Device and method for determining a glucose concentration
Patent Information
- Application Number
- EP2023757595
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-08-19
- Filing Date
- 2023-08-15
- Publication Date
- 2025-06-25
AI Technical Summary
Invasive glucose measurement methods, such as blood sampling, are painful, time-consuming, and costly, and do not address the need for continuous monitoring without repeated self-injury.
A non-invasive glucose measurement device using a VCSEL that emits laser light into the anterior chamber of the eye, where the glucose concentration is determined by evaluating the self-mixing interference caused by chiral glucose in the eye fluid, utilizing a polarization grating and photodiode for accurate detection.
Enables pain-free, cost-effective, and ecologically efficient glucose monitoring without the need for needles or consumables, providing reliable and continuous glucose level tracking.
Smart Images
Figure 1.1
Abstract
Description
[0001] Device and method for determining a glucose concentration
[0002] The invention relates to a device and a method for determining a glucose concentration according to the main claims.
[0003] Glucose monitoring as a therapy-supporting measure had a major impact on diabetes therapy over 30 years ago. A decisive breakthrough was the availability of small, handy blood glucose meters that required only small amounts of blood as a sample and displayed the measurement result in a short time. One consequence was the widespread use of intensive insulin therapy (ICT), with the option of adjusting insulin doses based on food intake or elevated glucose levels.
[0004] However, the biochemical reaction associated with the use of enzymatic glucose conversion was tied to the collection of blood samples (SMBG - self-measurement of blood glucose). Even though modern devices only require drops of blood with a volume of less than 1 μl, and lancing devices and lancets enable painless or even painless blood collection, the repeated necessity of self-harm remains an essential measure.
[0005] This has only changed to a limited extent with the availability of continuous glucose monitoring (CGM) systems. While they allow people with diabetes to obtain continuous glucose data over time for up to 14 days, even this requires at least some self-harm when inserting the glucose sensor into the subcutaneous fat. Furthermore, even with factory-calibrated systems that do not require invasive SMBG for calibration, one is necessary to verify the CGM system's readings or in the case of implausible glucose values.
[0006] Overall, invasive glucose measurement is painful for humans, takes time, and causes high costs for consumables.
[0007] The problem solved by the present invention is to provide a non-invasive glucose measurement.
[0008] For this purpose, it is proposed to provide a device for determining a glucose concentration in the anterior chamber of a user's eye, comprising a VCSEL that emits laser light and an optical element for influencing the laser light. The VCSEL (vertical-cavity surface-emitting laser) and the optical element are configured so that the laser light enters the anterior chamber, an exit light from the anterior chamber penetrates the VCSEL, and the glucose concentration can be determined by an evaluation unit evaluating the resulting self-mixing interference within the VCSEL. The VCSEL preferably has a polarization grating.
[0009] Non-invasive glucose measurement is performed by applying a laser to the user's eye. The fluid in the anterior chamber, which is 98% water, contains three optically active elements (glucose, albumin, ascorbic acid). The laser beam is coupled into this fluid and interacts with it. The lower wavelength limit of > 800 nm is selected to prevent excessive absorption and thus unpleasant heating of the eye. The upper wavelength limit is < 1500 nm.
[0010] Non-invasive glucose measurement takes advantage of the fact that glucose is an enantiomer and is chiral in the anterior chamber of the eye. Laser light propagating through a fluid containing glucose undergoes birefringence. If linearly polarized light is then irradiated, the field vector, which is aligned according to the polarization, undergoes rotation by the chiral glucose by an angular amount that is directly proportional to the glucose concentration in the fluid in the anterior chamber of the eye. By determining the angular amount of rotation, the glucose concentration in the anterior chamber and thus the blood glucose level can be determined.
[0011] The laser light is coupled into the eye chamber and interacts with the chiral fluid. The exit light from the eye chamber is then analyzed for the angular amount of polarization rotation.
[0012] Due to the small size of the anterior chamber, the interaction path is very short, requiring a highly sensitive measurement system. Accordingly, a further development of the VCSEL can be equipped with a photodiode.
[0013] The exit light returned to the VCSEL, whose polarization vector is rotated by the specified angle, is partially coupled back into the resonator and detected there by the photodiode. The detected signal results from the coherent interference of the laser resonator field, which represents a standing wave, and the returned portion of the exit light. The resulting self-mixing interference exhibits a good signal-to-noise ratio, which can be excellently evaluated. This allows a statement about the glucose concentration to be obtained with a low error. The evaluation of the self-mixing interference and the photodiode is carried out by a connected evaluation unit.
