Light detection device and biological information acquisition method

Abstract

Provided are a more versatile light detection device that can acquire more biological information without the need for a complicated configuration and can also be worn at an arbitrary location on the human body and a biological information acquisition method that uses the light detection device.　According to the present invention, a light detection device that detects ambient light comprises: an optical filter that is a light-transmitting film into which a pigment has been incorporated and has a light-transmitting band and a light-blocking band within a wavelength range of 400–1000 nm; and a thin-film light sensor that is formed on the surface of the optical filter and detects at least a portion of ambient light in the light-transmitting band of the optical filter.

Description

Optical Detection Device, Method for Obtaining Biological Information

[0001] The present invention relates to an optical detection device and a method for obtaining biological information.

[0002] Conventionally, a device that includes a light source and a light receiver, irradiates light from the light source toward a human body, and obtains biological information from the light reflected by blood or the like is known. For example, in Patent Document 1 below, a light source and a light receiver are provided on a substrate, and the light emitted from the light source and reflected or transmitted through the human body is received by the light receiver, and a biological information acquisition device that obtains the pulse wave of a subject based on the detection signal output from the light receiver is disclosed.

[0003] Japanese Patent Application Laid-Open No. 2019-000723

[0004] In recent years, devices equipped with a function for obtaining biological information, so-called "wearable devices," have attracted attention in ornaments such as wristwatches that are worn daily. Wearable devices can obtain, to some extent, the biological information of a person who is wearing them daily without having to visit a facility equipped with dedicated measuring instruments such as a hospital or a clinic. Therefore, the number of people using wearable devices has been increasing because it is easy to manage health continuously without stress.

[0005] Recently, a wristwatch-type wearable device equipped with a light source and a light receiver at a position facing the wearer's skin when worn has been generally used as a wearable device that can obtain biological information related to blood or blood vessels, which is biological information.

[0006] However, the wearable devices equipped with a light source and a light receiver as described above have the following problems.

[0007] First, biological information related to blood or blood vessels is diverse, including pulse waves and blood oxygen saturation, and the wavelength of light suitable for acquiring each type of biological information differs. This is because the reflection spectrum differs for each substance in the blood related to the information being measured. However, the light source installed in the device has a fixed intensity spectrum of emitted light and cannot be easily changed. In particular, LEDs, which are commonly used as light sources, are known to have a narrow emission spectrum (half-width of about several tens of nm), which severely limits the range of wavelengths that can be used as detection light.

[0008] One possible solution to the above-mentioned problems is to employ a light source that emits light exhibiting a broad intensity spectrum. However, simply employing a light source that emits light exhibiting a broad intensity spectrum will also broaden the intensity spectrum of the light received by the photodetector, leading to a relative decrease in the signal intensity in the desired wavelength band. This is essentially equivalent to increasing noise for the photodetector, which may affect the accuracy of the acquired biological information.

[0009] Furthermore, it is known that not only LEDs, but all light sources in general emit light when power is supplied, but they also generate a considerable amount of heat at the same time as emitting light. Therefore, wearable devices with the above-described configuration face challenges such as the need for heat distribution design to avoid causing discomfort to the wearer when worn.

[0010] Furthermore, the wristwatch-type wearable device is merely one form. The placement of wearable devices is not limited to the wrist; it is conceivable that they may be worn on more flexible parts of the body, such as the fingertips or around the neck. In other words, the ability to acquire more biometric information and to be attached to any part of the human body are considered to be factors that will increase the versatility of wearable devices.

[0011] Therefore, the object of the present invention is to provide a more versatile optical detection device that can acquire more biological information without requiring a complex configuration and can be attached to any position on the human body, and a method for acquiring biological information using the optical detection device.

[0012] The inventors diligently conducted research to solve the above problems. Examples of embodiments of the present invention obtained as a result are shown below.

[0013] [1] A light detection device for detecting ambient light, comprising: an optical filter having a light-transmitting band and a light-blocking band in the wavelength range of 400 nm to 1000 nm, wherein the light-transmitting film contains a dye; and a thin-film light sensor formed on the surface of the optical filter for detecting at least a portion of the ambient light that belongs to the light-transmitting band of the optical filter.

[0014] In this specification, "ambient light" refers to light emitted from sunlight or indoor lighting (such as incandescent bulbs or fluorescent lamps). More specifically, "ambient light" refers to light that illuminates outdoors or spaces where people pass by, rather than light emitted from a light source provided in conjunction with the detection device. In other words, the above-mentioned light detection device does not detect specific light emitted from a corresponding light source, but rather detects the light that is routinely shining around people.

