Fabrication

About: Fabrication is a research topic. Over the lifetime, 20475 publications have been published within this topic receiving 235676 citations.

Multifunctional Integrated Transparent Film for Efficient Electromagnetic Protection

Abstract: Silver nanowire (Ag NW) has been considered as the promising building block for the fabrication of transparent electromagnetic interference (EMI) shielding films. However, the practical application of Ag NW-based EMI shielding films has been restricted due to the unsatisfactory stability of Ag NW. Herein, we proposed a reduced graphene oxide (rGO) decorated Ag NW film, which realizes a seamless integration of optical transparency, highly efficient EMI shielding, reliable durability and stability. The Ag NW constructs a highly transparent and conductive network, and the rGO provides additional conductive path, showing a superior EMI shielding effectiveness (SE) of 33.62 dB at transmittance of 81.9%. In addition, the top rGO layer enables the hybrid film with reliable durability and chemical stability, which can maintain 96% and 90% EMI SE after 1000 times bending cycles at radius of 2 mm and exposure in air for 80 days. Furthermore, the rGO/Ag NW films also possess fast thermal response and heating stability, making them highly applicable in wearable devices. The synergy of Ag NW and rGO grants the hybrid EMI shielding film multiple desired functions and meanwhile overcomes the shortcomings of Ag NW. This work provides a reference for preparing multifunctional integrated transparent EMI shielding film.

Additive-manufacturing of 3D glass-ceramics down to nanoscale resolution

Abstract: Fabrication of a true-3D inorganic ceramic with resolution down to the nanoscale (∼100 nm) using a sol–gel resist precursor is demonstrated. This method has an unrestricted free-form capability, control of the fill-factor, and high fabrication throughput. A systematic study of the proposed approach based on ultrafast laser 3D lithography of organic–inorganic hybrid sol–gel resin followed by a heat treatment enabled the formation of inorganic amorphous and crystalline composites guided by the composition of the initial resin. The achieved resolution of 100 nm was obtained for 3D patterns of complex free-form architectures. Fabrication throughput of 50 × 103 voxels per second is achieved; voxel – a single volume element recorded by a single pulse exposure. A post-exposure thermal treatment was used to form a ceramic phase, the composition and structure of which were dependent on the temperature and duration of the heat treatment as revealed by Raman micro-spectroscopy. The X-ray diffraction (XRD) showed a gradual emergence of the crystalline phases at higher temperatures with a signature of cristobalite SiO2, a high-temperature polymorph. Also, a tetragonal ZrO2 phase known for its high fracture strength was observed. This 3D nano-sintering technique is scalable from nanoscale to millimeter dimensions and opens a conceptually novel route for optical 3D nano-printing of various crystalline inorganic materials defined by an initial composition for diverse applications for microdevices designed to function in harsh physical and chemical environments and at high temperatures.

Design and fabrication of a silicon-based mems rotary engine

Abstract: Design and fabrication of a Silicon-based MEMS rotary engine are discussed in this paper. This work is part of an effort currently underway to develop a portable, autonomous power generation system potentially capable of having an order of magnitude improvement in energy density over alkaline or lithium-ion batteries. Central to the development of this power generation system are small-scale rotary internal combustion engines fueled by high energy density liquid hydrocarbons capable of delivering power on the order of milli-Watts. The rotary (Wankei-type) engine is well suited for MEMS fabrication due to its planar geometry, high specific power, and self-valving operation with a minimal number of moving parts. The smallest "micro-rotary" engine currently being fabricated has an epitrochoidalshaped housing under 1 mm 3 in size and with a rotor swept volume of 0.08 mm 3. This paper discusses some of the fabrication issues unique to MEMS fabrication of a rotary engine at this small scale. High precision, high aspect ratio structures are necessary to provide adequate sealing for high compression ratios. Effects such as footing and lateral to vertical etch rates must be minimized for proper engine operation. A fabrication process is necessary for the complex, multiheight geometry of the housing and rotor assembly. Finally, a repeatable and simple assembly technique must be developed in order to mass-produce these engines. Fabrication of a Silicon-based micro-rotary engine is being conducted in U.C. Berkeley's Microfabrication Laboratory. The engine system is composed of three main components: rotor, housing, and shaft. The engine and rotor housing mast be entirely fabricated from Silicon without embedded oxide to prevent thermal mismatch or structural weakness at the Si-oxide interface. In order to meet this requirement, the fabrication processes for the housing consists of a two-mask two-etch process of a solid Silicon wafer. The fabrication of the rotor follows a similar process, utilizing deposited oxide as a release layer. Using Silicon Dioxide and photoresist for masking, housing and rotor structures are etched from solid Silicon using timed Deep Reactive Ion Etching (DRIE). A unique feature of these processes is the self-masking of the spur gear in the housing and the shaft thru hole in the rotor during the second DRIE steps, which give the necessary multi-level, cross-sectional profile.