Any device sent into outer space must have certain characteristics. It must be able to withstand the stress of propulsion into space. It must also be able to use power efficiently. And it must be able to operate under thermal extremes. It is also very favorable for such devices to be as small and lightweight as possible. Several space microdevices have been created that meet these criteria. Miniature gas chromatographic ionization detectors, ion mobility spectrometers, x-ray diffraction devices, and fluorescence instruments are all in various stages of development. Each of these devices plays an important role in exobiology, the science of extraterrestrial environments that may support life.
A number of space microdevices have micromechanical functions; they either sense or respond to detected conditions such as the presence of a chemical or heat. Ionization detectors can identify the chemical composition of a foreign sample. Model ionization detectors weigh only 0.008-0.06-oz (1-2 g), and are sensitive enough to detect compounds at 10-14 mol/sec. A miniature "stable isotope laserdiode spectrometer" has also been designed to determine sample ratios of carbon and oxygen isotopes. These advances in miniature space technology could help decrease the size and weight of the space vehicle's payload (cargo not required for basic travel operations).
Micromachines with thousands of other uses are on the drawing board, in the laboratory, and soon to be part of our lives. For years, intricate miniatures have been the pride of craftsmen who used intricate watches and toys to display their finesse. The twentieth century developments of silicon chips and electronics are allowing tiny machines with science-fiction-like capabilities. The first micromachine to catch the public's eye was probably the electric motor developed by engineers at the University of California in 1988 the motor was half as wide as a human hair. In 1996, the Japanese followed with a complete car, a replica of a 1936 Toyota sedan, that was the size of a grain of rice and had 24 moving parts. Micromachines have three dimensions (as opposed to the flat, essentially two-dimensional chips) and usually consist of a sensor, actuator, and motor or pump. They are called MEMS, an acronym for micro electrical mechanical systems. MEMS have endless practical uses and are already employed to sense when to deploy airbags in automobiles and to measure blood pressure from inside intravenous tubes (IV) in hospitals.
Micro-air vehicles or MAVS are bug-sized devices that fly and are also called entomopters. Despite the cute images they conjure, MAVS might have potential as miniature spy planes in hotel rooms, as flying cameras in any number of applications including security systems, and as collectors of air samples in contaminated areas or following explosions. After disasters like earthquakes, MAVS may be dispatched in buildings to search for survivors without imperiling rescuers. The cousins of MAVS are MARVS, or miniature autonomous robotic vehicles. MARVS can also be sent on dangerous missions to inspect for chemical or nuclear weapons, detect leaks, or search for land mines. MARVS navigate on tiny wheels, so obstacles like paperclips or pencils are major. Other hazards that face these tiny devices and their creators are static electricity that can paralyze gears, oils and residues that clog motors, and droplets of rain that impact the machines like bombs. But MEMS are inexpensive to mass produce, and they do not experience the problems of larger machines like metal fatigue.
See also Nanotechnology.
Gross, Michael. Travels to the Nanoworld: Miniature Machinery in Nature and Technology. Cambridge, MA: Perseus Publishing, 2001.
Key Technologies for the 21st Century: Scientific American: A Special Issue (Scientific American Series). New York: W. H. Freeman & Co., 1999.
Madou, Marc. Fundamentals of Microfabrication: The Science of Miniaturization. Boca Raton, FL: CRC Press, 2002.