Viscosity of Water in Nano-Confinement

Since the early 1970s there is a notion that water near polar or charged surfaces is somehow ordered or structured, leading to a so called structural component of the disjoining pressure

Self assembled three-dimensional nonvolatile memories

A promising strategy for for the realisation of three-dimensional memories could be the self assembly of articial sub-micron elements (smarticles). Such elements can be realised by combining edge-lithography techniques and anisotropic etching. The first experiments into this direction are encouraging

Electrostatic micro walkers : micro electromechanics and micro tribology

The Micro Walker project ,which is reported in this thesis, focuses on the development of linear micro-motors with a large dynamic range (reach : resolution). The key question for this project is if it is possible to implement walking motion in MEMS, and what can be the performance of linear micromotors employing walking motion. From their potential application in data storage guiding specifications are derived: An output acceleration of a mg load larger than 100 m / s2, 10 nm resolution, reach larger than 10 mm, a driving voltage below 30 V and a maximum linear size smaller than 1 mm. The linear micromotors to made in the project, are based on variable capacitance electrostatic actuation and surface micromachining fabrication technology. Electrostatic motors have already been made in the 18th century. The first known variable capacitance motor has been built by Zipernowski in 1889. Different propulsion principles for linear micromotors have been found in literature: Inertial drive, elastic inertial drive, impact drive, traveling field surface drive, scratch drive, zigzag drive, transformation of rotary into linearly motion, and walking motion. The latter principle is implemented in the project. Controlled friction in clamp feet is necessary for walking. Therefore, microtribology is one of the main topics in this thesis. The focus is on shearing friction in elastic adhesive contacts

Capillarity effect in silicon based nanochannels

Using silicon based micromachining we have developed different techniques to create 1D and 2D confined nanochannels, with a characteristic diameter down to 5 nm. A short introduction to these techniques will be given. Capillary action in channels of this small size is a strong effect

High-Performance Shuffle Motor Fabricated by Vertical Trench Isolation Technology

Shuffle motors are electrostatic stepper micromotors that employ a built-in mechanical leverage to produce large output forces as well as high resolution displacements. These motors can generally move only over predefined paths that served as driving electrodes. Here, we present the design, modeling and experimental characterization of a novel shuffle motor that moves over an unpatterned, electrically grounded surface. By combining the novel design with an innovative micromachining method based on vertical trench isolation, we have greatly simplified the fabrication of the shuffle motors and significantly improved their overall performance characteristics and reliability. Depending on the propulsion voltage, our motor with external dimensions of 290 μm × 410 mm displays two distinct operational modes with adjustable step sizes varying respectively from 0.6 to 7 nm and from 49 to 62 nm. The prototype was driven up to a cycling frequency of 80 kHz, showing nearly linear dependence of its velocity with frequency and a maximum velocity of 3.6 mm/s. For driving voltages of 55 V, the device had a maximum travel range of ±70 μm and exhibited an output force of 1.7 mN, resulting in the highest force and power densities reported so far for an electrostatic micromotor. After five days of operation, it had traveled a cumulative distance of more than 1.5 km in 34 billion steps without noticeable deterioration in performance.\u

Surface Assisted Combustion of Hydrogen-Oxygen Mixture in Nanobubbles Produced by Electrolysis

The spontaneous combustion of hydrogen–oxygen mixture observed in nanobubbles at room temperature is a puzzling phenomenon that has no explanation in the standard combustion theory. We suggest that the hydrogen atoms needed to ignite the reaction could be generated on charged sites at the gas–liquid interface. Equations of chemical kinetics augmented by the surface dissociation of hydrogen molecules are solved, keeping the dissociation probability as a parameter. It is predicted that in contrast with the standard combustion, the surface-assisted process can proceed at room temperature, resulting not only in water, but also in a perceptible amount of hydrogen peroxide in the final state. The combustion time for the nanobubbles with a size of about 100 nm is in the range of 1–100 ns, depending on the dissociation probability

A UHF 4th-order band-pass filter based on contour-mode PZT-on-silicon resonators

A UHF 4th-order band-pass filter (BPF) based on the subtraction of two 2nd-order contour-mode resonators with slightly different resonance frequencies is presented. The resonators consists of a 1 μm pulsed-laser deposited (PLD) lead zirconate titanate (PZT) thin-film on top of a 3 μm silicon (PZT-on-Si). The resonators are actuated in-phase and their outputs are subtracted. Utilizing this technique, the outputs of the resonators are added up constructively while the feed-through signals are eliminated. The BPF presented a bandwidth of approximately 28.6 MHz and more than 30 dB stopband rejection at around 700 MHz