Accelerometers: An instrument that
measures acceleration or gravitational force capable of imparting
acceleration. Accelerometers may also be used for detecting and measuring
Actuators: Mechanisms for activating
process control equipment by use of pneumatic, hydraulic, or electronic
Anisotropic etching: Etching which
involves different etch rates in different directions in the material.
Annealing: The process of heating
and then cooling a metal, alloy, or glass, usually to remove internal
stresses and to make the material less brittle. Also, cooling slowly,
usually in a furnace.
Aspect ratio: A ratio of one dimension
to another, such as the ratio of the span to mean chord of a wing, or the
ratio of the height to the width of a doorway.
Baked: A term used to characterize
films (such as paint) which have been heated to speed the evaporation
of thinners (in the case of paint) and/or to promote the reaction of
binder components so as to form a hard film.
Buffered: Pertaining to an acid or base
solution to which a substance capable of neutralizing the acid or base
has been added.
Capacitor: A device that consists of
two conductors (such as parallel metal plates) insulated from each other
by a dielectric. A capacitor introduces capacitance (i.e., the ratio of
the charge on one of the conductors of a capacitor to the potential
difference between the conductors) into a circuit, stores electrical
energy, blocks the flow of direct current, and permits the flow of
Chemical vapor deposited: Pertaining to
the growth of thin solid films on a crystalline substrate as the result of
thermochemical vapor-phase reactions. Chemical vapor deposition is
normally abbreviated as CVD.
Closed-loop feedback: An automatic
control system for an operation or process in which feedback in a closed
path or group of paths acts to maintain output at a desired level.
CMOS: Complementary metal oxide
semiconductor. A CMOS device is formed by the combination
of a PMOS (p-type-channel metal oxide semiconductor device) with an
NMOS (n-type-channel metal oxide semiconductor device. See planar devices for definitions of p- and
Demultiplex: To separate a
multiplex signal into its component parts. See multiplex.
Double-diffused devices: Devices
(transistors) in which two pn junctions are formed in the
semiconductor wafer by gaseous diffusion of both p-type and n-type
impurities; see planar devices for
definitions of p- and n-type
to a mechanical device, system, or process that is
electrostatically or electromagnetically actuated or controlled.
Epitaxial: Pertaining to
semiconductor layers having the same crystalline orientation as
the substrates on which they are grown.
Etching: Removal of portions of a layer
of conductive material from a usually insulating base through chemical or
electrolytic means. In wet etching, the material is dissolved when
immersed in a chemical solution. In dry etching, the material is sputtered
or dissolved using reactive ions or a vapor phase etchant.
Inertial measurement units: In
inertial navigators, platforms that maintain sensing instruments in a
precise angular orientation in space. Inertial navigators, also known as
inertial navigation systems, are self-contained systems that can
automatically determine the position, velocity, and attitude of a moving
vehicle by means of the double integration of the outputs of
accelerometers that are either strapped to the vehicle or stabilized with
respect to inertial space.
Accelerometers that detect a change in inertia (resistance to
change in momentum) of the mass or body to which they are
attached and convert that change into a useful input signal for
an information-gathering system.
Integrated circuit: An
interconnected array of active and passive elements integrated with a
single semiconductor substrate or deposited on the substrate by a
continuous series of compatible processes, and capable of performing
at least one complete electronic circuit function. Also known as
Internal stresses: Stress systems
within solids that are not dependent on external forces. Also known as
Ion implantation: Introducing
impurities into the near-surface regions of solids by directing a beam of
ions at the solid.
Isotropic etching: Etching which takes
place at the same rate in different directions of a material.
Junctions: Regions of transition
between two different semiconducting regions in a semiconductor device
(such as a pn junction), or between a metal and a semiconductor.
Micromachining: Machining (i.e.,
performing various cutting or grinding operations on a piece of work) for
the purpose of fabricating memsmechanical parts.
Micrometer: A unit of length equal
to one-millionth of a meter.
