Photoacoustic detection device comprising a protective film

Abstract

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

Description

Technical Field

[0001] The technical field of this invention is the detection of analytes via photoacoustic detection. Background Technology

[0002] Photoacoustic detection is based on detecting sound waves generated by the absorption of pulsed or amplitude-modulated incident electromagnetic waves by the medium being analyzed. The sound waves are formed after the molecules of interest present in the medium being analyzed are heated by the absorption of the incident wave. This heating causes modulated thermal expansion of the medium, which is the origin of the sound waves.

[0003] Photoacoustic detection can be specialized for a specific analyte by tuning the wavelength of the incident electromagnetic wave to the absorption wavelength of the analyte. Photoacoustic detection has thus been applied to detect the types of gases in gases or to detect the presence of specific molecules in biological tissues. The wavelength of the incident wave is often in the infrared range.

[0004] Photoacoustic detection is a non-invasive analytical technique that can be applied to scattering or opaque media.

[0005] The application of photoacoustic detection to biological tissues is described in the following publications:

[0006] -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);

[0007] - "Windowless ultrasound photoacoustic cell for in-vivo mid-IRspectroscopy of human epidermis: Low interference by changes of air pressure, temperature, and humidity caused by skin contact opens the possibility for anon-invasive monitoring of glucose in the interstitial fluid", Rev.Sci.Instrum.84,084901(2013).

[0008] These publications utilize amplitude-modulated laser sources activated at frequencies ranging from tens of Hz to tens of kHz. The aim is to estimate the concentration of glucose in the interstitial fluid at depths of 10 μm to 100 μm below the user's skin surface. For this purpose, a photoacoustic detection device positioned against the user's skin is used.

[0009] The photoacoustic detection device includes a transducer configured to detect amplitude-modulated acoustic waves under the influence of periodic heating introduced by a modulated light wave. More specifically, the photoacoustic detection device is configured to detect periodic pressure modulation, the period of which depends on the modulation frequency of the light wave. The response of the photoacoustic device can be calibrated to establish a correlation between the measured pressure modulation and the amount of analyte present in the analyzed medium.

[0010] Water vapor emitted from the skin during sweating can cause problems. This vapor can condense and form droplets, which can damage the transducer. Furthermore, dust or other unwanted elements, such as skin debris, can accumulate in the device during use. The purpose of this invention is to solve these problems. Summary of the Invention

[0011] The first subject of this invention is a photoacoustic detection device intended to apply pressure to a medium to be analyzed via a contact surface, the device comprising:

[0012] - A hollow cavity opening onto a contact hole, which is formed in the contact surface;

[0013] - A pulsed or amplitude-modulated light source configured to emit an incident beam in the emission spectrum that passes through the cavity to the contact aperture when activated;

[0014] - An acoustic transducer connected to the cavity and configured to detect sound waves extending through the cavity;

[0015] This allows the acoustic transducer to detect the sound waves generated by the heating of the medium when the medium is irradiated by the incident light beam.

[0016] in:

[0017] - The cavity includes a membrane extending through the cavity and facing the contact surface;

[0018] - The membrane is defined by a lower surface and an upper surface, and the membrane includes a through-hole formed between the lower surface and the upper surface.

[0019] A "through-hole" is a hole between the lower and upper surfaces of a membrane that allows air to pass through.

[0020] The device may include any of the following features, either individually or in a combination that is technically feasible.

[0021] - The radius of each through-hole is 5μm to 25μm.

[0022] - The membrane is defined as a pore factor corresponding to the ratio of the cumulative area of ​​each pore to the total area of ​​the lower or upper surface of the membrane, for example, 0.05 to 0.3.

[0023] - The thickness of the membrane ranges from 100 μm to 1 mm.

[0024] - The membrane is located inside the cavity at a non-zero distance from the contact surface.

[0025] Advantageous:

[0026] - The membrane is configured such that when the light source is activated, the incident light beam passes through the membrane before reaching the contact hole;

[0027] - The membrane includes intersecting segments corresponding to the portions of the membrane through which the light beam passes;

[0028] - At least in the intersecting segments, the film is made of a transparent material with a transmittance in the emission band greater than 0.4 and preferably greater than 0.8.

