SENSOR DEVICE FOR DETECTING A PERMANENT GAS

Abstract

The invention relates to a sensor device (1) for detecting a gas (G), particularly a permanent gas such as H.sub.2, CO, CO.sub.2, CH.sub.4, comprising: an adsorption filter (30) comprising a body (2) consisting of a molecular sieve material, a sensing element (10) for detecting said gas (G), and a carrier (4) for carrying the sensing element (10), wherein the carrier (4) comprises an opening (50) via which said gas (G) to be detected can reach the sensing element (10), and wherein the adsorption filter (30) is connected, particularly glued, to the carrier (4) and closes said opening (50) so that said gas (G) to be detected can diffuse through said body (2) towards the sensing element (10).

Claims

1. A sensor device (1) for detecting a gas (G), comprising: an adsorption filter (30) comprising a dimensionally stable body (2) consisting of a molecular sieve material, wherein said body comprises a diameter (D) in the range from 0.2 mm to 5 mm, a sensing element (10) for detecting said gas (G), a carrier (4) for carrying the sensing element (10), wherein the carrier (4) comprises an opening (50) via which said gas (G) to be detected can reach the sensing element (10), and wherein the adsorption filter (30) is connected or glued to the carrier (4) and closes said opening (50) so that said gas (G) to be detected can diffuse through said body (2) towards the sensing element (10).

2. The sensor device (1) according to claim 1, characterized in that said body (2) comprises a diameter (D) in the range from 0.5 mm to 3 mm, particularly 1 mm to 2 mm.

3. The sensor device (1) according to claim 1 or 2, characterized in that said adsorption filter (30) comprises merely a single body (2) of said molecular sieve material.

4. The sensor device according to one of the preceding claims, characterized in that said body (2) is one of: a bead, a section of a bead, a pellet, a plate.

5. The sensor device according to one of the preceding claims, characterized in that the molecular sieve material is one of or comprises on of: a zeolite, a silica gel, clay, activated carbon, a polymer adsorbent, an aromatic polyimide, polyether ether ketone (PEEK), a perfluoropolymer, poly(2,6-diphenylphenylene oxide), cellulose acetate.

6. The sensor device according to one of the preceding claims, characterized in that the body (2) is embedded in a form fitting manner in a material (3) of the adsorption filter (30).

7. The sensor device according to one of the preceding claims, characterized in that that the adsorption filter (30) is an adsorption filter plate (30), wherein the body (2) and said material (3) of the carrier (4) form said adsorption filter plate (30), and wherein said adsorption filter plate (30) comprises a front side (30a) and an opposing back side (30b).

8. The sensor device according to claim 7, characterized in that the body (2) extends from the front side (30a) to the back side (30b) of the adsorption filter plate (30) and thus forms a passage for the gas (G) to be detected through the adsorption filter plate (30), wherein a front side (2a) of the body (2) forms an area of said front side (30a) of the adsorption filter plate (30), and wherein a back side (2b) of the body (2) forms an area of said back side (30b) of the adsorption filter plate (30).

9. The sensor device according to one of the preceding claims, characterized in that the carrier (4) comprises a front side (4a) in which a recess (5) is formed, wherein the sensing element (10) is arranged in said recess (5) and wherein the recess (5) comprises said opening (50).

10. The sensor device according to claims 7 and 9, characterized in that the adsorption filter plate (30) is connected to the carrier (4) so that the back side (30b) of the adsorption filter plate (30) faces the front side (4a) of the carrier (4) and the gas (G) to be detected can diffuse via said body (2) through the adsorption filter plate (30) to reach the sensing element (10), wherein particularly the back side (30b) of the adsorption filter plate (30) is glued to the front side (4a) of the carrier (4) or wherein particularly the back side (30b) of the adsorption filter plate (30) is connected in a form-fitting manner to the front side (4a) of the carrier (4).

11. The sensor device according to claim 9 or 10, characterized in that said body (2) covers said opening (50) of the recess (5) of the carrier (4).

12. The sensor device according to one of the claims 1 to 5, characterized in that the carrier (4) forms a housing enclosing an internal space (42) of the carrier (4), wherein the sensing element (10) is arranged at least in sections in said internal space (40), and wherein the body (2) is glued to the carrier (4) such that the body (2) is arranged inside the internal space (40) and closes said opening (50).

13. Method for producing a sensor device, particularly according to one of the claims 1 to 11, wherein a plurality of bodies (2) formed out of a molecular sieve material is arranged in a two-dimensional plane, wherein a free space between the bodies (2) is filled with a material (3) that is cured, wherein an adsorption filter plate (30) is formed in which the bodies (2) are embedded in said material (3) and each body (2) extends from a front side (30a) of said adsorption filter plate (30) to a back side (30b) of said adsorption filter plate (30), and wherein each body (2) is arranged in front of an associated sensing element (10) for forming a corresponding number of sensor devices (1).

