Design, fabrication, and testing of silicon microgimbals for super-compact rigid disk drives

This paper documents results related to design optimization, fabrication process refinement, and micron-level static/dynamic testing of silicon micromachined microgimbals that have applications in super-compact computer disk drives as well as many other engineering applications of microstructures and microactuators requiring significant out-of-plane motions. The objective of the optimization effort is to increase the in-plane to out-of-plane stiffness ratio in order to maximize compliance and servo bandwidth and to increase the displacement to strain ratio to maximize the shock resistance of the microgimbals, while that of the process modification effort is to simplify in order to reduce manufacturing cost. The testing effort is to characterize both the static and dynamic performance using precision instrumentation in order to compare various prototype designs

Silicon micromachined SCALED technology

Silicon micromachining technology will play an important role in the fabrication of high-bandwidth servo controlled microelectromechanical (mechatronic) components for super-compact disk drives. At the University of California, Los Angeles, and the California Institute of Technology, for the last three years, we have initiated a number of industry-supported joint research projects to develop the necessary technology building blocks for an integrated drive design of the future. These efforts include a silicon read/write head microgimbal with integrated electrical and mechanical interconnects, which targets the next-generation 30% form factor pico-sliders, and an electromagnetic piggyback microactuator in super-high-track-density applications, both of which utilize state-of-the-art silicon micromachining fabrication techniques

Silicon microstructures and microactuators for compact computer disk drives

Advances in VLSI and software technology have been the primary engines for the ongoing information revolution. But the steady stream of technical innovations in magnetic disk recording technology are also important factors contributing to the economic strengths of the computer and information industry. One important technology trend for the disk drive industry has been that of miniaturization. As this trend continues, future disk drives will have the same form factor as VLSIs, storing gigabytes of data. Silicon micromachining technology will play an important role in the fabrication of high-bandwidth servo-controlled microelectromechanical components for future super-compact disk drives. At UCLA and Caltech, for the past two years (1992-94) we have initiated a number of industry-supported joint research projects to develop microstructures and microactuators for future generation super compact magnetic recording rigid disk drives, including one to design and fabricate silicon read/write head microsuspensions with integrated electrical and mechanical interconnects, which target the next generation 30% form factor pico-sliders, and one for electromagnetic piggyback microactuators in super high-track-density applications, both of which utilize state-of-the-art silicon micromachining fabrication techniques

Proteomic comparison of biomaterial implants for regeneration of peripheral nerve tissue

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 81-85).Tissue regenerates resulting from the healing of transected peripheral nerve differ in morphological and electrophysiological properties based on the biomaterial implant used to bridge the interneural wound gap. At gap lengths >/=10 mm, impermeable silicone tubes promote little to no nerve regenerate unlike its porous, degradable collagen alternative. This study assayed rat sciatic nerve wounds treated with silicone and collagen tubes at a 14-day time point for concentration differences in transforming growth factor beta 1, 2, 3 (TGF [beta]1, [beta]2, and [beta]3) and alpha smooth muscle actin ([aipha] SMA) to measure disparities in proteins associated with wound healing that may determine nonregenerative from regenerative outcomes. Transected nerves treated with silicone or collagen tubes were compared on a "whole wound" basis to determine differences in protein expression over the entire tissue and on a "per segment" basis to determine local differences in protein expression over ~2-4 mm regions of tissue. Immunofluorescent comparisons of wounds were performed on cross sections taken along the length of the nerve. In each cross section, a region of interest (ROI) was defined from the periphery of the regenerate tissue to -65 gm radially inwards where presence of a contractile capsule was reported by earlier investigators and also observed in this study. A 200% increase in whole wound TGF [beta]3 levels in the collagen compared to the silicone treatment group was determined by immunoblot (p=0.0026). A 30-50% increase in whole wound TGF [beta]1 levels was found in the silicone compared to the collagen treatment group, which was statistically significant by only one of the two assays used (enzyme-linked immunosorbent assay; p=0.0021).(cont.) There was no significant difference in TGF [beta]2 levels between treatment groups. Whole wound expression of a SMA was 440% greater in the silicone treatment group than in the collagen treatment group by immunoblot measurement. Immunofluorescent measurement indicated that a SMA expression in the ROI was 160% greater in silicone than in collagen treated wounds, with significant differences in the nerve stumps (proximal, p=.0243; distal, p=.0021). Proteomic comparisons suggest that collagen tubes are more effective at promoting nerve regenerate than silicone tubes due to heightened levels of TGF 03, less [alpha] SMA expression, and possibly decreased levels of TGF p1 at early stages of wound healing. Trends in protein differences observed in nerve wounds treated with regenerative versus nonregenerative devices are consistent with differences observed in wounds in the early fetal versus adult healing stages. Results from this study support early fetal regeneration as a model for induced regeneration in the peripheral nerve.by Kathy K. Miu.S.M