[0014] Preferably, a polarization grating can be mounted on an output facet of the VCSEL. The polarization grating polarizes the light exiting the output facet and filters the exit light entering the VCSEL. The power portion of the exit light coupled into the VCSEL's resonator depends on the glucose content or the angular rotation in the ocular fluid, since only a portion of the exit light aligned according to the polarization grating can reenter the VCSEL or the photodiode. The remaining portion is filtered out by the polarization grating.
[0015] Furthermore, self-mixing interference allows light of the same polarization as the light inside the cavity to be detected, since light of a different polarization does not cause interference.
[0016] Furthermore, a VCSEL with an integrated photodiode is particularly space- and weight-saving and, compared to edge emitters, is approximately 5x more temperature-stable with regard to the temperature dependence of the emitted wavelength.
[0017] Non-invasive glucose monitoring eliminates the need for needles, allowing blood glucose levels to be measured without damaging the skin. This avoids the risk of infection or pain caused by contaminated needles.
[0018] Since non-invasive glucose measurement, unlike invasive glucose measurement, does not use needles, it requires no consumables. Therefore, non-invasive glucose measurement provides a method that offers generally increased ecological and economic efficiency.
[0019] The VCSEL has an emission region on its surface from which the laser light emerges from the VCSEL.
[0020] The invention can also be implemented with a VCSEL array comprising a plurality of VCSELs. Further developments and embodiments of the invention are specified in the subclaims.
[0021] Advantageously, the first optical element can have a mirror surface, wherein the mirror surface is arranged in the beam path of the exit light, such that the exit light is reflected by the mirror surface. The laser light and the exit light propagate along the beam path. The beam path specifies the direction of the laser light or the exit light. The first optical element can either reflect the exit light back into the anterior chamber of the eye, where it again strikes the chiral fluid, or at least partially guide it past the anterior chamber of the eye along a beam path defined by the mirror surface. Different beam paths can be realized using the optical element.
[0022] Preferably, the anterior chamber of the eye is positioned between the VCSEL and the first optical element. The laser light from the VCSEL enters the anterior chamber of the eye, and after exiting the eye chamber, the laser light, which is now the exit light from the eye chamber, strikes the mirror surface of the optical element. The anterior chamber of the eye is positioned by positioning the device, for example, in the area of the user's face, between the VCSEL and the first optical element.
[0023] In a special refinement, the laser light from the VCSEL preferably enters the anterior chamber of the eye directly, and the exit light directly hits the mirror surface. The laser light from the VCSEL can be radiated into the anterior chamber of the eye without the influence of an optical element.
[0024] Alternatively or additionally, the light emerging from the VCSEL can be focused into the anterior chamber of the eye. For this purpose, an optical element in the form of a refractive and / or diffractive lens and / or a lens made of photonic metamaterials can be used, which is placed between the VCSEL and the eye chamber. Such an optical element can be applied directly to the emission region, creating a one-piece VCSEL with an optical element. This achieves high intensity in the anterior chamber of the eye and thus correspondingly strong interactions between the light and the chiral fluid.
[0025] Such an optical element designed as a lens can be combined with all embodiments. The lens can be arranged both in the beam path of the laser light and in the beam path of the exit light and can be combined with the other optical elements in such a way that efficient light yield from the VCSEL is ensured. In particular, the beam can be focused and / or collimated by the lens. The beam can be focused into the anterior chamber of the eye and / or onto the emission region.
[0026] It is particularly preferred that the anterior chamber of the eye is arranged between the first optical element and the VCSEL, and that the mirror surface is preferably aligned perpendicular to the beam path of the exit light, so that the exit light is reflected back into the anterior chamber of the eye. The exit light reflected by the first optical element, which preferably re-enters the anterior chamber directly, exits the anterior chamber again after re-entry to be coupled into the VCSEL. This can result in a further rotation of the re-entering exit light by the angular amount, so that the light exiting the second time has an additionally rotated polarization direction.
[0027] It can be provided that the anterior eye chamber is positioned between the first and a second optical element such that the beam path of the laser light runs through the anterior eye chamber. If the device is positioned in the area of the user's face, the eye chamber is arranged between the first and second optical elements such that the laser light from the VCSEL is first reflected by the second optical element towards the anterior eye chamber and then penetrates the anterior eye chamber. The exit light from the eye chamber then strikes the first optical element. The exit light reflected by the first optical element does not re-enter the anterior eye chamber. The exit light is guided past the anterior eye chamber because the first optical element is not aligned perpendicular to the beam path of the exit light.The first optical element forms an angle with the beam path of the exit light coming from the eye chamber that is different from 90° and sufficient to guide the reflected light past the eye chamber. Preferably, the exit light that is guided past is coupled into the VCSEL at least indirectly after further reflection by the second optical element. Preferably, a lens is arranged on the emission region into which the returning light is recoupled into the VCSEL. This lens allows the light to be coupled in more easily and ensures that it fulfills the resonance conditions necessary for interference within the cavity of the VCSEL. For example, a refractive lens, a diffractive lens, and / or a lens made of metamaterials can be used.
