3.6.3 Quality of resonance
As you will see when you read Section 6 Vibrations and resonance the quality of a resonance, Q, is defined as ω/Δω. Here, ω is the resonant frequency, and Δω is the frequency range over which the amplitude of the oscillation is greater than half the maximum amplitude at resonance.
The MEMS sensors that so far have achieved the best measurement resolution are pressure sensors that rely on the pressure applied to a membrane changing the tension in a resonant beam attached to it, and thereby changing the frequency at which it resonates. The reason for this high resolution is that frequency (in effect, time) is a quantity that we are able to measure to parts per billion accuracy with great ease. Crucial to using this fact to advantage in a resonant sensor is ensuring that the resonance of that sensor is very sharp – in other words, of very high Q.