Pressure sensor including bridge circuit for detecting permeability of a magnetic layer

A pressure sensor comprising:

• a sensor body comprising a deforming part deformable under an applied pressure to be detected and a non-deforming part subjected to a constant pressure, the deforming part having an opening for introducing the applied pressure;
• a magnetic layer made of a material having large magnetostriction, which magnetic layer being fixed on the deforming part and on the non-deforming part;
• first and second permeability detector elements disposed to detect the permeability of the magnetic layer on the deforming part and on the non-deforming part, respectively, each of the first and second permeability detector elements having an inductance and an internal resistance, the first and second permeability detector elements being connected in series;
• a first resistor connected to the first permeability detector element, the resistance of the first resistor being smaller than the impedance of the first permeability detector element;
• and
• a second resistor connected to the second permeability detector element and to the first resistance, the resistance of the second resistor being smaller than the impedance of the second permeability detector element;
• wherein a bridge is constructed by the first and second permeability detector elements and the first and second resistors for taking out a difference of the voltages generated in the first and second permeability detector elements.