Research experiments on pressure-difference sensors with ferrofluid

• The principle of pressure difference sensor with ferrofluid was illustrated.
• The parameters of ferrofluid, such as density and magnetization, were measured. The magnetization curves of the ferrofluid were sketched.
• Four series of U tubes with different diameter were designed and manufactured.
• The experiments were made to analyze the factors of the tube diameter and the concentration of ferrofluid on the output-input pressure difference.
• The sensitivity of the pressure difference sensor with ferrofluid was studied and the corresponding conclusions were obtained.

Ferrofluid has distinctive properties and can be applied in many industrial uses, especially in sensors. The principles of pressure-difference sensors with ferrofluid were illustrated and experiments were demonstrated. Four types of ferrofluids with different concentrations were selected for the experiments performed. Then, the parameters of ferrofluid, such as density and magnetization, were measured. The magnetization curves of the ferrofluid were sketched. Four U tubes with different diameters were designed and built. Experiments were conducted to analyze the impacts of tube diameter and ferrofluid concentration on the output voltage/pressure difference performance. According to the experiment results, the tube diameter has little effect on the sensor output voltage. With the concentration of ferrofluid increasing, the output voltage and sensitivity of the pressure-difference sensor increases. The measurable range of the sensor also increases with the increasing concentration of ferrofluid. The workable range and the sensitivity of the designed sensor were (−2000~+2000)Pa and 1.26 mV/Pa, respectively.