[0015] Furthermore, in this specification, "film" is used to refer to a member having flexibility. In addition, "flexibility" as used herein refers to the characteristic of not showing cracking in the test using a mandrel diameter of Φ10 according to JIS K5600-5-1 (flexural resistance (cylindrical mandrel method)).

[0016] Furthermore, in this specification, the term "thin film" is used for elements that have an overall thickness of 1 mm or less and are formed to be flexible, and there is no distinction between single-layer films and multi-layer films.

[0017] [2] The light detection device according to [1] above, wherein the light-transmitting film is a film mainly composed of a resin that exhibits light transmittance to light with a wavelength in the range of 400 nm to 1000 nm.

[0018] In this specification, "exhibiting light transmission" is used to mean a transmittance of 40% or more.

[0019] Furthermore, in this specification, the term "main component" is used to mean the component with the highest concentration.

[0020] [3] The light detection device according to [2] above, wherein the light-transmitting film is a film mainly composed of a thermoplastic resin.

[0021] [4] The light-detecting device according to any one of [1] to [3] above, wherein the light-transmitting film has a thickness in the range of 1 μm to 20 μm.

[0022] [5] The light-shielding band of the optical filter has a limiting band over a range of 100 nm or more in which the average transmittance is 2% or less, according to any one of [1] to [4] above.

[0023] [6] The photodetector according to any one of [1] to [5] above, wherein the change in transmittance per 1 nm between the light-transmitting band and the light-shielding band is 0.75% / nm or more.

[0024] In this specification, "between the light-transmitting band and the light-shielding band" is used to mean the region in which the transmittance transitions from 10% to 40%.

[0025] [7] A method for acquiring biological information, comprising attaching a light detection device described in any one of [1] to [6] above to the skin of a subject, detecting ambient light that has passed through the subject's body, and acquiring the subject's biological information based on a detection signal output from the light sensor.

[0026] In this specification, the term "attach" is used to encompass any method of fixing to a desired location on the human body, such as placing it so as to cover the skin and fixing it solely by electrostatic force, fixing it to the skin using adhesive or tape, or wrapping it around fingers or wrists and fixing it in place.

[0027] According to the present invention, it is possible to provide a more versatile optical detection device that can acquire more biological information without requiring a complex configuration and can be attached to any position on the human body, as well as a method for acquiring biological information using the optical detection device.

[0028] This is a schematic diagram illustrating one embodiment of a method for acquiring biological information. This is a schematic diagram illustrating one embodiment of a method for acquiring biological information. This is a graph showing the pulse wave waveform when the pressure is 2N in one embodiment. This is a graph showing the pulse wave waveform when the pressure is 0N in one embodiment. This is the transmittance characteristic of the optical filter in one embodiment. This is a graph showing the pulse wave waveform when the pressure is 2N in one embodiment. This is a graph showing the pulse wave waveform when the pressure is 0N in one embodiment. This is the transmittance characteristic of the optical filter in one embodiment. This is a graph showing the pulse wave waveform when the pressure is 0N in one embodiment. This is a diagram showing the waveform obtained by simulating the transmission spectrum of an optical film. This is a graph showing the pulse wave waveform when the pressure is 2N in a comparative example. This is a graph showing the pulse wave waveform when the pressure is 0N in a comparative example. This is the transmittance characteristic of the optical filter in a comparative example.

[0029] Hereinafter, embodiments of the light irradiation device and the biological information acquisition method of the present invention will be described with reference to drawings and other figures as appropriate. However, the light irradiation device and the biological information acquisition method of the present invention can be implemented in many different forms, and are not limited to the embodiments described below. In order to make the explanation clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in this specification and each figure, elements similar to those described above with respect to previously shown figures are denoted by the same reference numerals or similar reference numerals (such as numerals followed by an apostrophe), and detailed explanations may be omitted as appropriate.

[0030] In this specification, "up" refers to a relative position with respect to the surface of the optical filter (for example, the surface forming the light sensor), where "up" is the direction away from the surface of the optical filter. Furthermore, "up" includes both being in contact with an object (i.e., "on") and being located above an object (i.e., "over"). Conversely, "down" refers to a relative position with respect to the surface of the optical filter, where "down" is the direction towards the surface of the optical filter.

[0031] <Translucent Film> A translucent film is a flexible film that exhibits light transmission to light with wavelengths in the range of 400 nm to 1,000 nm. In addition, a translucent film is used in which a light-transmitting band and a light-blocking band are formed within the wavelength range of 400 nm to 1,000 nm by incorporating a dye.

