Spectroscopic measurement system using diffuse reflectance of a medium to be analyzed

Abstract

A spectroscopic measurement system with diffuse reflectance for a medium (M) to be analyzed, comprising: - a substrate (1); - an electroluminescent device (2), arranged on a first zone (Z1) of a surface (10) of the substrate (1), and configured to emit light; the electroluminescent device (2) having an output surface (S) through which the light is transmitted to the medium (M) to be analyzed; - a first photodetector (D1), arranged on a portion of the output surface (S) of the electroluminescent device (2) so as to receive a portion of the light and such that the output surface (S) retains a free zone (ZL); - a second photodetector (D2), arranged on a second zone (Z2) of the surface (10) of the substrate (1) to receive the light transmitted through the free zone (ZL) and diffusely reflected by the medium (M) to be analyzed. Figure 5

Description

Title of the invention: Spectroscopic measurement system with diffuse reflectance of a medium to be analyzed technical field

[0001] The invention relates to the technical field of diffuse reflectance spectroscopy.

[0002] The invention finds its application in particular in the non-invasive identification of biochemical components (e.g. oxygenation rate, blood glucose, hydration rate, etc.) in a biological tissue such as the skin. State of the art

[0003] A spectroscopic measurement system with diffuse reflectance known from the prior art, in particular from document WO 2023 / 094887 A1, comprises: - a substrate, comprising a surface intended to be oriented towards a medium to be analyzed, the surface having first and second adjacent zones; - a light source, arranged on the first area of ​​the substrate surface, and configured to emit light radiation in a range of wavelengths; - an output coupler, arranged on the second zone of the substrate surface, and having an output surface through which a majority part (e.g. 99%) of the light radiation is transmitted to a medium to be analyzed; - a wavemeter, arranged on the second zone of the substrate surface; - a photodetector, arranged on the second area of ​​the substrate surface to receive the light radiation transmitted by the output surface of the output coupler and reflected diffusely by the medium to be analyzed.

[0004] The light radiation emitted by the light source is fractionated such that: (i) a majority part (e.g. 99%) of the emitted light radiation is guided towards the output coupler in order to transmit the majority part of the light radiation to the medium to be analyzed; (ii) a minority part (e.g. 1%) of the emitted light radiation is guided to the wavemeter in order to deduce the luminous power emitted by the light source.

[0005] Determining the number of photons emitted by the light source towards the medium to be analyzed is essential in order to obtain a spectroscopy with significant diffuse reflectance.

[0006] Such a spectroscopic measurement system with diffuse reflectance, as presented in the prior art, is not entirely satisfactory insofar as the presence of waveguides (to the output coupler and to the wavemeter) complicates the manufacturing of the measurement system and introduces significant optical losses, thus reducing the system's efficiency (increasing energy consumption). Furthermore, the output coupler and the wavemeter occupy a substantial area of ​​the second zone of the substrate surface, introducing a certain lateral bulk that may cause discomfort when the measurement system is worn by a patient. Description of the invention

[0007] The invention aims to remedy, in whole or in part, the aforementioned drawbacks. To this end, the invention relates to a spectroscopic measurement system with diffuse reflectance for a medium to be analyzed, comprising: - a substrate, comprising a surface intended to be oriented towards the medium to be analyzed, the surface having first and second adjacent zones; - an electroluminescent device, arranged on the first area of ​​the substrate surface, and configured to emit light radiation in a range of wavelengths; the electroluminescent device having an output surface through which the light radiation is transmitted to the medium to be analyzed; - a first photodetector, called the reference photodetector, arranged on a part of the output surface of the electroluminescent device so as to receive part of the light radiation and so that the output surface retains a free area; - a second photodetector, called the measurement photodetector, arranged on the second area of ​​the substrate surface to receive the light radiation transmitted by the free area of ​​the output surface of the electroluminescent device and reflected diffusely by the medium to be analyzed.

[0008] Thus, such a system according to the invention eliminates the need for waveguides compared to the prior art. Indeed, on the one hand, there is no output coupler since the light radiation is transmitted directly via the output surface of the electroluminescent device. On the other hand, the reference photodetector (which allows the light power emitted by the electroluminescent device to be deduced) is arranged on a portion of the output surface of the electroluminescent device. Furthermore, this results in a reduced lateral footprint compared to the prior art by stacking the reference photodetector on the electroluminescent device.

