FORMATION OF HIGHLY POROUS GAS-SENSING LAYERS BY DEPOSITION OF NANOPARTICLES PRODUCED BY FLAME SPRAY PYROLYSIS

• US 20090291024A1
• Filed: 11/25/2005
• Published: 11/26/2009
• Est. Priority Date: 12/09/2004
• Status: Abandoned Application

• Current Assignee: Eth Zuerich
• Original Assignee: Eth Zuerich
• Inventors: Barsan, Nicolae, Gurlo, Aleksander, Pratsinis, Sotiris, Roessler, Albert, Weimar, Udo, Maedler, Lutz
• Application Number:
  US11/720,943
• Publication Number:
  US 20090291024A1
• Time in Patent Office: Days
• US Class Current: 422/68.1
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G01N 27/127 comprising nanoparticles

Abstract

The invention relates to a method of producing a gas sensor comprising the steps of

• • a. Positioning a sensor substrate (7) in a flame spray pyrolysis apparatus (1);
  • b. Generating an aerosol phase comprising sensing material nanoparticles by flame spray pyrolysis (FSP) of a precursor substance;
  • c. Depositing the sensing material particles contained in the aerosol, in particular nanoparticles of the sensing material, onto the sensor substrate (7) directly from the aerosol phase to form a porous sensing layer (15).

Claims

1. Method of producing a gas sensor comprising the steps of

a. Positioning a sensor substrate (7) in a flame spray pyrolysis apparatus (1);

b. Generating an aerosol phase comprising sensing material nanoparticles by flame spray pyrolysis (FSP) of a precursor substance;

c. Depositing the sensing material particles contained in the aerosol, in particular nanoparticles of the sensing material, onto the sensor substrate (7) directly from the aerosol phase to form a porous sensing layer (15) on the sensor substrate (7).

2. Method according to claim 1, characterized in that the sensing material is functionalized prior to deposition.

3. Method according to claim 1, characterized in that pure and functionalized sensing material, in particular nanoparticles of pure and functionalized sensing material, is synthesized by flame spray pyrolysis.

4. Method according to claim 1, characterized in that the sensing material is a metal oxide and/or a mixed metal oxide and/or at least one of said materials functionalized with a noble metal, in particular SnO₂, ZnO/SnO₂ and/or Pt/SnO₂.

5. Method according to claim 1, characterized in that prior to depositing the sensing material electrode assemblies are prefabricated on the sensor substrate (7).

6. Method according to claim 1, characterized in that a mask is applied to the substrate (7) before deposition in order to deposit the sensing material in the desired sensor area.

7. Method according to claim 1, characterized in that the substrate temperature (T_sub) is controlled during deposition, in particular kept at a constant temperature, preferably at 120°

C.

8. Method according to claim 1, characterized in that the substrate (7) is located at the stagnation point of the impinging jet of the flame (8).

9. Method according to claim 1 characterized in that the substrate (7) is being moved in spatial relation to a flame nozzle during deposition, in particular rotated.

10. Method according to claim 1, characterized in that the sensor substrate is positioned in the flame to give a deposition temperature which is lower than the melting point of the sensing material.

11. Method according to claim 1, characterized in that a stack of layers having different functionalities is deposited by changing the aerosol composition during deposition of the sensing material on the sensor substrate (7).

12. Sensor produced in a method according to claim 1 comprising a porous sensing layer (15) deposited on a substrate (7) from an aerosol comprising sensing material particles, in particular nanoparticles.

13. Sensor according to claim 12, characterized in that the sensor substrate (7) is a ceramic or micro-machined substrate.

14. Sensor according to claim 12, characterized in that the sensor substrate comprises at least one pre-fabricated electrode assembly, in particular interdigitated electrodes.

15. Sensor according to claim 12, characterized in that the sensor substrate comprises a heater assembly, in particular on the back side of the active sensing area.

16. Sensor fabrication system comprising a flame spray reactor (1), a delivery system, in particular a precursor pump (2) and a precursor supply line connected to a nozzle (3), a flame ring (4) surrounding the nozzle exit and a sensor substrate holder (9) disposed above the nozzle (3).

17. Sensor fabrication system according to claim 16, characterized in that the sensor substrate holder (9) is connected to cooling means.

18. Sensor fabrication system according to claim 16, characterized in that the sensor substrate holder (9) is a water cooled copper block.