Microbalance

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Microbalance is an instrument capable of measuring amounts of mass to at least 1 million parts of a gram (g - the unit symbol for gram). Commercially available instruments today have the capacity of measuring the total sample weight of about 0.2 g to 1.0 g. Because of this total weight limitation, microbalances are used to accurately measure small amounts of a sample. Generally used in a laboratory as a standalone instrument, microbalances are also incorporated in other instruments, such as thermogravimetry, sorption/desorption systems, and surface property instruments. Microbalance has two properties that are required to measure weights accurately: Repeatability and Accuracy. In a microbalance instrument, repeatability is the instrument's ability to have a sample read the same value at different times it is weighed. Accuracy is the instrument's ability to show the true weight of the sample; this is usually performed by calibrating the instrument with a known standard weight (referenced to NIST).

Quartz Crystal Microbalance is a very sensitive mass deposition sensor based on 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. Quartz Crystals Microbalance is capable to measure mass deposition down to 0.1 nanograms.