Recent reports describing photoluminescence in porous silicon have heightened the level of interest it as a unique electronic material, and created need for more complete understanding mechanism formation. The various models formation are reviewed known electrochemical morphological properties discussed with intention unifying different into comprehensive explanation structure silicon. Because specific surface dissolution chemistry is critical pore formation, some prominent reactions also...

The cause of neuronal degeneration in Alzheimer's disease (AD) has not been completely clarified, but variously attributed to increases cytosolic calcium and increased generation reactive oxygen species (ROS). β‐amyloid fragment (Aβ) the amyloid precursor protein induces influx, ROS apoptosis. Homocysteine (HC), a neurotoxic amino acid that accumulates neurological disorders including AD, also influx oxidative stress, which shown enhance excitotoxicity, leading We examined possibility HC may...

The anodic current‐potential characteristics of four types silicon in aqueous solutions have been studied. According to the surface condition samples anodized at different potentials, there are generally three regions on a curve: porous formation region where current changes exponentially with potential, electro‐polishing constant region, and transition between. A diagram is presented indicate conditions for electropolishing Porous considered be result competition reactions between oxide...

A method is described to control the thickness of single-crystal silicon membranes, fabricated by wet anisotropic etching. The technique an electrochemical etch-stop on epitaxial layer used yield better over membranes (+or-0.2 mu m s.d.) and hence improve reproducibility piezoresistive pressure sensors. output characteristics such sensors are compared with previously not utilizing accurate membrane thickness. benefits approach become apparent when reductions in pressure-sensitivity...

Dielectrophoresis is an effective method for capturing nanoparticles and assembling them into nanostructures. The frequency of the dielectrophoretic alternating current (ac) electric field greatly influences morphology resultant nanoparticle assemblies. In this study, regimes associated with specific gold assembly morphologies were identified. Gold suspended in water captured by microelectrodes at different frequencies onto thin silicon nitride membranes. assemblies examined transmission...

Embryogenesis is a highly regulated process in which the precise spatial and temporal release of soluble cues directs differentiation multipotent stem cells into discrete populations specialized adult cell types. In spinal cord, neural progenitor are directed to differentiate neurons through action mediators released from nearby organizing centers, such as floor plate paraxial mesoderm. These signals combine create spatiotemporal diffusional landscapes that precisely regulate development...

A physical model is presented which quantitatively describes the threshold voltage instability, commonly known as drift, in n-channel Si/sub 3/N/sub 4/-gate pH ISFET's. The origin of so-called drift postulated to be associated with relatively slow conversion silicon nitride surface a hydrated SiO/sub 2/ or oxynitride layer. rate hydration modeled by hopping and/or trap-limited transport mechanism dispersive transport. Hydration leads decrease overall insulator capacitance time, gives rise...

A transmission electron microscopy study of porous silicon reveals that pores selectively propagate in the 〈100〉 crystallographic directions on both n- and p-type silicon, independent dopant concentration or anodization conditions.

Micro-electro-mechanical (MEM) translational tabs are introduced for active load control on aerodynamic surfaces such as wind turbine rotor blades. Microtabs mounted near the trailing edge of blades, deploy approximately normal to surface, and have a maximum deployment height order boundary-layer thickness. Deployment tab effectively changes sectional chamber blade, thereby changing its characteristics. A with blade section chord ratio, h/c, 0.01 causes an increase in lift coefficient, C1,...

The fabrication of nanopores in thin silicon nitride and aluminum oxide membranes by water vapor assisted, low-energy (0.2-20 kV) electron beam machining using a scanning microscope (SEM) is described. Using this technique, pores with diameters ranging size from < 5 to 20 nm are easily formed. characterized SEM, transmission microscopy (TEM) atomic force (AFM). mechanism etching briefly discussed.

The fabrication using silicon micromachining and characterization of an acoustic Lamb wave actuator is presented. intended use the device for mass transport sensor applications. consists dual interdigitated transducers patterned on a thin-film composite membrane nitride, platinum, sol-gel-derived piezoelectric ceramic (PZT) thin film. properties are presented along with preliminary applications to mechanical liquid delivery systems. Improved signals improved achieved PZT over present devices...

Reversible tubing connections for glass micro-fluidic systems are realized using electro-chemical discharge machining of three-dimensional vias. The reversibly connect standard sized plastic to holes in borosilicate microscope slides. Tubing demonstrated on a sealed, channel which is fabricated between two slides SU-8. experimentally tested withstand up 30 psi (~206 kPa) air pressure without leaking.

Transverse and axial trapping forces are calculated in the ray optics regime for a multiple-beam fiber-optic light-force trap dielectric microspheres located both on off axis relative to beam axis. Trap efficiencies evaluated as functions of effective index refraction microspheres, normalized sphere radius, waist separation distance. Effects linear polarization electric field focusing through microlenses considered. In case counterpropagating two-beam trap, using at distal ends fiber focus...

The mechanism by which an intense electron beam can produce holes in thin films of silicon nitride has been investigated using a combination situ energy loss spectrometry and microscopy imaging. A brief review interactions that lead to material different materials is also presented. nitrogen decreases with decreasing although still observable at 150keV ceases completely 120keV. linear behavior the rate coupled dependency indicates process primarily one direct displacement, involving...

A presentation of etch stop engineering is presented with a review the present state art in micro‐machining. This assumes global definition for an and focuses on salient examples common techniques, as well unique and/or novel methods. table representative stops also summary.

Cross-sectional and plan-view transmission electron micrograph analysis of the structure porous silicon reveals that pore walls are also porous, yielding a large distribution sizes for given sample. This infrastructure appears to be universal morphological feature silicon, independent formation conditions doping. It is proposed observed microstructure explains recently reported results adsorption isotherm experiments.