Micromachined inferential opto-thermal gas sensor
AssigneeHoneywell Inc.
InventorR. Andrew Wood
Life of this patent
Estimating the term…
Abstract
A micromachined integrated opto-thermal sensor having a rapidly intensity varying or pulsing light source, an interference filter, shadow masking or reflective blocking of light from thermal sensors, or differential operation, a gas cavity into which the detected gas can flow into via a channel or filter, and thermal detector elements to sense the heating of the gas caused by the absorption of light at a particular wavelength by the specific gas to be detected. Another version of the sensor is one with a dual cavity. One cavity contains the gas to be detected and the other cavity is sealed from the ambient environment and contains no gas. Signals from the detectors from the cavities are subtracted from each other resulting in the elimination of a fixed signal due to radiation impinging the detectors.
Claims18
A gas/fluid sensor comprising:
- a substrate having a plurality of pits;
- an array of thermoelectric sensors formed on said substrate over the plurality of pits;
- a narrow band pass filter proximate to and at a first distance from said array of thermoelectric sensors resulting in a space between said array of thermoelectric sensors and said narrow band pass filter;
- a shadow mask formed on said narrow band pass filter;
- and
- an external radiation source situated proximate to said narrow band pass filter.
A gas/fluid sensor comprising:
- a substrate having a plurality of pits;
- an array of thermal sensors formed on said substrate over the plurality of pits;
- a narrow band pass filter proximate to and at a first distance from said array of thermal sensors resulting in a space between said array of thermal sensors and said narrow band pass filter;
- radiation blocking areas formed on said narrow band pass filter;
- and
- an external radiation source situated proximate to said narrow band pass filter.
A micromachined integrated circuit gas/fluid sensor comprising:
- a first wafer having a first surface;
- a narrow band pass filter for a first wavelength formed on a second surface of said first wafer;
- a second wafer having a first surface proximate to said narrow band pass filter;
- a plurality of pits formed on a second surface of said second wafer, wherein each pit of said plurality of pits substantially reflects radiation impinging the pit;
- a plurality of areas formed in the second surface of said second wafer, wherein each area substantially transmits radiation of the first wavelength;
- a plurality of thermal sensors proximate to the second surface of said second wafer wherein each thermal sensor of said plurality of thermal sensors is situated over a pit of said plurality of thermal sensors;
- a third wafer having a first surface at a distance from but adjacent to said plurality of thermal sensors and the second surface of said second wafer to form a cavity having an opening so that a gas or fluid from the ambient environment about the sensor may enter and/or exit the cavity;
- and
- an external radiation source situated proximate to said first wafer.
Dependencies are inferred from the claim text.