[0028] In particular, the beam path of the laser light from the VCSEL can extend directly to the second mirror. The laser light is radiated directly from the VCSEL onto the second optical element, where it is preferably reflected, so that the beam path preferably extends directly into the anterior chamber of the eye.
[0029] In a preferred embodiment, the beam path of the laser light intersects at least once. For example, the beam path of the laser light from the VCSEL can intersect with the beam path of the exit light. This allows for a particularly compact design of the device, since the beam paths of the exit light and the laser light are located in the same spatial volume.
[0030] Furthermore, the beam path of the reflected output light extends from the first to the second optical element. As a result, the output light is reflected at the first optical element and propagates toward the second optical element, where it is reflected again. Preferably, it is then coupled into the VCSEL to trigger self-mixing interference.
[0031] A filter for the exit light can be provided by a third optical element, which creates a phase delay of a quarter wavelength as the laser light passes through. To ensure a particularly efficient filtering effect, the third optical element is positioned between the anterior chamber of the eye and the VCSEL in the beam path of the laser light from the VCSEL and the exit light. The exit light, which is linearly polarized and rotated by the angular amount relative to the laser light from the VCSEL due to the chiral fluid present in the anterior chamber, is circularly polarized by a so-called quarter-wave plate, which can be the third optical element. This allows the exit light to be distinguished from stray light based on the polarization.If the laser light from the VCSEL also passes through the quarter-wave plate and the linear polarization of the laser light is aligned with the optical axis of the quarter-wave plate, the laser light remains linearly polarized. Thus, the laser light from the VCSEL and the exit light from the anterior chamber of the eye have different polarizations and can be distinguished from each other.
[0032] Preferably, a fourth optical element can be provided, which either replaces the third optical element or is added in addition to the third optical element. The fourth optical element can be a liquid crystal module that polarizes the laser light before it enters the anterior chamber of the eye. Preferably, the polarization is rotated by an angular amount by the liquid crystal.
[0033] The liquid crystal module is controlled by a driver device so that it modulates the laser light into at least two different polarization types, for example periodically. For example, in one modulation state, the laser light can have a polarization that coincides with the optical axis of the third optical element, and in another modulation state, the polarization direction of the laser light can be tilted by an angular amount relative to the optical axis of the third optical element, wherein the third optical element is a quarter-wave plate. In particular, the frequency with which the different polarization types are adjusted is higher than the frequency of an average human eye movement, so that the polarization type is changed at least once while the eye is at rest.In crystal optics, the optical axis refers to the direction in an optically anisotropic (birefringent) crystal along which each polarization component of a light beam experiences the same refractive index. It should not be confused with the optical axis of optical systems.
[0034] In a further development of the invention, a reference VCSEL can emit a reference laser light whose polarization is selected such that it reacts less with the chiral fluid in the eye chamber than the laser light of the device's VCSEL described above. Preferably, the reference laser light is fully circularly polarized when coupled into the anterior chamber, since circularly polarized light does not interact with the chiral fluid in the same way as linearly polarized light.
[0035] The reference laser light of the reference VCSEL can be collimated with the laser light of the VCSEL, wherein in particular an optics containing an optical waveguide brings the reference laser light of the reference VCSEL and the laser light of the VCSEL along a common beam path.
[0036] The device comprising the VCSEL and at least one optical element can be incorporated into a pair of glasses intended to be worn by a user with a device that allows a user of the glasses to determine their own blood glucose level. For example, the glasses can be data glasses, virtual reality glasses, augmented reality glasses, or conventional prescription glasses. The device can be incorporated into the glasses frame. Furthermore, a battery for powering the device can be attached to the glasses.
[0037] According to the method, to determine a glucose concentration in the anterior chamber of a user's eye, the device emits laser light from the VCSEL, whereby the laser light enters the anterior chamber of the eye and then exits. The exit light is then received by the VCSEL. Within the VCSEL, the light coupled into the cavity of the VCSEL generates self-mixing interference. An evaluation unit connected to the VCSEL, which preferably has a microcontroller, evaluates the self-mixing interference with respect to a glucose concentration in the anterior chamber, thereby determining the glucose concentration.
