A microbalance is an instrument capable of making precise measurements of weight of objects of relatively small mass: of the order of a million parts of a

gram The gram (originally gramme; SI unit symbol g) is a Physical unit, unit of mass in the International System of Units (SI) equal to one thousandth of a kilogram. Originally defined in 1795 as "the absolute Mass versus weight, weight of a volume ...

. In comparison, a standard

analytical balance An analytical balance (or chemical ''balance'') is a class of balance designed to measure small mass in the sub-milligram range. The measuring pan of an analytical balance (0.1 mg resolution or better) is inside a transparent enclosure with do ...

is 100 times less sensitive; i.e. it is limited in precision to 0.1 milligrams. Microbalances are generally used in a laboratory as standalone instruments but are also incorporated into other instruments, such as thermogravimetry, sorption/desorption systems, and surface property instruments. It is the precision of the microbalance that distinguishes it from other weighing devices.

Types

A quartz crystal microbalance (QCM) is a very sensitive mass deposition sensor based on the piezoelectric properties of the quartz crystal. This technique uses the changes in resonance frequency of the crystal to measure the mass on the surface because the resonance frequency is highly dependent on any changes of the crystal mass. A quartz crystal microbalance is capable of measuring mass deposition down to 0.1 nanograms. The sensitivity of the microbalance is lessened the closer the fulcrum is to the middle. A tapered element oscillating microbalance (TEOM) is an instrument used for real-time detection of aerosol particles by measuring their mass concentration. It makes use of a small vibrating glass tube whose oscillation frequency changes when aerosol particles are deposited on it. TEOM-based devices have been approved by the U.S. Environmental Protection Agency for environmental air quality monitoring, and by the U.S.

Mine Safety and Health Administration The Mine Safety and Health Administration (MSHA) () is a small agency of the United States Department of Labor which administers the provisions of the Federal Mine Safety and Health Act of 1977 (Mine Act) to enforce compliance with mandatory sa ...

for monitoring

coal dust Coal dust is a fine-powdered form of coal which is created by the crushing, grinding, or pulverizer, pulverization of coal rock. Because of the brittle nature of coal, coal dust can be created by mining, transporting, or mechanically handling it. ...

exposure for miners to prevent several respiratory diseases. Alternative types of torsional balances include: * Quartz fibre torsion ultramicrobalance * Torsion ultramicrobalance * Torsion nanobalance * Ultramicrobalance * Nanobalance

References

{{science-stub Laboratory equipment Weighing instruments

Types

See also

References