[0009] The system according to the invention may include one or more of the following characteristics.

[0010] According to one feature of the invention, the electroluminescent device comprises at least one organic light-emitting diode.

[0011] Thus, an advantage provided by such an electroluminescent device is to obtain a wide emission angle with little loss in luminance between the center and the periphery, so that the output surface is homogeneous.

[0012] According to one feature of the invention, the first photodetector comprises at least one organic photodiode.

[0013] Thus, an advantage provided by such a photodetector is that it can be easily manufactured on the electroluminescent device, particularly when the electroluminescent device is organic.

[0014] According to one feature of the invention, the second photodetector comprises at least one organic photodiode.

[0015] Thus, one advantage provided is the ability to easily manufacture the first and second photodetectors simultaneously when they are organic.

[0016] According to one feature of the invention, the electroluminescent device comprises successively: - a first electrode, arranged on the first area of ​​the substrate surface; - a stack of layers, including an emissive layer configured to emit light radiation in the wavelength range; - a second electrode, transparent across the wavelength range, and having a surface defining the output surface of the electroluminescent device.

[0017] The second electrode must be transparent across the wavelength range in order to transmit the light emitted by the emitting layer. The first electrode is advantageously reflective across the wavelength range in order to reduce optical losses. Thus, a constraint is lifted on the nature of the substrate, which may not be reflective across the wavelength range to reduce optical losses. However, if the first electrode is not reflective across the wavelength range, it is then possible to use a substrate that is reflective across the wavelength range in order to reduce optical losses.

[0018] According to one feature of the invention, the first photodetector comprises successively: - a first electrode, transparent in the wavelength range, and arranged on a part of the output surface of the electroluminescent device; - a stack of layers, including an absorbing layer configured to absorb light radiation in the wavelength range; - a second electrode, reflective in the wavelength range.

[0019] The first electrode is transparent in the wavelength range so that the light radiation emitted by the electroluminescent device can reach the absorbing layer. The second electrode is reflective in the wavelength range so that the residual light radiation, not absorbed by the absorbing layer, does not propagate into the medium to be analyzed.

[0020] According to one feature of the invention, the first electrode of the first photodetector is arranged on a lateral part of the output surface.

[0021] Thus, one advantage provided is to facilitate access for an electrical connection of the first photodetector while optimizing the distribution of light radiation towards the medium to be analyzed.

[0022] According to a feature of the invention: - the output surface has an area, denoted "As"; - the first electrode of the first photodetector occupies an area, denoted "AP", satisfying: Ap — n where "n" is a natural number greater than or equal to 2.

[0023] Thus, one advantage provided is that it facilitates the determination of the number of photons emitted by the electroluminescent device towards the medium to be analyzed in order to obtain meaningful diffuse reflectance spectroscopy. The total number of photons emitted at a given instant by the electroluminescent device corresponds to "n" times the number of photons detected by the first photodetector at that instant. The number of photons emitted at a given instant by the electroluminescent device towards the medium to be analyzed (i.e., transmitted via the free zone of the output surface) corresponds to "n-1" times the number of photons detected by the first photodetector at that instant.

[0024] According to a feature of the invention: - The output surface area is between 6400 pm2 and 14400 pm2, preferably between 8100 pm2 and 12100 pm2; - "n" is equal to 2.

[0025] Thus, one advantage of this geometric configuration is that it eliminates the need for an electronic arithmetic calculation component while maintaining a satisfactory distribution of light radiation between the free zone (and therefore the medium to be analyzed) and the first photodetector. Indeed, the number of photons emitted at a given instant by the electroluminescent device towards the medium to be analyzed (i.e., transmitted via the free zone of the output surface) then corresponds to the number of photons detected by the first photodetector at that given instant.

[0026] According to a feature of the invention, the substrate is made of a material that is reflective in the wavelength range.

[0027] Thus, one advantage provided is to relieve a constraint on the first electrode of the electroluminescent device in order to reduce optical losses. Indeed, when the If the substrate is made of a material that is reflective in the wavelength range, the first electrode of the electroluminescent device may not be reflective in the wavelength range.

