The paper is mainly concerned with the study of negative refraction phenomenon dependent on the incident light frequency in 2D photonic crystal which consists of a hexagonal lattice of circular dielectric rods with Si. The result indicates that along with the accretion of incident light frequency, the angle of refractive light and negative refractive index in absolute terms become smaller gradually. This law offers an application of differentiating two close incident light frequencies. And a sample has been made successfully to realize negative refraction phenomenon.
A methodology for the simulation of a reciprocating displacement micro-pump is presented. First a check valve model was analyzed using coupled FEM to obtain the characteristics relationship between flow rate and the pressure as well as the minimum valve opening pressure. Then a model for the micro-pump actuator driven by PZT disks is proposed and simulated. The pump model takes into account the effects of chamber pressure and geometrical parameters. The maximum downward deflection of the actuating membrane is taken as the target parameter to analyze. It was found that the maximum membrane deflection could reach over 10micrometers microns, much larger than the radial displacement. This 'displacement amplification' is the underlying working principle of this kind of micro-pump. Quantitative analyses of the effects of various factors on the deflection are conducted. It is found that the thickness of the membrane has the biggest influence on the deflection. For each membrane thickness, there exists an op[t9kum PZT disk thickness that gives the maximum deflection at a particular electric field. Other factors with less influence on the deflection are also investigated. An optimum set of design parameters for the micro-pump is obtained form the analyses.
In this paper, an electrochemical actuator was fabricated and tested. The good linearity relationship between the dosing rate and the electrolysis current has been achieved for the demonstrative electrochemical actuator in the selected electrolyte and electrode material cell from 50 micro-A to 1000 micro-A electrolysis current. The microflow rate less than the evaporation that can be obtained by an improved standard gravimetric method in situ. The error resulted from tested work liquid inevitable evaporation was also excluded by the improved approach at very low microflow testing. The on-line testing method can be used as very low microflow rate calibration. The lowest stable flow rate was 0.19 micro-liter/min (3.2nl/s). The response time was also shown by the means of on-line measurement.
A 3D model of one type of micro pumps was supposed and analyzed using finite element method (FEM). The pump had square shape cavity and was driven by a square shape PZT component. The finite element analysis (FEA) took into consideration of the effects of PZT component dimensions, membrane thickness, pump chamber pressure and other geometric parameters. Modal analyses were also conducted. Compression ratio of the pump chamber was taken as the prime parameter for the analyses. It was found that the membrane thickness and the PZT plate thickness played major roles in determining the compression ratio. For each membrane thickness, there was always an optimum PZT plate thickness that gave the maximum compression ratio. Curves showing the relationship between the optimum PZT plate thickness and the membrane thickness at different chamber pressures were given, based on the FEA results. A set of optimum pump design parameters was proposed.
HF acid eroded Si wafers were used as substrates for deposition diamond film by HFCVD. The nucleation process and film characteristics were studied. Enhanced nucleation density to the level for abraded Se substrate and pronounced (111) texture of the obtained continuous diamond film were observed.
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