A two-dimensional Reynolds equation was established for isothermal compressible gas between the two faces of a dry gas face seal with both spiral grooves and an inner annular groove onto the hard face. The opening force, the leakage rate, the axial film stiffness and the film stiffness to leakage ratio were calculated by finite element method. The comparisons with the sealing performances of a typical gas face seal only with spiral grooves onto its hard face were made. The effects of the face geometric parameters on the static behavior of such a seal were analyzed. The optimization principle for geometric parameters of a dry gas face seals with spiral grooves and an inner annular groove was presented. The recommended geometric parameters of spiral grooves and circular groove presented by optimization can ensure larger axial stiffness while lower leakage rates.

This paper presents optimization of phase reflection sawtooth gratings with a period of 2.0 μ m and a depth of 0.2 μ m based on the Fourier transformation (FT) and the rigorous coupled wave analysis (RCWA). And its fabrication on oxygen free Cu and electroless Ni-coated surfaces by using diamond cutting in a shaping process whose toolpath is interfered to provide smaller period. The diffraction efficiencies were estimated 100% for FT, 83.0% and 79.0% for TE and TM polarization of the incident light at a depth of 0.2 μ m. It was found that electroless Ni-coated surface had better performance in terms of machining and optical functionality. From optical testing, the diffraction efficiencies were measured 84.0% and 84.4% for TE and TM polarization, respectively.

A new structure of MEMS Uncooled capacitive focal plane array (FPA) is presented and its thermo-mechanical behaviors are studied. A surface process with poly-silicon as a sacrificial layer was developed, and in which poly-silicon was dry etched by SF 6 in an ICP system of STS. The etching rates of poly-silicon in lateral and vertical can reach 3.8 and 5.6μm/min after the optimization of the process. The process is simple and compatible with most of the IC processes.

This paper presents a design optimization of a membrane-based ultrasonic piezoelectric transducer using micromachining by finite element simulation. The transducer can be used to generate ultrasound using the piezoelectric film to excite the vibration of the transducer membrane. The objective is to maximize the vibration magnitude of the membrane by optimizing the structure of the transducer, when the exciting signal is fixed. The size and the shape of the piezoelectric film were selected as the design parameters to optimize the structure of the transducer. Based on the theoretical analysis, it is found that the absolute values of the stresses in the center and the boundary of the diaphragm are greater than that on the other regions of the film, with the directions of the stress on center and boundary opposite to each other. In order to achieve the maximum exciting efficiency, the discrepancy in the stresses between the center and the boundary on the diaphragm should be maximized. In this paper, totally four different piezoelectric film structures are analyzed for optimizing the exciting efficiency of the transducer. The finite element models of the transducer were created using ANSYS. The simulations based on the three design options were performed; and through the comparison of the simulation results, the optimal structural parameters of the piezoelectric film are identified. Finally, the direction of the design improvement for the exciting efficiency of the transducer is provided.

Benefited by the progress of material science, Light-Emitting Diodes (LED) with UV-emitting have been produced successfully. Like other LEDs, UV-LEDs exhibit several advantages, such as energy conservation, long life, compact, and quick response. The UV-LED application to microlithography is attractive. In contrast to point light sources requiring lens to generate parallel light beams, an array of UV-LEDs can emit nearly parallel light beams easily. UV-LEDs only need 3 to 4 voltages to ignite, which is much lower than that required by mercury short arc lamps. The cost of using UV-LEDs is also much lower than current solutions. In this study, we used UV-LEDs as the light source in the laboratory lithography system. LEDs, whose emitting spectrum distributed between 370 to 410 nm mostly, were displaced on the bottom of a heat sink. Two 10-by-10 cm 2 test masks, where the smallest pattern was 20 μm, were used to examine the resolution ability of this combination. Each light module was utilized to exposure photosensitized printed circuit board (PCB). After etching, the printed patterns were observed under microscope. The minimum reproducible feature size was 100 μm. Through the 4” mask, the uniformity was decent, and could be improved by using LEDs from the same batch, collimator, or LED displacement optimization. In the future, standard g-line process can be performed, and further tests will be performed to check the limits of the UV-LED system. Based on these preliminary tests, it seems like the usage of UV-LEDs should be a feasible solution for microlithography.