[0028] The invention finally relates to a method for manufacturing a spectroscopic measurement system with diffuse reflectance of a medium to be analyzed, comprising the steps: a) using a substrate, comprising a surface intended to be oriented towards the medium to be analyzed, the surface having first and second adjacent zones; b) form an electroluminescent device on the first area of ​​the substrate surface, the electroluminescent device being configured to emit light radiation in a range of wavelengths; the electroluminescent device having an output surface through which the light radiation is transmitted to the medium to be analyzed; c) form a first photodetector, called the reference photodetector, on a part of the output surface of the electroluminescent device so as to receive part of the light radiation and so that the output surface retains a free area; d) form a second photodetector, called the measurement photodetector, on the second area of ​​the substrate surface to receive the light radiation transmitted by the free area of ​​the output surface of the electroluminescent device and reflected diffusely by the medium to be analyzed.

[0029] Thus, as mentioned previously, such a method according to the invention eliminates the need for waveguides compared to the prior art. Indeed, on the one hand, there is no output coupler since the light radiation is transmitted directly via the output surface of the electroluminescent device. On the other hand, the reference photodetector (which allows the light power emitted by the electroluminescent device to be deduced) is arranged on a portion of the output surface of the electroluminescent device. Furthermore, this results in a reduced lateral footprint compared to the prior art by stacking the reference photodetector on the electroluminescent device.

[0030] The method according to the invention may include one or more of the following features.

[0031] According to one feature of the invention, steps c) and d) are concurrent.

[0032] Thus, one advantage obtained is a reduction in the execution time of the process.

[0033] According to one feature of the invention, step b) comprises the following steps: bi) form a first electrode on the first area of ​​the substrate surface; b2) form a stack of layers on the first electrode, the stack comprising an emissive layer configured to emit light radiation in the wavelength range; b3) form a second electrode, transparent in the wavelength range, on the stack of layers, and presenting a surface defining the output surface of the electroluminescent device; a process in which concurrent steps c) and d) include the steps: - to form a first electrode on a part of the output surface of the electroluminescent device as well as on the second area of ​​the substrate surface; - to form a stack of layers, including an absorbing layer configured to absorb light radiation in the wavelength range, on the first electrode of the first photodetector as well as on the first electrode of the second photodetector; - to form a second electrode on the stack of layers of the first photodetector as well as on the stack of layers of the second photodetector.

[0034] According to one feature of the invention, step b) is preceded by the steps: - to form initial contact pads, arranged on the first area of ​​the substrate surface for the resumption of electrical contact of the second electrode of the electroluminescent device; - to form second contact pads, arranged on the first area of ​​the substrate surface for re-establishing electrical contact of the second electrode of the first photodetector; - to form third contact pads, arranged on the second area of ​​the substrate surface for resuming electrical contact of the second electrode of the second photodetector; process in which: - the second electrode of the electroluminescent device formed during step b3) extends over the first area of ​​the substrate surface so as to be electrically connected to the first contact pads; - the second electrode of the first photodetector and the second electrode of the second photodetector formed during the concomitant steps c) and d) extend respectively over the first and second areas of the surface of the substrate, so as to be respectively electrically connected to the second and third contact pads.

[0035] Thus, one advantage provided is to facilitate the resumption of electrical connection while limiting the execution time of the process.

[0036] Definitions

[0037] - By "substrate", we mean a self-supporting physical support, made of a material a base from which an electroluminescent device and a photodetector can be formed. A substrate can be a "slice" (also called a " wafer (in English) which is generally in the form of a disc cut from an ingot of crystalline material.

[0038] - By "wavelength range", we mean an interval of values ​​in which The wavelength of the light emitted by the electroluminescent device is included. The range of values ​​may tend towards a value when the light is monochromatic.

[0039] - By "free zone", we mean an area of ​​the exit surface of the device electroluminescent which is not covered by the first photodetector (i.e. the reference photodetector).

[0040] - By "reflective", it is meant that the element has a reflection coefficient in intensity greater than or equal to 60%, preferably greater than or equal to 80%, more preferably greater than or equal to 90%, averaged over the wavelength range.

[0041] - By "transparent", it is meant that the element has a coefficient of transmission intensity greater than or equal to 60%, preferably greater than or equal to 80%, more preferably greater than or equal to 90%, averaged over the wavelength range. Brief description of the drawings

[0042] Other features and advantages will become apparent in the detailed description of different embodiments of the invention, the description being accompanied by examples and references to the accompanying drawings.