[0038] This simple and advantageous method can be used to determine glucose concentrations regularly at specific time intervals. Glucose measurement can be started after a period without a measurement. The time intervals can be of equal length or individually programmed. For example, the time intervals can be selected so that glucose measurements are taken at mealtimes, as this is when there is a high probability that food intake will cause blood glucose levels to rise for technical reasons. Another alternative is to measure blood glucose levels continuously, as long as the device is held against the eye, for example, through glasses. Each method has a different temporal resolution, and the measurement results obtained are recorded in a chronological log of glucose concentrations at different times and stored in the device's memory.The protocol is available in digital form and can be read from the device, for example, via radio or a physical interface such as USB.
[0039] The protocol can be transferred from the device to a computing device such as a smartphone or to a cloud, where it is further processed and made available to a user or a physician, for example.
[0040] The invention is explained in more detail below using exemplary embodiments with reference to the accompanying drawings.
[0041] They show:
[0042] Fig. 1 shows a device for determining a glucose concentration in the anterior chamber of a user's eye with a VCSEL, wherein a first optical element with a mirror surface reflects the laser light from the VCSEL,
[0043] Fig. 2 shows a further device for determining a glucose concentration in the anterior chamber of a user's eye with a VCSEL, wherein a first optical element with a mirror surface reflects the exit light from the eye chamber,
[0044] Fig. 3 shows an alternative device for determining a glucose concentration in the anterior chamber of a user's eye using a VCSEL, wherein a first and a second optical element with respective mirror surfaces reflect the laser light and the exit light,
[0045] Fig. 4 shows another device for determining a glucose concentration in the anterior chamber of a user's eye using a VCSEL, wherein a third optical element with a quarter-wave plate influences the laser light from the VCSEL, utilizing the reflection of the light in the anterior chamber,
[0046] Fig. 5 shows another device for determining a glucose concentration in the anterior chamber of a user's eye with a VCSEL, wherein a fourth optical element with a liquid crystal module influences the laser light from the VCSEL,
[0047] Fig. 6 shows a further device for determining a glucose concentration in the anterior chamber of a user's eye with a VCSEL, wherein an additional reference VCSEL is provided which emits a reference laser light, and
[0048] Fig. 7 shows a spectacle device with at least one of the devices from one of the preceding Figs. 1 to 6.
[0049] Figures 1 to 6 show different embodiments of a device 10 for determining a glucose concentration in the anterior chamber 12 of a user's eye 14. Each of the devices 10 uses a VCSEL (vertical-cavity surface-emitting laser) 11 that emits laser light 16, which is coupled into the anterior chamber 12.
[0050] The VCSEL 11 has an emission region on its surface from which the laser light 16 exits the VCSEL 11.
[0051] Preferably, the wavelength of the laser light 16 is not shorter than the cutoff wavelength > 800 nm and not higher than the upper cutoff wavelength < 1500 nm, so that reflection of the laser light 16 in the anterior chamber 12 of the eye is possible.
[0052] The devices 10 enable non-invasive glucose measurement via measurement using laser light 16 on the user's eye 14. There, the fluid of the anterior chamber 12, which consists of 98% water and contains glucose, albumin, and ascorbic acid, is irradiated by the laser light 16. The laser light 16 interacts with the glucose in the fluid in the anterior chamber 12, since glucose is present chirally in the fluid in the anterior chamber 12. The field vector of the incident, linearly polarized laser light 16 is rotated by a certain angular amount when it interacts with the chiral fluid. The laser light then exits the anterior chamber 12 as exit light 20. The angular amount of rotation of the polarization of the exit light 20 relative to the polarization of the laser light 16 entering the anterior chamber is proportional to the concentration of glucose in the fluid in the anterior chamber.
[0053] The exit light 20 from the anterior chamber 12 of the eye enters the VCSEL 11. In the cavity of the VCSEL 11, the exit light 20 interacts with the standing wave between the Bragg mirrors of the resonator of the VCSEL 11. This creates what is known as self-mixing interference between the exit light 20 and the standing wave. The self-mixing interference can be evaluated by an evaluation unit 13. By evaluating the angular amount of rotation by the evaluation unit 13 of the device 10, the glucose concentration in the anterior chamber of the eye and thus the blood sugar content can be determined. The VCSEL 11 preferably has a polarization grating mounted on the emission region from which the laser light 16 exits and from which the exit light 20 re-enters the VCSEL 11.The polarization grating of the VCSEL 11 determines the intensity of the self-mixing interference according to the polarization of the exit light 20 entering the VCSEL 11. Based on this intensity, the angular polarization of the exit light 20 can be determined.