[0029] The membrane can be non-porous in the intersecting sections. "Non-porous" means that there are no through holes.

[0030] The transparent material may be composed of at least one material selected from the following: Si, Ge, AlN, ZnSe, BaF2, CaF2, KBr, ZnS, and sapphire.

[0031] At least in the intersecting sections, the upper surface of the membrane may include an anti-reflective coating.

[0032] The anti-reflective coating can be applied to the entire upper surface and optionally to the entire or partial lower surface.

[0033] Based on feasibility, the membrane is monolithic. It is made from a single material (ignoring any optional hydrophobic or antireflective coatings).

[0034] Based on a feasibility study, the membrane:

[0035] - Outside the intersecting segments, it is made of the first material;

[0036] - In the intersecting segments, auxiliary materials forming the transparent material are used.

[0037] The membrane may include a hydrophobic coating, especially on the lower surface.

[0038] According to one embodiment,

[0039] - The cavity is defined by transverse walls and side walls, with the side walls extending between the transverse walls and the contact surface;

[0040] - The membrane extends between two opposite sides of the sidewall.

[0041] The transverse wall can be parallel to the contact surface.

[0042] According to one embodiment, the membrane is removably disposed in the cavity.

[0043] The light source can be a laser source.

[0044] The volume of the cavity can be less than 50 μL.

[0045] The invention will be better understood by referring to the following figures and by reading the description of examples of embodiments that appear below in the specification. Attached Figure Description

[0046] Figure 1A An embodiment of a photoacoustic detection device is shown.

[0047] Figure 1B The diagram schematically shows the cavity of the device divided into a lower cavity and an upper cavity.

[0048] Figure 1C The membrane is shown schematically.

[0049] Figure 2 The transmission function is shown considering the reflection at the interface of a silicon film with a thickness of 300 μm.

[0050] Figure 3 A droplet is schematically shown forming on the lower surface of the membrane and penetrating into a pore in the membrane.

[0051] Figure 4A The modeled cavity is shown, in which a membrane separates the lower cavity and the upper cavity.

[0052] Figure 4B schematically shown Figure 4A The equivalent circuit diagram of the cavity modeled.

[0053] Figure 4C The modulation amplitude of the pressure in the lower and upper cavities is shown, taking into account the two pore factors of the membrane.

[0054] Figure 5A A variation is shown in which the membrane includes a non-porous portion in the intersection segment corresponding to the portion of the membrane through which the incident light beam passes.

[0055] Figure 5B A variant is schematically shown in which the membrane is a composite membrane formed by a "standard" material that is not necessarily transparent in the infrared and an auxiliary material that is transparent in the infrared and arranged in the intersecting segments. Detailed Implementation

[0056] Figure 1AAn apparatus 1 for implementing the present invention is schematically shown. Apparatus 1 is configured to apply against a medium 2 to be analyzed. The apparatus includes a contact surface 3 intended to be applied against the medium to be analyzed. The contact surface is designed to conform to the medium it is intended to press against. The contact surface is, for example, flat.

[0057] In this example, medium 2 is the user's skin. The device includes a light source 10 configured to emit a light beam 11 that propagates to the medium 2 to be analyzed. The light source 10 is pulsed or amplitude modulated. The light beam 11 is at an absorption wavelength λ that includes the analyte 4 present in the medium. a It emits in the emission band Δλ. One purpose of device 1 is to detect the presence of analyte 4 and, optionally, to estimate its concentration.

[0058] Analyte 4 can be a molecule present in bodily fluids. It can, for example, involve glucose or bodily analytes such as cholesterol, triglycerides, urea, albumin, alcohol (e.g., ethanol), or tetrahydrocannabinol.

[0059] The emission band is preferably located in the visible or infrared light, for example, at wavelengths from 3 μm to 15 μm. Preferably, the emission band Δλ is narrow enough that device 1 is dedicated to a single analyte. When the analyte is glucose, the emission band is concentrated at the absorption wavelength of glucose, which corresponds, for example, to 1034 cm⁻¹. -1 The wavenumber. The light source 10 can be a pulsed laser source, such as a wavelength-tunable quantum cascade laser (QCL). The emission band Δλ is located in the infrared.