[0043] [Fig-1] is a schematic cross-sectional view illustrating a substrate on which an electroluminescent device and a first electrode of the measurement photodetector are formed.

[0044] [Fig.2] is a schematic cross-sectional view illustrating the formation of a first electrode of the reference photodetector on a part of the output surface of the electroluminescent device.

[0045] [Fig.3] is a schematic cross-sectional view, illustrating the formation of an electrically insulating resin.

[0046] [Fig.4] is a schematic cross-sectional view, illustrating the formation of stacks of layers, each comprising an absorbing layer, to form the reference photodetector and the measurement photodetector.

[0047] [Fig.5] is a schematic cross-sectional view, illustrating the formation of a second electrode of the reference photodetector and the measurement photodetector.

[0048] It should be noted that the drawings described above are schematic and are not necessarily to scale for the sake of readability and to simplify their understanding. The sections are made along the normal to the surface of the substrate intended to be oriented towards the medium to be analyzed. Detailed description of the implementation methods

[0049] Identical elements or elements performing the same function shall bear the same reference numerals for the different embodiments, for the sake of simplification. Measurement system

[0050] An object of the invention is a spectroscopic measurement system with diffuse reflectance of a medium M to be analyzed, comprising: - a substrate 1, comprising a surface 10 intended to be oriented towards the medium M to be analyzed, the surface 10 having first and second adjacent zones Z1, Z2; - an electroluminescent device 2, arranged on the first zone Z1 of the surface 10 of the substrate 1, and configured to emit light radiation in a range of wavelengths; the electroluminescent device 2 having an output surface S through which the light radiation is transmitted towards the medium M to be analyzed; - a first photodetector Dl, called the reference photodetector, arranged on a part of the output surface S of the electroluminescent device 2 so as to receive a part of the light radiation and so that the output surface S retains a free area ZL; - a second photodetector D2, called measurement, arranged on the second zone Z2 of the surface 10 of the substrate 1 to receive the light radiation transmitted by the free zone ZL of the output surface S of the electroluminescent device 2 and reflected diffusely by the medium M to be analyzed.

[0051] Substrate

[0052] The substrate 1 comprises a surface 10, preferably flat, intended to be oriented towards the medium M to be analyzed. In other words, the surface 10 is intended to face the medium M to be analyzed. The surface 10 has first and second adjacent zones Z1, Z2.

[0053] According to a first embodiment, the substrate 1 is made of a material reflective in the wavelength range. When the wavelength range is the visible domain, the substrate 1 can be made of a material chosen from silicon, a metal coated with an electrical insulator, a flexible polymer-type material (e.g., polymethyl methacrylate PMMA) coated with a reflective metallic layer and an electrical insulator.

[0054] According to a second embodiment, the substrate 1 is made of a non-reflective (e.g., transparent) material in the wavelength range. When the wavelength range is the visible domain, the substrate 1 can be made in a material chosen from among glass, a flexible polymer-type material (e.g. polymethyl methacrylate PMMA).

[0055] By way of non-limiting example, the substrate 1 may have a thickness of between 50 pm and 1 mm.

[0056] Electroluminescent device

[0057] The electroluminescent device 2 is arranged on the first zone ZI of the surface 10 of substrate 1. The electroluminescent device 2 is configured to emit light radiation within a range of wavelengths. The wavelength range can be the visible spectrum [380 nm, 850 nm], allowing, in particular, the analysis of skin oxygenation levels and pulse wave measurement. The wavelength range can also be the infrared spectrum, for example [900 nm, 1600 nm], allowing, in particular, the analysis of blood glucose levels and hydration levels.

[0058] The electroluminescent device 2 has an output surface S through which the emitted light radiation is transmitted to the medium M to be analyzed. By way of non-limiting example, the output surface S may have an area, denoted "As", between 6400 pm2 and 14400 pm2, preferably between 8100 pm2 and 12100 pm2.

[0059] The electroluminescent device 2 advantageously comprises at least one organic light-emitting diode. However, it is possible to consider at least one inorganic light-emitting diode as the electroluminescent device 2.

