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CN-114674751-B - Photoacoustic detection apparatus including protective film

CN114674751BCN 114674751 BCN114674751 BCN 114674751BCN-114674751-B

Abstract

A photoacoustic detection device (1) intended to be applied against a medium (2) to be analyzed via a contact surface (3), comprising-a hollow cavity (20) opening onto a contact hole (22) formed in the contact surface, -a pulsed or amplitude modulated light source (10) configured to emit an incident light beam (11) in an emission band (Δλ) through the cavity (20) to the contact hole when activated, -an acoustic transducer (28) connected to the cavity and configured to detect an acoustic wave (12) extending through the cavity, such that under irradiation of the medium by the incident light beam the acoustic transducer detects an acoustic wave generated by heating of the medium (2), wherein-the cavity comprises a membrane extending through the cavity facing the contact surface, -the membrane is delimited by a lower face ( i ) and an upper face (23, S ) comprising a through hole (23, O ) generated between the lower face and the upper face.

Inventors

  • Jean Guillaume kutar
  • Alan Greer
  • Maris Fournier

Assignees

  • 原子能和替代能源委员会

Dates

Publication Date
20260512
Application Date
20211223
Priority Date
20201224

Claims (14)

  1. 1. A photoacoustic detection device (1) intended to be applied against a medium (2) to be analyzed via a contact surface (3), the device comprising: -a hollow cavity (20) open onto a contact hole (22) formed in the contact face; -a pulsed or amplitude modulated light source (10) configured to emit an incident light beam (11) in an emission band (Δλ) through the cavity (20) to the contact hole when it is activated; -an acoustic transducer (28) connected to the cavity and configured to detect sound waves (12) extending through the cavity; such that under the effect of the medium being irradiated by the incident light beam, the acoustic transducer detects acoustic waves generated by the heating of the medium (2); Wherein: -the cavity comprises a membrane extending through the cavity facing the contact surface; -the film is delimited by a lower face (23 i ) and an upper face (23 S ), the film comprising a through hole (23 O ) produced between the lower face and the upper face; -the membrane is located within the cavity at a non-zero distance (d) from the contact surface (3).
  2. 2. The apparatus of claim 1, wherein each through hole (23 O ) has a radius of 5 μm to 25 μm.
  3. 3. The apparatus of claim 1, wherein: -the membrane defines a pore factor corresponding to the ratio of the cumulative area of each through-hole to the total area of the lower or upper face of the membrane; -the pore factor is 0.05 to 0.3.
  4. 4. The apparatus of claim 1, wherein the film has a thickness of 100 μιη to 1mm.
  5. 5. The apparatus of claim 1, wherein: -the membrane is arranged such that, when the light source is activated, the incident light beam passes through the membrane before reaching the contact hole (22); -the film comprises intersecting segments (23 int ) corresponding to the portion of the film traversed by the light beam; -at least in the intersecting segments, the film is made of a transparent material having a transmittance in the emission band higher than 0.4.
  6. 6. The apparatus of claim 5, wherein the membrane is non-porous in the intersecting segments.
  7. 7. The apparatus of claim 5, wherein the transparent material is composed of at least one material selected from Si, ge, alN, znSe, baF 2 、CaF 2 , KBr, znS, sapphire.
  8. 8. The apparatus of claim 5, wherein at least in the intersecting segments, an upper face of the film comprises an anti-reflective coating.
  9. 9. The apparatus of claim 5, wherein the membrane: -outside said intersecting section, made of a first material (23 1 ); -in said intersecting sections, made of an auxiliary material (23 a ) forming said transparent material.
  10. 10. The apparatus of claim 1, wherein the membrane comprises a hydrophobic coating on the lower face.
  11. 11. The apparatus of claim 1, wherein: -the cavity is delimited by a transverse wall (21 2 ) and a side wall (21 1 ) extending between the transverse wall and the contact face; -the membrane extends between opposite faces of the side wall.
  12. 12. The apparatus of claim 1, wherein the membrane is removably disposed in the cavity.
  13. 13. The apparatus of claim 1, wherein the light source is a laser source.
  14. 14. The device of claim 1, wherein the volume of the lumen is less than 50 μl.

