Analyte monitoring device and methods of use
An analyte monitor includes a sensor, a sensor control unit, and a display unit. The sensor has, for example, a substrate, a recessed channel formed in the substrate, and conductive material disposed in the recessed channel to form a working electrode. The sensor control unit typically has a housing adapted for placement on skin and is adapted to receive a portion of an electrochemical sensor. The sensor control unit also includes two or more conductive contacts disposed on the housing and configured for coupling to two or more contact pads on the sensor. A transmitter is disposed in the housing and coupled to the plurality of conductive contacts for transmitting data obtained using the sensor. The display unit has a receiver for receiving data transmitted by the transmitter of the sensor control unit and a display coupled to the receiver for displaying an indication of a level of an analyte. The analyte monitor may also be part of a drug delivery system to alter the level of the analyte based on the data obtained using the sensor.
1. A system, comprising:
an in vivo glucose sensor having a distal portion configured for placement in an interstitial fluid of a user and a proximal portion, the sensor comprising:
a working electrode;
a sensing layer comprising glucose oxidase; and
a layer configured to limit transport of one or more biomolecules;
wherein the in vivo glucose sensor is configured to generate signals at the working electrode; and
a sensor control unit comprising at least one contact in electrical communication with the proximal portion of the sensor, the sensor control unit configured to receive the generated signals, convert the generated signals to glucose concentration data, the sensor control unit further comprising a transmitter configured to communicate the glucose concentration data to a remote device;
wherein the glucose concentration data has a first average level of in vivo accuracy during a first time period after a predetermined time period after sensor placement in the interstitial fluid of a user, and a second average level of in vivo accuracy during a second time period after the predetermined time period after sensor placement in the interstitial fluid, wherein the first time period precedes the second time period and the second average level of in vivo accuracy is greater than the first average level of in vivo accuracy.
2. The system of claim 1 , wherein the sensor control unit further comprises an adhesive patch including an opening through which the sensor is disposed.
3. The system of claim 2 , wherein the remote device comprises a display unit configured to display a graph of the vivo glucose concentration over a period of time.
4. The system of claim 3 , wherein the glucose oxidase is configured to catalyze a reaction of glucose to form hydrogen peroxide.
5. The system of claim 4 , wherein the predetermined time period after sensor placement in the interstitial fluid comprises a sensor stabilization period.
6. The system of claim 5 , wherein the first time period is a day of a sensor wear time period and the second time period is a subsequent day of the sensor wear time period.
7. The system of claim 6 , wherein the first average level of in vivo accuracy corresponds to a first mean absolute relative difference value, the second average level of in vivo accuracy corresponds to a second mean absolute relative difference value, and the second mean absolute relative difference value is less than the first mean absolute relative difference value.
8. The system of claim 6 , wherein the subsequent day immediately follows the day of the first time period.
9. The system of claim 8 , wherein the first average level of in vivo accuracy corresponds to a first mean absolute relative difference value, the second average level of in vivo accuracy corresponds to a second mean absolute relative difference value, and the second mean absolute relative difference value is less than the first mean absolute relative difference value.
10. The system of claim 9 , wherein the second mean absolute relative difference value decreases by about 4% to about 24% from the first mean absolute relative difference value.
11. The system of claim 6 , wherein the day of the first time period is a first day of the sensor wear time period and the subsequent day is a second day of the sensor wear time period.
12. The system of claim 6 , wherein the day of the first time period is a first day of the sensor wear time period and the subsequent day is a third day of the sensor wear time period.
13. The system of claim 6 , wherein the day of the first time period is a second day of the sensor wear time period and the subsequent day is a third day of the sensor wear time period.
14. The system of claim 1 , wherein the first time period is a first day of a sensor wear time period and the first average level of in vivo accuracy is lower than an average level of in vivo accuracy on each subsequent day of the sensor wear time period.
15. The system of claim 1 , wherein the second time period is a last day of a sensor wear time period and the second average level of in vivo accuracy is higher than an average level of in vivo accuracy on each prior day of the sensor wear time period.
16. The system of claim 1 , further comprising a third average level of in vivo accuracy during a third time period of a sensor wear time period after the predetermined time period after sensor placement in the interstitial fluid, wherein the second time period precedes the third time period and the third average level of in vivo accuracy is greater than the first average level of in vivo accuracy.
17. The system of claim 16 , further comprising a fourth average level of in vivo accuracy during a fourth time period of the sensor wear time period after the predetermined time period after sensor placement in the interstitial fluid, wherein the third time period precedes the fourth time period and the fourth average level of in vivo accuracy is greater than the third average level of in vivo accuracy.
18. The system of claim 1 , wherein the vivo glucose sensor is factory calibrated.
19. The system of claim 1 , wherein the system is configured to determine the in vivo glucose concentration using at least factory-determined calibration data without the need for an independent glucose measurement taken after sensor placement.
20. The system of claim 1 , wherein the vivo glucose sensor further comprises a counter electrode including silver/silver chloride.
21. The system of claim 1 , wherein the layer is configured to prevent the penetration of one or more interferents into a region around the working electrode.
22. The system of claim 1 , wherein the in vivo glucose sensor is operatively coupled to the sensor control unit after sensor placement in the interstitial fluid.
23. The system of claim 1 , wherein the sensor control unit is reusable.
24. The system of claim 1 , further comprising a mounting unit configured to receive the sensor control unit after sensor placement in the interstitial fluid.
25. The system of claim 24 , wherein the mounting unit comprises a bottom surface with an adhesive layer.
26. The system of claim 1 , wherein the remote device comprises a drug delivery unit.
27. The system of claim 26 , wherein the drug delivery unit comprises an insulin pump.
28. The system of claim 1 , wherein the remote device is configured to provide at least one of an audio or vibratory alert in anticipation of the glucose concentration falling below a predetermined threshold.
29. The system of claim 1 , wherein the remote device is configured to provide a first alert having a first intensity when glucose the glucose concentration falls below a first predetermined threshold level and a second alert having a second intensity greater than the first intensity when the glucose concentration falls below a second predetermined threshold level lower than the first predetermined threshold level.
30. The system of claim 1 , wherein the remote device is configured to provide a first alert and a repeated alert, wherein the repeated alert has an intensity greater than the first alert.