An example would be a transferrin- quartz crystal microbalance (QCM). Most such instruments use a quartz crystal microbalance as the sensor. Various types of sensitive microbalance have been developed for this purpose. Quartz crystal microbalance (QCM) is an acoustic sensor built around a disk shaped quartz crystal. It is the precision of the microbalance that distinguishes it from other weighing devices. The TEOM uses a hollow glass tube as a microbalance. 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.