[0054] To support the detection of the coupled exit light 20 in the VCSEL 11, a photodiode is preferably integrated into the VCSEL 11. The evaluation unit 13 is connected to the VCSEL 11 and the photodiode.
[0055] Fig. 1 shows a device 10 with a VCSEL 11, whose laser light 16 runs along a first beam path 221 from the VCSEL 11 to a first optical element 241. The first optical element 241 has a mirror surface 26, by which the exit light 20 or the laser light 16 is influenced in such a way that it is reflected. The reflected laser light 16 runs along a second beam path 222 from the first optical element 241 to the anterior chamber 12 and enters the anterior chamber 12. In the anterior chamber 12, the laser light 16 interacts with the chiral fluid and at least a portion of the laser light 16 is reflected by the eye lens and exits the anterior chamber 12 again as exit light 20. Between the first and the second beam path, the light is preferably reflected once and changes its direction of propagation.
[0056] After exiting the anterior chamber 12, the exit light 20 is coupled back into the VCSEL 11 along a third beam path 223, which runs from the anterior chamber 12 to the VCSEL 11.
[0057] Alternatively, the laser light 16 can first be coupled into the anterior eye chamber 12 before it exits the eye chamber 12 as exit light 20 after reflection in the eye chamber 12 or at the iris of the eye 14 and is reflected at an optical element to then re-enter the VCSEL.
[0058] In principle, the anterior eye chamber 12 is arranged between the first optical element 241 and the VCSEL 11, although this may also be the case in the following embodiments.
[0059] In Fig. 2, the first optical element 24, i.e. the mirror that the light first hits, is arranged in the first beam path 221 after the anterior chamber 12. The mirror surface 26 is aligned perpendicular to the first beam path 221, so that the exit light 20 is reflected back into the anterior chamber along a second beam path 222, which runs essentially parallel to the first beam path 221. This allows the polarization vector of the light to be rotated even further by an angular amount. After exiting the anterior chamber 12 again, the exit light 20 re-enters the VCSEL 11, wherein the exit light 20 propagates along the second beam path 222 and in the opposite direction to the laser light 16. Alternatively or additionally, the light 16 exiting the VCSEL 11 can be focused into the anterior chamber by means of an optical element.For this purpose, an optical element in the form of a refractive and / or diffractive lens and / or a lens made of photonic metamaterials can be used, which is arranged between the VCSEL 16 and the eye chamber 12. Such an optical element can be attached directly to the emission region of the VCSEL 11, thus providing a one-piece VCSEL 11 with an attached optical element. This achieves a high intensity in the anterior eye chamber 12 and thus correspondingly strong interactions of the light 16 with the chiral fluid.
[0060] Such an optical element embodied as a lens can be combined with all embodiments. The lens can be arranged both in the beam path 221, 222, 223, 224 of the laser light 16 and in the beam path 221, 222, 223, 224 of the exit light 20 and can be combined with the remaining optical elements 241, 242, 243, 244 in such a way as to ensure efficient light yield from the VCSEL 11. In particular, the beam can be focused and / or collimated by the lens. The beam can be focused into the anterior chamber 12 of the eye and / or onto the emission region.
[0061] The laser light 16 from the VCSEL 11 enters directly into the anterior chamber 12, and the exit light from the anterior chamber 12 directly strikes the mirror surface 26 of the first optical element 24, from where it is reflected and subsequently recoupled into the anterior chamber 12. It then enters the VCSEL 11 directly from the anterior chamber 12 to trigger self-mixing interference.
[0062] The laser light 16 is preferably not reflected in the anterior chamber 12, but exits the anterior chamber 12 on an opposite side relative to the location of the laser light 16 entering the anterior chamber 12. The beam paths 221, 222 of the laser light 16 and the exit light 20 are collimated, running along a straight axis to which the first optical element 241 is perpendicular. The emission region on the VCSEL 11, the entry point of the laser light 16 into the anterior chamber 12, and the exit point of the exit light 20 from the anterior chamber 12 lie on a common axis.
[0063] In order for the laser light 16 or the exit light 20 to run along a collinear first and second beam path 221, 222, the anterior eye chamber 12 is arranged between the first optical element 241 and the VCSEL 11.
[0064] In Fig. 3, an embodiment of the device 10 is shown in which the anterior eye chamber 12 is positioned between the first and a second optical element 241, 242.
