Pressure activated calibration system for chemical sensors

A sensor calibrating system comprising:

• a reservoir for storing a fluid material to be sensed;
• a sensor array;
• an outlet nozzle;
• a conduit providing flow communication between the reservoir and the outlet nozzle, the conduit including a first portion defining a dosing chamber for storing a measured quantity of the fluid material, the dosing chamber being disposed immediately adjacent to the outlet nozzle, the conduit further including a second portion disposed immediately adjacent to the dosing chamber and between the dosing chamber and the reservoir, and means contained in the second portion of the conduit for preventing flow of fluid material from the dosing chamber toward the reservoir, the means responsive to a pressure gradient in the conduit;
• a low pressure source in the range of about 3 psig arranged to supply the pressure gradient, the pressure gradient measuring about 300-500 psig per second over a predetermined time period;
• and
• a valve system, the valve system including only a first valve and a second valve, the valve system adapted to apply the pressure gradient to the dosing chamber to thereby pressurize the dosing chamber for the predetermined time period.

A method of calibrating a sensor comprising:

• providing a reservoir containing a material to be sensed;
• providing a sensor array, the sensor array including an acoustic wave device;
• providing an outlet nozzle;
• providing a conduit in flow communication between the reservoir and the outlet nozzle, the conduit including a first portion defining a dosing chamber for storing a measured quantity of the fluid material, the dosing chamber being disposed immediately adjacent to the outlet nozzle, the conduit further including a second portion disposed immediately adjacent to the dosing chamber and between the dosing chamber and the reservoir;
• providing the second portion of the conduit with means for preventing flow of fluid material from the dosing chamber toward the reservoir, the means responsive to a pressure gradient in the conduit;
• providing a low pressure source in the range of about 3 psig;
• providing a valve system, the valve system having a first valve disposed between the dosing chamber and the outlet nozzle, the first valve arranged to isolate the dosing chamber from the outlet nozzle, the valve system further including a second valve disposed between the pressure source and the dosing chamber, the second valve arranged to isolate the pressure source from the dosing chamber;
• cycling the valve system to apply a pressure gradient of about 300 psig per second over a predetermined time period;
• ejecting the measured quantity during the predetermined time period;
• and
• obtaining a sensor reading indicative of the presence of the measured quantity adjacent to the sensor array.