Determination of liquid density with a low frequency mechanical sensor based on quartz tuning fork

A novel sensor is presented for measuring liquid density. It consists of a PZT rectangular plate as an actuator for piezoelectric excitation and a quartz tuning fork placed on top of PZT as a sensor for resonant frequency detection. The resonant frequency is determined from the sensing voltage created in tuning fork when the excitation frequencies of PZT actuator are swept around the resonant frequencies of tuning fork. And the liquid density result is extracted from the resonant frequency. The density values of five kinds of organic solvents are measured and compared with the standard values. All experimental results are in agreement with the standard values and the maximum standard deviation is less than ±8%.