The design, numerical simulation and fabrication process of a silicon micro flat heat pipe with axially micromachining triangle grooves are discussed. In this paper the structure of a silicon micro flat heat pipe is presented firstly. Then numerical simulation is undertaken to evaluate the thermal performance of micro flat heat pipe. Using MATLAB a one-dimensional model is developed and solved numerically to investigate the flow of liquid and vapor in triangle grooves. The effect of interfacial and vapor shear stress is considered in the model. The results obtained from this simulation contain axial variation of pressure difference between vapor and liquid, velocity of liquid and vapor and film thickness. In addition maximum heat transport capacity of MHP is calculated. The results predicted by the model are compared with the published results in literature and show good agreement. These numerical results are used to determine the structural parameters of final prototypes. Finally a silicon/methanol prototype was fabricated to demonstrate the feasibility of heat spreading using this type of MHP. The MHP grooves capped by a glass wafer were fabricated by using bulk micromachining and anode bonding techniques. Detailed fabrication process of a silicon micro flat heat pipe with axial triangle grooves is presented.
A high-g overload protected piezoresistive accelerometer with the cave form section and two-end-fixed beams was introduced in this paper. Based on the finite element method (FEM) simulation, an optimal design of the microstructure was presented. The accelerometer was fabricated by standard IC process, ICP plasma etching and silicon anodic bonding technique. The testing results show that the accelerometer can bear 20,000g shock, the non-linearity reaches to 0.5% in the ±50g full scale, sensitivity reaches 0.8mV/g, and the operation frequency range is from DC to 2kHz.
In this paper a novel capacitive micro-vibration sensor with multi-folding beams, fabricated by bulk micromachining, is presented. The microstructures of the vibration sensor are simulated by the finite element method (FEM). The relations between the structural parameters and the sensitivity and frequency response of the sensor were considered in the simulation. The static and modal analyzing results of the sensors show that the higher sensitivity and mechanical strength with multi-folding beam structure were achieved. The microstructure with beam thickness under 400um can be fabricated with DRIE technology. When the area of silicon proof mass is 2.5×10<sup>5</sup> μm2, and the thickness of the proof mass vary from 40 μm to 80 μm, the mechanical noise is about 9×10<sup>-6</sup>g/√<i>Hz</i>. The sensor with resonant frequency up to 5kHz can be used to measure the vibration signal in a wider frequency range.