Nanotechnology Integrates Mechanical and Electrical Components with NEMS
NEMS, or nanoelectromechanical systems, are devices that integrate nanoscale mechanical and electrical components into a single component. NEMS are built on semiconductor chips using integrated circuit manufacturing techniques. By manufacturing mechanical components on the same silicon chip that contains electrical circuits used for controlling the mechanism or amplifying a signal, you significantly reduce the size, cost, and power requirements for these devices.
Currently, the practical version of this methodology is focused on microelectromechanical systems (MEMS), which are used for sensors. An example of a MEMS sensor is the acceleration sensor that deploys airbags in a crash. MEMS are also used in game controllers to sense your movements and use that data to control an action figure in a game. Medical applications for MEMS include blood pressure and low blood sugar sensors.
NEMS can make some types of sensors more sensitive. Researchers believe that moving to NEMS, which reduces the size of the mechanical components on a chip to the nanoscale, can improve the capabilities of devices that need extremely sensitive measurements.
Researchers have developed chemical and bacterial NEMS sensors using nanocantilevers. Nanocantilevers have been fabricated with thicknesses as low as 20 nm. These act like a guitar string that vibrates at a certain resonance frequency when plucked. Nanocantilevers have been functionalized with antibodies that bond to viruses or bacteria, and the added weight of the virus or bacteria changes the frequency at which the cantilever vibrates.
Researchers have developed a NEMS resonator that is sensitive enough to measure the mass of individual molecules. The resonator consists of a ribbon 100 nanometers thick and 2 micrometers long. When a molecule lands on the ribbon, the frequency of its oscillation changes; the amount of the change depends on the mass of the molecule.
Because methods to manufacture NEMS devices use the same techniques for manufacturing integrated circuits, researchers envision NEMS devices that have an array of these resonators, just as integrated circuits have arrays of memory cells. Arrays of resonators that measure the mass of many molecules at the same time could be useful in understanding how biological systems work so systems similar to them can be built.