The relationship between shifted frequency and mass is defined by Sauerbrey’s equation. A 1 Hz shift with a 9 MHz sensor equals approximately 1 ng, A 1 Hz shift with NDK’s 30 MHz QCM sensor equals 35 pg. NDK’s 30 MHz QCM sensor will provide a higher sensitivity of measurement when compared to a conventional QCM sensor which are only available up to 27 MHz.