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The fabrication of Fresnel focusing lenses operating at frequencies of 100 and 200 MHz was investigated in order to enhance the focusing efficiency of ultrasonic energy. The effects of process parameters on the four-level Fresnel lens profiles were discussed to find a most feasible fabrication procedure through these experiments. The quality of Fresnel lenses was improved when two-and three-mask processes using SiO2 film as the hard mask were employed. Besides, a better side-wall profile of Fresnel lens was obtained by using the three-mask process as compared to the two-mask one.

In this paper, we propose a new approach for fabrication processes of microstructures composed of diffractive optical elements (DOE) and security elements. The holographic lithography is combined with laser lithography to obtain highly secured holographic labels for products protection. The secret key is an untraceable and hardly reproducible geometry and can be embedded in the labels or stickers to increase the level of security and diminish the possibility of products counterfeiting. In our process, the holographic structure composed of DOEs, and the key are designed separately by two authorized designers and recombined using double exposure followed by a single development step. The layout of microstructures that composes the security key are known only by the designer.

The microfluidic has been applied to the field of bio-medicine, micro fluidic electronic in recent years. In this paper we reported a simple methodology to fabricate PDMS microfluidic channels. The method consists of three main fabrication steps: (1) Direct write the micrometric PCL 2D or 3D pattern by the near-field melt-electrospinning. (2) Cast the PDMS on the printed PCL pattern. (3) Completely remove the embedded sacrificial PCL layer by soaking and flushing with acetone. Uniformity of the morphology of the micro channels and well-alignment could be easily achieved due to include the dimensions achievable using this method. We have also designed and fabricated a few micro fluidic channels. SEM and white-light interferometer images were taken to illustrate the characters of essential parts. This work demonstrated the potential utilization of this technique.

Flapping wing aerial vehicles continue to be a growing field, with ongoing research into unsteady, low Reynolds number aerodynamics and micro fabrication. However research into deformation and stress of flapping wing continues to lag, especially based on composites model. One flapping cycle was divided into twelve segments, and maximum defmortion and stress were calculated in each segment. The results show that the maximum sdeformation at the beginning stages of downstroke is 19% larger than the maximum deformation at the beginning stages of upstroke, and the maximum stress at the beginning stages of downstroke is 29.9 larger than the maximum stress at the beginning stages of upstroke. This research is helpful to answer that why insect wings are so perfect through long evolution, thus improving the design of flapping-wing aerial vehicles.

Electroforming technology is an important part of micro fabrication andfine parts and composite materials prepared by the electroforming technology has broad application prospects. This paper describes the principle and method of electroforming, introduces the development and the basic elements of electroforming, then concludes the research status and main research direction and trend of this technology.

In recent year, the sensitivities of atomic spin devices are improved greatly with the realization of spin exchange relaxation free (SERF) regime. Usually the SERF regime is realized using orthogonal beams scheme, i.e. one pump beam to polarize the atoms and the other orthogonal probe beam to measure the polarization. Due to the requirement of four optical windows for the atomic vapor cell, the orthogonal beams scheme has difficulties for micro fabrication. In this paper, we research a new scheme for SERF realization using only one beam, which facilitates the micro fabrication greatly. Furthermore, the fabrication processes of the MEMS atomic vapor cell with two out-of-plane optical windows are designed and performed. In the end, the possibility of increasing the relaxation time by nanotechnology is discussed.

Nanomaterials such as 1-dimensional nanowires and nanotubes and 2-dimensional graphene are the promising materials for novel device developments due to their unique physical and chemical properties. For field emission applications, nanomaterials are excellent candidate for an electron source by advantages of their small dimensions and high aspect ratios. In this study, we used GaN nanowires as the nanomaterials synthesized by Vapor-Liquid-Solid method. The field emission devices were then fabricated using the general Si microfabrication techniques. Moreover, the field emission properties of the GaN nanowires were characterized using cold field emission theory. It is demonstrated that the fabrication techniques shown in this study are efficient to fabricate field emission devices using nanomaterials.

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.

In order to test the micro-cutting force during the process of micro-fabrication, a precise sensor needs to be designed. This study, micro-cutting force sensor based on principle of precise resistance strain is designed, which is made of octagonal ring elastic element, makes it possible to measure the micro-cutting force in both a convenient and practical way. Experiments show that the sensor can not only detect micro-cutting force, but also provide a feasible experimental method for the mechanism study of micro-fabrication.

This paper investigated the impact of area effect in the batch mode micro-EDM on shape accuracy and surface morphology of the machined microstructures, as well as electrode wear, using both the positive-type and the negative-type electrode arrays fabricated by the UV-LIGA process. Experimental results showed that ,with the increase of electrode-pair scale from Φ1mm, Φ2mm, Φ4mm to Φ8mm, the shape accuracy of the machined stainless steel microstructures increased, but the eroded microcavities of the machined area reduced in both the positive-type and the negative-type micro-EDM using the same electrical pulse parameters. It was also found that, with the same pulse energy and electrode-pair area, the electrode wear reduced as the electrode-couple area increased, and the wear ratio in the positive-type micro-EDM was larger than that in the negative-type micro-EDM.

The armature fabricated with the sacrificial layer techniques is an important part of micro electromagnetic relay. So the sacrificial layer is one of the key fabrication processes in the realization of prototype of micro electromagnetic relay. In this paper several sacrificial layers including Copper, Polyimide and Positive photoresist are studied based on the investigation of the research on sacrificial layer and binding the characteristic of micro electromagnetic relay’s fabrication process.

The curing characteristics of a photocurable resin are critical factors that often decide the ultimate resolution and structural sharpness of a final product fabricated by microstereolithography (μ-STL). In this study, we investigated the curing characteristics of the FA1260T photopolymer under a visible laser light of 442nm wavelength. Modification of the curing property of the FA1260T is attempted to reduce the cure depth (Dc) by adding a radical quencher to the resin. Also, an organic solvent was used to reduce the resin viscosity for an improvement of the flatness of the liquid surface during layer-by-layer curing. As a result, the minimum Dc has been reduced over a factor of 3 with no abrupt increase. Samples of three dimensional microstructures fabricated using the modified FA1260T are presented.

A free-standing photosensitive polyimide film with thickness of 10µm is fabricated with the different curing temperatures using a micro fabrication process. The microtensile specimens of a strip type are made to facilitate a tensile testing. The Young’s modulus and yield strength of photosensitive polyimide film are measured with various strain rates from 10-4 /s to 10-3 /s by using a microtensile test. Also, the hardness and Young’s modulus of polyimide films are obtained from nanoindentation test. Finally, the mechanical properties measured from microtensile test are compared with those from nanoindentation test.

Diamond replicas, concerning to the fidelity, were quantitatively evaluated in this work. We analyzed the dimensions and morphology of the silicon molds and diamond replicas by atomic force microscopy. The micrometric and nanometric characterization were performed for different substrate pretreatments.

The main function of the substrate is to sustain and improve the performance of the thin-film. The property and surface configuration of the substrate material have a huge influence on the characteristics of the thin-film. Fabrication of substrate for the micro-transformer can choose a variety of materials, including the silicon, metal, glass, quartz, ceramics, plastics, polymer, etc. Different materials used as substrate have different effects on voltage gain and insertion loss of the transformer. At present, the silicon is used in most cases for its excellent properties. However, it is increasingly found that there exists some problems to gain better performance, such as the parasitic effect. And so, to employ other materials is essential. This paper discusses the effects induced by using different substrate materials. Through the analysis, a general cognition about how to choose the materials can be obtained, which is helpful to design and fabrication of the micro-transformer.