Patent ID: 9378448
Filing Date: 2016-06-28
CPC Classification: G06K

Claim Text:
1. Method of passively monitoring a strain exerted on an object, the method comprising: with an antenna provided to an RFID sensor tag, receiving an interrogation signal transmitted by a RFID reader; creating a stable supply voltage that is input to a transducer associated with the RFID sensor tag from an induced voltage created as a result of a current induced by the interrogation signal; with an RF filter, blocking from the supply voltage a component of voltages created by currents induced in circuit traces by a RF field generated by the RFID reader; with the transducer, sensing the strain and outputting a signal on the order of 10's of microvolts indicative of the strain while energized by the induced voltage; with an amplifier, amplifying the signal from the transducer and filtering RF noise out of the signal to produce a desired signal; and transmitting, from the antenna, the desired signal indicative of the strain that is received by the RFID reader.