The invention belongs to the technical field of pressure sensors, and particularly relates to a
wireless passive
pressure sensor for detecting bolt pretightening force, which comprises a pressure-sensitive
capacitor and an outer ring encapsulation ring, the
voltage-sensitive
capacitor comprises an inner ring basin cavity, and an upper insulation pad, an upper polar plate, an elastic
cushion layer, a lower polar plate and a lower insulation pad which are sequentially arranged in the inner ring basin cavity from top to bottom, the bottom of the inner ring
pelvic cavity, the upper insulating pad, the upper polar plate, the elastic
cushion layer, the lower polar plate and the lower insulating pad are provided with concentric holes to form a central through hole of the
voltage-sensitive
capacitor; the outer ring
potting ring wraps the outer ring of the inner ring basin cavity, and a circuit and an antenna are arranged in the outer ring
potting ring; the circuit is a
frequency conversion circuit which is connected with the upper polar plate and the lower polar plate; and the circuit is also connected with the antenna. The sensor realizes
wireless passive real-time monitoring, is convenient to install, does not need
direct current power supply, does not have a
signal processing unit inside, only transmits frequency signals, and is high in response speed.