Patent ID: 7619739

Claim:
A method of determining the presence of a target agent in an environment, comprising the steps of: obtaining a first sample from the environment; introducing the first sample to at least one detection module; filtering the first sample through at least a first filter and a second filter which are part of the at least one detection module, wherein the first filter and the second filter comprise porous Bragg gratings, further wherein the first filter contains at least one detection molecule for binding the target agent thereto and the second filter contains no detection molecules for binding the target agent thereto; measuring an optical property of the first filter and the second filter after filtering the first sample there through; comparing the measured optical property of the first filter to the measured optical property of the second filter to determine a presence of the target agent; measuring an optical property of a third filter which is not exposed to the first sample, the third filter comprising a porous Bragg grating; and comparing the measured optical property of the third filter to the measured optical property of the first and second filters to determine a presence of spurious signals caused by the environment.