[0060] According to other embodiments, the light source can be a filament-based source or a light-emitting diode (LED). According to these embodiments, it is preferable to associate the light source with a bandpass filter to define a sufficiently narrow emission band focused on the absorption wavelength in question. However, a laser source is preferred.

[0061] exist Figure 1A In the embodiment shown, device 1 includes an optical component 15 configured to direct a light beam 11 emitted by a light source toward the medium 2 to be analyzed.

[0062] Apparatus 1 is designed to be applied against the medium 2 to be analyzed. It includes a shroud 21 arranged to contact the medium and define the boundary of a cavity 20. The cavity 20 opens into the medium 2 through a contact hole 22 formed in a contact surface 3. A light beam 11, after being reflected by an optical element 15, passes through the cavity 20 and through the contact hole 22 to propagate to the medium 2. The apparatus includes a transparent window 17 configured to allow the incident light beam 11 to pass through.

[0063] exist Figure 1AIn the illustrated device, the optical component 15 is a reflector in the form of a reflecting prism. Preferably, the incident beam 11 is incident perpendicularly or substantially perpendicularly to the medium 2. "Substantially perpendicularly" means perpendicular within an angular tolerance of ±30°.

[0064] In the presence of analyte 4 in medium 2, an acoustic wave called photoacoustic wave 12 is formed. Photoacoustic wave 12 is an acoustic wave formed by the periodic heating of the medium by a pulsed or amplitude-modulated incident light beam 11. A portion of photoacoustic wave 12 extends through cavity 20 to be detected by acoustic transducer 28. Acoustic transducer 28 is connected to cavity 20 via sound channel 25. The acoustic transducer may be a microphone having a detection spectrum range that includes the frequencies of the photoacoustic wave. The photoacoustic wave is amplitude-modulated at the pulse frequency or amplitude modulation frequency of the light source. Thus, at the transducer, the pressure is amplitude-modulated.

[0065] Enclosure 21 includes:

[0066] - Lateral member 211, which preferably extends parallel to the axis Z perpendicular to the contact surface 3. Lateral member 211 forms a sidewall defining the cavity boundary.

[0067] - A transverse member 212 extends parallel to or substantially parallel to the contact surface 3, facing the contact surface. The transverse member 212 extends parallel to or substantially parallel to the contact hole 22. Figure 1A In the illustrated embodiment, the transverse member 212 includes a window 17. The transverse member 212 forms a transverse wall defining the cavity boundary.

[0068] "Approximately parallel" means parallel within an angular tolerance of ±30° or ±20°.

[0069] Side 211 extends between contact surface 3 and transverse surface 212.

[0070] The device includes a protective cover 30 surrounding the aforementioned components. A light source is arranged on a support member 13 connected to the cover 30.

[0071] As mentioned in the publication Kottmann "Mid-infrared photoacoustic detection of glucose in human skin: towards non-invasive diagnostics", Sensors 2016, 16, 1663, the following relationship can be established between the modulation amplitude A of the photoacoustic wave at the modulation frequency f and the volume V of the cavity 20:

[0072]

[0073] in:

[0074] -∝ is the proportional operator;

[0075] -I 11 (λ) is the intensity of the incident beam at wavelength λ;

[0076] -α(λ) is the absorption coefficient of the analyzed medium at wavelength λ;

[0077] -V is the volume of the cavity, which may include the vocal tract;

[0078] -f is the modulation frequency of the sound wave.

[0079] When the frequency f and intensity I of the light beam are set 11 When the amplitude of the photoacoustic wave detected by the acoustic transducer is α(λ), the modulation amplitude A is proportional to the absorption coefficient α(λ) of the medium. However, the absorption coefficient is considered to be proportional to the concentration of the analyte in the medium. Thus, by measuring the modulation amplitude A with the acoustic transducer 28, the concentration of analyte 4 in the medium can be estimated by taking into account the absorption coefficient α(λ) of the medium.

[0080] The device includes a membrane 23 located within a cavity 20 between the contact surface 3 and the transducer 28. For example... Figure 1B As shown, membrane 23 divides the cavity into:

[0081] -The lower cavity 20 extending between the contact surface 3 and the membrane 23 i ;as well as

[0082] - Upper cavity 20 extending between membrane 23 and transducer 28 s .

