Assay wells with hydrogel as a well-contents separator
In a polymer assay cartridge having wells containing reagents, beads and sample, where the wells are covered (e.g., with Parafilm® or films) and shipped to the point of care, the reagents and well contents can leak out. The reagent solutions are made semi-solid by adding hydrogel reagents and cooling to form a gel. Preferably, the hydrogel is heated before an assay is conducted with the cartridge, and pigmented beads in the wells indicate melting or excessive heating, or congealing of the hydrogel, based on pigment color change.
1. An assay device stable for shipment comprising:
a plurality of wells which are a series of openings connected by first channels in a first surface of a body of the assay device, wherein said wells are filled with assay reagents in a hydrogel solution and at least one well contains microbeads;
at least one air gap in the first channels to separate fluids in the wells, wherein when gelled, the hydrogel interfaces with air in the air gap and prevents movement of all assay reagents and the microbeads from the wells into the air gap.
2. The device of claim 1 wherein the hydrogel is gelatin.
3. The device of claim 2 wherein the gelatin in the solution is at least 150 Bloom.
4. The device of claim 3 wherein the gelatin portion of the solution is less than 10% gelatin.
5. The device of claim 3 wherein the gelatin in the solution is Bloom range 180-200.
6. The device of claim 4 wherein the gelatin in the solution is at a concentration range of 1 to 4%.
7. The device of claim 1 wherein the microbeads are magnetic microbeads.
8. The device of claim 1 wherein second channels extending transverse to the first channels intersect the first channels.
9. The device of claim 8 wherein the second channels extend from the first surface through the body to its opposite surface.
10. The device of claim 1 wherein plastic paraffin film substantially covers the first surface.
11. The device of claim 1 further including encoding the body with a QR or other code.
12. The device of claim 10 further including adhering a paper or polymer layer substantially covering said plastic paraffin film.
13. The device of claim 12 further including a QR or other code imprinted on the inner side of the paper or polymer layer.
14. The device of claim 12 wherein the plastic paraffin film and the paper or polymer layer combined thickness is about 100 to 500 microns.
15. The device of claim 10 wherein the plastic paraffin film is adhered to substantially flat portions of said first surface which have an uneven finish.
16. The device of claim 15 wherein said substantially flat portions have a 600 grit finish.
17. The device of claim 15 wherein said substantially flat portions have a SPI B-1 grade finish.
18. The device of claim 1 wherein the body of the assay device is formed of polystyrene, polytetrafluoroethylene (“Teflon®”) or polyethylene.
19. The device of claim 1 wherein the microbeads are magnetic or paramagnetic.
20. The device of claim 19 wherein the assay device is placed within range of magnets which attract the microbeads.
21. The device of claim 20 wherein the assay magnets are housed in a moveable magnet holder.