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Microbalance
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. In comparison, a standard analytical balance 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 de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 resonance is disturbed by the addition or removal of a small mass due to oxide growth/decay or film deposition at the surface of the acoustic resonator. The QCM can be used under vacuum, in gas phase ("gas sensor", first use described by King) and more recently in liquid environments. It is useful for monitoring the rate of deposition in thin film deposition systems under vacuum. In liquid, it is highly effective at determining the affinity of molecules (proteins, in particular) to surfaces functionalized with recognition sites. Larger entities such as viruses or polymers are investigated as well. QCM has also been used to investigate interactions between biomolecules. Frequency measurements are easily made to high precision (discussed b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