14. Method for producing a sensor device, particularly according to one of the claims 1 to 11, wherein a plurality of bodies (2) formed out of a molecular sieve material is arranged on a single carrier (4) that comprises a plurality of sensing elements (10) so that each body (2) is associated to one of the sensing elements (10), wherein a free space between the bodies (2) is filled with a material (3) that is cured, wherein an adsorption filter plate (30) is formed that is connected or glued to the single carrier (4), and wherein the carrier (4) with the attached adsorption filter plate (30) is separated into a plurality of individual sensor devices (1).

15. Method for producing a sensor device (1), particularly according to one of the claims 1 to 11, wherein a plate-shaped body formed out of a molecular sieve material is arranged on a single carrier (4) that comprises a plurality of sensing elements (10), wherein molecular sieve material of the plate-shaped body (2) is removed around each sensing element (10) to form separate adsorption filter bodies (2), wherein each adsorption filter body (2) is associated to one of the sensing elements (10), and wherein a free space between said bodies (2) is filled with a material (3) that is cured to seal the respective adsorption filter body (2) to the carrier (4), and wherein the carrier (4) with the attached adsorption filter bodies is separated into a plurality of individual sensor devices (1).

Description

[0059] Further features, advantages and embodiments of the present invention will be described below with reference to the Figures, wherein

[0060] FIG. 1 shows a cross sectional view of three sensor devices according to the invention (upper row), and a top view of said sensor devices (lower row);

[0061] FIG. 2 shows a further embodiment of a sensor device according to the invention;

[0062] FIG. 3 shows a sensor signal of a sensor device for detecting a permanent gas with adsorption filter according to the invention (upper signal) and without adsorption filter (lower signal);

[0063] FIGS. 4 to 8 show an exemplary process for producing a sensor device according to the present invention.

[0064] FIG. 1 shows three sensor devices according to the invention in a cross sectional view (upper part) and as well as top view of these sensors 1. The sensor devices can be produced using one of the methods described herein. Particularly, the shown three sensors 1 may be produced as a single component and may then be separated into individual sensor devices 1.

[0065] In the following a single sensor device 1 shall be described. Particularly, the sensor device 1 is configured for detecting the presence of a gas in the vicinity of the sensor device 1, particularly a permanent gas such as H.sub.2, CO, CO.sub.2, CH.sub.4. For this, the sensor device 1 comprises an adsorption filter 30 comprising a particularly dimensionally stable body 2 consisting of a molecular sieve material, and a sensing element 10 for detecting said gas G. Sensing elements 10 that are suitable for detecting said gases G are known in the state of the art. The filter 10 serves for filtering other gaseous components that disturb the detection process or produce signals that shall be suppressed.

[0066] The sensor device 1 further comprises a carrier 4 for carrying the sensing element 10, wherein the carrier 4 comprises an opening 50 via which said gas G to be detected can reach the sensing element 10 so as to interact with the sensing element 10 and be detected by the sensing element 10.

[0067] Further, the adsorption filter 30 is glued to the carrier 4 and thereby closes said opening 50 so that said gas G to be detected can diffuse through said body 2 towards the sensing element 10. Thus a gas-tight seals extends around the opening 50 between the plate 30 and the carrier 4.

[0068] As shown in FIG. 1, the body 2 is embedded in a form fitting manner (particularly with an adhesive bond) in a carrier material 3 of the adsorption filter 30, e.g. by means of potting, molding or the like. Particularly, said carrier material can be a fluid epoxy resin which is eventually cured to form an adsorption filter plate 30.

[0069] Particularly, this adsorption filter plate 30 that is formed by the body 2 and the carrier material 3 encapsulating the latter, comprises a planar front side 30a and an opposing planar back side 30b, which back side 30b runs parallel to the front side 30a. Furthermore, the embedded body 2 extends inside the adsorption filter plate from the front side 30a to the back side 30b and thus forms a passage of flow path for the gas G to be detected through the adsorption filter plate 30. As further shown in FIG. 1, a front side 2a of the body 2 is flush with said front side 30a of the adsorption filter plate 30 and thus forms an area of said front side 30a, and a back side 2b of the body 2 is flush with the back side 30b and forms an area of said back side 30b of the adsorption filter plate 30. The sizes of these areas can be adjusted by shaping the front and back side 30a, 30b correspondingly (e.g. by cutting or grinding or other processes).

[0070] Furthermore, the carrier 4 comprises a planar front side 4a in which a recess 5 is formed, wherein the sensing element 10 is arranged in said recess 5 (e.g. on the bottom of the recess 5). Further, the sensing element 10 may fill said recess 5 completely. The recess 5 further comprises said opening 50, which opening 50 extends in the plane of the planar front side 4a of the carrier 4.

[0071] In order to achieve a gas tight seal between the carrier 4 and the plate 30, the adsorption filter plate 30 is glued with its back side 30b to the front side 4a of the carrier 4 so that the gas G to be detected can diffuse via said body 2 through the adsorption filter plate 30 to reach the sensing element 10 mounted on the carrier 4.