[0083] Therefore, membrane formation occurs within cavity 20. i With the upper cavity 20 s The protective barrier between them. This makes the upper cavity 20 s and enter the lower cavity 20 through the contact hole 22 i Water droplets, dust, or other unwanted elements that may appear in the lower cavity can be isolated.

[0084] The membrane 23 is located within the cavity 20 and is positioned at a non-zero distance d from the contact hole 22. Specifically, during the implementation of the device, it is preferable that the membrane 23 does not come into contact with the skin 2 to avoid interfering with the heating of the gas surface layer in contact with the skin 2. The membrane is positioned at a certain distance such that an air layer is maintained between the contact hole 22 and the membrane. The distance between the membrane and the contact hole is preferably greater than 200 μm or 500 μm.

[0085] The membrane preferably extends exactly through the cavity when facing the contact surface 3. The membrane extends between opposite points on the side. The membrane is preferably arranged parallel to, or substantially parallel to, the contact surface.

[0086] The membrane 23 is held within the cavity 20 by a retainer 24. In this example, the membrane is inserted into the retainer 24. The membrane 23 may be removable, allowing for replacement and / or cleaning of the membrane.

[0087] When the light source 10 is activated, the light beam 11 passes through the membrane 23 before reaching the contact hole 22. The membrane includes intersecting segments 23 corresponding to the portion of the membrane through which the light beam 11 passes. int .

[0088] At least in the intersecting segment 23 int In this process, the film is formed of a material with high transmittance in the spectral band Δλ of the emitted light beam 11. "High transmittance" means that the material has a transmittance preferably higher than 0.4, or even more preferably higher than 0.8, for example, about 0.9 or higher. The material may be, for example, silicon. "Transmittance" refers to the proportion of light intensity transmitted through the film 23. The film may be partially or completely formed of Si or other materials transparent in the infrared, such as porous Si, Ge, AlN, ZnSe, BaF2, CaF2, KRr, ZnS, or sapphire.

[0089] Figure 2 The transmittance (y-axis) of a 300 μm thick Si film is shown according to wavelength (x-axis—unit: μm). Transmittance is particularly affected by the transmittance from the upper surface 23. S The effect of reflection. This can be seen, especially on the upper surface 23. S Preferably, the upper surface 23 S and lower surface 23 i An anti-reflective coating is applied to enhance transmittance to achieve a value close to 1. The anti-reflective coating can take the form of a "quarter-wave" sheet deposited in the form of a thin layer. This thin layer can be deposited on the entire or a portion of the upper surface (and preferably on the entire or a portion of the lower surface) without posing a risk of blocking the vias due to the small thickness of the thin layer.

[0090] The membrane can also be composite, at the intersection segment 23 int This includes materials considered sufficiently transparent in the infrared and other materials outside the intersecting segments. See below for reference. Figure 5B An example describing a composite membrane.

[0091] To enable pressure modulation to be transmitted to transducer 28 through cavity 20, the membrane includes a through-hole 23 extending exactly through the thickness of the membrane. O Through hole in Figure 1C As shown in the diagram. The vias are sized to transmit pressure regulation through the membrane 23 while blocking droplets or dust. These vias 23 enable the lower cavity 20. i With the upper cavity 20 S The air connection between them.

[0092] Figure 3 The lower surface 23 of the film 23 is shown. i Droplets on the membrane. The images show droplets on the lower surface of the membrane and at the through-hole 23, respectively. O wetting angle θ R and θ A Here, we consider that the condensation of water vapor caused by sweating may form microdroplets. Assuming the droplets are tiny, capillary forces dominate relative to gravity. Due to the lower surface 23... i and via through hole 23 O The droplet interacts with capillary forces that counteract the pressure difference, i.e., the pressure difference across the membrane. These capillary forces cause a pressure difference Δp experienced by the droplet, which can be expressed by the following formula:

[0093]

[0094] in:

[0095] -γ: is the surface tension of the liquid / air; when the liquid is water, γ = 0.073 N / m; when the liquid is a biological buffer solution more representative of sweat, γ = 0.03 N / m;

[0096] -r: Enables through-hole 23 O The radius;

[0097] -R: refers to the lower part 23 i The radius of the wetted line on the surface.

