Glucose sensor calibration

1. A method of calibrating a glucose sensor, which method comprises:

(a) preparing a first glucose-containing calibration solution by combining water or an aqueous solution with alpha and beta glucose, the alpha and beta glucose being provided in solid form;

(b) exposing a glucose sensor to said first glucose-containing calibration solution and determining the sensor output;

(c) exposing the glucose sensor to one or more further calibration solutions having different glucose concentrations from each other and from said first glucose-containing calibration solution and determining the sensor output for the or each calibration solution; and

(d) determining a calibration curve from the sensor output data collected in steps (b) and (c).

2. A method according to claim 1 , wherein step (c) involves exposing the glucose sensor to two or more calibration solutions.

3. A method according to claim 1 , further comprising preparing at least one of the one or more further calibration solutions used in step (c) by combining water or an aqueous solution with alpha and beta glucose, the alpha and beta glucose being provided in solid form.

4. A method according to claim 1 , wherein the first glucose-containing calibration solution of step (a), and the or each glucose-containing calibration solution of step (c), is prepared using from 25% alpha glucose and 75% beta glucose to 50% alpha glucose and 50% beta glucose.

5. A method according to claim 4 , wherein the first glucose-containing calibration solution of step (a), and the or each glucose-containing calibration solution of step (c), is prepared by combining water or an aqueous solution with freeze-dried glucose.

6. A method according to claim 1 , wherein the determination of sensor output in step (b) is carried out within 2 minutes of combining the solid glucose and water or aqueous solution.

7. A method according to claim 1 , wherein the method further comprises:

exposing the sensor to a zero-glucose calibration solution comprising water or an aqueous solution and containing no glucose and determining the sensor output;

and wherein

the first glucose-containing calibration solution is prepared by combining said zero-glucose calibration solution with alpha and beta glucose, the alpha and beta glucose being provided in solid form; and

the second glucose-containing calibration solution is prepared by adding a further amount of alpha and beta glucose to said first glucose-containing calibration solution, the alpha and beta glucose being provided in solid form.

8. A method according to claim 7 wherein the first glucose-containing solution is prepared by combining the zero-glucose calibration solution with freeze-dried glucose, and wherein the second glucose-containing calibration solution is prepared by adding a further amount of freeze-dried glucose to the first glucose-containing solution.

9. A calibration apparatus comprising

a first compartment (1) containing water or an aqueous solution; and

a second compartment (2) containing glucose in solid form,

wherein the second compartment contains alpha glucose and beta glucose, and wherein the first compartment is separated from the glucose-containing compartment(s) by a water impermeable dividing material.

10. A calibration apparatus according to claim 9 , wherein the ratio of alpha glucose: beta glucose in the or each glucose-containing compartment is the same or different and is in the range 25:75 to 50:50.

11. A calibration apparatus according to claim 9 wherein the second compartment contains freeze-dried glucose.

12. A glucose sensor kit comprising a glucose sensor and a calibration apparatus according to claim 9 .

13. A glucose sensor kit according to claim 12 wherein the second compartment of the calibration kit contains freeze-dried glucose.

14. A glucose sensor kit according to claim 12 , wherein the glucose sensor comprises a sensing portion comprising a receptor for glucose, said sensing portion being located within the first compartment of the calibration kit.

15. A glucose sensor kit according to claim 12 , wherein the glucose sensor comprises:

a glucose receptor having an affinity for glucose;

a fluorophore associated with said glucose receptor, the fluorescence of said fluorophore being altered in the presence of glucose;

a light emitter; and

a detector.

16. A calibration apparatus comprising

a first compartment (1) containing water or an aqueous solution;

a second compartment (2) containing glucose in solid form; and

a third compartment (3) containing glucose in solid form,

wherein at least one of the second and third compartments contains alpha glucose and at least one of the second and third compartments contains beta glucose, and

wherein the first compartment is separated from the glucose-containing compartments by a water impermeable dividing material.

17. A calibration apparatus according to claim 16 , wherein both the second and third compartments contain a mixture of alpha and beta glucose.

18. A calibration apparatus according to claim 16 wherein the second compartment and the third compartment contain freeze-dried glucose.