DE-102024124894-B4 - Housing for a sensor and sensor

Abstract

A housing (1) for a sensor (2), comprising a housing upper part (3) and a housing lower part (4) which, when assembled, form a receiving space (5) suitable for receiving a circuit board (6) with at least one LED (15a, 15b) emitting light through the housing lower part (4), wherein several passages (10a, 10b, 10c) are formed in the housing lower part (4), each separated from the other by at least one partition (11a, 11b), and wherein a receiving space or receiving tray (9b) for an optical filter (12) is formed in or on the housing lower part (4) adjoins at least one partition (11a, 11b), is characterized in that, with regard to the objective of providing a sensor which receives signals of the light to be detected as reliably and clearly as possible, independent of the angles of incidence of the light reflected from a human or animal body onto the sensor, in or on the housing lower part (4) a structure (7) for guiding light is formed or arranged which is applicable to the optical filter (12).

Inventors

• Ralf Heinrich
• Siegfried Driemer
• Daniel Koch
• Christiane Spilger

Assignees

• EAGLE ACTUATOR COMPONENTS GMBH & CO. KG

Dates

Publication Date

20260513

Application Date

20240830

Claims (7)

1. Housing (1) for a sensor (2), comprising a housing upper part (3) and a housing lower part (4), which in the assembled state form a receiving space (5) suitable for receiving a circuit board (6) with at least one LED (15a, 15b) emitting light through the housing lower part (4), wherein several passages (10a, 10b, 10c) are formed in the housing lower part (4), each separated from the other by at least one partition (11a, 11b), and wherein a receiving space or receiving tray (9b) for an optical filter (12) is formed in or on the housing lower part (4) adjoins at least one partition (11a, 11b), characterized in that a structure (7) for guiding light is formed or arranged in or on the housing lower part (4), which is oriented towards the optical filter (12), wherein the structure (7) is designed as a perforated grid, wherein each hole (21) forms or leads into a light channel, wherein at least one hole (21) has a diameter or width in the range of 0.01 to 0.8 mm, and wherein at least one hole (21) as a light channel has a length in the range of 0.5 to 2 mm.
2. Housing (1) according Claim 1 , characterized in that the structure (7) is designed as a grid of holes, wherein at least two holes (21) are separated from each other by a bridge (20) whose width (20a) is in the range of 0.01 to 1 mm.
3. Housing (1) according to one of the preceding claims, characterized in that the Structure (7) is arranged and formed between two opaque partitions (11a, 11b), each partition (11a, 11b) separating two passages (10a, 10b, 10c) in the lower part of the housing (4).
4. Housing (1) according to one of the preceding claims, characterized in that the housing upper part (3) and/or the housing lower part (4) is/are made of a plastic which is glass-free, in particular contains no glass fibers.
5. Sensor (2) comprising a housing (1) according to one of the preceding claims and a circuit board (6), wherein the circuit board (6) carries two LEDs (15a, 15b) for emitting excitation light and a photodiode (16) for detecting fluorescence light, wherein the LEDs (15a, 15b) each project into a first and a third passage (10a, 10c), wherein the photodiode (16) projects into a second passage (10b) which opens into the structure (7), wherein the passages (10a, 10c) for the LEDs (15a, 15b) are each separated from the second passage (10b) for the photodiode (16) by an opaque partition (11a, 11b) and wherein an optical filter (12) is accommodated in the receiving tray (9b).
6. Sensor (2) after Claim 5 , characterized in that the optical filter (12) has a glass plate (13a) which carries an optical thin-film filter (13b).
7. arrangement comprising a sensor (2) according to Claim 5 or 6 and a light-tight adhesive film (19) which is arranged on the lower part of the housing (4) and has a recess (22) through which both excitation light and reflected light can pass.

Description

The invention relates to a housing for a sensor according to the preamble of claim 1. From the DE 10 2023 104 302 A1 A housing for such a sensor is already known. With such a sensor, the function of human or animal organs can be examined by injecting a marker into them. The marker typically contains a substance that can be stimulated to fluoresce by exposure to excitation light. The decrease in fluorescence over time can be considered an indicator of how well an organ, particularly a kidney, is breaking down or excreting the marker or substance. The sensor can be worn close to the body to detect the fluorescence. The DE 10 2016 115 607 A1 discloses a measuring system with a flow cell device. WO 2022 / 174 277 A1 reveals an optical unit onto which a fluorescent dye is applied. CN 103 411 941 A reveals an imaging technology. DE 20 2010 014 729 U1 It reveals a sensor with a grid that tightens skin. Against this background, the EP 0 966 306 B1 A method for measuring physiological functions is already known. It is proposed to inject a patient with fluorophores or chromophores that fluoresce upon excitation with light and are subsequently excreted by kidney cells. This allows for the examination of kidney function. The EP 2 317 911 B1 Against this background, a sensor patch is revealed which features an excitation light source and a detector. EP 2 895 073 B1 reveals an adhesive functional strip with a sensor head with LED light and a photodiode. To the housing of the sensor as mentioned above DE 10 2023 104 302 A1 Special requirements apply. On the one hand, the housing must direct excitation light from LEDs to the body of humans or animals, and on the other hand, reliably direct the fluorescent light, which is reflected back towards the sensor by the excitation light, to a photodiode. The aim is to minimize the amount of extraneous light, i.e., light superimposed on the fluorescent light, that falls on the photodiode. DE 10 2023 104 302 A1 Against this background, this already reveals an optical filter that rests against a partition wall with as few gaps as possible and allows excitation light from the LEDs to pass through in the direction of emission, but should be largely opaque to excitation light falling back towards the photodiode. Naturally, the optical filter should allow fluorescent light to pass through, which is reflected by a marker in the human or animal body, so that the photodiode can detect it. Glass filters or thin-film filters are known from the prior art that block blue light from LEDs and allow green light, i.e., fluorescent light, to pass through. However, a transmission curve of such a thin-film filter only reflects the optical conditions when light hits the filter perpendicularly. In fact, the transmission behavior of a filter can exhibit an angular dependence with respect to the angle of incidence of the light beam. The frequency band to be filtered by the filter can be influenced by the angle of incidence of the incident light. The frequency band can shift towards shorter wavelengths, so that light with shorter wavelengths can penetrate the filter more easily and is blocked less than desired when the light strikes the filter at a larger angle of incidence. The following approximate formula applies to the shift by a wavelength interval: Δλ≈k⋅sin2α In this formula, Δλ is the wavelength interval around which the displacement occurs, and α is the angle of incidence. During a measurement, blue excitation light reflected from a patient's skin can therefore strike the filter at an angle of incidence other than 90°. As a result, the reflected blue light is blocked less effectively by the filter than it would be at a 90° angle, and thus interferes with the fluorescence light. The photodiode can therefore receive signals even from light it is not intended to detect. The invention is therefore based on the objective of providing a sensor that receives reliable and clear signals of the light to be detected, as independently as possible of the angles of incidence of the light reflected from a human or animal body onto the sensor. The present invention solves the aforementioned problem through the features of claim 1. According to the invention, it was first recognized that only specific types of light may be guided through a structure to a photodiode in order to avoid signal distortion. It was further recognized that an optical filter must be combined with a structure that allows only light rays that have previously struck the optical filter at a small angle of incidence to pass through to the photodiode, while blocking, diverting, or suppressing other light rays. The light rays that strike the optical filter essentially perpendicularly or at a very small angle of incidence are defined and filtered by the optical filter according to the specific application and are then allowed to pass through the structure. In this way, light of a specific frequency range is allowed to pass through, while light of an