[0032] Any material can be used for the light-transmitting film as long as it satisfies the above characteristics, but from the viewpoint of self-supporting properties, a material mainly composed of thermoplastic resin is preferred, such as cycloolefin polymer, polycarbonate, polyarylate, polyimide, polyester, etc.

[0033] Furthermore, the light-transmitting film may be one that has a light-blocking band in the wavelength range of 400 nm to 1,000 nm without containing any dye. Similarly, in this case, the light-transmitting band and the light-blocking band may be formed in the wavelength range of 400 nm to 1,000 nm by containing a dye.

[0034] Furthermore, the translucent film is preferably in the range of 1 μm to 20 μm in thickness, from the viewpoint of sufficient strength and ease of manufacture, and from the viewpoint of ensuring detection accuracy by the light sensor. As the thickness of the translucent film increases, the noise included in the detection signal of the light sensor increases when the pressure applied by the light detection device to the subject's skin is small when the light detection device is attached. This will be described in detail later in the Examples section.

[0035] <Dye> The dye according to the present invention is not particularly limited as long as it has a maximum absorption wavelength in the range of 400 to 1,000 nm. For example, the dye may be made by selecting only one type from the following group of materials, or by mixing two or more types.

[0036] The pigments may be either organic or inorganic pigments. Preferred examples of organic pigments include those with the color index (C.I.) names C.I. Pigment Red 166, C.I. Pigment Red 177, C.I. Pigment Red 224, C.I. Pigment Red 242, C.I. Pigment Red 254, C.I. Pigment Red 264, C.I. Pigment Green 7, C.I. Pigment Green 36, C.I. Pigment Green 58, C.I. Pigment Blue 15:6, C.I. Pigment Blue 80, C.I. Pigment Yellow 83, C.I. Pigment Yellow 129, C.I. Pigment Yellow 138, C.I. Pigment Yellow 139, C.I. Examples of pigments include Pigment Yellow 150, C.I. Pigment Yellow 180, C.I. Pigment Yellow 185, C.I. Pigment Yellow 211, C.I. Pigment Orange 38, C.I. Pigment Violet 23, carbon nanotubes, and fullerenes. The pigments may also contain pigments that do not have a maximum absorption wavelength in the 400-1,000 nm range. Examples of pigments that do not have a maximum absorption wavelength in the 400-1,000 nm range include carbon black, titanium black, and graphene. Preferred specific examples of inorganic pigments include titanium dioxide, strontium titanate, barium titanate, zinc oxide, magnesium oxide, zirconium oxide, aluminum oxide, barium sulfate, silica, talc, mica, aluminum hydroxide, calcium silicate, aluminum silicate, and zinc sulfide.

[0037] Furthermore, the pigment may also be a dye, and examples include pyrazole azo compounds, anilino azo compounds, triarylmethane compounds, anthraquinone compounds, anthrapyridone compounds, benzylidene compounds, oxonol compounds, pyrazolotriazole azo compounds, pyridone azo compounds, cyanine compounds, phenothiazine compounds, pyrrolopyrazole azomethine compounds, xanthene compounds, phthalocyanine compounds, benzopyran compounds, indigo compounds, pyromethene compounds, triarylmethane compounds, cyanine compounds, azo compounds, etc. Also, as a yellow dye, quinophthalone compounds, etc. may be used. Examples of near-infrared absorbing dyes include pyrrolopyrrole compounds, rylene compounds, oxonol compounds, squarylium compounds, cyanine compounds, crokonium compounds, phthalocyanine compounds, naphthalocyanine compounds, pyrylium compounds, azurenium compounds, indigo compounds, and pyromethene compounds. In addition, squarylium compounds, pyrrole ring-containing compounds, squarylium compounds having an aromatic ring at the α-amide position, compounds having a crokonium skeleton, and dihydrocarbazole-bis-type squarylium compounds can also be used.

[0038] When using pigments as dyes, pigments purified by recrystallization, reprecipitation, solvent washing, sublimation, vacuum heating, or a combination thereof may be used. Furthermore, the pigment may be used after its particle surface has been modified with a resin, if desired. Examples of resins used to modify the pigment particle surface include vehicle resins or various commercially available pigment dispersion resins. Additionally, the pigment may be used after its primary particles have been refined by so-called salt milling.

[0039] When using a pigment as the dye, it can be used together with a dispersant and a dispersing aid. As the dispersant, for example, a suitable dispersant such as a cationic, anionic, or nonionic dispersant can be used, but a polymer dispersant is preferred. Specifically, examples include urethane-based dispersants, polyethyleneimine-based dispersants, polyoxyethylene alkyl ether-based dispersants, polyoxyethylene alkylphenyl ether-based dispersants, polyethylene glycol diester-based dispersants, sorbitan fatty acid ester-based dispersants, polyester-based dispersants, and acrylic-based dispersants.

