Device having a flow channel
A device having a flow channel, wherein at least one flow-terminating interface is used to control the flow of liquid in the flow channel. The flow-terminating interface prevents the flow of the liquid beyond the interface. In one aspect, the invention provides a sensor, such as, for example, a biosensor, in the form of a strip, the sensor being suitable for electrochemical or optical measurement. The sensor comprises a base layer and a cover layer, and the base layer is separated from the cover layer by a spacer layer. The base layer, cover layer, and spacer layer define a flow channel into which a liquid sample is drawn therein and flows therethrough by means of capillary attraction. The flow of the sample is terminated by a flow-terminating interface positioned in the flow channel.
1. A sensor strip comprising:
(a) a base layer having a first major surface and a second major surface;
(b) a cover layer having a first major surface and a second major surface, the first major surface of said cover layer facing the first major surface of said base layer;
(c) a spacer layer interposed between the first major surface of said cover layer and the first major surface of said base layer to separate said cover layer from said base layer;
(d) a flow channel having walls formed by said first major surface of said cover layer, said first major surface of said base layer, and said spacer layer, said flow channel having a reaction site therein, wherein said reaction site includes an electrode arrangement, said flow channel being of such dimensions that a liquid sample can be drawn therein and can flow therethrough by means of capillary attraction;
(e) a flow-terminating interface applied to or formed in said first major surface of said cover layer, said flow-terminating interface capable of terminating flow of a sample of liquid in said flow channel at said flow-terminating interface;
(f) a sample application zone, where a liquid sample is introduced into said flow channel; and
(g) at least one opening communicating with said flow channel to allow gas to be vented from said flow channel.
2. The sensor strip of claim 1 , wherein said electrode arrangement comprises a working electrode and a dual-purpose reference electrode/counter electrode.
3. The sensor strip of claim 2 , wherein said electrode arrangement further includes a trigger electrode.
4. The sensor strip of claim 2 , wherein said electrode arrangement further includes a reagent system on at least said working electrode.
5. The sensor strip of claim 4 , wherein said reagent system comprises an enzyme and a mediator for said enzyme.
6. The sensor strip of claim 1 , wherein said electrode arrangement comprises a working electrode, a counter electrode, and a reference electrode.
7. The sensor strip of claim 6 , wherein said electrode arrangement further includes a trigger electrode.
8. The sensor strip of claim 6 , wherein said electrode arrangement further includes a reagent system on at least said working electrode.
9. The sensor strip of claim 8 , wherein said reagent system comprises an enzyme and a mediator for said enzyme.
10. The sensor strip of claim 1 , wherein said at least one opening is formed in said spacer layer.
11. The sensor strip of claim 1 , wherein said at least one opening is formed in said cover layer.
12. The sensor strip of claim 1 , wherein said spacer layer comprises a layer of adhesive.
13. The sensor strip of claim 12 , wherein said adhesive is formed from a radiation-curable adhesive.
14. The sensor strip of claim 12 , wherein said adhesive is formed from a water-borne adhesive or a solvent-borne adhesive.
15. The sensor strip of claim 1 , wherein said spacer layer comprises a backing having a layer of adhesive on both major surfaces thereof.
16. The sensor strip of claim 1 , wherein said flow-terminating interface is a hydrophilic/hydrophobic interface.
17. The sensor strip of claim 16 , wherein said hydrophilic/hydrophobic interface comprises a layer of hydrophobic material having a coating of hydrophilic material thereon, a portion of said hydrophilic material being removed to expose said hydrophobic material to said liquid in said flow channel.
18. The sensor strip of claim 16 , wherein said hydrophilic/hydrophobic interface comprises a layer of hydrophilic material having a coating of hydrophobic material thereon, a portion of said hydrophobic material being removed to expose said hydrophilic material to said liquid in said flow channel.
19. The sensor strip of claim 1 wherein said first major surface of said cover layer comprises a hydrophilic material having a hydrophobic coating applied to a portion thereof.
20. The sensor strip of claim 1 , wherein said first major surface of said cover layer comprises a hydrophobic material having a hydrophilic coating applied to a portion thereof.
21. The sensor strip of claim 1 , wherein said flow-terminating interface comprises a plurality of openings in said cover layer.
22. The sensor strip of claim 1 , wherein at least one dimension of said flow channel at said flow-terminating interface is of sufficient size that the force attributable to capillary attraction is insufficient to permit additional fluid to enter said flow channel.
23. A device for allowing the flow of a liquid and for terminating the flow of said liquid, said device comprising;
(a) a flow channel bounded by a wall, said flow channel having dimensions to allow a liquid to flow by capillary attraction; and
(b) a flow-terminating interface to terminate the flow of said liquid in said flow channel at said flow-terminating interface, wherein said flow-terminating interface comprises a plurality of openings in said wall of said flow channel.