MEMS-based biodegradable controlled release system with micro multi-chambers can respectively enclose two drugs in different chambers to realize a combination therapy. In order to synchronously obtain the linear release of two drugs, it is necessary to completely investigate the topology optimization of the system. This paper introduces the theory of multi-objective topology optimization into MEMS-based biodegradable controlled release system for the combination therapy. Furthermore, a new method of CA-based evolutionary structural optimization (CA-ESO) is presented to accomplish the topology optimization of this controlled release system. The result shows that the optimized drug delivery system can achieve the objective of the synchronizing linear release for two drugs. The conclusion illustrates that the CA-ESO method proposed in this paper is validity for the topology optimization of MEMS-based biodegradable controlled release system.

P2i’s plasma process allows the attachment of ultra-low surface energy coatings, one third that of PTFE, to a wide range of substrates, including, glass, metals and polymers. This gas phase process can penetrate complex structures with nano and micro features to form well adhered nano thin films suitable for microfluidic devices. By using this technique multiple assays show comparable performance on miniaturization without the need for individual optimization.

Under the operating conditions of high collision and strong vibration, a new high-g piezoresistive accelerometer (with a full range of 150000g) is designed. This design consists of 4-beams and 1-tower. This structure possesses superior anti-shock ability. In optimizing this piezoresistive bridge structure, a tower is etched directly from the back of the mass in KOH by using the (111) plane etch-stop technique. Since the distances between the mass center of the tower and the mass centers of the beams are shortened, anti-shock ability in transverse directions is improved. In addition, the fabrication process is relatively straightforward. Finally, it is found by impact experiments that the linearity of the optimized design lies within 9% for measurements in the range of 0–150000g.

Radiofrequency (RF) ablation is a minimally invasive technique for tumor treatment. Intended benefits of oncological RF ablation include the availability of tumor treatment in nonsurgical candidate, minimal risk to patient, reduced morbidity and shorter recovery period compared with those after conventional surgery, and the potential for treatment on an outpatient basis. RF ablation, by producing heat energy that raises the temperature of the target tissue to a degree sufficient to cause thermally mediated coagulation necrosis, has been shown to be remarkably effective for thermal ablation of small tumors. Although RF hyperthermia has been successful in ablating small tumors, further optimization of the ablation technique is required to induce the larger volumes of coagulation that are necessary to treat larger tumors. In addition, due to the extremely irregular shape of tumor in clinics, the conventional RF ablation technique is hard to produce a conformal lesion to exactly enwrap the tumor as could as possible. This may lead to “dead region” within the area between RF probes and thus a failed treatment. To obtain a conformal treatment of complex tumor, strategies to flexibly control the size and shape of the ablated zone are desired.

In this paper, we present the multi-objective optimization for an entire microsystem, a novel capacitive electrostatic feedback accelerometer. From the energy relations of the coupled electrostatic-field, the dynamic model of the system is constructed. Aiming at the global performance, a multi-objective optimization model, where sensitivity, resolution and damping resonant frequency are selected as objectives, is established based on the concept of multidisciplinary design optimization (MDO). Genetic algorithm (GA) is used to solve this problem, and compared with a traditional optimization approach, sequence quadratic programming (SQP). Both the two algorithms can achieve our aim commendably, and the optimal solution given by GA is more satisfied. The research provides us a good foundation to develop the stochastic and implicit parallel properties of GA to obtain Pareto optimal solutions.