[0040] <Optical Filters> Optical filters are manufactured to be flexible using a light-transmitting film containing a dye. Whether or not they are flexible is confirmed, as described above, by whether or not cracks are observed in the test using a mandrel diameter of Φ10 according to JIS K5600-5-1 (flexural resistance (cylindrical mandrel method)).

[0041] Furthermore, from the viewpoint of transmitting as much light as possible in the wavelength band to be detected while blocking as much light as possible in the wavelength band to be blocked (wavelength band that becomes noise in the extraction of desired biological information), it is preferable that the optical filter has a limiting band within the blocking band in a range of 100 nm or more where the average transmittance is 2% or less.

[0042] Furthermore, the optical filter preferably transmits as much light as possible in the wavelength range to be detected, while blocking as much light as possible in the wavelength range to be blocked (wavelength range that becomes noise in the extraction of desired biological information). From this viewpoint, the change in transmittance per 1 nm between the light-transmitting band and the light-blocking band is preferably 0.75% / nm or more, and more preferably 0.80% / nm or more.

[0043] Optical filters, constructed from a light-transmitting film containing a dye, can achieve transmittance characteristics that are independent of the angle of incidence of light. Such characteristics are suitable for use when attached to any part of the human body, allowing light in the wavelength range to be detected to pass through and light in the wavelength range to be blocked from ambient light that is expected to be incident from any direction.

[0044] <Optical Sensor> An optical sensor is a sensor formed in a thin film shape on an optical filter, and outputs a detection signal corresponding to the intensity of received light. Specific examples of the optical sensor include a sensor fabricated by laminating a transparent electrode made of a metal oxide film (e.g., ITO), a hole transport layer (e.g., PEDOT:PSS), an organic active layer, an electron transport layer (e.g., ZnO), and a metal electrode (e.g., Ag) in this order. Note that the optical sensor may employ a sensor with a configuration other than the above, but it is formed in a thin film shape with a total thickness of 1 mm or less so as to be flexible in order to be a flexible light detection device formed on an optical filter.

[0045] Each electrode of the optical sensor is connected to a terminal (PC, tablet, smartphone, etc.) to which a detection signal output from the optical sensor (e.g., a current corresponding to the intensity of received light) is input, an arithmetic processing unit (microcomputer, LSI, etc.), a storage unit (semiconductor memory, hard disk, etc.), a communication unit (communication cable, transceiver antenna, etc.), and the like.

[0046] <Light Detection Device> A light detection device is fabricated by forming an optical sensor on the surface of an optical filter. A specific fabrication example is to form polyimide on the optical filter with a thickness of 1 to 2 μm, and then sequentially form the metal oxide film of the above-described optical sensor on the formed polyimide. A sealing film (parylene) is formed on the metal electrode of the optical sensor to fabricate a flexible light detection device. Alternatively, polyimide is formed on a glass substrate with a thickness of 1 to 2 μm, and then sequentially form the metal oxide film of the above-described optical sensor on the formed polyimide. A sealing film (parylene) is formed on the metal electrode of the optical sensor. After forming up to the sealing film, the glass substrate is peeled off and integrated with an optical filter or the like as appropriate to fabricate a flexible light detection device.

[0047] 〈Biological Information Acquisition Method〉 Figures 1A and 1B are diagrams schematically showing an example of an embodiment of a biological information acquisition method. Figures 1A and 1B illustrate a mode in which a light detection device 10 is wrapped around a finger 2 of a subject, and ambient light L1 transmitted through the finger 2 is detected by a light sensor 11. As described above, a recent wearable device is generally recognized as a device equipped with a function for acquiring biological information in a decoration such as a wristwatch that is worn daily, and often has the shape of a decoration such as a wristwatch or a ring. Here, for the sake of convenience of explanation, an embodiment in which it is wrapped around the finger 2 of the subject, which is schematically shown in Figures 1A and 1B, will be described.

[0048] In the biological information acquisition method, first, the light detection device is attached to a position suitable for obtaining the biological information of the subject so that the light receiving part of the light sensor corresponds to the skin.

[0049] Next, a detection signal of the light sensor generated by detecting ambient light transmitted through the human body is acquired, and by analyzing the detection signal, desired biological information is derived.

