Remotely powered and remotely interrogated wireless digital sensor telemetry system to detect corrosion

Abstract

A corrosion sensing system includes a reader, a radiation receiving device, a sensing transponder, and a member. The sensing transponder includes a communications device, a processor, and a sensor. The member is subject to corrosion. The sensor is located to detect corrosion of the member. The communications device is connected for transmitting sensor data. The transponder is powered by electricity derived from electromagnetic radiation transmitted by the reader that is received by the radiation receiving device.

What is claimed is: 
     
         1 . An electronic system, comprising:
 a reader;   a common radiation receiving device; and   a plurality of remotely powered and remotely interrogated transponders, wherein all of said transponders are connected to said common radiation receiving device, wherein each of said transponders is powered with energy derived from radiation received by said common radiation receiving device, wherein each of said transponders has an address, and wherein each of said transponders has a system to transmit data so as to avoid collisions.   
     
     
         2 . An electronic system as recited in  claim 1 , wherein said system to avoid collisions includes a random timing generator. 
     
     
         3 . An electronic system as recited in  claim 1 , wherein each of said transponders includes a memory for data logging. 
     
     
         4 . An electronic system as recited in  claim 1 , wherein each of said transponders includes an energy storage device. 
     
     
         5 . An electronic system as recited in  claim 1 , wherein each of said transponders includes a device for two way communication. 
     
     
         6 . An electronic system as recited in  claim 1 , wherein said common radiation receiving device includes one from the group consisting of a coil and an antenna. 
     
     
         7 . An electronic system as recited in  claim 6 , wherein said coil includes a tap. 
     
     
         8 . An electronic system as recited in  claim 1 , wherein each of said transponders includes a sensor. 
     
     
         9 . An electronic system as recited in  claim 8 , wherein said common radiation receiving device is connected to deliver an excitation voltage to each of said sensors. 
     
     
         10 . An electronic system as recited in  claim 9 , wherein data from said sensor is conditioned to provide sensor data ratiometric with magnitude of excitation voltage provided by said radiation receiving device. 
     
     
         11 . An electronic system as recited in  claim 10 , wherein excitation voltage provided by said radiation receiving device is rectified and wherein data from said sensor is rectified and amplified to provide sensor data ratiometric with magnitude of excitation voltage provided by said radiation receiving device. 
     
     
         12 . An electronic system as recited in  claim 10 , wherein excitation voltage provided by said radiation receiving device is digitized and wherein data from said sensor is digitized to provide sensor data ratiometric with magnitude of excitation voltage provided by said radiation receiving device. 
     
     
         13 . An electronic system as recited in  claim 10 , wherein said radiation receiving device includes a coil having multiple taps, wherein said excitation voltage is voltage at one of said taps, wherein said one tap is dynamically selected depending on loading to provide impedance matching and efficient energy transfer. 
     
     
         14 . An electronic system as recited in  claim 10 , further comprising a capacitive divider, wherein said capacitive divider includes an output. 
     
     
         15 . An electronic system as recited in  claim 14 , wherein said excitation voltage is voltage at said output. 
     
     
         16 . An electronic system as recited in  claim 8 , wherein said sensor comprises at least one from the group including a displacement sensor, a pressure sensor, a force sensor, a torque sensor, and a temperature sensor. 
     
     
         17 . An electronic system as recited in  claim 16 , wherein said displacement sensor comprises a variable reluctance transducer. 
     
     
         18 . An electronic system as recited in  claim 1 , further comprising a housing for said transponders, wherein said housing contains said transponders. 
     
     
         19 . An electronic system as recited in  claim 18 , wherein said housing is hermetically sealed. 
     
     
         20 . An electronic system as recited in  claim 19 , wherein said hermetically sealed housing is formed of conductive material, wherein said radiation receiving device is within said hermetically sealed housing, wherein said radiation receiving device is for receiving electromagnetic radiation having a frequency low enough to penetrate through said conductive material, wherein said radiation receiving device is connected to provide electrical energy derived from said electromagnetic radiation. 
     
     
         21 . An electronic system as recited in  claim 20 , wherein said frequency is less than 125 kHz. 
     
     
         22 . An electronic system as recited in  claim 21 , wherein said frequency is less than about 44 kHz. 
     
     
         23 . An electronic system as recited in  claim 22 , wherein said frequency is about 4 kHz. 
     
     
         24 . An electronic system as recited in  claim 1 , wherein all power for operating each of said transponders is derived from power radiated from said reader and received by said radiation receiving device. 
     
     
         25 . An electronic system as recited in  claim 1 , further comprising a rechargeable energy storage device, wherein said rechargeable energy storage device is connected to be recharged with power derived from said radiation receiving device. 
     
     
         26 . An electronic system as recited in  claim 25 , wherein said energy storage device is connected to provide a higher power than is available from said radiation receiving device. 
     
     
         27 . An electronic system as recited in  claim 1 , wherein each of said transponders includes a processor connected to receive power derived from said radiation receiving device. 
     
     
         28 . An electronic system as recited in  claim 27 , wherein each of said transponders includes a sensor, wherein said sensor is connected to provide sensor data to said processor. 
     
     
         29 . An electronic system as recited in  claim 28 , wherein each of said transponders includes an analog/digital converter. 
     
     
         30 . An electronic system as recited in  claim 28 , wherein said processor includes an integrated clock. 
     
     
         31 . An electronic device system as recited in  claim 30 , wherein said integrated clock comprises an RC clock. 
     
     
         32 . An electronic system as recited in  claim 1 , wherein said system to transmit data includes a switched reactance circuit. 
     
     
         33 . An electronic system as recited in  claim 32 , wherein said switched reactance circuit includes a reactive component switchably connected to affect electromagnetic radiation radiated from said reader. 
     
     
         34 . An electronic system as recited in  claim 1 , wherein said system to transmit data includes an RF transmitter. 
     
     
         35 . An electronic system as recited in  claim 1 , wherein said reader includes a radiation transmitting device, wherein said reader comprises a circuit to detect changes in loading of said radiation transmitting device, as a result of switching of said switched reactance circuit in said sensor transponder. 
     
     
         36 . An electronic system as recited in  claim 1 , wherein each of said transponders includes a non-volatile memory connected for storing sensor data. 
     
     
         37 . An electronic system as recited in  claim 1 , further comprising a member subject to corrosion, wherein at least one of said transponders includes a sensor that is located to detect corrosion of said member.