Biomedical subjects

Noel C MacDonald

Publications and source records attributed to Noel C MacDonald.

3 recordsLinked to original sources

PubMed2006

Beam-supported AlN thin film bulk acoustic resonators.

A novel, suspended thin film bulk acoustic wave resonator (SFBAR) has been fabricated from an aluminum nitride film sputtered directly on a (100) silicon substrate. The suspended membrane design uses thin beams to support, as well as electrically connect, the resonator and has been fabricated using both thin film processing and bulk silicon micromachining. The quality factor and the effective electromechanical coupling coefficient were characterized as a function of the number and the length of the support beams. The length of the support beams was found to affect neither the quality factor at resonance nor the effective electromechanical coupling factor. However, longer support beams did facilitate better frequency pair response. Device performance varied with the number of support beams: 70% of the resonators tested showed a higher figure of merit with eight support beams than with four support beams.

Journal Article↗

PubMed2005

Control of particles in microelectrode devices.

The impact of the convective fluid motion induced by the electric fields on the dielectrophoretic manipulation of particles is investigated theoretically and experimentally. By means of a simplified model a channel with a periodic array of microelectrodes we show that electroconvective flows induce the formation of traps for particles, providing a dynamical mechanism to control microparticles in such devices. We demonstrate experimentally the theoretically predicted dynamical phenomena.

Journal Article↗

PubMed2004

High-aspect-ratio bulk micromachining of titanium.

Recent process developments have permitted the highly anisotropic bulk micromachining of titanium microelectromechanical systems (MEMS). By using the metal anisotropic reactive ion etching with oxidation (MARIO) process, arbitrarily high-aspect-ratio structures with straight sidewalls and micrometre-scale features have been bulk micromachined into titanium substrates of various thicknesses, ranging from 0.5-mm sheet down to 10-microm free-standing titanium foils. Bulk micromachined structures are generally free of residual stresses and are preferred when large, rigid, flat and/or high-force actuators are desired. However, so far there has been a limited ability to select materials on the basis of specific application in bulk micromachining, primarily because of the predominance of MEMS processes dedicated to single-crystal silicon, such as silicon deep reactive ion etching. The MARIO process permits the creation of bulk titanium MEMS, which offers potential for the use of a set of material properties beyond those provided by traditional semiconductor-based MEMS. Consequently, the MARIO process enables the fabrication of novel devices that capitalize on these assets to yield enhanced functionalities that would not be possible with traditional micromechanical material systems.

Manufactured Materials↗