What is QCM?

QCM stands for the Quartz Crystal Microbalance. It is a device that measures the changes in mass and transduces them into electrical signals. These signals are then fed to the computer that gives a visual display of what the QCM measures in terms of frequency shifts w.r.t. time.

It is a very sensitive technique when it comes to measuring very very small mass changes e.g in the nanograms per mL range i.e. the ppb limits. The system is very reliable as it always shows the same results when the same amount of mass is deposited on it. This thing is particularly useful in the field of sensors.

Nowadays, molecularly imprinted polymers are coated as thin films onto the surface of quartz that has been already modified with a gold electrode to transduce the mass change signal. These MIPs are sensitive to a target molecule and when any such molecule comes to the surface of the gold electrode, they add mass to the QCM and this mass change is recorded in the form of electrical signal.