The sensor of a tuning fork densitometer is designed based on the vibration principle of components, with a vibration element resembling a tuning fork with two prongs. The prongs vibrate due to a piezoelectric crystal located at the root of the prongs. The vibration frequency is detected by another piezoelectric crystal. Through phase shifting and amplification circuits, the prongs are stabilized at their natural resonant frequency. When the medium flows past the prongs, the change in medium mass causes a shift in the resonant frequency.