Wirelessly Interrogated Wear or Temperature Sensors

Such sensors could be embedded in brake pads.

Sensors for monitoring surface wear and/or temperature without need for wire connections have been developed. Excitation and interrogation of these sensors are accomplished by means of a magnetic-field-response recorder — an apparatus previously reported in “Magnetic-Field-Response Measurement-Acquisition System” (lar-16908), NASA Tech Briefs, Vol. 30, No. 6 (June 2006), page 28. To recapitulate: The magnetic-field-response recorder is placed near, but not touching, the sensor of interest. This apparatus generates an alternating magnetic field that excites oscillations in the resonant circuit, measures the magnetic response of the circuit, and determines the resonance frequency from the response.