OSCILLATOR ELEMENT FOR PHOTO ACOUSTIC DETECTOR

• US 20100045990A1
• Filed: 11/05/2007
• Published: 02/25/2010
• Est. Priority Date: 11/10/2006
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Kalkman, Jeroen, Van Kesteren, Hans Willem, Helwegen, Ivon Franciscus
• Granted Patent: US 8,040,516 B2
• Time in Patent Office: Days
• US Class Current: 356/432
• CPC Class Codes: G01N 2021/1704 in gases
• CPC Class Codes: G01N 2021/1708 with piezotransducers
• CPC Class Codes: G01N 21/1702 with opto-acoustic detection, e.g. for gases or analysing solids
• CPC Class Codes: G01N 2291/02809 Concentration of a compound, e.g. measured by a surface mass change
• CPC Class Codes: G01N 29/02 Analysing fluids using acoustic emission techniques G01N29/14 ; constructional or flow details for analysing fluids G01N29/222; optoacoustic fluid cells G01N29/2425

Abstract

An oscillator element (10) for use in a photo acoustic detector is provided for detecting a concentration of a sample in a sample mixture. The photo acoustic detector uses a light beam (11) for excitation of molecules of the sample (15) in proximity of an excitation area (25) of the oscillator element (10). The excitation results in resonance of the oscillator element (10). The oscillator element (10) comprises piezoelectric material (20) for generating a voltage when mechanically distorted and electrodes (21-24), at least partially covering a surface of the oscillator element (10) for registering the generated voltage. The excitation area (25) is arranged in such a way that heating of the electrodes (21-24) in the excitation area (25) by the light beam (11) is avoided.

Claims

1. An oscillator element (10) for use in a photo acoustic detector for detecting a concentration of a sample (15) in a sample mixture, the photo acoustic detector using a light beam (11) for excitation of molecules of the sample (15) in proximity of an excitation area (25) of the oscillator element (10), the excitation resulting in resonance of the oscillator element (10), the oscillator element (10) comprising:

piezoelectric material (20) for generating a voltage when mechanically distorted and

electrodes (21-24), at least partially covering a surface of the oscillator element (10) for registering the generated voltage, characterized in that

the excitation area (25) is arranged in such a way that heating of the electrodes (21-24) in the excitation area (25) by the light beam (11) is avoided.

2. An oscillator element (10) according to claim 1, wherein the electrodes (21-24) do not cover the surface of the oscillator element (10) in the excitation area (25).

3. An oscillator element (10) according to claim 1, wherein the electrodes (21-24) have a high reflection coefficient for light at a wavelength of the light beam (11).

4. An oscillator element (10) according to claim 3, wherein the electrodes (21-24) are covered by a coating for obtaining the high reflection coefficient.

5. An oscillator element (10) according to claim 1 wherein the electrodes (21-24) are at least partly made of a transparent, electrically conductive material.

6. An oscillator element (10) according to claim 1, wherein the piezoelectric material (20) is quartz.

7. An oscillator element (10) according to claim 1, wherein the piezoelectric (20) material is shaped as a tuning fork.

8. An oscillator element (10) according to claim 7, wherein the excitation area (25) is situated at an end of two prongs of the tuning fork.

9. A photo acoustic detector comprising an oscillator element (10) as described in claim 1.