[0050] As an example of a combination of the biological information to be acquired, the mounting position of the light detection device, and the wavelength range of the light to be used, in the acquisition of a pulse wave, as shown in Figures 1A and 1B, the light detection device 10 is attached to the finger 2 of the subject, and a mode in which light of green light (wavelength 490 nm to 550 nm) among the light included in the ambient light L1 is used can be cited.

[0051] Since the above biological information acquisition method does not require a light source such as an LED as long as ambient light exists, no power is required to light the light source. Therefore, the above biological information acquisition method is more energy-saving than a conventional biological information acquisition method that detects light emitted from a conventional light source and reflected inside the human body.

[0052] Further, since the above biological information acquisition method enables reading of the detection signal without applying a voltage or supplying a current, it is also more energy-saving than a conventional biological information acquisition method in this respect.

[0053] <Flexural Resistance Test> For flexural resistance, a TQC wide-type mandrel bending tester was used to bend the sample with a mandrel diameter of Φ10, and the presence or absence of cracks was visually confirmed.

[0054] <Spectral Transmittance Measurement> The characteristics of the optical filter were calculated from transmittance measurements in each wavelength range using samples prepared under the same conditions as those used for the bending resistance test. Transmittance measurements at each wavelength were performed using a Hitachi High-Technologies Corporation spectrophotometer (U-4100) with unpolarized light incident perpendicularly from the substrate of the diffractive optical element, under room temperature conditions of 25°C.

[0055] <Acquisition of Biological Information> To acquire biological information, samples prepared under the same conditions as those used in the flexural resistance test were used. A photodetector was attached to the index finger of the subject's hand, and the detection signal (current) output from the photodetector was input to an analog front-end. The subject's pulse wave was acquired by analyzing the detection signal using the analog front-end. In order to confirm the effect of the thickness of the translucent film, pulse wave acquisition was performed for each sample with the photodetector attached and pressed against the subject's skin with a pressure of 2N and without pressure (0N), and the waveforms were compared.

[0056] <Dye Materials> The dye materials used in the examples described below were prepared by combining dyes 1 to 10 listed below. Note that the dyes and dye combinations described below are merely examples to illustrate the examples.

[0057] Dye 1 is BONASORB UA-3912 manufactured by Orient Chemical Industries.

[0058] Dye 2 is Disperse Orange 47 manufactured by Arimoto Chemical Industry Co., Ltd.

[0059] Dye 3 is YRC-18 manufactured by Yamada Chemical Industry Co., Ltd.

[0060] Dye 4 is a dye represented by the following structural formula (1).

[0061]

[0062] Dye 5 is a dye represented by the following structural formula (2).

[0063]

[0064] Dye 6 is a dye represented by the following structural formula (3).

[0065]

[0066] Dye 7 is a dye represented by the following structural formula (4).

[0067]

[0068] Dye 8 is a dye represented by the following structural formula (5).

[0069]

[0070] Dye 9 is a dye represented by the following structural formula (6).

[0071]

[0072] Dye 10 is a dye represented by the following structural formula (7).

[0073]

[0074] [Example 1] In Example 1, a material containing 3 parts by mass of dye 1, 3 parts by mass of dye 2, 3 parts by mass of dye 3, and 3 parts by mass of dye 4 in 100 parts by mass of JSR ARTON G7810 was applied to a glass substrate to create a coating film with a final thickness of 10 μm. The coating film was dried to form an optical filter, and then peeled off from the glass substrate to produce the product.

[0075] The optical sensor was fabricated by depositing a polyimide film on an optical filter, and then layering a transparent electrode (ITO), a hole transport layer (PEDOT:PSS), an organic active layer (PMDPP3T:PCBM), an electron transport layer (ZnO), and a metal electrode (Ag) on ​​the polyimide film in that order.

[0076] Each electrode of the optical sensor is connected to the processing unit via wiring patterns formed on an optical filter. The processing unit displays the detection signal (current) input from the optical sensor directly as time-series current waveform data on the display unit.

[0077] Figure 2A is a graph showing the pulse wave waveform when the pressure in Example 1 is 2N, and Figure 2B is a graph showing the pulse wave waveform when the pressure in Example 1 is 0N. As shown in Figures 2A and 2B, the pulse wave waveform can be clearly observed in Example 1. The signal-to-noise ratio (SNR) is 24.1 dB in Figure 2A and 11.1 dB in Figure 2B, and these levels are considered sufficient for everyday health management performed by the general public.

[0078] Figure 2C shows the transmittance characteristics of the optical filter of Example 1. The optical filter of Example 1 had a transmission band of 521–587 nm in its transmission spectrum, and the limiting bands where the average transmittance was 2% or less were 400–520 nm and 595–975 nm. The change in transmittance per nm between the light-transmitting band and the light-blocking band was 3.8% / nm.

