Li Guo Chen

Movement Modeling and Testing of a Novel Trans-Scale Precision Positioning Stage Based on the Stick-Slip Effect

A novel trans-scale precision positioning stage based on the stick-slip effect was developed. Combining with LuGre friction model, the flexible movement model of the stick-slip driving was established and simulated in Simulink software. Simulation analysis got the displacement and speed curve of slider and the net displacement of each step was calculated. The movement of slider lags behind the PZT actuator. The testing prototype of the stage driving by stick-slip effect was designed and the movement parameters of forward and reverse direction was tested, the results of movement model and simulation was verified by the testing datas. The problem of the difference of forward and reverse movement was proposed.

Design of a Hybrid-Type Electrostatically Driven Microgripper Integrated Vacuum Tool

This work is focused on design and fabrication of a hybrid-type electrostatic silicon microgripper integrated vacuum tool. Vacuum tools are integrated in this novel microgripper in order to improve its pick and place capability. Surface and bulk micromachining technology is employed to fabricate the microgripper from single crystal silicon wafer (i.e., no silicon on insulator wafer is used). And the bonding technology is used to form the gas pipes for the vacuum tool. The linear motion of the microactuator is converted into a rotational gripping motion by a system of spring beams. At a driving voltage of 80V, a deflection of 25μm at the arm tip of the gripper is achieved.

Research on Low Temperature Anodic Bonding Based on Interface Pretreatment of Dielectric Barrier Discharge Plasma

A simple composite bonding that combines dielectric barrier discharge (DBD) plasma activation with anodic bonding has been developed to achieve strong silicon/glass bonding at low temperature. The realization of low temperature bonding is attributed to enhance the hydrophilicity and smooth of silicon and glass surfaces and form lots of free radical after the DBD plasma (including-OH, -H, O, and heat) reacts with the interfaces. And these further reduce the difficulty of chemical bond switching, and improve the speed of the intimate contact formation. The experimental result show that the bonding temperature strongly decreased 100°C by using composite anodic bonding with DBD pretreatment which strength kept constant, and 10MPa bonding strength was obtained at 250°C/900V after the bonding interface was treated for 10s under the conditions of AC1.5KV/25KHz and the clearance 100μm.

Micromachined Tri-Axis Capacitive Accelerometer Based on the Single Mass

A novel micromachined tri-axis capacitive accelerometer based on the single mass is proposed in this paper. The presented accelerometer contains a single proof mass acting as the sensitive element which is suspended by two flexible beams above the substrate, and an array of movable and fixed electrodes is utilized. To match the sensitivity design requirement, the differential capacitive detection is utilized, and the cross-sensitivity problem of three orthogonal axes is avoided ideally. The accelerometer structure is based on the EPI-poly process to realize the 18 microns thickness. Thus the detection capacitance, sensitivity and reliability are improved, the mechanical noise is decreased. To reduce the thermomechanical stress’ effect on the offset, a special anchor-middle structure is designed. Simulation results show that the offset is insensitive to the thermomechanical stresses and the sensor has a good consistency in three axes which has been validated by the testing results.

Research on the Stiffness Modeling of the High Precision Positioning Platform under the Thermal Model

The heat of the positioning platform is mainly caused by conduction of each functional unit, when it affected by the influence of internal and external heat source at work, the temperature of units would change, and the condition would make the platform component stiffness change, then lead to positioning platform dynamic characteristics change. In this paper, the finite method analysis platform dynamic connection stiffness with the regularity of temperature change, and by using the grey correlation method to optimize the platform stiffness influence of the four largest temperature sampling point, through the neural network modeling method to establish high precision positioning platform stiffness model, provide theory for the research on platform of dynamic characteristics of the model.

Study on the Stiffness of Positioning Platform with Large Trip and High Precision under Thermal to Structure Coupling

Thermal influences the stiffness, and then affects dynamic characteristics of the platform. The paper appoints a method to calculate the global stiffness of the positioning platform with large trip and high precision, and find the rule that the platform stiffness changing with the temperature to follow. The rule provides a fundamental basis for establishing vibration model of the platform. The main method to collect analysis data is finite element. Firstly, choose a number of points from the surfaces of the platform. Through the experiment data of thermal stress coupling analysis on the platform and a degree of grey incidence, the degree of correlation between all concerned points and thermal displacement can be solved. The key points are confirmed the one which have large degree of grey incidence which also have large influence on the stiffness, and will be the input value of stiffness model of the platform. Calculate the global stiffness value of positioning platform under different temperature using the finite element method analysis. Establish the stiffness model using BP neural network.

Gold Ball Wire Bonding Energy Transfer Mechanism and Experimental Studies

Because of the complexity of bonding process, the mechanism of bonding has been unable to agree. Accoding to previous research, a new bond energy transfer model is established: bond energy equals to energy caused by temperature rising and the friction energy.Then do experiment on bonding time, bonding stress and ultrasonic energy.Experimental results show that as the increase of process parameters, the bonding strength first increases then decrease, which consistent with the hypothesis.

The Forming Mechanism of Surface Defects on Machined Surface in High-Speed Cutting of SiCp/Al Composites

For investigating the machined surface defects in high-speed cutting of SiCp/Al composites. The simulation and experiment of high-speed cutting process is done. The simulation of high-speed cutting process using the Cowper-Symonds model is established to explore the forming mechanism of the machined surface defects. The results show that the machined surface defects include small pit, big pit, groove and the raised particle. The experiment which uses the same cutting parameters with the simulation of FEM (Finite Element Method) model is carried out to verify the results of FEM simulation. The results indicate that the forming mechanism of machined surface defects prove to be true.

Selecting of the Temperature Measurement Points for Positioning Platform with Large Trip and High Precision Thermally Induced Error Compensation Model

In the technology of thermal error compensation in positioning platform with large trip and high precision, selecting the temperature measurement points rationally is particular important for successfully establishing the model of compensation. The method uses simulation to track platform heat distribution and thermal deformation under various thermal conditions. Temperature variables are grouped by different surfaces of the platform. Then a degree of grey incidence from grey system theory is introduced to identify the key temperature measurement points of each surface. Through the experiment data of thermal stress coupling analysis on the platform, the degree of correlation between all temperature measurement points and thermal displacement can be solved. The key temperature measurement points are confirmed by the largest value of the degree of correlation of each surface.

Design of a Single-Plate Electrowetting-on-Dielectric Device

Due to its simple structure, low consumption of energy but strong driving forces, Electrowetting on Dielectric (EWOD) is used most frequently in digital microfluidics for manipulation and control of droplets. In this paper, the internal mechanism of EWOD is explained though establishing the geometric model of unipolar board structure digital microfluidic chip. The digital simulation software COMSOL Multiphysics is applied to analyze the coupling fields. The results show that external flow velocity of micro-droplet is greater than the internal velocity. Based on the theoretic analysis, surface micromachining technologies are employed to fabricate the single-plate EWOD chip. Finally, an experiment platform is set up to test this chip. Experimental results show that 2μL droplet can be driven in velocity of 10cm/s and two droplets can be merged successfully. It will possibly provide an effective solution to the manipulation of droplets.