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Silicon Mold (silicon + mold)
Selected AbstractsManufacturing Silicon Carbide Microrotors by Reactive Hot Isostatic Pressing within Micromachined Silicon MoldsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2002Jing-Feng Li A novel ceramic microfabrication process,based on the idea of silicon carbide (SiC) reaction sintering within a micromachined silicon mold,has been developed to produce a SiC microroter for miniaturized gas turbines. The new process involves the micromachining of silicon molds; filling the molds with powder mixtures of ,-SiC, graphite, and phenol resin; bonding the molds with an adhesive; reaction sintering by hot isostatic pressing (HIP); and the releasing of a reaction-sintered workpiece from the mold by wet etching. Using this process, we have successfully fabricated SiC microrotors with a diameter of 5 mm, whose complicated geometry was well transferred from the negative shape of the micromachined silicon mold. The reaction-HIPed SiC ceramics within Si molds showed reasonably good mechanical properties, which are comparable to those of the commercialized reaction-sintered SiC ceramics. [source] QUANTITATIVE SENSORY TESTING AND SWEAT FUNCTION IN FRIEDREICH'S ATAXIA.JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2000CORRELATION WITH CUTANEOUS INNERVATION To evaluate small fiber function in Friedreich's Ataxia (FA), we performed in 7 patients pin-prick, thermal thresholds, and sweat test. All tests were performed in four different sites: hand dorsum, anterior thigh, lateral distal leg, and foot dorsum. The same subjects underwent 3 mm punch skin biopsy from fingertip, anterior thigh, and lateral distal leg. We used a thin needle mounted on a calibrated nylon wire for the pin-prick test, and a Medoc 2001 TSA system for thermal threshold assessment. Sweat test was performed using a silicon mold after stimulation with pilocarpine by iontophoresis. Skin specimens, cut into 100-,m-thick sections, were double-stained using primary antibodies specific for collagen and nervous fibers and secondary antibodies labeled with Cy3 and Cy5 fluorophores. Tridimensional digitized images were obtained from z-series of 2-,m-thick optical sections acquired with a confocal microscope. We found in all patients in the more distal sites definite signs of functional impairment of the small fibers. These data correlated with the skin innervation morphological findings that showed, in the same sites, a sensible loss of small fibers regarding both the epidermal free endings and the subepidermal neural plexus. Less severe morphological abnormalities were found in the proximal sites. The large fiber neuropathy in FA is well documented. Our data show a length-dependent involvement of small fibers in the pathological process. [source] Fabrication of optical waveguide devices using gas-assisted UV micro/nanoimprinting with soft moldPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11 2007Y.-J. Weng Abstract Wavelength limitation and diffraction of light are the bottlenecks encountered in the production of structures by conventional lithography. Nano-imprinting has been a potential process for mass production of nanometer structures at low cost. This paper reports an innovative process to replicate the ridge-shaped microstructures on the silicon mold onto the photoresist using gas-assisted pressing mechanism and soft mold. The microstructures on the silicon mold are replicated unto PC films. The soft mold is obtained by casting the PDMS with the PC film as templates, PDMS mold and UV-curable photoresist are brought into contact, and are pressurized by gas and cured by UV-light at the same time. After curing, structures for optical wave guilding can be obtained, In this process, through the control of gas pressure, the residual layer of the ridge-shaped component for light guilding can eliminated. Etching is no longer needed to get rid of the residual layer. This process is effective for mass production for replication of microstructures at low cost. Copyright © 2007 John Wiley & Sons, Ltd. [source] Manufacturing Silicon Carbide Microrotors by Reactive Hot Isostatic Pressing within Micromachined Silicon MoldsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2002Jing-Feng Li A novel ceramic microfabrication process,based on the idea of silicon carbide (SiC) reaction sintering within a micromachined silicon mold,has been developed to produce a SiC microroter for miniaturized gas turbines. The new process involves the micromachining of silicon molds; filling the molds with powder mixtures of ,-SiC, graphite, and phenol resin; bonding the molds with an adhesive; reaction sintering by hot isostatic pressing (HIP); and the releasing of a reaction-sintered workpiece from the mold by wet etching. Using this process, we have successfully fabricated SiC microrotors with a diameter of 5 mm, whose complicated geometry was well transferred from the negative shape of the micromachined silicon mold. The reaction-HIPed SiC ceramics within Si molds showed reasonably good mechanical properties, which are comparable to those of the commercialized reaction-sintered SiC ceramics. [source] Fabrication of lab-on chip platforms by hot embossing and photo patterningBIOTECHNOLOGY JOURNAL, Issue 11 2007Devendra K. Maurya Abstract In this paper, we review the approaches developed in our laboratory to fabricate polymer-based microfluidic devices to suit a range of applications in bio- or chemical analysis. Thermoplastic materials such as polycarbonate (PC) and poly(methyl methacrylate) (PMMA) are used to fabricate microfluidic devices via hot embossing. To emboss microchannels, we use hard stamps fabricated in silicon or soft stamps molded on poly(dimethylsiloxane) (PDMS). Hard stamps are fabricated on silicon wafers through photolithography and deep reactive ion etching (DRIE). Soft stamps are fabricated by casting PDMS prepolymer on silicon molds. To enclose the fluidic channels, direct fusion bonding was found to produce the highest bond strength with minimal structural deformation. One-step photolithographic methods have also been explored to produce via photochemical patterning microfluidic structures in photocurable materials. We use the photocurable capabilities of a PDMS copolymer, which incorporates a methacrylate crosslinker. Microfluidic channels are produced via one step-photopatterning processes by crosslinking the prepolymer mixture through a photomask. The smaller feature size attainable was 100 ,m. Structures with higher spatial resolution are fabricated through a photoimprinting process whereby a mold is pressed against the precured mixture during UV crosslinking exposure. The application of the fabricated fluidic devices in electrophoretic ion analysis is also presented. [source] | ||||||||||