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MEMS structure for flow sensor

  • US 7,603,898 B2
  • Filed: 12/19/2007
  • Issued: 10/20/2009
  • Est. Priority Date: 12/19/2007
  • Status: Active Grant
First Claim
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1. A flow sensor, comprising:

  • a backing structure including;

    a first major surface and an opposing second major surface spaced apart by a thickness of the backing structure;

    a first channel opening extending through the entire thickness of the backing structure from the first major surface to the second major surface;

    a second channel opening, laterally spaced from the first channel opening, and extending through the entire thickness of the backing structure from the first major surface to the second major surface;

    a sensing structure including;

    a substrate having a first major surface and an opposing second major surface spaced by a thickness of the substrate, the substrate having a cavity opening extending through the entire thickness of the substrate from the first major surface to the second major surface;

    a topside layer having a top side and a back side, the back side of the topside layer secured relative to the first major surface of the substrate, at least a portion of the topside layer suspended over the cavity opening in the substrate;

    a heater element and a plurality of sensing elements secured relative to the top side of said portion of said topside layer that is suspended over the cavity opening in the substrate, wherein a first one of said plurality of sensing elements is located adjacent said heating element in a first lateral direction and a second one of said plurality of sensing elements is located adjacent said heating element in a second lateral direction that is opposite to the first lateral direction;

    the first major surface of the backing structure is bonded to the second major surface of the substrate such that the first channel opening of the backing structure is in fluid communication with the cavity opening of the substrate and the spaced second channel opening of the backing structure is in fluid communication with the cavity opening of the substrate;

    wherein the first channel opening of the backing structure, the cavity opening in the substrate and the second channel opening of the backing structure form a fluid flow channel that directs fluid flow from adjacent the second major surface of the backing structure to the back side of the topside layer, and back to adjacent the second major surface of the backing structure.

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