Implanted sensor processing system and method for processing implanted sensor output

Abstract

A quantitative measurement system includes an external unit and an internal unit and is provided for obtaining quantitative analyte measurements, such as within the body. In one example application, the internal unit would be implanted either subcutaneously or otherwise within the body of a subject. The internal unit contains optoelectronics circuitry, a component of which may be comprised of a fluorescence sensing device. The optoelectronics circuitry obtains quantitative measurement information and modifies a load as a function of the obtained information. The load in turn varies the amount of current through coil, which is coupled to a coil of the external unit. A demodulator detects the current variations induced in the external coil by the internal coil coupled thereto, and applies the detected signal to processing circuitry, such as a pulse counter and computer interface, for processing the signal into computer-readable format for inputting to a computer.

What is claimed is: 
     
         1 . A system comprising:
 a sensor unit for taking quantitative analyte measurements, the sensor unit including a first inductor forming part of a power supply for said sensor unit, a load coupled to said first inductor, and a sensor circuit for modifying said load in accordance with sensor measurement information obtained by said sensor circuit;   a reader including a second inductor that is mutually inductively coupled to said first inductor upon said second inductor being placed within a predetermined proximal distance from said first inductor, a driver for driving said second inductor to induce a charging current in said first inductor, a detector for detecting variations in a load on said second inductor induced by changes to said load in said sensor unit and for providing information signals corresponding to said load changes, and a processor for receiving and processing said information signals.   
     
     
         2 . The system of  claim 1 , wherein said sensor circuit comprises an indicator that emits radiation in proportion to levels of said analyte. 
     
     
         3 . The system of  claim 2 , wherein said load comprises a photosensitive resistor that receives radiation from said indicator. 
     
     
         4 . The system of  claim 2 , wherein said sensor circuit further comprises a radiation source configured to emit electromagnetic radiation that stimulates emission of the radiation. 
     
     
         5 . The system of  claim 2 , wherein said indicator emits fluorescent radiation in proportion to levels of said analyte. 
     
     
         6 . The system of  claim 5 , wherein said load comprises a photosensitive resistor that receives fluorescent radiation from said indicator. 
     
     
         7 . The system of  claim 4 , wherein said radiation source for emitting electromagnetic radiation stimulates emission of fluorescent radiation. 
     
     
         8 . The system of  claim 1 , wherein said sensor unit is implantable in the body of a mammal. 
     
     
         9 . The system of  claim 1 , wherein said power supply further includes a charging capacitor that is charged by said charging current. 
     
     
         10 . The system of  claim 1 , wherein said detector of said reader includes an amplitude modulation (AM) demodulator for detecting changes in amplitude of a voltage waveform caused by changes in said load, said voltage waveform being inductively reflected into said second inductor through said first inductor. 
     
     
         11 . The system of  claim 10 , wherein said processor includes a pulse counter for converting said detected changes in waveform amplitude into pulses suitable for being converted into computer-readable form. 
     
     
         12 . The system of  claim 1 , wherein said reader includes a computer configured to receive the processed information signals. 
     
     
         13 . The system of  claim 1 , wherein said sensor circuit comprises an indicator that absorbs radiation in proportion to levels of said analyte. 
     
     
         14 . The system of  claim 1 , wherein the sensor unit is an internal sensor unit. 
     
     
         15 . The system of  claim 14 , wherein the internal sensor unit is a partially or fully internal sensor unit. 
     
     
         16 . The system of  claim 1 , wherein the driver comprises an oscillator. 
     
     
         17 . A sensor device for detecting the presence or concentration of an analyte in a medium, comprising:
 a sensor body;   an indicator having a characteristic that is affected by the presence or concentration of an analyte;   a detector configured to detect a signal from said indicator, said signal being indicative of the characteristic of the indicator; and   a first inductor coupled to said detector, said first inductor being adapted to receive from a second inductor a magnetically induced electric current, and being further adapted to induce in said second inductor an electric current that changes as a function of the signal detected by said detector.   
     
     
         18 . The sensor device of  claim 17 , further comprising a radiation source in said sensor body, wherein the radiation source is configured to emit radiation within said sensor body. 
     
     
         19 . The sensor device of  claim 18 , wherein the indicator is positioned on said sensor body to receive radiation emitted by said radiation source. 
     
     
         20 . The sensor device of  claim 18 , wherein said characteristic is an optical characteristic, and the detector comprises a photosensitive element configured to receive light emitted by said indicator. 
     
     
         21 . The sensor device of  claim 17 , wherein magnetically induced electric current supplies power to the sensor device. 
     
     
         22 . The sensor device of  claim 17 , wherein the sensor body is an enclosed sensor body and has an outer surface surrounding said sensor body. 
     
     
         23 . The sensor device of  claim 17 , wherein the detector is located in the sensor body. 
     
     
         24 . The sensor device of  claim 17 , wherein the first inductor is located in the sensor body. 
     
     
         25 . The sensor device of  claim 17 , wherein the indicator comprises a matrix layer on the exterior surface of the sensor body, and indicator molecules are distributed throughout the matrix layer.