Thermal flux sensor with heating nanofilaments

Patent metadata

Field	Value
Publication number	US-11480480-B2
Application number	US-201916705405-A
Country	US
Kind code	B2
Filing date	Dec 6, 2019
Priority date	Dec 7, 2018
Publication date	Oct 25, 2022
Grant date	Oct 25, 2022

Abstract

A heat flux sensor comprising:
an array of nanofilaments suspended with respect to a support, each nanofilament comprising an electrically conducting material, the array being able to be biased by an electric power source to circulate an electric current in each of the nanofilaments, at least one resonator of the nanoelectro-mechanical system (NEMS) type comprising:
a beam consisting of a nanofilament forming a side of the array, an actuation device able to generate a vibration of the beam under the effect of an excitation signal, a detection device configured to measure a displacement of the beam during the vibration and emit an output signal having a resonance at the resonant frequency of the resonator, the resonant frequency depending on the intensity of the electric current flowing through the beam, a temperature variation of the array of heating nanofilaments induced by a variation in a characteristic of a fluid surrounding the array causing an intensity variation of the current flowing through the beam resulting in a variation in the resonant frequency of the resonator.

First claim

The invention claimed is:

1. A heat flux sensor comprising:
an array of nanofilaments suspended with respect to a support, each nanofilament comprising an electrically conducting or semiconductor material, said array being able to be biased by an electric power source to circulate an electric current in each of said nanofilaments,
at least one resonator of the nanoelectro-mechanical system (NEMS) type comprising:
a beam consisting of a nanofilament forming a side of the array,
an actuation device able to generate a vibration of said beam under the effect of an excitation signal,
a detection device configured to measure a displacement of the beam during said vibration and emit an output signal having a resonance at the resonant frequency of the resonator, said resonant frequency depending on the intensity of the electric current flowing through the beam, a temperature variation of the array of heating nanofilaments induced by a variation in a characteristic of a fluid surrounding said array causing an intensity variation of a current flowing through the beam resulting in a variation in the resonant frequency of said resonator.

2. The sensor of claim 1 , comprising at least two resonators the beams of which are arranged along two opposite sides of the array of nanofilaments.

3. The sensor of claim 1 , wherein each nanofilament is embedded at both ends into the support.

4. The sensor of claim 1 , wherein all the nanofilaments of the array have a same cross-section.

5. The sensor of claim 1 , wherein the cross-section of each nanofilament has a width and a thickness each between 10 and 500 nm.

6. The sensor of claim 1 , wherein each nanofilament is arranged at a distance from an adjacent nanofilament.

7. The sensor of claim 6 , wherein the distance between two adjacent nanofilaments is between 0.5 and 1.5 μm.

8. The sensor of claim 1 , wherein the beams have a different length from a length of the other nanofilaments.

9. The sensor of claim 1 , wherein each nanofilament is formed by a semiconductor material, such as silicon.

10. The sensor of claim 9 , wherein each resonator has a different doping level from a doping level of the other nanofilaments.

11. The sensor of claim 9 , wherein the support is formed by the same semiconductor material as the nanofilaments, and the support has a different doping level from the doping level of the nanofilaments other than the beams.

12. The sensor of claim 1 , wherein the support is formed by a different material from the material of the nanofilaments, said material being chosen to thermally insulate the array of nanofilaments and each resonator from the rest of the sensor.

13. The sensor of claim 12 , wherein the material of the support is porous.

14. The sensor of claim 1 , further comprising a substrate with respect to which the support is suspended.

15. The sensor of claim 14 , wherein the support has a plurality of through holes extending transversally to a main surface of the substrate.

16. The sensor of claim 1 , wherein the nanofilaments other than the beams are connected to each other through bridges.

17. The sensor of claim 1 , wherein the number of nanofilaments is between 10 and 1000.

18. The sensor of claim 1 , wherein the actuation device is of the electrostatic type.

19. The sensor of claim 1 , wherein the detection device comprises a piezoresistive gauge integral with the beam.

20. A gas sensor comprising the heat flux sensor of claim 1 .

21. A gas analysis system comprising a chromatography column and at least one sensor of claim 1 arranged at an outlet of said chromatography column.

22. A flowmeter comprising the heat flux sensor of claim 1 .

Assignees

• Commissariat Energie Atomique
• Apix Analytics

Inventors

• Ollier Eric
• Alava Thomas
• Benedetto Kévin
• Ladner Carine
• Colinet Eric

Classifications

• G01N29/036

  by measuring frequency or resonance of acoustic waves · CPC title

• B81B2201/0271

  Resonators; ultrasonic resonators · CPC title

• G01N2291/02881

  Temperature · CPC title

• B81B7/008

  MEMS characterised by an electronic circuit specially adapted for controlling or driving the same (B81B7/0087 takes precedence; arrangements for starting, regulating, braking, or otherwise controlling an actuator H02N; control arrangements or circuits for visual indicators G09G3/00) · CPC title

• G01N29/022 Primary

  Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices (microdevices per se B81B) · CPC title