[0060] According to one embodiment, the electroluminescent device 2 comprises successively: - a first electrode 20, arranged on the first area of ​​the substrate surface; - a 21-layer stack, including an emissive layer configured to emit light radiation in the wavelength range; - a second electrode 22, transparent in the wavelength range, and having a surface defining the output surface S of the electroluminescent device 2.

[0061] By way of non-limiting example, the stacking of 21 layers may include: - a filler injection layer, for example made of Dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,l 1-hexacarbonitrile; - a charge transport layer, for example made of 2,2',7,7'-Tetra(N,N-di-p-tolyl)amino-9,9-spirobifluorene; - a charge-blocking layer, for example made of N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine; - an emitting layer, chosen according to the range of wavelengths; - a charge-blocking layer, for example made of N,N'-Bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine; - a charge transport layer, for example made of 4,7-Diphenyl-1,10-phenanthroline; - a layer for injecting charges, for example made of LiF.

[0062] Reference photodetector

[0063] The first photodetector DI is arranged on a portion of the output surface S of the electroluminescent device 2 such that the output surface S retains a free area ZL. The free area ZL of the output surface S transmits a portion of the light emitted by the electroluminescent device 2 to the medium M to be analyzed. The remaining portion of the light emitted by the electroluminescent device 2 is received by the first photodetector D1.

[0064] The first DI photodetector advantageously comprises at least one organic photodiode.

[0065] According to one embodiment, the first photodetector DI comprises successively: - a first electrode D10, transparent in the wavelength range, and arranged on a part of the output surface S of the electroluminescent device 2; - a DI 1 stack of layers, including an absorbing layer configured to absorb light radiation in the wavelength range; - a second electrode D12, reflective in the wavelength range.

[0066] By way of non-limiting example, the DI 1 stacking of layers may comprise: - a charge transport layer, for example made of 2,2',7,7'-Tetra(N,N-di-p-tolyl)amino-9,9-spirobifluorene; - a charge-blocking layer, for example made of N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine; - an absorbing, photosensitive layer, chosen according to the range of wavelengths, for example made in a ZnPc:C60 mixture for the visible range; - a charge-blocking layer, for example made of N,N'-Bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine; - a charge transport layer, for example made of 4,7-Diphenyl-1,10-phenanthroline.

[0067] The first electrode D10 of the first photodetector DI is arranged directly on a part of the output surface S of the electroluminescent device so that the first electrode D10 of the first photodetector DI is in contact with the second electrode 22 of the electroluminescent device 2.

[0068] The first electrode D10 of the first photodetector DI is advantageously arranged on a lateral part of the output surface S of the electroluminescent device 2.

[0069] The first electrode D10 of the first photodetector DI occupies an area, denoted "AP", advantageously satisfying: Ap — n where "n" is a natural number greater than or equal to 2.

[0070] When the area of ​​the outlet surface S (“As”) is between 6400 pm2 and 14400 pm2, preferably between 8100 pm2 and 12100 pm2, then “n” is advantageously equal to 2.

[0071] Measurement photodetector

[0072] The second photodetector D2 is arranged on the second area Z2 of the surface 10 of the substrate 1 to receive the light radiation transmitted by the free area ZL of the output surface S of the electroluminescent device 2, and then reflected diffusely by the medium M to be analyzed.

[0073] The second photodetector D2 advantageously comprises at least one organic photodiode.

[0074] According to one embodiment, the second photodetector D2 comprises successively: - a first electrode D20, reflective in the wavelength range, and arranged on the second zone Z2 of the surface 10 of the substrate 1; - a D21 stack of layers, including an absorbing layer configured to absorb light radiation in the wavelength range; - a second D22 electrode, transparent in the wavelength range.

[0075] More specifically, the absorbing layer of the stack D21 of layers of the second photodetector D2 is configured to absorb the light radiation reflected diffusely by the medium M to be analyzed.

[0076] By way of non-limiting example, the D21 stack of layers may include: - a charge transport layer, for example made of 2,2',7,7'-Tetra(N,N-di-p-tolyl)amino-9,9-spirobifluorene; - a charge-blocking layer, for example made of N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine; - an absorbing, photosensitive layer, chosen according to the range of wavelengths, for example made in a ZnPc:C60 mixture for the visible range; - a charge-blocking layer, for example made of N,N'-Bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine; - a charge transport layer, for example made of 4,7-Diphenyl-1,10-phenanthroline.