[0065] The laser light 16 from the VCSEL 11 propagates along a first beam path 221 directly to the second optical element 242 and is reflected by the second optical element 242 at a mirror surface 26, which is aligned such that the second beam path 222 of the laser light 16 passes through the anterior chamber 12. Accordingly, the laser light 16 reflected by the second optical element 242 is coupled into the anterior chamber 12.
[0066] Preferably, the coupled laser light 16 passes through the anterior chamber 12 without reflection in the chamber 12, so that the exit light 20 exits on an opposite side of the chamber 12. The second beam path 222 passes through the anterior chamber 12 and is reflected by the first optical element 241.
[0067] After reflection by the first optical element 241, the exit light 20 propagates along a third beam path 223 back toward the second optical element 242. The exit light 20 reflected by the first optical element 241 is not coupled into the anterior chamber 12, but rather guided past it. For this purpose, the mirror surface 26 of the first optical element 241 is tilted relative to the second beam path 222, so that the mirror surface 26 is not aligned perpendicular to the second beam path 222.
[0068] The first and third beam paths 221, 223 intersect according to the embodiment of Fig. 3.
[0069] The exit light is reflected by the second optical element 241 and propagates along a fourth optical path 224 to the VCSEL 11. It is then coupled into the VCSEL 11 to trigger the self-mixing interference.
[0070] Fig. 4 shows a further embodiment of the device 10, in which an optical element is provided as a filter for the exit light 20. The filter represents a third optical element 243, which creates a phase delay of a quarter wavelength in the passing light. The third optical element 243 is positioned between the anterior chamber 12 and the VCSEL 11 in a first beam path 221 of the laser light 16 from the VCSEL 11 and a second beam path 222 of the exit light 20.
[0071] The third optical element 243 is a quarter-wave plate. If the laser light 16 from the VCSEL 11 passes through the quarter-wave plate and the linear polarization of the laser light 16 is aligned with the optical axis of the quarter-wave plate, the laser light 16 remains linearly polarized.
[0072] The exit light 20, which is rotated by the angular amount relative to the laser light 16 from the VCSEL 11 by the chiral fluid present in the anterior chamber 12, is also linearly polarized. However, due to the angular amount, the polarization is also tilted relative to the optical axis of the quarter-wave plate. If the exit light 20 now strikes the quarter-wave plate with the polarization tilted by the angular amount, the exit light 20 is circularly polarized. This allows the exit light 20 to be distinguished from scattered light or from the laser light 16 based on the polarization, since the laser light 16 from the VCSEL 11 and the exit light 20 from the anterior chamber 12 have different polarizations.
[0073] Fig. 5 shows a device 10 having a fourth optical element 244 provided for modulating the laser light 16 or the exit light 20. The fourth optical element 244 comprises a liquid crystal module connected to a driver device 30. The liquid crystal module polarizes the laser light 16 before it enters the anterior chamber 12 of the eye.
[0074] The liquid crystal module is controlled by the driver device 30 such that it sets the laser light 16 in at least two different polarization types or polarization directions. For example, two different linear polarization directions can be set. Alternatively, more than two polarization directions can be set.
[0075] The polarization can be adjusted periodically by the driver device 30, for example.
[0076] Furthermore, the third optical element 243 can be arranged in the beam path 221, 222 of the laser light 16 or the exit light 20. For example, the laser light 16 can be tilted once in the direction of the optical axis of the third optical element 243, which is a quarter-wave plate, and once by an angular amount relative to the optical axis of the third optical element 243. The third optical element 243 can distinguish between the two polarization types or directions, since the tilting of the polarization axis relative to the optical axis of the quarter-wave plate can generate circular polarization or a modified linear polarization.
[0077] In particular, the frequency at which the different polarization types are adjusted is higher than the frequency of an average human eye movement, so that the polarization type is changed at least once while the eye is at rest. Thus, the glucose concentration in the anterior chamber 12 of the eye can be measured using the laser light 16 modulated by the fourth optical element 244, wherein the sensitivity of the laser light 16 to the chiral fluid in the anterior chamber 12 of the eye can be adjusted.
[0078] A liquid crystal module can also be used in any of the other embodiments shown in Figs. 1 to 6. The liquid crystal module can be arranged in the beam path of the output light 20 or the laser light 16 in any of the embodiments. Furthermore, multiple liquid crystal modules can also be used.
[0079] Alternatively or additionally, the light can be modulated within the VCSEL 11. For example, a piezoelectric element can be attached to the VCSEL 11, which creates a mechanical stress in the VCSEL 11 that has a corresponding orientation with respect to the crystal orientation of the semiconductor material of the VCSEL 11, so that the laser light 16 leaves the VCSEL 11 with a desired polarization. The piezoelectric element can be controlled periodically, for example, by the driver device.
