ISOLATED INTRAVENOUS ANALYTE MONITORING SYSTEM

• US 20080249385A1
• Filed: 04/04/2007
• Published: 10/09/2008
• Est. Priority Date: 04/04/2007
• Status: Abandoned Application

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Edwards Lifesciences Corporation
• Inventors: Phan, Luong Ngoc
• Application Number:
  US11/696,675
• Publication Number:
  US 20080249385A1
• Time in Patent Office: Days
• US Class Current: 600/347
• CPC Class Codes: A61B 2562/182 Electrical shielding, e.g. using a Faraday cage
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors

Abstract

A continuous intravenous analyte monitoring system includes an amperometric biosensor detecting an analyte concentration in the blood, a controller receiving a signal from the biosensor and computing the concentration, and an isolation device isolating the biosensor from EMI. A CPU may be coupled to the controller via the isolation device for continuous output of sensed concentration to a display unit. Isolated circuits may include a temperature sensor transmitting biosensor temperature to the controller for correction of the computed concentration, a multiplexer combining biosensor and temperature sensor signals, and an A/D converter converting multiplexed input to the controller. The biosensor may be a multi-electrode sensor having a working electrode immobilizing an glucose oxidase enzyme to detect blood glucose concentration. The biosensor and temperature sensor may be located in vivo using a catheter for continuous monitoring.

Claims

1. An analyte monitoring system, comprising:

a biosensor sensing an analyte concentration in vivo and outputting a signal corresponding to the analyte concentration;

a controller receiving the signal and computing the analyte concentration therefrom; and

an isolation means coupled to the controller and isolating the biosensor from electrical and magnetic noise.

2. The analyte monitoring system of claim 1 further comprising a CPU coupled to the controller via the isolation means and receiving the computed analyte concentration for output to a display.

3. The analyte monitoring system of claim 2 further comprising an isolated circuit and a non-isolated circuit, the isolation means separating the isolated circuit from the non-isolated circuit, the isolated circuit including the biosensor and the controller, and the non-isolated circuit including the CPU.

4. The analyte monitoring system of claim 3 wherein the isolation means provides an isolation space between the isolated circuit and the non-isolated circuit between about 0.3 in. and about 1.0 in.

5. The analyte monitoring system of claim 4 wherein the isolation means comprises an optical isolator.

6. The analyte monitoring system of claim 4 wherein the isolation means comprises a DC/DC converter.

7. The analyte monitoring system of claim 2 further comprising a display unit coupled to the CPU, the isolation means electrically and magnetically isolating the display unit from the biosensor.

8. The analyte monitoring system of claim 7 wherein the CPU continually updates the computed analyte concentration for output to the display unit.

9. The analyte monitoring system of claim 1 wherein the biosensor comprises a four-electrode sensor.

10. The analyte monitoring system of claim 9 wherein the four-electrode sensor includes at least one enzyme electrode.

11. The analyte monitoring system of claim 10 wherein the enzyme electrode immobilizes glucose oxidase.

12. The analyte monitoring system of claim 3 further comprising a temperature sensor in the isolated circuit coupled to the controller.

13. The analyte monitoring system of claim 12 wherein the controller corrects the computed analyte concentration according to temperature sensed by the temperature sensor.

14. The analyte monitoring system of claim 13 wherein the sensed temperature represents temperature of the biosensor.

15. The analyte monitoring system of claim 12 further comprising a multiplexer in the isolated circuit, the multiplexer receiving the signal from the biosensor and a second signal from the temperature sensor and transmitting them as multiplexed output to the controller.

16. The analyte monitoring system of claim 15 further comprising an analog-to-digital converter in the isolated circuit, converting analog multiplexed output to digital data for the controller.

17. An isolated intravenous analyte monitoring system, comprising:

an isolated sensing circuit including

an in vivo biosensor sensing an analyte level in blood and outputting a signal corresponding to the analyte concentration; and

a controller receiving the digital data and computing therefrom a concentration of the analyte;

a non-isolated computer circuit including

a CPU processing the computed analyte concentration; and

a display unit coupled to the CPU and displaying the computed analyte concentration; and

an isolation device providing EMI isolation between the isolated sensing circuit and the non-isolated computer circuit.

18. The analyte monitoring system of claim 17 wherein the isolated sensing circuit further comprises:

a potentiostat converting output from the biosensor to voltage;

a multiplexer multiplexing voltage signals from the potentiostat; and

an analog-to-digital converter converting multiplexer output to digital data for output to the controller.

19. The analyte monitoring system of claim 18 wherein the isolated sensing circuit further comprises:

a thermistor sensing temperature of the amperometric sensor; and

a resistance-to-voltage converter converting resistance of the thermistor to voltage;

wherein the multiplexer multiplexes voltage output from the resistance-to-voltage converter with voltage output from the potentiostat.

20. The analyte monitoring system of claim 17 wherein the isolation device comprises a DC/DC converter.

21. The analyte monitoring system of claim 20 wherein the DC/DC converter receives non-isolated DC power from the CPU and provides isolated DC power to the isolated sensing circuit.

22. An isolated intravenous glucose monitoring system, comprising:

an in vivo enzyme electrode immobilizing glucose oxidase and outputting a signal proportional to blood glucose concentration;

an in vivo temperature sensor outputting a signal proportional to temperature of the enzyme electrode;

a controller computing a temperature-corrected blood glucose concentration signal from the temperature signal and the blood glucose concentration signal; and

an isolation means isolating the enzyme electrode, the temperature sensor, and the controller from electrical and magnetic noise.