Implantable analyte sensor

Abstract

An implantable analyte sensor including a sensing region for measuring the analyte and a non-sensing region for immobilizing the sensor body in the host. The sensor is implanted in a precisely dimensioned pocket to stabilize the analyte sensor in vivo and enable measurement of the concentration of the analyte in the host before and after formation of a foreign body capsule around the sensor. The sensor further provides a transmitter for RF transmission through the sensor body, electronic circuitry, and a power source optimized for long-term use in the miniaturized sensor body.

1 . An electrochemical analyte sensor for measuring an analyte concentration, the sensor comprising:
 a sensor body comprising electronic circuitry encapsulated within the sensor body; and   a plurality of electrodes that extend from an outer surface of the sensor body to the encapsulated electronic circuitry, wherein the electrodes are mechanically and electrically connected and aligned to the electronic circuitry prior to encapsulation within the sensor body.   
     
     
         2 . The sensor according to  claim 1 , wherein the electrodes are swaged to the electronic circuitry. 
     
     
         3 . The sensor according to  claim 1 , wherein the electrodes are welded using a technique selected from the group consisting of spot welding, ultrasonic welding, and laser welding. 
     
     
         4 . The sensor according to  claim 1 , wherein the electrodes and electronic circuitry are encapsulated in the sensor body by a molding process. 
     
     
         5 . The sensor according to  claim 1 , wherein the sensor body comprises a water vapor permeable material. 
     
     
         6 . The sensor according to  claim 5 , wherein the electronic circuitry is spaced from the water vapor permeable sensor body, such that water vapor penetration within a fixed distance from the electronic circuitry is inhibited. 
     
     
         7 . The sensor according to  claim 6 , wherein the electronic circuitry is spaced from the water vapor permeable sensor body by epoxy. 
     
     
         8 . The sensor according to  claim 7 , wherein the electronic circuitry is spaced from the water vapor permeable sensor body by a glass tube. 
     
     
         9 . The sensor according to  claim 7 , wherein the electronic circuitry is spaced from the water vapor permeable sensor body by parylene. 
     
     
         10 . The sensor according to  claim 7 , wherein the electronic circuitry is spaced from the water vapor permeable sensor body by one or more hermetic containers. 
     
     
         11 . The sensor according to  claim 1 , wherein the sensor body comprises a substantially seamless exterior with the electrodes extending through the sensor body to an outer surface thereof. 
     
     
         12 . An implantable analyte sensor, comprising:
 electronics encapsulated within a water vapor permeable body, wherein the electronics comprise a microprocessor module and an RF module that has an RF transceiver with a phase-locked loop, and wherein the microprocessor module is programmed to initiate re-calibration of the phase-locked loop responsive to detection of off-frequency shift.   
     
     
         13 . An electrochemical glucose sensor comprising a three-electrode system, the sensor comprising:
 an electrochemical cell comprising a working electrode, reference electrode, and counter electrode; and   a potentiostat configured to control a potential between the working electrode and the reference electrode, wherein an allowable range for the counter electrode voltage is set sufficiently wide such that the glucose sensor is configured to react with other reducible species when oxygen becomes limited and sufficiently narrow to ensure the circuitry does not allow excessive current draw or bubble formation to occur when in use.   
     
     
         14 . The sensor of  claim 13 , wherein limiting the current of at least one of a working electrode amplifier or a counter electrode amplifier to a preset current value configures the allowable range. 
     
     
         15 . The sensor of  claim 13 , wherein setting an op-amp to be offset from battery ground configures the allowable range. 
     
     
         16 . The sensor of  claim 13 , wherein a reference voltage setting of from about +0.6V to about +0.8V with respect to battery ground configures the allowable range. 
     
     
         17 . The sensor of  claim 16 , wherein a reference voltage setting of about +0.7V with respect to battery ground configures the allowable range. 
     
     
         18 . The sensor of  claim 13 , wherein the electrochemical cell is configured and arranged for transcutaneous implantation. 
     
     
         19 . The sensor of  claim 13 , further comprising an RF module, wherein the RF module is operably connected to the potentiostat. 
     
     
         20 . The sensor of  claim 19 , further comprising a receiver configured to receive RF transmissions from the RF module. 
     
     
         21 . The sensor of  claim 20 , wherein the receiver comprises a display configured to display sensor data.