[0079] [Example 2] In Example 2, a material containing 10 parts by mass of dye 1, 10 parts by mass of dye 2, 10 parts by mass of dye 3, and 10 parts by mass of dye 4 in 100 parts by mass of JSR ARTON G7810 was coated onto a glass substrate to form an optical filter with a final thickness of 2 μm, and then peeled off from the glass substrate.

[0080] The optical sensor was fabricated by depositing a polyimide film on an optical filter, and then layering a transparent electrode (ITO), a hole transport layer (PEDOT:PSS), an organic active layer (PMDPP3T:PCBM), an electron transport layer (ZnO), and a metal electrode (Ag) on ​​the polyimide film in that order.

[0081] Each electrode of the optical sensor is connected to the processing unit via wiring patterns formed on an optical filter. The processing unit displays the detection signal (current) input from the optical sensor directly as time-series current waveform data on the display unit.

[0082] Figure 3A is a graph showing the pulse wave waveform when the pressure in Example 2 is 2N, and Figure 3B is a graph showing the pulse wave waveform when the pressure in Example 2 is 0N. As shown in Figures 3A and 3B, the pulse wave waveform in Example 2 can be clearly observed. The signal-to-noise ratio (SNR) is 25.7 dB in Figure 3A and 20.5 dB in Figure 3B, and these levels are considered sufficient for everyday health management performed by the general public.

[0083] Figure 3C shows the transmittance characteristics of the optical filter of Example 2. The optical filter of Example 2 had a transmission band of 518–600 nm in its transmission spectrum, and the limiting bands where the average transmittance was 2% or less were 400–515 nm and 610–960 nm. The change in transmittance per nm between the light-transmitting band and the light-blocking band was 4.3% / nm.

[0084] In Example 1 and Example 2, it was confirmed that the ratio of the noise level to the signal level was clearly different when the light detection device was not pressed against the subject's skin. This difference in the ratio of the noise level to the signal level is unlikely to be due to the material of the optical filter, and is presumed to be caused by the thickness of the optical filter (translucent film) affecting the contact state between the light detection device and the subject's skin. This is consistent with the fact that the difference in the ratio of the noise level to the signal level becomes smaller when the light detection device is pressed against the subject's skin. In other words, according to these results, it is presumed that the thinner the optical filter (translucent film), the easier it is for the light detection device to come into contact with the subject's skin without pressure, and the less noise is generated in the light detected by the light sensor.

[0085] [Example 3] In Example 3, a material containing 1 part by mass of dye 1, 1.3 parts by mass of dye 2, 2 parts by mass of dye 4, 1.3 parts by mass of dye 5, 1.3 parts by mass of dye 6, 0.8 parts by mass of dye 7, and 1.5 parts by mass of dye 8 in 100 parts by mass of JSR ARTON G7810 is applied to a glass substrate to form an optical filter with a final thickness of 20 μm, and then peeled off from the glass substrate.

[0086] The optical sensor was fabricated by depositing a polyimide film on a glass substrate and then layering a transparent electrode (ITO), a hole transport layer (PEDOT:PSS), an organic active layer (PMDPP3T:PCBM), an electron transport layer (ZnO), and a metal electrode (Ag) in that order on top of the polyimide film.

[0087] Each electrode of the optical sensor is connected to the processing unit via wiring patterns formed on an optical filter. The processing unit converts the detection signal (current) input from the optical sensor into a voltage signal, and then displays the obtained time-series current waveform data on the display unit.

[0088] Figure 4 is a graph plotting the current signal detected in Example 3 after converting it to voltage. The optical filter in Example 3 had a transmission spectrum with a transmission band of 676–722 nm, and a limiting band where the average transmittance was 2% or less at 400–665 nm and 780–990 nm. The change in transmittance per nm between the light-transmitting band and the light-blocking band was 1.1% / nm.

[0089] [Example 4] In Example 4, a material containing 1.5 parts by mass of dye 1, 2.3 parts by mass of dye 2, 2.3 parts by mass of dye 5, 2.3 parts by mass of dye 6, 0.8 parts by mass of dye 7, 0.8 parts by mass of dye 9, and 0.4 parts by mass of dye 10 in 100 parts by mass of JSR ARTON G7810 is applied to a glass substrate to form an optical filter with a final thickness of 10 μm, and then peeled off from the glass substrate.