[0077] Environment to be analyzed

[0078] By way of non-limiting example, the medium M to be analyzed is a skin-type biological tissue containing chromophores. In particular, melanosomes and blood cells in the skin act as scattering centers for light radiation dispersed throughout the medium M to be analyzed. For example, a person skilled in the art can analyze skin color (complexion) based on diffuse reflectance measurements from optical models using Mie theory.

[0079] Encapsulation and electrical insulation

[0080] Advantageously, the first and second photodetectors D1, D2 are covered with an encapsulation layer designed to protect them against the medium M to be analyzed, air, humidity, etc. The encapsulation layer is transparent across the wavelength range. The encapsulation layer may be multilayered. The encapsulation layer is advantageously impermeable to water, water vapor, oxygen, and external aggressions such as perspiration. By way of non-limiting examples, the encapsulation layer may comprise at least one material selected from SiO₂, TiO₂, Al₂O₃, and parylene.

[0081] The system according to the invention advantageously comprises an electrically insulating resin R arranged to insulate: - the first and second electrodes 20, 22 of the electroluminescent device 2 between each other; - the first and second electrodes D10, D12 of the first photodetector Dl between each other; - the first and second electrodes D20, D22 of the second photodetector D2 between each other. Manufacturing process

[0082] An object of the invention is a method for manufacturing a spectroscopic measurement system with diffuse reflectance of a medium M to be analyzed, comprising the steps: a) using a substrate 1, comprising a surface 10 intended to be oriented towards the medium M to be analyzed, the surface 10 having first and second adjacent zones Z1, Z2; b) form an electroluminescent device 2 on the first area Zl of the surface 10 of the substrate 1, the electroluminescent device 2 being configured to emit light radiation in a range of wavelengths; the electroluminescent device 2 having an output surface S through which the light radiation is transmitted to the medium M to be analyzed; c) form a first photodetector Dl, called the reference photodetector, on a part of the output surface S of the electroluminescent device 2 so as to receive part of the light radiation and so that the output surface S retains a free area ZL; d) form a second photodetector D2, called measurement, on the second zone Z2 of the surface 10 of the substrate 1 to receive the light radiation transmitted by the free zone ZL of the output surface S of the electroluminescent device 2 and reflected diffusely by the medium M to be analyzed.

[0083] Step a)

[0084] Step a) consists of using a substrate 1, comprising a surface 10 intended to be oriented towards the medium M to be analyzed. In other words, the surface 10 is intended to face the medium M to be analyzed. The surface 10 has first and second adjacent zones Z1, Z2. The technical characteristics of the substrate 1 described above apply to step a) of the process according to the invention.

[0085] Step b)

[0086] Step b) consists of forming an electroluminescent device 2 on the first area Zl of the surface 10 of the substrate 1. The electroluminescent device 2 is configured to emit light radiation in a range of wavelengths. The electroluminescent device 2 has an output surface S through which the light radiation is transmitted to the medium M to be analyzed. The technical characteristics of the electroluminescent device 2 described above apply to step b) of the method according to the invention.

[0087] Step b) may include the following steps: bi) form a first electrode 20 on the first zone Zl of the surface 10 of the substrate 1; b2) form a stack 21 of layers on the first electrode 20, the stack 21 comprising an emissive layer configured to emit light radiation in the wavelength range; b3) form a second electrode 22, transparent in the wavelength range, on the stack 21 of layers, and having a surface defining the output surface S of the electroluminescent device 2.

[0088] Step c)

[0089] Step c) consists of forming a first photodetector Dl, called the reference photodetector, on a portion of the output surface S of the electroluminescent device 2 such that the output surface S retains a free area ZL. The free area ZL of the output surface S transmits a portion of the light emitted by the electroluminescent device 2 to the medium M to be analyzed. The other portion of the light emitted by the electroluminescent device 2 is received by the first photodetector DL

[0090] The technical characteristics of the first DI photodetector described above apply to step c) of the process according to the invention.

