Method of making a sensor
View Patent ↗A thin film sensor, such as a glucose sensor, is provided for transcutaneous placement at a selected site within the body of a patient. The sensor includes several sensor layers that include conductive layers and includes a proximal segment defining conductive contacts adapted for electrical connection to a suitable monitor, and a distal segment with sensor electrodes for transcutaneous placement. The sensor electrode layers are disposed generally above each other, for example with the reference electrode above the working electrode and the working electrode above the counter electrode. The electrode layers are separated by dielectric layer.
1. A method of making a flexible analyte sensor, the method comprising:
providing a base layer;
forming a first electrode layer on the base layer, wherein the first electrode layer includes a first electrode;
forming a first insulative layer on the first electrode layer;
forming a second electrode layer on the first insulative layer, wherein the second electrode layer includes a second electrode; and
forming a second insulative layer on the second electrode layer, wherein the first and second electrodes are in a staggered configuration, and wherein the second electrode layer is disposed directly above the first electrode layer.
2. The method of claim 1 , wherein the providing the base layer includes spin-coating polyimide onto a rigid substrate.
3. The method of claim 1 , wherein the forming the first electrode layer includes surface sputtering a chrome-based layer on the base layer.
4. The method of claim 3 , wherein the forming the first electrode layer further includes surface sputtering a gold-based layer on the chrome-based layer.
5. The method of claim 1 , wherein the forming the first insulative layer includes spin-coating polyimide onto the first electrode layer.
6. The method of claim 1 , wherein a first aperture is formed in the first insulative layer to expose at least a portion of the first electrode.
7. The method of claim 6 , wherein the first aperture is formed by a photoresist process.
8. The method of claim 1 , further comprising depositing platinum black on one or more of the first and second electrodes.
9. The method of claim 1 , wherein the forming the first electrode layer further includes forming a first conductive trace leading from the first electrode to a first conductive pad configured to electrically connect to sensor electronics, and the forming the second electrode layer further includes forming a second conductive trace leading from the second electrode to a second conductive pad configured to electrically connect to sensor electronics.
10. The method of claim 9 , wherein the sensor electronics communicate wirelessly with a monitor.
11. The method of claim 10 , wherein the wireless communication is selected from the group consisting of radio frequency, infrared, WiFi, ZigBee and Bluetooth.
12. The method of claim 10 , wherein the type of wireless communication is one of single frequency communication, spread spectrum communication, adaptive frequency selection, and frequency hopping communication.
13. The method of claim 1 , further comprising:
forming a third electrode layer on the second insulative layer, wherein the third electrode layer includes a third electrode; and
forming a third insulative layer on the third electrode layer, wherein the first, second and third electrodes are in a staggered configuration.
14. The method of claim 13 , wherein the third electrode layer is disposed directly above the second electrode layer.
15. The method of claim 13 , wherein one of the electrodes is a counter electrode, one of the electrodes is a reference electrode, and one of the electrodes is a working electrode.
16. The method of claim 13 , further comprising depositing one or more compounds selected from the group consisting of silver and silver chloride on the third electrode.
17. The method of claim 16 , further comprising coating at least a portion of the first electrode and the second electrode with an enzyme layer including glucose oxidase.
18. The method of claim 17 , further comprising vapor cross-linking the enzyme layer.
19. The method of claim 17 , wherein the enzyme layer further includes albumin.
20. The method of claim 17 , further comprising forming an adhesion promoter layer above the enzyme layer.
21. The method of claim 17 , further comprising forming a glucose limiting membrane over the enzyme layer.
22. The method of claim 21 , wherein the glucose limiting membrane comprises at least one a silane and polyamine.
23. The method of claim 21 , further comprising forming a hydrophilic layer over the glucose limiting membrane.