In vitro analyte sensor and methods of use
In vitro electrochemical sensors that provide accurate and repeatable analysis of a sample of biological fluid are provided. Embodiments include sensors that include a sample chambers having overhangs extending therefrom.
1. A cantilevered analyte sensor for determining the concentration of an analyte in a sample, the sensor comprising:
a first substrate and a second substrate;
a sample chamber positioned between the first and second substrates; and
an overhanging substrate wall at a sample receiving end of the sensor, wherein the sample chamber comprises at least two unbounded sides at the sample receiving end of the sensor.
2. The sensor of claim 1 , wherein the overhanging substrate wall provides a capillary volume that ranges from about 10 nL to about 10,000 nL.
3. The sensor of claim 2 , wherein the capillary volume ranges from about 100 nL to about 1000 nL.
4. The sensor of claim 1 , wherein about 10% to about 95% of the perimeter of the sample chamber is unbounded.
5. The sensor of claim 4 , wherein about 50% to about 95% of the perimeter of the sample chamber is unbounded.
6. The sensor of claim 1 , wherein the sample chamber comprises three unbounded sides.
7. The sensor of claim 1 , wherein the overhang ranges from about 0.05% to about 50% of the length of the sensor.
8. The sensor of claim 1 , wherein the overhang has a surface area that ranges from about 0.1 mm 2 to 1 cm 2 .
9. The sensor of claim 1 , wherein the overhang has a length of at least about 0.1 mm.
10. The sensor of claim 9 , wherein the overhang has a length of at least about 1 mm.
11. The sensor of claim 1 , wherein the overhang is contiguous with the second substrate.
12. The sensor of claim 10 , wherein the length of the second substrate is greater than the length of the first substrate.
13. The sensor of claim 1 , wherein the substrates are displaced along their longitudinal axes.
14. The sensor of claim 1 , wherein the sample chamber has a volume of no more than about 1 microliter.
15. The sensor of claim 12 , wherein the sample chamber has a volume of no more than about 0.5 microliter.
16. The sensor of claim 13 , wherein the sample chamber has a volume of no more than about 0.1 microliter.
17. The sensor of claim 1 , wherein the sensor is a glucose sensor.
18. A sensor for determining the concentration of an analyte in a sample, the sensor comprising:
a first substrate and a second substrate;
a sample chamber positioned between the first and second substrates; and
an overhang configured to form a capillary chamber when positioned in opposition to a surface,
wherein the sample chamber comprises at least two unbounded sides at a sample receiving end of the sensor.
19. The sensor of claim 16 , wherein the capillary chamber has a volume that ranges from about 10 nL to about 10,000 nL.
20. The sensor of claim 17 , wherein the volume ranges from about 100 nL to about 1000 nL.
21. The sensor of claim 18 , wherein the sensor is a cantilever sensor.
22. An analyte sensor comprising:
a first substrate and a second substrate;
a sample chamber positioned between the first and second substrates; and
an overhanging substrate wall at a sample receiving end of the sensor,
wherein the sample chamber comprises at least two unbounded sides at the sample receiving end of the sensor providing a single access port, wherein the access port is the only opening in the sample chamber and the access port provides for both the ingress and egress of liquid and gas.
23. The sensor of claim 20 , wherein the access port has a curved portion.
24. The sensor of claim 20 , wherein the sample chamber comprises three adjacent sides and the three adjacent sides provide the access port.
25. An integrated system for the determination of analyte in biological fluid, the system comprising:
a housing having an interior space;
at least one cantilevered analyte sensor for determining the concentration of an analyte in a sample positioned in the interior space, the sensor comprising:
a first substrate and a second substrate;
a sample chamber positioned between the first and second substrates; and
an overhanging substrate wall at a sample receiving end of the sensor,
wherein the sample chamber comprises at least two unbounded sides at the sample receiving end of the sensor; and
a processor for determining the concentration of an analyte applied to a sensor.
26. The integrated system of claim 23 , further comprising a skin piercing element.
27. A system for determining the concentration of an analyte in a sample, the system comprising:
a cantilevered analyte sensor for determining the concentration of an analyte in a sample, the sensor comprising a first substrate and a second substrate; a sample chamber positioned between the first and second substrates; and an overhanging substrate wall at a sample receiving end of the sensor, wherein the sample chamber comprises at least two unbounded sides at the sample receiving end of the sensor; and
a meter.
28. A method of providing a sample to a sample chamber of an analyte sensor comprising:
contacting an overhang at a sample receiving end of the sensor with the sample to provide the sample to the sample chamber, wherein the analyte sensor comprises:
a first substrate and a second substrate;
the sample chamber positioned between the first and second substrate; and
an overhanging substrate wall at a sample receiving end of the sensor,
wherein the sample chamber comprises at least two unbounded sides at the sample receiving end of the sensor.
29. The method of claim 26 , wherein the contact comprises positioning the overhang in opposition to a surface to provide a capillary volume by the overhang and the surface.
30. The method of claim 27 , wherein the capillary volume ranges from about 10 nL to about 10,000 nL.
31. The method of claim 28 , wherein the capillary volume ranges from about 100 nL to about 1000 nL.
32. The method of claim 26 , further comprising determining the concentration of an analyte in at least a portion of the sample in the sample chamber.
33. The method of claim 30 , wherein the analyte concentration is determined using about 1 microliter of sample or less.
34. The method of claim 30 , wherein the analyte concentration is determined using coulometry.
35. The method of claim 30 , wherein the analyte concentration is determined using amperometry.
36. The method of claim 30 , wherein the analyte concentration is determined using potentiometry.
37. The method of claim 30 , wherein the analyte concentration is determined using photometry.
38. The method of claim 26 , wherein the overhang is contiguous with the second substrate, and the contacting comprises first contacting the overhang with the sample and then contacting the first substrate and/or the sample chamber with the sample.
39. A kit comprising:
a cantilevered analyte sensor for determining the concentration of an analyte in a sample, the sensor comprising:
a first substrate and a second substrate;
a sample chamber positioned between the first and second substrates; and
an overhanging substrate wall at a sample receiving end of the sensor, wherein the sample chamber comprises at least two unbounded sides at the sample receiving end of the sensor; and
a meter.