[0098] Expression (2) originates from Cho, H.-Y. Kim, JYKang, and TSKim, "How the capillary burst microvalve works", J. Colloid Interface Sci., vol. 306, no. 2, p. 379-385, February 2007. Expression (2) defines the conditions under which a droplet can penetrate a through-hole with a circular cross-section. When Δp > 0, the membrane blocks the droplet.

[0099] The droplet forms a meniscus, which is then joined to the through-hole 23. O The droplet is subjected to capillary forces that tend to propel it into the interior of the capillary formed by the through-hole. The resulting pressure is... The remaining portion of the droplet is retained on the lower surface 23. i It is subjected to capillary forces. The resulting pressure is

[0100] To increase the wetting angle θ R It can be applied to the lower surface 23 of the membrane. iApply a hydrophobic surface treatment. Specifically, when the film-forming material is Si, a hydrophilic material, the wetting angle with water is 5°. When considering droplets in biological buffer solutions, this better approximates the situation encountered when the device is applied to a user's skin, where the wetting angle is approximately 20° to 40°. Applying a hydrophobic surface treatment, such as silanization (grafting hydrophobic silane functional groups), increases the wetting angle with water to 110° and with biological buffer solutions to 80°. The hydrophobic surface treatment thus enhances the ability to retain droplets on the lower surface of the membrane. The hydrophobic treatment can also "overflow" onto the inner surface of the pores.

[0101] Besides the wettability of the liquid, surface tension γ is also a key factor. When the through-hole 23... o When the diameter of the droplet is equal to 20 μm (r = 10 μm) and the liquid is water (γ = 0.073 N / m) or a biological buffer (γ = 0.03 N / m), applying expression (1) yields Δp = 0.14 bar and Δp = 0.06 bar, respectively. Therefore, a pressure higher than Δp must be applied to allow the droplet to pass through the membrane via capillary action. This estimate is made by considering R = 20 μm.

[0102] The radius of the through-hole is preferably from 5 μm to 25 μm, and more preferably from 5 μm to 15 μm. As the radius increases, the transmission of pressure regulation is optimized, but the numerical value Δp decreases: the membrane is less able to prevent liquid from passing through the through-hole. This disadvantage can be mitigated to some extent by adjusting the lower surface 23. i Overcome this by applying a hydrophobic surface treatment.

[0103] The thickness ε of the membrane 23 is preferably from 100 μm to 1 mm, and more preferably from 150 μm to 750 μm.

[0104] The radius of each via also depends on the film thickness ε. The vias can be formed in the Si substrate via photolithography and subsequent wet etching. In this case, it is possible to form vias with a diameter approximately one-tenth of the thickness ε, or even smaller if necessary.

[0105] The membrane is sized to allow pressure modulation to be transmitted between the lower and upper portions of the cavity. The number of vias must be determined such that the membrane's effect on the photoacoustic waves is negligible within the frequency range corresponding to the pulse frequency of the light source.

[0106] The pore factor of the membrane corresponds to the ratio of the cumulative area of ​​each pore to the total area of ​​the lower (or upper) surface. The pore factor can be from 0.01 to 0.3. The inventors have modeled the transmission of amplitude modulation of photoacoustic wave 12 for two pore factors. The model is generated by considering the acoustic impedance of the membrane formation as analogous to electrical impedance. Figure 4AThe diagram shows the modeled cavity 20 (left image) and the diaphragm 23 (right image) positioned at an intermediate height, forming an acoustic impedance equivalent to the resistive reactance Z. (Using...) Figure 4B The RLC circuit shown models the acoustic impedance. The diaphragm corresponds to the lower cavity 20. i With the upper cavity 20 s The circuit between R M L M C M .

[0107] The modeled cavity has a diameter of 4.45 mm. 3 The volume and height h are 1.5 mm. Two different porosity factors were considered:

[0108] - First pore factor, which corresponds to 1000 through holes with a radius of 10 μm: The value of the first pore factor is 0.1;

[0109] - Second pore factor, which corresponds to 100 through holes with a radius of 10 μm: The value of the second pore factor is 0.01.

[0110] The thickness of the modeled membrane is 200 μm.

