MEMS structure for flow sensor
First Claim
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.
1 Assignment
0 Petitions
Accused Products
Abstract
A MEMS based flow sensor is disclosed which generally incorporate isolation between a sensing structure and the sensed media. An internal flow channel can be configured by attaching a backing structure with flow openings to the back of the sensing structure. The sensing structure can be composed of a insulating layer with heating element and a dual sensing element which comprises of resistive thin films positioned in a Wheatstone bridge configuration over a backside cavity. The dual sensing element and its associated wirebonds can be isolated from the sensing media by directing the fluid through the internal flow channel. The completed sensing structure can be over packaged with standard processes such as epoxies and seals.
-
Citations
20 Claims
-
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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A flow sensor, comprising:
-
a backing structure having two spaced openings each extending entirely through the backing structure; a sensing structure including a substrate having an etched cavity extending entirely therethrough, and a topside layer having a top side and a back side, where the back side of the topside layer is secured relative to the substrate with at least a portion of the topside layer suspended over the etched cavity in the substrate, the sensing structure further having a heater element and a plurality of sensing elements disposed adjacent the top side of the topside layer, wherein two of said plurality of sensing elements are arranged on opposing lateral sides of said heating element; the sensing structure further having a plurality of electrical conductive leads extending above the top side of the topside layer and to said heater element and said plurality of sensing elements; and the backing structure is bonded to the sensing structure such that the two spaced openings in the backing structure are in fluid communication with the etched cavity in the substrate to provide a fluid flow path to the back side of the topside layer. - View Dependent Claims (10, 11, 12, 13, 14, 15)
-
-
16. A MEMS flow sensor, comprising:
-
a backing structure having two separate spaced apart openings for fluid flow formed there through; a sensing structure including a substrate having a backside cavity extending from a top side of the substrate to an opposing bottom side of the substrate, the sensing structure further having a topside layer secured relative to the top side of the substrate such that at least a portion of the topside layer is suspended over the backside cavity in the substrate thereby exposing a back side of the topside layer to the backside cavity, the sensing structure further having a heater element and at least one sensing element positioned over the top side of the topside layer, the backing structure is bonded to the sensing structure such that the two separate spaced apart openings in the backing structure are in fluid communication with the backside cavity in the substrate to provide a fluid flow path along the back side of the topside layer. - View Dependent Claims (17, 18, 19, 20)
-
Specification