Monolithic: 1. Formed from a single crystal, such as a monolithic silicon chip. 2. Produced in or on a
monolithic chip, as a monolithic circuit. A monolithic integrated
circuit (MIC) is an IC having elements formed in place on or within a
semiconductor substrate, with at least one element being formed within
the substrate. See substrate and
Multiplex: (adjective) Being or
relating to a system of transmitting several messages, programs, or
signals simultaneously on the same circuit or radio frequency channel.
(transitive verb) To send (messages or signals) by a multiplex system.
(intransitive verb) To multiplex messages or signals.
Nanosatellites: Very small lightweight
[under 20 kg (44 lbs)] satellites containing memselectronic equipment,
components, and payloads.
Passivation: The protection (as of a
solid state device) against contamination by coating or surface
treatment. Growth of an oxide layer on the surface of a semiconductor
to provide electrical stability by isolating the transistor surface
from electrical and chemical conditions in the environment.
Photons: Quanta (plural of quantum,
i.e., very small increments or parcels of electromagnetic radiation (such
Piezoelectric: Having the ability to generate a voltage when mechanical force is applied, or to produce a
mechanical force when a voltage is applied, as in a piezoelectric
Piezoresistive effect: The change in
the electrical resistivity of a metal or semiconductor that is produced
by mechanical stress.
Piezoresistors: Resistors that
undergo a change in resistivity when undergoing mechanical stress. See
Planar devices: Semiconductor devices
having planar electrodes in parallel planes, made by alternate diffusion
of p- and n-type impurities into a substrate. p-type semiconductors have
electron hole densities exceeding the conduction electron densities.
n-type semiconductors have conduction electron densities exceeding the
Polycrystalline Si: Silicon (Si) which
is composed of aggregates of individual Si crystals.
Polyimides: Polymeric compounds
containing multiple imides, i.e., NH groups derived from ammonia (NH3) by
replacement of two hydrogen atoms by metals or equivalents of acid
Proof mass: A predetermined test mass
in a measuring device or machine, such as in acceleration measurement
equipment, which serves as the reference mass for the quantity to be
Resistors: Devices designed to have
definite amounts of electrical resistance; used in circuits to limit
current flow or to provide voltage drops.
Semiconductors: Solid crystalline
materials whose electrical conductivities are intermediate between that
of conductors and insulators, and which are usually strongly
Sputtering: 1. The ejection of atoms
or groups of atoms from the surface of the cathode (negative electrode)
of a vacuum tube as the result of heavy-ion impact. 2. The use of this
process to deposit a thin layer of metal on a glass, plastic, metal, or
other surface in a vacuum.
Strain gauges: Instruments for
measuring the strain, or response to stress, on a structure. The stress is
essentially the load on the structure. The load may be dynamic (such as
the impact load of a meteor crashing on the Earths surface) or static
(such as the load a television set applies to the floor or stand it is
constantly resting upon). In the case of the meteor crashing to the Earth,
the strain may be the subsequent crater that is formed. In the case of the
television set sitting upon a surface, the strain is the (invisible)
pressure that the floor or stand is enduring.
Substrate: The material of which
something is made and from which it derives its special qualities. In
electronics, it is the physical material on which a memscircuit is
fabricated; used primarily for mechanical support and insulating
purposes, as with ceramic, plastic, and glass substrates; semiconductor
and ferrite substrates may also provide useful electrical functions.
Tensile: Pertaining to the stress
(i.e., tension) resulting from the elongation of an elastic body.
Thermal diffusion: A phenomenon in
which a temperature gradient in a mixture of fluids gives rise to a flow
of one constituent relative to the mixture as a whole. Also known as
Transducer: Any device or element
which converts an input signal into an output signal of a different
form; examples include the memsphone, phonograph pickup, loudspeaker,
barometer, automobile horn, and doorbell.
Transistor: An active component of
an electronic circuit consisting of a small block of semiconducting
material to which at least three electrical contacts are made, usually
two closely spaced rectifying (i.e., converting an alternating current
(ac) to a unidirectional one) contacts and one ohmic (nonrectifying)
contact; it may be used as an amplifier, detector, or switch.