters are initialized and set, the signal acquisition unit is used for acquiring feedback signals, the PID solving unit is used for solving controlled quantity, when the values of the feedback signals are greater than the threshold values of the feedback signals, the PWM output unit is used for controlling a brushless direct current motor to drive a probe and a tray to move, when the values of the feedback signals are less than the threshold values of the feedback signals, the DA unit is used for controlling a piezoelectric ceramic to drive the tray to move, meanwhile, the feedback signals and the controlled quantity are transmitted to the upper computer for display, and the steps are repeated till a control objective is satisfied or an end command is received. The controller is used for the control on a sample scanning image and is small in size; the robustness and intelligence of the controller are improved; the observation imaging speed can be increased under the condition of maintaining the resolution ratio.

Description

technical field [0001] The invention relates to the field of control of brushless DC motors and piezoelectric ceramics, in particular to a controller and a control method of an FPGA-based scanning ion conductance microscope. Background technique [0002] Scanning ion conductance microscopy is a scanning probe microscopy technique whose principle is as follows figure 2 Shown: An Ag / AgCl electrode is placed in an electrolyte-filled glass micropipette as a scanning probe, and a non-conductive sample is placed at the bottom of an electrolyte reservoir. As the glass micropipette approaches the sample surface, the ionic conductance decreases due to the reduced space that restricts the free flow of ions into the glass micropipette tip. When the glass micropipette probe is scanning close to the sample surface, the change of conductance between the electrode in the glass micropipette and another Ag / AgCl electrode in the electrolytic cell is monitored in real time, and the probe is m...

AI Technical Summary

Problems solved by technology

In the scanning ion conductance microscope experiment, the tip of the probe should be moved down vertically to the nanometer distance from the sample surface. The traditional controller focuses on the construction of the protection circuit or the drive circuit, mainly through the feed control of piezoelectric ceramics. The scanning observation experiment showed problems such as slow control and long imaging time of the experiment, and less consideration was given to the system architecture and human-computer interaction

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