[0080] Furthermore, alternatively or additionally, a heating element can be provided which, by heating the semiconductor material, generates mechanical stresses in the semiconductor material which, as in the piezo element, affect the polarization of the laser light 16.
[0081] In Fig. 6, a further embodiment is shown in which, in addition to the VCSEL 11, a reference VCSEL 34 is provided which emits a reference laser light 28 which propagates along a reference beam path 311 to the eye 14.
[0082] The polarity of the reference laser light 28 is selected such that it interacts less with the chiral fluid in the anterior chamber 12 than the laser light 16 of the VCSEL 11 of the device 10. Preferably, the reference laser light 28 is completely uniformly circularly polarized when coupled into the anterior chamber 12, since circularly polarized light is not rotated by the interaction with the fluid in the eye.
[0083] In order for the reference laser light 28 to be circularly polarized, it can pass through a reference optical element 245, which is a quarter-wave plate, wherein the reference laser light 28 from the reference VCSEL 34 is tilted by an angle of, for example, 45° relative to the optical axis of the quarter-wave plate. The circularly polarized reference laser light 28 is reflected as a likewise circularly polarized reference exit light 33. The reference exit light 33 is linearly polarized again by the reference optical element 245. In doing so, it can trigger self-mixing interference in the reference VCSEL 34. This allows conclusions to be drawn about the eye movement and / or the glucose concentration in connection with the VCSEL 11.
[0084] Preferably, the reference optical element 245 and the optical element 243 can be integrated in one piece in one component.
[0085] The VCSEL 11 in Fig. 6 is implemented, by way of example, in the device 10 of Fig. 4. The laser light 16 of the VCSEL 11 and the reference laser light 28 preferably propagate on nearly collinear beam paths 221, 311. Likewise, the exit light 20 and the reference exit light 33 can propagate on nearly collinear beam paths 222, 312. For example, a VCSEL array can be used that has at least two emission regions, with at least one emission region being provided for the reference laser light 28 and another emission region for the laser light 16.
[0086] In a further alternative or addition, the reference laser light 28 of the reference VCSEL 34 can propagate collinearly with the laser light 16 of the VCSEL 11 along a beam path by using appropriate optics. The optics can comprise, for example, an optical waveguide. Fig. 7 shows a pair of glasses 36 intended to be worn by a user, which has at least one of the devices 10 of Figs. 1 to 6 in the glasses frame 38. An optical element 241, 242, 243, 244, 245 can be arranged in the glasses frame 38 opposite the VCSEL 11 with respect to a spectacle lens 40.
[0087] For example, the eyeglass device 36 can be data glasses, virtual reality glasses, augmented reality glasses, or conventional vision-aid glasses. Furthermore, a battery for supplying power and controlling the device 10 of the device can be attached to the eyeglass device 36.
[0088] All described embodiments of the device 10 can determine the glucose concentration at regular time intervals. Glucose measurement is started after a time interval in which no measurement is taken. The time intervals can be of equal length or individually programmed. For example, the time intervals can be selected so that glucose measurements are taken at mealtimes, since then there is a high probability that food intake will cause the blood sugar level to rise for technical reasons.
[0089] Furthermore, blood sugar levels can be measured during physical activities such as exercise.
[0090] At the same time, the device's control system can indicate to the user the glucose level in the eye chamber 12 and recommend an insulin dose or glucose intake accordingly. The recommendation can be displayed on the spectacle lens 40, in the eye 14, and / or on a computer such as a smartphone.
[0091] A temporal protocol can be created that displays the time course of the glucose concentration in the eye chamber 12. The protocol is available in digital form and can be read from the device, for example, via radio or a physical interface such as USB.
[0092] The protocol can be transferred from the device to a computing device such as a smartphone or to a cloud, where it is further processed and made available, for example, to a user or a doctor.
