MEMS INTERSTITIAL PROTHROMBIN TIME TEST

• US 20090093697A1
• Filed: 08/11/2008
• Published: 04/09/2009
• Est. Priority Date: 08/10/2007
• Status: Active Grant

• Current Assignee: Infotonics Technology Center, Inc.
• Original Assignee: Infotonics Technology Center, Inc.
• Inventors: KOWARZ, Marek W., SARBADHIKARI, Kamal K., Ashe, Philip Ryan, MIR, Jose
• Granted Patent: US 8,328,720 B2
• Time in Patent Office: Days
• US Class Current: 600/369
• CPC Class Codes: A61B 5/02035 Determining blood viscosity

Abstract

A method of determining a prothrombin time is disclosed. A mediator is applied to a stratum corneum. The stratum corneum is penetrated to allow the mediator to enter a region containing interstitial fluid and interact with at least one capillary, causing blood and/or blood components to leak from the at least one capillary into the region containing interstitial fluid. A characteristic affected by the blood and/or blood components is measured in the region containing interstitial fluid which correlates to the prothrombin time. A system for measuring prothrombin time is also disclosed. The system has a mediator, one or more microneedles, and a processor directly or indirectly coupled to the one or more microneedles and configured to determine a coagulation change in blood or blood components in a region around the one or more microneedles after the one or more microneedles penetrate a stratum corneum.

Claims

1. A method of determining a prothrombin time, comprising:

applying a mediator to a stratum corneum;

penetrating the stratum corneum to allow the mediator to enter a region containing interstitial fluid and interact with at least one capillary, causing blood and/or blood components to leak from the at least one capillary into the region containing interstitial fluid; and

measuring a characteristic affected by the blood and/or blood components in the region containing interstitial fluid which correlates to the prothrombin time.

2. The method of claim 1, wherein applying the mediator to the stratum corneum comprises applying the mediator in a liquid form to the stratum corneum.

3. The method of claim 1, wherein applying the mediator to the stratum corneum comprises bringing a microneedle coated with the mediator into contact with the stratum corneum.

4. The method of claim 3, further comprising dry-coating the mediator onto the microneedle.

5. The method of claim 3, further comprising liquid-coating the mediator onto the microneedle.

6. The method of claim 1, wherein a microneedle is used to penetrate the stratum corneum.

7. The method of claim 1, wherein the mediator is a histamine.

8. The method of claim 1, wherein the mediator is selected from the group consisting of serotonin, norepinephrine, EDTA, and a hormone.

9. The method of claim 1, wherein the measured characteristic affected by the blood and/or blood components in the region containing interstitial fluid which correlates to the prothrombin time is selected from the group consisting of:

a viscosity;

a physical property;

an optical property;

an electrical property;

a chemical property;

a stiffness;

a strain;

a mechanical impedance;

an electrical impedance; and

a capacitance.

10. The method of claim 1, further comprising applying a coagulation activator to the stratum corneum, and wherein penetrating the stratum corneum also allows the coagulation activator to enter the region containing interstitial fluid, and the blood and/or blood components which have been caused to leak from the at least one capillary into the region containing interstitial fluid can interact with the coagulation activator.

11. The method of claim 10, wherein the coagulation activator is selected from the group consisting of thromboplastin, staphylocoagulase, glycoproteins, phospholipids, and lypo-proteins.

12. A system for measuring prothrombin time, comprising:

a mediator;

one or more microneedles;

a processor directly or indirectly coupled to the one or more microneedles and configured to determine a coagulation change in blood or blood components in a region around the one or more microneedles after the one or more microneedles penetrate a stratum corneum.

13. The system of claim 12, wherein the mediator is coated onto at least one of the microneedles.

14. The system of claim 12, further comprising an actuator configured to penetrate the one or more microneedles through the stratum corneum and into a region containing interstitial fluid.

15. The system of claim 12, wherein the processor is configured to determine the coagulation change in blood or blood components in the region around the one or more microneedles by applying a voltage across a plurality of microneedles and monitoring a capacitance change between the microneedles.

16. The system of claim 12, further comprising a coagulation activator.

17. The system of claim 16, wherein the coagulation activator is coated onto at least one of the microneedles.

18. The system of claim 12, further comprising an image capturing system configured for automated or semi-automated visual analysis of one or more coagulated wheals which result following the penetration of the stratum corneum.

19. The system of claim 12, wherein the processor'"'"'s determination of the coagulation change in blood or blood components in a region around the one or more microneedles occurs while the needles are penetrating the stratum corneum.

20. A system for prescribing a dosage of blood thinner for a patient, comprising:

a mediator;

one or more microneedles;

a processor directly or indirectly coupled to the one or more microneedles and configured to;

determine a coagulation change in blood or blood components in a region around the one or more microneedles after the one or more microneedles penetrate a stratum corneum;

store one or more patient characteristics;

store one or blood thinner dosing rules; and

determine a recommended blood thinner dosage based on the one or more patient characteristics, the one or more blood thinner dosing rules, and the determined coagulation change.