[0111] Figure 4C This shows the amplitude of the voltage suppression based on the modulation frequency (x-axis – Hz) (y-axis – arbitrary units):

[0112] -In the lower cavity 20 i In the middle (curve a – solid black line) and in the upper cavity 20 s In the middle (curve b – gray solid line), consider the first hole factor;

[0113] -In the lower cavity 20 i In the middle (curve c – black dashed line) and in the upper cavity 20 s In the middle (curve d – gray dashed line), consider the second pore factor.

[0114] Figure 4C The effect of the pore factor on the transmission of pressure modulation from one side of the membrane to the other is shown. It is evident that a smaller second pore factor leads to a decrease in pressure modulation of membrane transmission, especially at high frequencies.

[0115] To prevent the transmission of beam 11 from undergoing diffraction effects, the intersecting section 23 of the film... int It can be without holes, such as Figure 5A As shown. A non-porous segment may include an application to the upper surface 23. s And preferably also applied to the lower surface 23 i The anti-reflective coating. The anti-reflective coating can be a thin layer or a photonic crystal. "A non-porous segment" refers to a segment that does not contain through holes.

[0116] The membrane can be monolithic, meaning it is formed from a single material, ignoring any optional anti-reflective treatments or any optional hydrophobic treatments. Figure 5B A variation is shown where the membrane is a composite membrane. Outside the intersection section, the membrane is composed of a standard first material 231 that is not necessarily transparent in the infrared. Within the intersection section, the membrane includes auxiliary material 23. a The auxiliary material is transparent in the infrared light. The first material 231 can be a material of a standard porous membrane, such as Gore-Tex (registered trademark). Auxiliary material 23 a Unlike the first material 231.

Claims

1. A photoacoustic detection device (1) designed to apply pressure to a medium (2) to be analyzed via a contact surface (3), the device comprising: - A hollow cavity (20) opening onto a contact hole (22), the contact hole being formed in the contact surface; - A pulsed or amplitude-modulated light source (10) configured to emit an incident beam (11) in the emission spectrum (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; This allows the acoustic transducer to detect sound waves generated by heating the medium (2) when the medium is irradiated by the incident light beam. in: - The cavity includes a membrane extending through the cavity and facing the contact surface; -The membrane passes through the lower surface (23) i ) and the upper surface (23 S The membrane defines a boundary and includes a through-hole (23) formed between the lower surface and the upper surface. O ); - The membrane is located inside the cavity, and the membrane is a non-zero distance (d) from the contact surface (3).

2. The device according to claim 1, wherein, Each through hole (23) O The radius of ) is 5μm to 25μm.

3. The device according to 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 surface of the membrane; - The pore factor is 0.05 to 0.

3.

4. The device according to claim 1, wherein, The thickness of the membrane is from 100 μm to 1 mm.

5. The device according to claim 1, wherein: - The membrane is configured such that when the light source is activated, the incident light beam passes through the membrane before reaching the contact hole (22); -The membrane includes intersecting segments (23) corresponding to the portions of the membrane through which the light beam passes. int ); - At least in the intersecting segments, the film is made of a transparent material with a transmittance greater than 0.4 in the emission band.

6. The device according to claim 5, wherein, The membrane is non-porous in the intersecting section.

7. The device according to claim 5, wherein, The transparent material is composed of at least one material selected from the following: Si, Ge, AlN, ZnSe, BaF2, CaF2, KBr, ZnS, and sapphire.

8. The device according to claim 5, wherein, At least in the intersecting segments, the upper surface of the membrane includes an anti-reflective coating.

9. The device according to claim 5, wherein, The membrane: -Outside the intersecting segment, it is made of a first material (231); - In the intersecting segment, the auxiliary material (23) forming the transparent material is used. a Made from ).

10. The device according to claim 1, wherein, The membrane includes a hydrophobic coating on its lower surface.

11. The device according to claim 1, wherein: - The cavity is defined by a transverse wall (212) and a side wall (211), the side wall extending between the transverse wall and the contact surface; - The membrane extends between two opposite faces of the sidewall.

12. The device according to claim 1, wherein, The membrane is removably disposed in the cavity.

13. The device according to claim 1, wherein, The light source is a laser source.

14. The device according to claim 1, wherein, The volume of the cavity is less than 50 μL.

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