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Method and sensor for detecting a chemical substance using an optically anisotropic material

  • US 7,897,406 B2
  • Filed: 12/19/2003
  • Issued: 03/01/2011
  • Est. Priority Date: 12/20/2002
  • Status: Active Grant
First Claim
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1. A method for indicating an end of life of a respirator cartridge, an air purifying cartridge or a filtration cartridge by detecting a chemical substance in an analyte, comprising steps of:

  • providing an optically anisotropic material forming a porous fiber or slab in a sorbent bed of the respirator cartridge, air purifying cartridge or filtration cartridge;

    subjecting the sorbent bed to the analyte;

    passing visible light through the anisotropic material by transilluminating the anisotropic material with the light;

    collecting at least a portion of the passed visible light; and

    detecting a change in a polarization state of the collected visible light, the change being indicative of the chemical substance in the analyte having reached the anisotropic material through the sorbent bed.

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