Papers by Author: Xiao Hu Zheng

Abstract: Process researching on high resolution and high ratio of depth to width of the negative photoresist (SU-8) process on micro-structure, by means of orthogonal experimental,drawing that the soft baking temperature and soft baking time have the greatest impact on the quality of the lithography. When the thick of photoresist is between 120μm with 340μm, the soft baking temperature is 90°C and the soft baking time is between 50min with 120min, the graphics quality is best. Then, analysis of characteristics of the ratio of high to depth on micro-structure electroforming shows that the mass transfer is the restrictive link of micro electroforming. Which can achieve the process parameters optimization of the lithography and electroforming micro-structure.

Abstract: The artificial neural network (ANN) and Orthogonal experimental design was applied in the research of main process parameters of electroforming Ni-Fe microstructure. In order to obtain the suitable parameters of the deposit, an ANN with 3 layers was built and trained based on orthogoality experiment using back propagation algorithm. The characteristics of the micro electroforming process were analysed systematically. And the optimal process parameters to obtain Ni-20% Fe deposition was as following: FeSO4•7H20 concentration: 5.5 g/L; PH value of the solution: 2.5; current density: 3.5 A/dm2; electrolyte temperature: 55 °C. The results indicate that the Ni-Fe deposit is bright and compact. Electrodeposited Ni-20% Fe has a strong paramagnetic effect with the smallest value of remanence 0.036 mA•m2 and the coercivity: 0.187 kA/m. The Ni-Fe micro electroplating process for the fabrication of microstructure was optimised.

Abstract: The relationship between the composition, coating microstructure and electromagnetic properties of electroforming Ni-Fe alloys was studied in this paper. And the optimal process parameters to obtain Ni-20%Fe deposition was as following: FeSO4•7H20 concentration was 6 g/L; PH value of the solution was 2.5; current density was 3.5 A/dm2; electrolyte temperature 55 °C. The results indicate that the Ni-Fe deposit is bright and compact, the crystal-planes of the plating were (111), (220) and (200). Electrodeposited Ni-20%Fe has a strong paramagnetism effect with the smallest remanence of 0.5 emu, The coercivity show a monotonic decrease with increasing Fe content in deposit, which proved that the electroformed Ni-20%Fe alloy has good electromagnetic property and could be used in MEMS actuator manufacturing.

Abstract: This paper investigated an novel wireless RF pressure sensor fabricated with SU-8 polymer. The sensor consists of an inductor (L) interconnected with pressure-variable capacitor (C) to form a LC resonant circuit. The fabricated devices is 4 × 3 mm² in size and houses 9 turns of Cu electro-plated coil with inductance of 100 nH. In this system, RF signal was transmitted from external antenna to the fabricated LC resonator. Then RF signal was changed as power of fabricated device via inductive coupling. The external antenna was modulated by resonant frequency of the LC resonator. By detecting this abrupt resonant frequency shift of the device, the pressure change of the device can be measured by wireless method.

Abstract: Using functions of the parametric design and assembling in Pro/E, the parametric model for parts of shaping machine was established and the virtual assembly of shaping machine was achieved according to the parts of the assembly relationship in Pro/E assembly environment. Using functions of gap analysis and interference check in Pro/E,it can check interference to find and amend parts structure of shaping machine and can analyse gap to find the assembly relationship of shaping machine. Through the motion simulation, it can simulate movement of various parts of shaping machine in virtual environment. Using the method of virtual assembly ,it can met the design requirement of shaping machine, reduce the design cost of shaping machine, shorten the product development cycle, improve the design efficiency. It has offered a kind of new design method and implementation way for research of the model.

Abstract: A micro grooved finger has smaller bending stiffness and can be used to improve the performance of some micro cantilever devices. The deflection and bending stiffness of a micro grooved finger are discussed in this paper. An analytical model of the deflection is built up to study the effect of the groove sizes on the bending stiffness and the deflection of the grooved finger. The calculation of the analytical model is consistent with the simulation and experiment results. When the grooves depth is 0.5 μm, the spring constant of grooved micro finger is 19.8% smaller than that of flat finger without groove patterns. The spring constant of the finger decreases with the increasing of the width and depth of the groove. A novel micro electric-thermal gripper is introduced based on the grooved finger. It consists of four sub-cantilever beams arranged at the diagonal lines of the square frame in the end of the main cantilever structure suspended from the silicon substrate, which guarantees an effective contact by the four-point contact area on the top surface to grab object of importance. The thermal expansion induced deflection makes the fingers moving vertically from an ‘open’ position to a working one. The grooved fingers help to decrease the bending stiffness of the finger and increase the deflection and the initial gap. The simple fabrication process has a feasibility of compatible and mass production.

Abstract: An analytical model of an eddy current sensor designed for noncontact distance measurement is presented. The device consists of two planar coil (driver coil and pickup coil) stacked on the magnetic core. The planar coil fabricated by UV-LIGA technology with SU-8 photoresist is illustrated, and the permalloy magnetic core electroforming process is presented also. Tested with 10-50 KHz sine signal, the output voltage of the sensing coil reached 30mv with a Ni target placed at a distance of 20μm. And the experimental showed a linear relation between the distance and output voltage within 60μm distance. The amplitude trend increases with the increasing of the frequency and amplitude of excited signal, which is according with the theory analytics. The whole size of the device is: Φ5mm×1.5mm. The results demonstrated that the device could nondestructive evaluate the distance and be easily integrated on chip, and the UV-LIGA Process could be used as a new method to fabricate the micro eddy current sensor massly.