Device for gas-sensoring electrodes

• US 6,325,979 B1
• Filed: 06/07/1999
• Issued: 12/04/2001
• Est. Priority Date: 10/15/1996
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Hahn, Dieter, Schumann, Bernd, Flik, Gottfried
• Primary Examiner(s): Warden, Jill
• Assistant Examiner(s): SINES, BRIAN J
• Application Number:
  US09/284,661
• Time in Patent Office: 911 Days
• Field of Search: 422/88, 422/83, 422/98, 338/34, 338/35, 73/232, 204/432, 204/430, 204/431, 204/415
• US Class Current: 422/88
• CPC Class Codes: G01N 2027/222 for analysing gases
• CPC Class Codes: G01N 27/12 of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid , for detecting components in the fluid

Abstract

A sensing element, in particular for an electrochemical sensor for determining gas concentrations, having at least one three-dimensional electrode arrangement, applied on a support plate and forming trenches of a depth for measuring changes in capacitance and/or conductivity in a gas-sensitive layer arranged to a height in the trenches, the height of the gas-sensitive layer being less than the depth of the trenches.

Claims

1. A sensing element, comprising:

a support plate;

at least one three-dimensional arrangement of electrodes applied on the support plate, the arrangement of electrodes forming trenches of a depth of between 10 μ

m and 100 μ

m;

a gas-sensitive layer arranged to a predetermined height only in the trenches, the arrangement of electrodes measuring changes in at least one of potential, capacitance and conductivity in the gas sensitive layer, the predetermined height of the gas-sensitive layer being less than the depth of the trenches; and

a catalytically active layer covering the gas sensitive layer.

2. The sensing element according to claim 1, further comprising:

a protective layer that is arranged in the trenches above one of the gas-sensitive layer and the catalytically active layer.

3. The sensing element according to claim 1, wherein the electrodes of the at least one three-dimensional arrangement of electrodes are arranged in the form of an interdigitated structure.

4. The sensing element according to claim 1, wherein the at least one three-dimensional arrangement of electrodes is formed from four individual electrodes, which allow a four-pole measurement.

5. The sensing element according to claim 1, wherein the support plate includes one of ceramic material, glass, aluminum oxide and a silicon/silicon dioxide mixture.

6. The sensing element according to claim 1, wherein the electrodes of the at least one arrangement of electrodes includes one of platinum, gold, silver, copper and nickel.

7. A sensing element, comprising:

a support plate;

at least two three-dimensional arrangements of electrodes applied on the support plate, the arrangements of electrodes forming trenches of a depth of between 10 μ

m and 100 μ

m;

a gas-sensitive layer arranged to a predetermined height only in the trenches, the arrangements of electrodes measuring changes in at least one of potential, capacitance and conductivity in the gas sensitive layer, the predetermined height of the gas-sensitive layer being less than the depth of the trenches; and

a catalytically active layer covering the gas sensitive layer.

8. An electrochemical sensor for determining a gas concentration, comprising:

at least one of a sensing element and sensor array, the at least one sensing element and sensor array, including

a support plate,

at least one three-dimensional arrangement of electrodes applied on the support plate, the arrangement of electrodes forming trenches of a depth of between 10 μ

m and 100 μ

m,

a gas-sensitive layer arranged to a predetermined height only in the trenches, the arrangement of electrodes measuring changes in at least one of potential, capacitance and conductivity in the gas sensitive layer, the predetermined height of the gas-sensitive layer being less than the depth of the trenches, and

a catalytically active layer covering the gas sensitive layer.

9. A method for manufacturing a sensing element having a three-dimensional electrode arrangement, comprising the steps of:

depositing an electroplating starter layer onto a support plate;

applying a photoresist at a thickness of between 10 μ

m to 100 μ

m onto the electroplating starter layer;

patterning the photoresist to form resist trenches;

filling the resist trenches by electroplating up to a defined height;

removing the photoresist to form electrode trenches;

etching away the electroplating starter layer from within the electrode trenches;

placing a gas sensitive material into the electrode trenches up to a predetermined height that is less than the depth of the electrode trenches; and

applying a catalytically active material onto the gas sensitive material in the electrode trenches.