AFM anodic oxidation has been an effective method for fabricating nanostructures. It has been applied in the fundamental research of nanoelectronics. Actually, AFM anodic oxidation is a chemical reaction process influenced by co-effects of many factors. Effects of synthesis roles of all factors on dimensions of oxide nanostructures and machining efficiency are major issues for the combination of AFM anodic oxidation technique and conventional micromachining techniques to fabricate electronics. Therefore, to fabricate oxide nanostructure effectively, orthogonal test was employed to study effects of three factors: bias voltage, machining velocity (or pulse interval) and the cantilever deflection on dimensions of nanostructures. Results showed that cantilever deflection had a significant effect on dot dimensions and had little effect on line dimensions. Based on optimization of nanostructure dimensions and machining efficiency, the optimal machining parameters (bias voltage, machining velocity or pulse interval and the cantilever deflection) on the surface of N-Si (111) were achieved under the conditions of humidity of 54% and at temperature of 23° C. Using the optimal machining parameters, regular nanostructures: lattice, annulus and complex Chinese words, were fabricated based on a novel AFM-based nanomachining system integrated a precision stage. The AFM tip was still and the precision stage moved the sample. The shortcoming of low repeatability positioning accuracy of AFM Piezo scanner during machining was eliminated. A larger machining scale with high accuracy can be realized on this system by the dot array-style fabricating method and the vector-style fabricating method.

In order to improve the situation that the design of microactuator is mostly based on the intuition and experience of researchers, the method of continuum topology optimization using the nodal density is introduced to the conceptual design of microactuator. This new method can ensure C0 continuity of density field in a fixed design domain. The ratio of mutual energy to strain energy of the mechanism is regarded as the objective function, where, the mutual energy and strain energy describe the kinematic function and structural function of microactuator respectively. The final configuration of microactuator is decided on the guide of conceptual design combined with the given working conditions. The finite element method is applied to analysis the transmission ratio and clamping force of microactuator. The prototype of the microactuator is fabricated by using micro-electroforming and SU-8 photolithography techniques and the displacement of the micro actuator is measured by using the stereo vision microscopy. The experimental results show that the properties of the micro actuator can satisfy the designing demands. This topological optimization method based on nodal density plays an important role in guiding the structure design of micro actuator.

A three-dimensional (3-D) parametric model of Tesla-type valves is proposed. A geometrical relationship is derived for optimization study, and based on the model, performance investigations in terms of diodicity and pressure-flow rate characteristics of the valve are numerically carried out with same hydraulic diameter and different aspect ratios (of the model cross-sectional dimensions) ranging from 0.5 to 4. The 3-D computational simulations show that, for the same hydraulic diameter, the unity aspect ratio gives higher diodicity at Reynolds number less than 500 and higher will be achieved with bigger aspect ratio when the Reynolds number is above 500. Investigations of pressure-flow rate characteristics of the Tesla valve show that Tesla valve with high aspect ratio gives more flow control ability.

Since compliant mechanism is usually required to perform in more than one environment, the ability to consider multiple objectives has to be included within the framework of topology optimization. And the topology optimization of micro-compliant mechanisms is actually a geometrically nonlinear problem. This paper deals with multiobjective topology optimization of micro-compliant mechanisms undergoing large deformation. The objective function is defined by the minimum compliance and maximum geometric advantage to design a mechanism which meets both stiffness and flexibility requirements. The weighted sum of conflicting objectives resulting from the norm method is used to generate the optimal compromise solutions, and the decision function is set to select the preferred solution. Geometrically nonlinear structural response is calculated using a Total-Lagrange finite element formulation and the equilibrium is found using an incremental scheme combined with Newton-Raphson iterations. The solid isotropic material with penalization approach is used in design of compliant mechanisms. The sensitivities of the objective functions are found with the adjoint method and the optimization problem is solved using the Method of Moving Asymptotes. These methods are further investigated and realized with the numerical example of compliant microgripper, which is simulated to show the availability of this approach proposed in this paper.