[0093] List of reference symbols
[0094] 10 Device
[0095] 11 VCSEL
[0096] 12 eye chambers
[0097] 13 Evaluation unit
[0098] 14 Eye
[0099] 16 Laser light 0 Exit light 21 First beam path 22 Second beam path 23 Third beam path 24 Fourth beam path 41 First optical element
[0100] 242 second optical element
[0101] 243 third optical element
[0102] 244 fourth optical element
[0103] 26 mirror surface
[0104] 28 Reference laser light
[0105] 30 Driver setup
[0106] 311 Reference beam path of the reference laser light
[0107] 312 Reference beam path of the reference exit light
[0108] 33 Reference exit light
[0109] 34 reference VCSELs
[0110] 36 glasses device
[0111] 38 eyeglass frames
[0112] 40 lenses
Claims
Claims Device (10) for determining a glucose concentration in the anterior chamber (12) of an eye (14) of a user, with a VCSEL (11) which emits a laser light (16), and an optical element (241, 242, 243, 244) for influencing the laser light (16) and / or an exit light (20), wherein the VCSEL (11) and the optical element (241, 242, 243, 244) are set up such that the laser light (16) enters the anterior chamber (12), wherein the exit light (20) from the anterior chamber (12) penetrates into the VCSEL (11), and by evaluating the resulting self-mixing interference within the VCSEL (11) by an evaluation unit (13), the glucose concentration can be determined.Device (10) according to claim 1, characterized in that a first optical element (241) has a mirror surface (26), wherein the mirror surface (26) is arranged in the beam path of the exit light (20) or the laser light (16) such that the exit light (20) can be reflected at the mirror surface (26). Device (10) according to claim 1 or 2, characterized in that the anterior eye chamber (12) is positioned along the beam path (221, 222, 223, 224) between the VCSEL (11) and the first optical element (241). Device (10) according to claim 3, characterized in that the laser light (16) from the VCSEL (11) preferably enters the anterior eye chamber (12) directly, and the exit light (20) directly strikes the mirror surface (26).Device (10) according to one of claims 2 to 4, characterized in that the anterior eye chamber (12) is arranged between the first optical element (241) and the VCSEL (11), wherein the mirror surface (26) is preferably aligned perpendicular to the beam path (221, 222, 223, 224) of the exit light (20) so that the exit light (20) can be reflected back into the anterior eye chamber (12). Device (10) according to one of the preceding claims, characterized in that the anterior eye chamber (12) is positioned between the first and a second optical element (242), such that the beam path (221, 222, 223, 224) of the laser light (16) runs through the anterior eye chamber (12). Device (10) according to claim 6, characterized in that the beam path (221, 222, 223, 224) of the laser light (16) from the VCSEL (11) runs directly to the second optical element (242). Device (10) according to claim 6 or 7, characterized in that the beam path (221, 222, 223, 224) of the laser light (16) crosses at least once. Device (10) according to one of claims 6 to 8, characterized in that the beam path (221, 222, 223, 224) of the exit light (20) extends from the first to the second optical element (242).Device (10) according to one of the preceding claims, characterized in that a third optical element (243) is provided, which generates a phase delay of a quarter wavelength when the laser light (16) passes through. Device (10) according to claim 10, characterized in that the third optical element (243) is positioned between the anterior eye chamber (12) and the VCSEL (11) in the beam path of the laser light (16) from the VCSEL (11) and the exit light (20). Device (10) according to one of the preceding claims, characterized in that a fourth optical element (244) is provided, which has a liquid crystal module that influences the polarization direction of the laser light (16) before it enters the anterior eye chamber (12), wherein the liquid module is connected to a driver device (30).Device (10) according to one of the preceding claims, characterized in that in addition to the VCSEL (11) a reference VCSEL (34) is provided, which emits a reference laser light (28) which propagates along a reference beam path (311) to the eye (14). Device (10) according to claim 13, characterized in that the reference laser light (28) and the laser light (16) propagate collinearly with each other. Device (10) according to one of the preceding claims, characterized in that an optical element is provided, which is a refractive and / or diffractive lens and / or a lens made of a photonic metamaterial, which is arranged between the VCSEL (11) and the anterior chamber (12). A spectacle device (36) for wear by a user, comprising a device (10) according to one of the preceding claims, such that a user of the spectacle device (36) can determine their own blood glucose level. A method for determining a glucose concentration in the anterior chamber (12) of an eye (14) of a user, comprising a device (10) according to one of the preceding claims, comprising the steps: - Emitting the laser light (16), - Entry and exit of the laser light (16) into the anterior chamber of the eye (12), - Receiving the laser light (16) with the VCSEL (11), - generating self-mixing interference within the VCSEL (11 ), - Evaluation of self-mixing interference with respect to glucose concentration in the anterior chamber of the eye (12), - Determining the glucose concentration. Method according to claim 17, characterized in that the glucose concentration is determined regularly at specific time intervals, so that a chronological log of the glucose concentrations at different times is created and stored in a memory of the device (10). Method according to claim 18, characterized in that the log is sent wirelessly from the device (10) to a computing device such as a smartphone or a cloud.