Advanced Materials Research Vols. 317-319

Abstract: The orifice which formed by the sudden change of channel’s scale on microfluidic chip and its application have introduced in this paper. The characteristics of orifice flow on microfluidic chip are studied by μ-PIV technology. The experimental PDMS chip is fabricated by hot press molding. The transient flow field experiment is carried out on the μ-PIV platform. The flow of thin-walled/thick-walled orifice was measured in experiment. There is flow constriction of orifice flow in jet state; the flow constriction of thick-walled orifice can pump the liquid in channel; and the critical Reynolds number of jet flow in microchannel structure is 190.

Abstract: Four types of MEMS actuators are presented in this paper. The effect of structure on three major performance parameters of these actuators, such as resonance frequency, pull in voltage and stroke, are studied by FEA and compared with each other. The result shows that, on the condition of the same spring length and the same spring width , O-shape actuator have the largest stroke and pull in voltage, but that of L-shape actuator is the smallest.

Abstract: A six-axis Micromachined Electrostatically Suspended Accelerometer (MESA) which is based on LIGA-type microfabrication was designed. MESA employs a levitated perforated plate as its proof mass. Three main purposes are considered for the design of the perforated proof mass: (1) reducing squeeze-film effect; (2) improving the dynamic response of MESA; (3) facilitating the etching of sacrificial layer under the plate. This paper utilized a finite element model for evaluating air squeeze film damping effect of perforated proof mass. Among several designs of perforated proof mass, the best choice was found. Besides, a system-level model created in CoventorWare is used to evaluate the effect of squeeze film damping and the dynamic response of the MESA.

Abstract: In recent years an increasing interest has grown in using Micro Electro Mechanical System (MEMS) fabrication technology in mechanical timepieces. The UV-LIGA process which combines ultraviolet lithography and electroforming is among micro-production technologies providing exciting possibilities. It has been established as industrial viable for the fabrication of various micromechanical components. Current limitations are that the technology is restricted to the use of nickel. It is too soft (~ 300HV) and has magnetic properties. It is not perfect for the movement of timepieces. However, by adding other materials, e.g. phosphor-Nickel (Ni-P), these alloys have their attractions, being stainless, non-magnetic and very high hardness. As a new technique, details are still being perfected. In this work, the process of Ni-P micro electroforming has been developed to extend UV-LIGA technology. And attempt has been made to investigate the magnetic properties and the hardness of the manufactured Ni-P alloy components. The results showed that the phosphor content can be controlled by different concentration of phosphorous acid (H3PO3) in the electrolyte solution. Corresponding properties have been analyzed which shows good hardness and lower magnetic properties. When the phosphorous content reaches over 12 wt%, the Ni-P alloy is with non-magnetic properties while pure nickel is ferromagnetic material. And the hardness of electroformed Ni-P alloy is about 600 HV and can be above 1000 HV after special heat treatment.

Abstract: With the rapid expansion of nanotechnology, assembling nano-materials and to create electrical/mechanical devices at micro and nano scales has become an increasingly important research area. An “OR” logical gate at nano-scale has been constructed with ZnO nanowires (NWs) via a mechanical nano-manipulator which placing inside the vacuum chamber of a scanning electron microscope (SEM). By means of the electrostatic interactions and the characteristics of ZnO NWs, the on/off effect between probe tip and NW can be controlled by controlling the voltage between them. Experimental results show that the fabrication of nano logic gates based on ZnO NWs is possible.

Abstract: The cantilever with a high-aspect-ratio and long probe is a key sub-system of the atomic force microscopes (AFMs) used to measure the surface aspect of the mechanical and optical devices. In this paper, a novel cantilever with a 50μm-length-probe and self-sensing piezoresistor was designed; and based on the micro fabrication technology, the processes were planned. The dynamic and static characteristics of the cantilever were analyzed on theory and finite element method (FEM). The results show that the length of the probe has no effect on the cantilever’s dynamic and static performance.

Abstract: This paper concentrates on how to generate manufacturing flow from the feature model of surface micromachined device. Firstly, the feature-based designing framework is presented, in which the manufacturing flow generation method plays an important role for feature mapping. Then, the graph-based approach makes benefit for the logical organizing and real-time adjusting of design features. The features combination approach is further presented to obtain layered model, which in turn corresponds to an optional manufacturing flow. In the meantime, some optimal operations are performed for better manufacturability. Finally, a polysilicon micro motor is used to illustrate the approach. In addition, the results are discussed to indicate the future work on scheme evaluation.

Abstract: MEMS is believed as a most promising technology in future. DHM is a powerful technique to characterize the behavior of MEMS. In the reconstruction process of a digital hologram, aberrations always exist, which is always removed by the software installed in the computer. We propose a method to obtain an aberration free digital hologram. The optical arrangement is presented to verify the possibility of our method, which is then improved by a space-fiber hybrid system. The system is flexible and useful in designing a practical digital holography microscope.

Abstract: Micro and Nano-satellites with their low thermal capacitance are vulnerable to rapid temperature fluctuations. Therefore, thermal control becomes more important, but the limitations on mass and electrical power require new approaches. Possible solutions to actively vary the heat rejection of the satellite in response to variations in the thermal load and environmental condition are the use of variable emissivity devices, such as micro louvers, micro thermal switches, etc. Micro louvers with small volume, low weight, less power consumption and large emissivity variation, will be the more suitable solution for micro and Nano-satellites thermal control. In this paper, a polyimide based micro louver is developed. The device structure was designed, the actuation voltage was analyzed theoretically and fabrication process was described. The main parameters were tested and results were presented.

Abstract: Taking A-C axis dual rotary working table of 5-axis CNC system as an example, the function of RTCP is introduced and the performing difference between standard NC code and RTCP code is analyzed in this paper. Then, the calculation method of RTCP compensation error has been illustrated. Taking the high precision as the objective, a new real time compensation RTCP module theory is presented and its algorithm implementation process is introduced. Then, this algorithm has been simulated using MATLAB and validated in hardware platform.