Microfluidic die with a high ratio of heater area to nozzle exit area

1. A device, comprising:

a substrate;

a plurality of heaters on the substrate, each heater having a heater area;

a plurality of nozzles disposed above the heaters, each nozzle having an entrance and an exit, each entrance being closer to a heater than the exit, the exit having a first nozzle area, a ratio of the heater area to the first nozzle area being greater than 9 to 1; and

a plurality of chambers disposed between the heaters and the nozzles.

2. The device of claim 1 wherein the nozzles are tapered such that the entrance has a second nozzle area, the second nozzle area being less than the heater area and the second nozzle area is greater than the first nozzle area.

3. The device of claim 2 wherein each chamber has a bottom surface having a chamber bottom area, the chamber bottom area being greater than the heater area.

4. The device of claim 2 wherein a ratio of the second nozzle area to the first nozzle area is greater than 1.2 to 1.

5. The device of claim 1 wherein the heater area exceeds 2000 μm 2 .

6. A device, comprising:

a substrate having an inlet path;

a plurality of heaters formed above the substrate, each heater having a heater area;

a plurality of chambers formed above the plurality of heaters; and

a plurality of tapered nozzles formed above the chambers, each tapered nozzle having an entrance adjacent to the chamber and an exit adjacent to an external environment, the entrance having a first nozzle area, and the exit having a second nozzle area, the heater area being greater than the first nozzle area, and the first nozzle area being greater than the second nozzle area, a ratio of the heater area to the second nozzle area being greater than 9 to 1.

7. The device of claim 6 further comprising a channel region between the inlet path and the plurality of chambers, the channel region including a plurality of funnel regions that feed fluid to the plurality of chambers.

8. The device of claim 7 further comprising a narrow fluid path between each funnel region and each chamber.

9. The device of claim 8 wherein each funnel region includes a first column to prevent in the fluid from blocking the fluid path.

10. The device of claim 9 further comprising a second column adjacent to the first column.

11. The device of claim 8 wherein each heater has a length and a width, a length of the fluid path being smaller than the length of the heater.

12. The device of claim 11 wherein a width of the fluid path is smaller than the width of the heater.

13. A method, comprising:

forming an inlet path in a substrate;

forming a plurality of heaters above the substrate, each heater having a heater area;

forming a plurality of chambers above the plurality of heaters; and

forming a plurality of tapered nozzles above the chambers, each a tapered nozzle having an entrance adjacent to the chamber and an exit adjacent to an external environment, the entrance having a first nozzle area, and the exit having a second nozzle area, the heater area being greater than the first nozzle area, and the first nozzle area being greater than the second nozzle area, a ratio of the heater area to the second nozzle area being greater than 9 to 1.

14. The method of claim 13 further comprising forming a channel region between the inlet path and the plurality of chambers, the channel region including a plurality of funnel regions that feed fluid to the plurality of chambers.

15. The method of claim 14 further comprising forming a narrow fluid path between each funnel region and each chamber.

16. The method of claim 15 further comprising forming a plurality of columns in the funnel region.