Biomedical subjects

D P Sheehan

Publications and source records attributed to D P Sheehan.

3 recordsLinked to original sources

PubMed2006

Orthogonally-oriented nanotube arrays: theory.

A novel surface involving ordered arrays of partially-embedded carbon nanotubes is developed theoretically. Analysis indicates it should exhibit ultra-low values for friction, adhesion and wear, and also possess superior thermal and electrical properties. The surface consists of orthogonally-oriented, self-assembling arrays of carbon nanotubes, partially embedded lengthwise in a solid substrate. Calculations indicate that stiction forces due to van der Waals interactions can be made small, perhaps more than an order of magnitude less than for Teflon and other advanced perfluorocarbons. Static and kinetic frictional forces could be three orders of magnitude less than for conventional solids.

Biophysics↗

PubMed2005

Intrinsically biased electrocapacitive catalysis.

We propose the application of the contact potential from metal-metal junctions or the built-in potential of semiconductor p-n junctions to induce or catalyze chemical reactions. Free of external sources, this intrinsic potential across microscale and nanoscale vacuum gaps establishes electric fields in excess of 10(7) Vm. The electrostatic potential energy of these fields can be converted into useful chemical energy. As an example, we focus on the production of superthermal gas ions to drive reactions. Analysis indicates that this intrinsically biased electrocapacitive catalysis can achieve locally directed ion energies up to a few electron volts and local gas temperature boosts in excess of 10(4) K. Practical considerations for implementation and experimental tests are considered.

Journal Article↗

PubMed2003

Modeling a submicrometer electrostatic motor.

Numerical models are developed for a recently proposed submicrometer device that uses the electric field energy of a biased parallel-plate semiconducting capacitor to propel a piston through the open capacitor gap. Through variation of design parameters or applied external bias, actuator forces on the order of hundreds of piconewtons are developed for device size scales ranging from 10(-7) m to 10(-4) m per side. A rotary configuration of the device is also presented.

Computer Simulation↗