[0072] Particularly, for achieving said gas-tight seal, the body 2 covers said opening 50 of the recess 5 of the carrier 4, wherein particularly said area 2b comprise a circumferential outer section 2c that is glued to a boundary region 4c of the front side 4a of the carrier 4, which boundary region 4c surrounds said opening 50.

[0073] As an example, FIG. 3 shows sensor signals for a sensor device 1 according to the invention for detecting CO.sub.2 as gas G. Particularly, the absorption filter 30 was prepared as described above with a 2 mm 13 zeolite bead and its thickness reduced to 700 m by grinding. As can be seen, the sensor 1 is not sensitive to ethanol anymore, and the response time to CO.sub.2 is only slightly decreased.

[0074] Furthermore, FIG. 2 shows an alternative embodiment of the present invention. Here, the carrier 4 forms a housing enclosing an internal space 42, wherein the sensing element 10 is now arranged in said internal space 42. Particularly, the body 2 is a leveled bead 2 that is glued to the carrier 4 using a glue material 3 such that the body 2 is arranged inside the internal space 42 and closes an opening 50 of the housing 4 formed in a top side 4a of the housing. Particularly, the leveled front side 2a of the body 2 is flush with said top side 4a of the housing 4.

[0075] Finally, FIGS. 4 to 8 show an exemplary method for producing a sensor device 1, particularly several sensor devices 1 in parallel, according to the present invention.

[0076] For this, a plurality of dimensionally stable bodies 2, here in the form of spheres having particularly different diameters and formed out of a molecular sieve material (i.e. each body forms a molecular sieve) is arranged in a two-dimensional plane (e.g. in equidistant intervals, e.g. according to a checkered pattern) by placing each body 2 on an associated recess 41 formed into a substrate 40 as shown in FIGS. 4 and 5.

[0077] Further, as can be seen in FIG. 6, a free space between the bodies 2 arranged on the substrate 40 is filled with a material 3 that is then cured, wherein an adsorption filter plate 30 is formed in which the bodies 2 are embedded in the material 3 and each body 2 extends from a front side 30a of said adsorption filter plate 30 to a back side 30b of said adsorption filter plate 30 as shown in FIG. 6(A), where the bodies protrude out of the material 3. Particularly, the substrate 40 can also form a transfer support for better handling of the adsorption filter plate 30 (see below) and for providing mechanical stabilization of the adsorption filter plate, particularly in case the adsorption filter plate 30 is relatively thin. Such a transfer support can remain on the sensor device or may be removed later on, e.g. after connecting the filter plate 30 to the carrier 4. As shown e.g. in FIGS. 4 to 6 also a separate transfer support 400 (in addition to substrate 40) may optionally be used to improve handling/mechanical stability of the filter plate 30. In case the transfer support 40, 400 remains on the sensor device, the transfer support is preferably arranged on the front side 30a of the adsorption filter plate 30 (cf. e.g. FIG. 7) and is then particularly configured to be permeable for the gas G that is to be detected. A transfer support 400 can also be applied/connected to the adsorption filter plate after the surfaces of the filter plate have been processed (cf. e.g. FIG. 7).

[0078] Further, the bodies 2 can also be completely covered with the material 3 at the front side as shown in FIG. 6(B).

[0079] Particularly, in both cases (complete filling or only partial filling of said free space between the bodies 2 with said material), the front side 30a of the adsorption filter plate 30 can be processed, e.g. by grinding or cutting, to achieve a flat front side 30a as shown in FIG. 7. Further, the plate 30 can be removed from the substrate 40 and also the back side 30b can be processed, e.g. by grinding or cutting, for achieving a flat back side 30b of the adsorption filter plate 30 such that the bodies 2 of the plate 30 extend from its front side 30a, where an area 2a of the respective body 2 forms a part of said front side 30a, to the back side 30b, where an area 2b of the respective body 2 forms a part of said back side 30b. Thus gas G can pass the plate 3 via the bodies 2 by entering via said areas 2a and leaving the plate 30 via said areas 2b.

[0080] Further, the adsorption filter plate 30 is arranged on a carrier 4 comprising a plurality of recesses 5 with openings 50 wherein a sensing element 10 for detecting said gas G is arranged in each recess 5, and wherein the plate 30 is arranged such on the carrier 4 that each body 2 is associated to one sensing element 10, particularly such that the area 2b of the respective body covers its associated recess 5 as shown in FIG. 8. Here, the material 3 of the plate 30 may be glued to a front side 4a of the carrier, in which front side 4a said recesses 5 receiving the sensing elements 10 are formed. In this way a seal is established around each recess 5 and gas can only enter the respective recess 5 via the respective body 2 that is formed out of said molecular sieve material.

[0081] After having connected the plate 30 to the carrier 4, this assembly can be separated into individual sensor devices 1 wherein each sensor device comprises a body 2 as a passage to a sensing element 10 as shown in FIG. 8 on the right hand side.

[0082] Alternative production methods are described above.