Nano Focus from MRS

Carbon nanotubes wired for pressure sensing 

Carbon nanotube (CNT)-based pressure sensors offer the advantages of ultra-low-power operation, wide dynamic range and ease of integration with microcavities for vacuum microelectronics, compared with conventional thermal conductivity gauges such as Pirani or thermocouple devices. The enhanced pressure sensitivity of CNT-based sensors, especially at large bias voltages, was attributed to the one-dimensional nature of electrical transport within the suspended tubes, as well as the contacts. These artifacts in suspended tubes were manifested by the presence of a negative differential conductance (NDC) regime in the device's IV curve. The feature was absent in the profile for unreleased tubes. The presence of the NDC suggests a large optical phonon density in suspended tubes at large biases, which affects tube temperatures and can be exploited to enhance the sensitivity of CNT-based pressure sensors.

Nanoparticles make self-erasing images
Materials displaying 'self-erasing' color images have been created by researchers, using specific nanoparticles that can assemble and disassemble themselves under different wavelengths of light. The materials are printed with ultraviolet (UV) light and erased with visible light. They are made by coating gold and silver nanoparticles with a single layer of azobenzene molecules, and then embedding the nanoparticles in thin, flexible 'organogel' films. When the films are exposed to UV light, the structural symmetry of the azobenzene molecules flips, and they acquire electric dipoles that make them attract. This attraction causes the nanoparticles to assemble, and thereby take on a new color. However, in an absence of UV light - or even better, in strong visible light - the particles revert to their original symmetry, and the color disappears over a period of time.

Posted in: