Detection of blockage in a porous member
A method of detecting at least a partial blockage in a porous member separating a first volume from a second volume or inner chamber of a device includes emitting pressure waves within the inner chamber by changing a volume of the inner chamber, measuring a response via a pressure sensor responsive to pressure waves positioned within the inner chamber, and determining if at least a partial blockage is present in the porous member based upon the response of the pressure sensor.
1. A gas sensor device to detect an analyte gas in an ambient environment, comprising:
a housing comprising an inner chamber and a port;
a porous member in operative connection with the port to separate the inner chamber from the ambient environment;
at least one sensor responsive to a target gas positioned within the inner chamber;
a sampling pump to pump air from the ambient environment into the inner chamber;
a pressure sensor responsive to pressure change within the inner chamber; and
circuitry in operative connection with the pressure sensor and with the sampling pump, in an interrogation mode, the circuitry controlling the sampling pump to vary pressure and determining if at least a partial blockage is present in the porous member based upon a response of the pressure sensor.
2. The gas sensor device of claim 1 wherein the sampling pump is positioned within the inner chamber and draws gas from the ambient environment into the inner chamber.
3. The gas sensor device of claim 1 comprising a plurality of gas sensors positioned within the inner chamber.
4. The gas sensor device of claim 1 wherein the porous member is a porous frit or a porous polymeric membrane.
5. The gas sensor device of claim 1 wherein the sampling pump is positioned outside the inner chamber and forces gas from the ambient environment into the inner chamber.
6. The gas sensor device of claim 5 wherein the porous member is the only path for flow into the inner chamber.
7. The gas sensor device of claim 6 further comprising a plenum in fluid connection with the sampling pump and with the porous member.
8. The gas sensor device of claim 1 wherein the circuitry oscillates the pressure during the interrogation mode.
9. The gas sensor device of claim 8 wherein the circuitry oscillates the pressure in a generally sinusoidal manner during the interrogation mode.
10. The gas sensor device of claim 9 wherein the frequency of oscillation is in the range of 1 Hz to 200 Hz.
11. The gas sensor device of claim 9 wherein the frequency of oscillation is less than 10 Hz.
12. A method of detecting at least a partial blockage in a porous member separating an inner chamber of a device, in which at least one gas sensor responsive to target gas is positioned, and an ambient environment, the device further including a sampling pump to pump air from the ambient environment into the inner chamber, comprising:
controlling the sampling pump to vary pressure in an interrogation mode, measuring a response via a pressure sensor positioned within the inner chamber, and determining if at least a partial blockage is present in the porous member based upon a response of the pressure sensor.
13. The method of claim 12 wherein the sampling pump is positioned within the inner chamber and draws gas from the ambient environment into the inner chamber.
14. The method of claim 12 comprising a plurality of gas sensors positioned within the inner chamber.
15. The method of claim 12 wherein the sampling pump is controlled to oscillate the pressure during the interrogation mode.
16. The method of claim 12 wherein the sampling pump is positioned outside the inner chamber and forces gas from the ambient environment into the inner chamber.
17. The method of claim 16 wherein the porous member is the only path for flow into the inner chamber.
18. The method of claim 17 further comprising a plenum in fluid connection with the sampling pump and with the porous member.