The development of autocatalytic structural materials for use in the sulfur-iodine process for the production of hydrogen

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2006.Includes bibliographical references (p. 63).The Sulfur-Iodine Cycle for the thermochemical production of hydrogen offers many benefits to traditional methods of hydrogen production. As opposed to steam methane reforming - the most prevalent method of hydrogen production today - there are no carbon dioxide emissions. Compared to other methods of hydrogen production, the efficiency of the cycle is excellent. Due to the high temperatures necessary for the cycle, which are generally greater than 8500C, several of the Generation IV nuclear reactor concepts are attractive thermal energy sources. However, the high temperature and corrosive reaction conditions of the cycle, involving reactions including the decomposition of H2SO4 at 400-9000C, present formidable corrosion challenges. The conversion of sulfuric acid to sulfur dioxide was the focus of this study. The alloying of structural materials to platinum has been proposed as a solution to this problem. A catalytic loop to test the materials was constructed. Sulfuric acid was pumped over the material at 903+20C. The sulfur dioxide production of the catalyst was measured as a means of quantifying the efficiency of the system as a function of temperature.(cont.) The maximum possible production of the material was calculated by using a mass balance. A gas chromatograph was used to calculate the actual production of sulfur dioxide. The results of the experiment show that an molecular conversion efficiency of 10% is attained when operating at 900C while using 800H + 5%Pt as a catalyst. The research confirms the catalytic activity of the material.by Kevin Miu.S.B

Silicon micromachined electromagnetic microactuators for rigid disk drives

It is projected that by the year 2001, the disk drive industry will be shipping products with track density on the order of 25,000 tracks-per-inch, which would require a servo bandwidth of at least 3 kHz. This paper presents initial fabrication results of an industry and government supported research project at Caltech and UCLA to develop piggyback electromagnetically driven microactuators for such applications, which are fabricated using the state-of-the-art silicon micromachining techniques

Silicon microstructures and microactuators for compact computer disk drives

Advances in VLSI and software technology have been the primary engines for the ongoing information revolution. But the steady stream of technical innovations in magnetic disk recording technology are also important factors contributing to the economic strengths of the computer and information industry. One important technology trend for the disk drive industry has been that of miniaturization. As this trend continues, future disk drives will have the same form factor as VLSIs, storing gigabytes of data. Silicon micromachining technology will play an important role in the fabrication of high-bandwidth servo-controlled microelectromechanical components for future super-compact disk drives. At UCLA and Caltech, for the past two years (1992-94) we have initiated a number of industry-supported joint research projects to develop microstructures and microactuators for future generation super compact magnetic recording rigid disk drives, including one to design and fabricate silicon read/write head microsuspensions with integrated electrical and mechanical interconnects, which target the next generation 30% form factor pico-sliders, and one for electromagnetic piggyback microactuators in super high-track-density applications, both of which utilize state-of-the-art silicon micromachining fabrication techniques

Silicon microstructures and microactuators for compact computer disk drives

Silicon micromachining techniques offer many exciting opportunities for fabricating both passive microstructures and active electromagnetic microactuators for significant form factor reduction and increase in recording density of future magnetic recording rigid disk drives. In this overview paper, the authors have presented some recent results and novel product concepts