Method and apparatus for automatic calibration

1. A method, comprising:

releasing droplets of a nitrite-containing solution to a target;

releasing droplets of an acidic solution to the target;

measuring, with a gas sensor, a concentration of nitric oxide (NO) gas produced by a mixture of the droplets of the nitrite-containing solution and the droplets of the acidic solution; and

adjusting a calibration parameter of the gas sensor based on the concentration of NO gas.

2. The method of claim 1 , further comprising controlling at least one of a rate at which droplets of the nitrite-containing solution or the droplets of the acidic solution are released to the target to produce a known concentration of NO.

3. The method of claim 1 , wherein at least one of the droplets of the nitrite-containing solution or the droplets of the acidic solution are released via at least one proportional valve.

4. The method of claim 1 , wherein at least one of the droplets of the nitrite-containing solution or the droplets of the acidic solution are released via at least one ink-jet style proportional valve.

5. The method of claim 1 , wherein the target is absorbent.

6. The method of claim 1 , further comprising:

inserting a cassette into a console that includes the gas sensor and is configured to automatically adjust the calibration parameter upon insertion of the cassette,

the cassette including the nitrite-containing solution, the acidic solution, a reservoir containing dinitrogen tetroxide (N 2 O 4 ) and configured to release nitrogen dioxide (NO 2 ), and a cartridge configured to reduce nitrogen dioxide (NO 2 ) to produce NO for inhalation.

7. The method of claim 1 , wherein the concentration of NO is measured over a period of time, the method further comprising:

integrating the concentration of NO over the period of time,

the calibration parameter adjusted based on a comparison of the concentration of NO integrated over the period of time to an expected value.

8. The method of claim 1 , wherein a quantity and a concentration of nitrite in the droplets of the nitrite-containing solution are known such that when the droplets of the nitrite-containing solution and the droplets of the acidic solution mix at the target a known quantity of NO is produced.

9. The method of claim 1 , wherein:

a quantity and a concentration of nitrite in the droplets of the nitrite-containing solution are known such that when the droplets of the nitrite-containing solution and the droplets of the acidic solution mix at the target a known quantity of NO is produced; and

a quantity and a concentration of acid in the droplets of the acidic solution are sufficient to completely react the quantity of the nitrite.

10. The method of claim 1 , further comprising waiting a predetermined time after releasing the droplets of the nitrite-containing solution and releasing the droplets of the acidic solution before measuring the concentration of NO.

11. The method of claim 10 , wherein the predetermined time is shorter than it takes for a reaction of nitrite in the nitrite-containing solution and acid in the acidic solution to reach pseudoequilibrium.

12. The method of claim 1 , further comprising:

waiting a predetermined time after releasing the droplets of the nitrite-containing solution and releasing the droplets of the acidic solution before; and

sweeping gasses generated by a reaction between the nitrite and the acid across the sensor to measure the concentration of NO after waiting the predetermined time.

13. The method of claim 1 , wherein the concentration of NO is measured over a period of time, the method further comprising:

integrating the concentration of NO over the period of time.

14. The method of claim 1 , wherein the concentration of NO is measured over a period of time, the method further comprising:

integrating the concentration of NO over the period of time,

the calibration parameter adjusted based on a comparison of the concentration of NO integrated over the period of time to an expected value.