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United States Patent m
 NDIR GAS SENSOR
 Inventor: Jacob Y. Wong, Santa Barbara, Calif.
 Assignee: Telaire Systems, Inc., Goleta, Calif.
 Appl. No.: 284,914
 Filed: Aug. 2,1994
Related U.S. Application Data
 Continuation of Ser. No. 195,523, Feb. 14, 1994, abandoned.
 Int. CI.* G01N 21/61
 U.S. Q 250/343; 250/338.4;
250/339.06; 250/339.13; 356/437
 Field of Search 250/343, 344, 349, 338.4,
250/339.06, 339.13; 356/343, 432, 434, 477
 References Cited
U.S. PATENT DOCUMENTS
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[ii] Patent Number: 5,444,249  Date of Patent: Aug. 22,1995
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Primary Examiner—Constantine Hannaher
Attorney, Agent, or Firm—Lyon & Lyon
 _ ABSTRACT
A miniaturized NDIR gas sensor is manufactured using semiconductor micromachining techniques from a semiconductor material such as Si or GaAs. The NDIR gas sensor comprises an optical waveguide, a light source at one end of the waveguide, at least one light detector at the end of the waveguide opposite the light source, a diffusion type gas sample chamber formed within the waveguide and interposed in the optical path between the light source and light detector so that the light source and light detector are thermally isolated from the gas sample, and a separate bandpass filter interposed between the light source and each light detector. Because the NDIR sensor is fabricated out of a semiconductor material, the source driver and signal processing electronics may be added directly to the sensor using integrated circuit fabrication techniques. Particles and smoke and dust may be kept out of the sample chamber by application of a gas permeable membrane over apertures in the sample chamber walls.
16 Claims, 4 Drawing Sheets