[0090] The optical sensor was fabricated by depositing a polyimide film on an optical filter, and then layering a transparent electrode (ITO), a hole transport layer (PEDOT:PSS), an organic active layer (PMDPP3T:PCBM), an electron transport layer (ZnO), and a metal electrode (Ag) in that order on top of the polyimide film.

[0091] Each electrode of the optical sensor is connected to the processing unit via wiring patterns formed on an optical filter. The processing unit converts the detection signal (current) input from the optical sensor into a voltage signal, and then displays the obtained time-series voltage waveform data on the display unit.

[0092] Figure 5 is a graph plotting the current signal detected in Example 4 after converting it to voltage. The optical filter in Example 4 had a transmission spectrum with a transmission band of 770-1000 nm, a limiting band where the average transmittance was 2% or less of 400-770 nm, a change in transmittance per nm between the light-transmitting band and the light-blocking band of 1.7% / nm, and nearly constant transmittance at wavelengths longer than 800 nm.

[0093] Figure 6 is a diagram showing the waveform of the simulated transmission spectrum of an optical film. In Figure 6, the transmission spectrum of Example 3 (dashed line) and the transmission spectrum of Example 4 (dotted line) are shown, and for reference, an example of the spectral sensitivity spectrum of a light sensor is shown with a solid line. As can be seen from Figures 4 and 5, the noise level appears to be lower in Example 4 than in Example 3. This is because, as shown in Figure 6, when designing the optical filter, it is determined whether the transmittance peak is formed at the wavelength that is most to be transmitted, or whether the filter is designed to transmit light at wavelengths longer than the desired wavelength without blocking it.

[0094] [Example 5] In Example 5, a material containing 0.6 parts by mass of dye 1, 1.2 parts by mass of dye 2, 1.2 parts by mass of dye 5, 1.2 parts by mass of dye 6, 0.4 parts by mass of dye 7, 0.4 parts by mass of dye 9, and 0.2 parts by mass of dye 10 in 100 parts by mass of JSR ARTON G7810 is applied to a glass substrate to form an optical filter with a final thickness of 60 μm, and then peeled off from the glass substrate.

[0095] The optical sensor was fabricated by depositing a polyimide film on an optical filter, and then layering a transparent electrode (ITO), a hole transport layer (PEDOT:PSS), an organic active layer (PMDPP3T:PCBM), an electron transport layer (ZnO), and a metal electrode (Ag) on ​​the polyimide film in that order.

[0096] The optical filter of Example 5 had a transmission spectrum with a transmission band of 770-1000 nm, a limiting band where the average transmittance was 2% or less of 400-770 nm, a change in transmittance per nm between the transmission band and the blocking band of 1.7% / nm, and nearly constant transmittance at wavelengths longer than 800 nm.

[0097] [Example 6] Example 6 is a sample fabricated using a thin-film OCA to integrate an optical filter and a photosensor. Specifically, Example 6 was fabricated by forming an optical filter on a glass substrate in the same manner as in Example 1, and then attaching OCA (NCF-D692 manufactured by Lintec Corporation, film thickness 5 μm).

[0098] The optical sensor was fabricated by depositing a polyimide film on a glass substrate, and then layering a transparent electrode (ITO), a hole transport layer (PEDOT:PSS), an organic active layer (PMDPP3T:PCBM), an electron transport layer (ZnO), and a metal electrode (Ag) on ​​the polyimide film in that order. After that, it was peeled off the glass substrate and attached to the OCA to be integrated with the optical filter.

[0099] The optical filter of Example 6 had a transmission spectrum with a transmission band of 521–587 nm, and the limiting bands where the average transmittance was 2% or less were 400–520 nm and 595–975 nm. The change in transmittance per nm between the light-transmitting band and the light-blocking band was 3.8% / nm.

[0100] [Example 7] Example 7 is the same as Example 1, except that Mitsubishi Gas Chemical's Yupizeta PCZ-500 was used instead of JSR's ARTON G7810.

[0101] The optical filter of Example 7 had a transmission band of 521–587 nm in its transmission spectrum, with limiting bands of 400–520 nm and 595–975 nm where the average transmittance was 2% or less, and the change in transmittance per nm between the light-transmitting band and the light-blocking band was 3.8% / nm.

[0102] [Comparative Example 1] In Comparative Example 1, an optical filter was fabricated on a glass substrate using a material containing 100 parts by mass of JSR ARTON G7810, with the following dyes: 0.6 parts by mass of dye 1, 1.2 parts by mass of dye 2, 1.2 parts by mass of dye 5, 1.2 parts by mass of dye 6, 0.4 parts by mass of dye 7, 0.4 parts by mass of dye 9, and 0.2 parts by mass of dye 10, so that the final thickness was 700 μm.

