Piezoimpedane and pressure sensors with NiZn ferrite device

The hydrostatic pressure effect on the magnetism, capacitance and impedance of a NiZn ferrite device has been investigated. Giant piezomagnetism, piezocapacitance and piezoimpedane independent on skin effect have been observed simultaneously under a pressure of several MPa. With increasing the frequency of the current applied across the ferrite device, the piezoimpedane has been found to undergo a maximum at a current frequency of 500 Hz. Under a pressure of 6 MPa, the maximum of piezoimpedane can reach about 71%. And the pressure sensitivity of the impedance can be higher than 0.18 MPa−1 when the pressure is lower than 3 MPa. Analysis shows that these giant pressure effects in the ferrite device result from the variation of the inner stress in the ferrite under an external pressure.