[0091] Step d)

[0092] Step d) consists of forming a second photodetector D2, called the measurement photodetector, on the second zone Z2 of the surface 10 of the substrate 1. The second photodetector D2 is arranged on the second zone Z2 of the surface 10 of the substrate 1 to receive the light radiation transmitted by the free zone ZL of the output surface S of the electroluminescent device 2, and then reflected diffusely by the medium M to be analyzed.

[0093] The technical characteristics of the second photodetector D2 described above apply to step d) of the process according to the invention.

[0094] Steps c) and d) are advantageously concurrent. Concurrent steps c) and d) advantageously comprise the following steps: - form a first electrode D10, D20 on a part of the output surface S of the electroluminescent device 2 as well as on the second area Z2 of the surface 10 of the substrate 1; - form a DI 1, D21 stack of layers, including an absorbing layer configured to absorb light radiation in the wavelength range, on the first electrode D10 of the first photodetector DI as well as on the first electrode D20 of the second photodetector D2; - form a second electrode D12, D22 on the DI 1 stack of layers of the first photodetector DI as well as on the D21 stack of layers of the second photodetector D2.

[0095] Contact pads

[0096] Step b) is advantageously preceded by the following steps: - to form first contact pads PI, arranged on the first zone ZI of the surface 10 of the substrate 1 for a resumption of electrical contact of the second electrode 22 of the electroluminescent device 2; - form second contact pads P2, arranged on the first zone ZI of the surface 10 of the substrate 1 for a resumption of electrical contact of the second electrode D12 of the first photodetector DI; - form third contact pads P3, arranged on the second zone Z2 of the surface 10 of the substrate 1 for a resumption of electrical contact of the second electrode D22 of the second photodetector D2.

[0097] The second electrode 22 of the electroluminescent device 2 formed during step b3) advantageously extends over the first area ZI of the surface 10 of the substrate 1 so as to be electrically connected to the first contact pads PI.

[0098] Advantageously, the second electrode D12 of the first photodetector DI and the second electrode D22 of the second photodetector D2 formed during the concomitant steps c) and d) extend respectively over the first and second zones Z1, Z2 of the surface 10 of the substrate 1, so as to be respectively electrically connected to the second and third contact pads P2, P3.

[0099] According to an alternative, the second contact pads P2 and the third contact pads P3 can be electrically connected to each other. In this case, the second electrode D12 of the first photodetector DI and the second electrode D22 of the second photodetector D2 can be common.

[0100] The invention is not limited to the embodiments described. A person skilled in the art is able to consider their technically operative combinations, and to substitute equivalents for them.

Claims

Demands

1. A spectroscopic measurement system with diffuse reflectance of a medium (M) to be analyzed, comprising: - a substrate (1), including a surface (10) intended to be oriented towards the medium (M) to be analyzed, the surface (10) having first and second adjacent zones (Z1, Z2); - an electroluminescent device (2), arranged on the first zone (Z1) of the surface (10) of the substrate (1), and configured to emit light radiation in a range of wavelengths; the electroluminescent device (2) having an output surface (S) through which the light radiation is transmitted towards the medium (M) to be analyzed; - a first photodetector (D1), called the reference photodetector, arranged on a part of the output surface (S) of the electroluminescent device (2) so as to receive a part of the light radiation and such that the output surface (S) retains a free zone (ZL);- a second photodetector (D2), called the measurement photodetector, arranged on the second zone (Z2) of the surface (10) of the substrate (1) to receive the light radiation transmitted by the free zone (ZL) of the output surface (S) of the electroluminescent device (2) and reflected diffusely by the medium (M) to be analyzed.;

2. System according to claim 1, wherein the electroluminescent device (2) comprises at least one organic light-emitting diode.

3. System according to claim 1 or 2, wherein the first photodetector (Dl) comprises at least one organic photodiode.

4. System according to any one of claims 1 to 3, wherein the second photodetector (D2) comprises at least one organic photodiode.

5. System according to any one of claims 1 to 4, wherein the electroluminescent device (2) successively comprises: - a first electrode (20), arranged on the first zone (Zl) of the surface (10) of the substrate (1); - a stack (21) of layers, comprising an emissive layer configured to emit light radiation in the wavelength range; - a second electrode (22), transparent in the wavelength range, and having a surface defining the output surface (S) of the electroluminescent device (2).