[0103] The optical sensor was fabricated by depositing a polyimide film on an optical filter, and then layering a transparent electrode (ITO), a hole transport layer (PEDOT:PSS), an organic active layer (PMDPP3T:PCBM), an electron transport layer (ZnO), and a metal electrode (Ag) on ​​the polyimide film in that order.

[0104] Each electrode of the optical sensor is connected to the processing unit via wiring patterns formed on an optical filter. The processing unit displays the detection signal (current) input from the optical sensor directly as time-series current waveform data on the display unit.

[0105] Figure 7A is a graph showing the pulse wave waveform of Comparative Example 1 when the pressure is 2N, and Figure 7B is a graph showing the pulse wave waveform of Comparative Example 1 when the pressure is 0N. In Comparative Example 1, as shown in Figure 7A, the pulse wave waveform can be clearly observed when the photodetector is pressed against the subject's skin with a pressure of 2N, but as shown in Figure 7B, the pulse wave waveform cannot be observed when the photodetector is not pressed against the subject's skin. The signal-to-noise ratio (SNR) is 24.8 dB in Figure 7A and -7.97 dB in Figure 7B, confirming that it is difficult to acquire biological information when the photodetector is not pressed against the subject's skin.

[0106] Figure 7C shows the transmittance characteristics of the optical filter of Comparative Example 1. The optical filter of Comparative Example 1 had a transmission band of 770-1000 nm in the transmission spectrum, a limiting band where the average transmittance was 2% or less in the 400-770 nm range, a change in transmittance per nm between the light-transmitting band and the light-blocking band of 1.7% / nm, and nearly constant transmittance at wavelengths longer than 800 nm.

[0107] In Comparative Example 1, cracking was observed in a bending resistance test conducted to confirm whether or not the material was flexible.

[0108] [Comparative Example 2] Comparative Example 2 is a sample using an optical filter (substrate) without a light-shielding band. A material containing 100 parts by mass of JSR ARTON G7810 was applied to a glass substrate to create a coating film with a final thickness of 10 μm. The coating film was dried to form an optical filter, which was then peeled off the glass substrate.

[0109] The optical sensor was fabricated by depositing a polyimide film on the optical filter, and then stacking a transparent electrode (ITO), a hole transport layer (PEDOT:PSS), an organic active layer (PMDPP3T:PCBM), an electron transport layer (ZnO), and a metal electrode (Ag) on ​​the polyimide film in this order.

[0110] Each electrode of the optical sensor is connected to the processing unit via wiring patterns formed on an optical filter. The processing unit displays the detection signal (current) input from the optical sensor directly as time-series current waveform data on the display unit.

[0111] In Comparative Example 2, even when the photodetector applied a pressure of 2N to the subject's skin, the pulse wave waveform could not be confirmed, making it difficult to acquire biological information. This suggests the need for a filter with a light-shielding band.

[0112] The light detection device and biometric information acquisition method of the present invention are thin, do not require a light source, and can be attached to fingers or other parts of the hand that are more bent than the wrist, thus achieving high versatility. They are suitable for use in the manufacture of wearable devices used for health management.

[0113] 1: Light detection device 2: Fingers 10: Optical film 11: Light sensor L1: Ambient light

Claims

1. A light detection device for detecting ambient light, comprising: an optical filter having a light-transmitting band and a light-blocking band in the wavelength range of 400 nm to 1000 nm, wherein the light-transmitting film contains a dye; and a thin-film light sensor formed on the surface of the optical filter for detecting at least a portion of the ambient light that belongs to the light-transmitting band of the optical filter.

2. The light-detecting device according to claim 1, wherein the light-transmitting film is a film mainly composed of a resin that exhibits light transmittance to light with a wavelength in the range of 400 nm to 1000 nm.

3. The light detection device according to claim 2, wherein the light-transmitting film is a film mainly composed of a thermoplastic resin.

4. The light detection device according to claim 1, wherein the light-transmitting film has a thickness in the range of 1 μm to 20 μm.

5. The light-shielding band of the optical filter has a limiting band over a range of 100 nm or more in which the average transmittance is 2% or less.

6. The photodetector according to claim 1, wherein the change in transmittance per 1 nm between the light-transmitting band and the light-shielding band is 0.75% / nm or more.

7. A method for acquiring biological information, comprising attaching a light detection device according to any one of claims 1 to 6 to the skin of a subject, detecting ambient light that has passed through the subject's body, and acquiring the subject's biological information based on a detection signal output from the light sensor.

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