Description

Photoacoustic detection apparatus including protective film Technical Field The technical field of the present invention is detection of analytes via photoacoustic detection. Background Photoacoustic detection is based on detecting acoustic waves generated by absorption of a pulsed or amplitude modulated incident electromagnetic wave by the medium being analyzed. The acoustic wave is formed after heating of the molecules of interest present in the analyzed medium by absorption of the incident wave. This heating causes a modulated thermal expansion of the medium, which expansion is the origin of the sound waves. Photoacoustic detection can be made specific to a particular analyte by adjusting the wavelength of the incident electromagnetic wave to the absorption wavelength of the analyte. Photoacoustic detection has thus been applied to detect gas species in gases, or to detect the presence of specific molecules in biological tissues. The wavelength of the incident wave is often in the infrared. Photoacoustic detection is a non-invasive analysis technique that can be applied to scattering or opaque media. The application of photoacoustic detection to biological tissue is described in the following publications: -Bauer AJ."IR-spectroscopy for skin in vivo:optimal skin sites and properties for non-invasive glucose measurement by photoacoustic and photothermal spectroscopy";Journal of Biophotonics 11(2018); -"Windowless ultrasound photoacoustic cell for in-vivo mid-IR spectroscopy of human epidermis:Low interference by changes of air pressure,temperature,and humidity caused by skin contact opens the possibility for a non-invasive monitoring of glucose in the interstitial fluid",Rev.Sci.Instrum.84,084901(2013). In these publications, amplitude modulated laser light sources activated at frequencies of tens Hz to tens kHz are used. The aim is to estimate the concentration of glucose in interstitial body fluids at a depth of 10 μm to 100 μm below the skin surface of the user. For this purpose, a photo acoustic detection device is used which is arranged against the skin of the user. The photoacoustic detection apparatus includes a transducer configured to detect amplitude modulated acoustic waves under the influence of periodic heating introduced by the modulated optical waves. More specifically, the photo acoustic detection device is arranged to detect a periodic pressure modulation, the period being dependent on the modulation frequency of the light wave. The response function of the photoacoustic apparatus can be calibrated to establish a correlation between the measured pressure modulation and the amount of analyte present in the analyzed medium. Water vapor emanating from the skin may cause difficulties due to perspiration. The water vapor may condense and form droplets, which may damage the transducer. Furthermore, dust or other undesirable elements, such as skin fragments, may accumulate in the device during use of the device. The present invention aims to solve this problem. Disclosure of Invention A first subject of the invention is a photoacoustic detection device intended to be applied against a medium to be analyzed via a contact surface, the device comprising: -a hollow cavity opening onto a contact hole formed in the contact face; -a pulsed or amplitude modulated light source configured to emit an incident light beam in an emission band through the cavity to the contact hole when it is activated; -an acoustic transducer connected to the cavity and configured to detect sound waves extending through the cavity; So that under the effect of the medium being illuminated by the incident light beam, the acoustic transducer detects the sound waves generated by the heating of the medium; Wherein: The cavity comprises a membrane extending through the cavity facing the contact surface; the membrane defines a boundary by a lower face and an upper face, the membrane comprising a through hole created between the lower face and the upper face. By "through-hole" is meant a hole between the lower and upper faces of the membrane, allowing air to pass through the hole. The apparatus may comprise any of the following features alone or in technically realizable combinations. The radius of each through hole is 5 μm to 25 μm. The membrane defines Kong Yinzi corresponding to the ratio of the cumulative area of each through hole to the total area of the lower or upper face of the membrane, the hole factor being for example 0.05 to 0.3. The thickness of the film is 100 μm to 1mm. The membrane is located within the cavity at a non-zero distance from the contact surface. Advantageously: The membrane is arranged such that when the light source is activated, the incident light beam passes through the membrane before reaching the contact hole; -the film comprises intersecting segments corresponding to the portions of the film traversed by the light beam; At least in the intersecting segments, the film is made of a transparent materia