6. A system according to any one of claims 1 to 5, wherein the first photodetector (Dl) comprises successively: - a first electrode (D10), transparent in the wavelength range, and arranged on a part of the output surface (S) of the electroluminescent device (2); - a stack (Dl 1) of layers, comprising an absorbing layer configured to absorb light radiation in the wavelength range; - a second electrode (D12), reflective in the wavelength range.

7. System according to claim 6, wherein the first electrode (D10) of the first photodetector (Dl) is arranged on a lateral part of the output surface (S).

8. System according to claim 6 or 7, wherein: - the output surface (S) has an area, denoted "As"; - the first electrode (D10) of the first photodetector (Dl) occupies an area, denoted "AP", satisfying: Ap — n where "n" is a natural number greater than or equal to 2.

9. System according to claim 8, wherein: - the area of ​​the outlet surface (S) is between 6400 pm2 and 14400 pm2, preferably between 8100 pm2 and 12100 pm2; - "n" is equal to 2.

10. System according to any one of claims 1 to 9, wherein the substrate (1) is made of a material reflective in the wavelength range.

11. A method for manufacturing a diffuse reflectance spectroscopic measurement system for a medium (M) to be analyzed, comprising the steps: a) using a substrate (1), comprising a surface (10) intended to be oriented towards the medium (M) to be analyzed, the surface (10) having first and second adjacent zones (Z1, Z2); b) forming an electroluminescent device (2) on the first zone (Z1) of the surface (10) of the substrate (1), the device

12.

13. electroluminescent (2) being configured to emit light radiation in a range of wavelengths; the electroluminescent device (2) having an output surface (S) through which the light radiation is transmitted to the medium (M) to be analyzed; c) form a first photodetector (Dl), called the reference photodetector, on a part of the output surface (S) of the electroluminescent device (2) so as to receive a part of the light radiation and so that the output surface (S) retains a free zone (ZL); d) form a second photodetector (D2), called measurement, on the second zone (Z2) of the surface (10) of the substrate (1) to receive the light radiation transmitted by the free zone (ZL) of the output surface (S) of the electroluminescent device (2) and reflected diffusely by the medium (M) to be analyzed. A method according to claim 11, wherein steps c) and d) are concurrent. A method according to claim 12, wherein step b) comprises the steps: bi) form a first electrode (20) on the first zone (Zl) of the surface (10) of the substrate (1); b2) form a stack (21) of layers on the first electrode (20), the stack (21) comprising an emissive layer configured to emit light radiation in the wavelength range; b3) form a second electrode (22), transparent in the wavelength range, on the stack (21) of layers, and having a surface defining the output surface (S) of the electroluminescent device (2); a process in which concurrent steps c) and d) include the steps: - form a first electrode (D10, D20) on a part of the output surface (S) of the electroluminescent device (2) as well as on the second zone (Z2) of the surface (10) of the substrate (1); - form a stack (DU, D21) of layers, including an absorbing layer configured to absorb light radiation in the wavelength range, on the first electrode (D10) of the first photodetector (D1) as well as on the first electrode (D20) of the second photodetector (D2); - form a second electrode (D12, D22) on the stack (DI 1) of layers of the first photodetector (D1) as well as on the stack (D21) of layers of the second photodetector (D2).

14. A method according to claim 13, wherein step b) is preceded by the steps: - forming first contact pads (PI), arranged on the first zone (Zl) of the surface (10) of the substrate (1) for re-establishing electrical contact of the second electrode (22) of the electroluminescent device (2); - forming second contact pads (P2), arranged on the first zone (Zl) of the surface (10) of the substrate (1) for re-establishing electrical contact of the second electrode (D12) of the first photodetector (Dl); - forming third contact pads (P3), arranged on the second zone (Z2) of the surface (10) of the substrate (1) for re-establishing electrical contact of the second electrode (D22) of the second photodetector (D2);a method wherein: - the second electrode (22) of the electroluminescent device (2) formed during step b3) extends over the first zone (Zl) of the surface (10) of the substrate (1) so as to be electrically connected to the first contact pads (PI); - the second electrode (D12) of the first photodetector (Dl) and the second electrode (D22) of the second photodetector (D2) formed during the concomitant steps c) and d) extend respectively over the first and second zones (Zl, Z2) of the surface (10) of the substrate (1), so as to be electrically connected respectively to the second and third contact pads (P2, P3).