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 unit of mass in the International System of Units (SI) equal to one one thousandth of a kilogram. Originally defined as of 1795 as "the absolute weight of a volume of pure water equal to th ...

. 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 d ...

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 Thermogravimetric analysis or thermal gravimetric analysis (TGA) is a method of thermal analysis in which the mass of a sample is measured over time as the temperature changes. This measurement provides information about physical phenomena, such ...

, sorption/desorption systems, and surface property instruments. It is the precision of the microbalance that distinguishes it from other weighing devices.

Types

quartz crystal microbalance A quartz crystal microbalance (QCM) (also known as ''quartz microbalance'' (QMB), sometimes also as ''quartz crystal nanobalance'' (QCN)) measures a mass variation per unit area by measuring the change in frequency of a quartz crystal resonator. The ...

(QCM) is a very sensitive mass deposition sensor based on the piezoelectric properties of the

quartz crystal Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

. 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 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 aeroso ...

(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 The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...

for environmental air quality monitoring, and by the U.S.

Mine Safety and Health Administration The Mine Safety and Health Administration (MSHA) () is a large 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 safe ...

for monitoring

coal dust Coal dust is a fine powdered form of which is created by the crushing, grinding, or pulverizing of coal. Because of the brittle nature of coal, coal dust can be created during mining, transportation, or by mechanically handling coal. It is a form ...

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