Method of and system for determining parameter of fluid

Abstract

To provide a system for determining a refractive index or concentration of a component in sample fluid.SOLUTION: A system (10) comprises a transparent sensing element (12) with a plurality of pores (122) for receiving fluid. The pores reflect or scatter radiation emitted by a radiation emitter (14) of the system differently depending on the refractive index of the fluid. The radiation is detected by one or more detectors (16). The refractive index of the sample fluid is determined on the basis of the detected scattered and / or reflected radiation when the sample fluid is fed into the pores, the corresponding detected scattered and / or reflected radiation when first calibration fluid and second calibration fluid having predetermined refractive indices and predetermined absorptions at at least two wavelengths are fed into the pores, the predetermined refractive indices and the predetermined absorptions. Alternatively, the concentration of the component in the sample fluid absorbing at a given wavelength is determined when the calibration fluid is fed into the pores.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and a system for determining parameters of a fluid, and more particularly, to a method and a system for determining parameters in a fluid present in a permeable element having several holes and in which the calibration is performed using the refractive index of a calibration fluid.

Background Art

[0002] The related art can be found in US Patent No. 2006 / 285115, US Patent No. 10830695, International Patent No. WO2019 / 197308, and International Patent No. WO2017 / 085162.

Summary of the Invention

Means for Solving the Problems

[0003] In a first aspect, the present invention relates to a method for determining the refractive index of a fluid, the method comprising: a) obtaining a first optical signal from a sensing element having a plurality of holes containing a first fluid having a first predetermined refractive index and a first predetermined absorption at at least a first and a second wavelength; b) obtaining a second optical signal from the sensing element, the holes containing a second fluid having a second predetermined absorption at at least a first and a second wavelength and a second predetermined refractive index, the second predetermined refractive index being different from the first predetermined refractive index; c) obtaining a third optical signal from the sensing element, the holes containing a third fluid; d) determining the refractive index of the third fluid based on the first, second, and third optical signals, the first and second predetermined absorptions, and the first and second refractive indices. and includes.

[0004] According to this aspect of the invention, the desired parameter of the fluid is the refractive index. As will be further explained below, the sensing element with holes is well-suited for determination such that the holes act to reflect or scatter radiation and this scattering or reflection depends on the refractive index of the fluid.

[0005] The fluid can be a liquid, a gas, a suspension, or the like. The fluid can be used to calibrate the detection environment or system and / or can be a sample. The parameter of the fluid can be desired to be determined. The term "sample" can refer to a whole blood sample, in which case the "liquid" is the plasma fraction of whole blood, cerebrospinal fluid, urine, pleural fluid, ascites, wastewater, a pre-prepared fluid for any type of injection, a fluid having components detectable by spectroscopy, or a gas such as air, a carbon dioxide-containing gas, a carbon monoxide-containing gas, etc., which can be a part that can enter the holes well. Of course, a sample that does not include the part filtered out by the hole size can form a liquid.

[0006] The term "whole blood" refers to blood composed of plasma and cell components. Plasma represents about 50% - 60% of the volume, and cell components represent about 40% - 50% of the volume. The cell components are erythrocytes (red blood cells), leucocytes (white blood cells), and thrombocytes (platelets). Preferably, the term "whole blood" refers to the whole blood of a human subject, but can also refer to the whole blood of an animal. Erythrocytes constitute about 90% - 99% of the total number of all blood cells. They are shaped as biconcave discs with a diameter of about 7μm and a thickness of about 2μm in an undeformed state. Erythrocytes are very flexible, which enables them to reduce their diameter to about 1.5μm and pass through very narrow capillaries. Inside one of the erythrocytes The nuclear component is hemoglobin, which binds to oxygen for transport to tissues, then releases the oxygen and binds to carbon dioxide to be delivered to the lungs as a waste product. Hemoglobin is responsible for the red color of red blood cells and thus the red color of blood as a whole. White blood cells make up less than about 1% of the total number of all blood cells. They have a diameter of about 6 to about 20 μm. White blood cells are involved in the body's immune system, for example, against bacterial or viral invasions. Platelets are the smallest blood cells, having a length of about 2 to about 4 μm and a thickness of about 0.9 to about 1.3 μm. They are cell fragments containing enzymes and other substances important for coagulation. In particular, they form a temporary platelet thrombus that helps seal breaks in blood vessels.

[0007] The term "blood plasma (or plasma)" refers to the liquid portion of blood and lymphatic fluid that constitutes about half of the volume of blood (e.g., about 50% - 60% by volume). Plasma has no cells. It contains all the clotting factors, especially fibrinogen, and contains about 90% - 95% water by volume. Plasma components include electrolytes, lipid metabolites, such as markers for infections or tumors, enzymes, substrates, proteins, and additional molecular components.

[0008] The term "wastewater" refers to water that has been used in washing, flushing, or in a manufacturing process, and thus contains waste and / or particles and is therefore not suitable for drinking and food preparation.

[0009] According to the first aspect, the first fluid is present within a plurality of pores of the sensing element, and the first fluid has a first predetermined refractive index and a predetermined first absorption at least at the first and second wavelengths. Often, three or more wavelengths are used in the determination, and sometimes the absorption spectrum of the fluid is known within a certain wavelength interval. The first fluid can be provided into or at the pores by a supply element such as a pump or the like. The first fluid can be supplied to or into the pores using capillary action or a similar automatic process. Alternatively, the first fluid can be automatically provided into the pores, such as during the creation of the pores.

[0010] Typically, an optical signal is obtained by directing radiation at least at the first and second wavelengths towards the pores and detecting the emitted radiation reflected and / or scattered by the pores. The pores can be closed at one end and can have a single opening around the sensing element, such as into a flow channel provided to direct the fluid into the pores. The pores can be separate or interconnected. The pores can be more or less parallel and can extend away from the surface where the opening is provided.

[0011] Pumps, valves, flow channels, fluid containers, and the like can be provided to continuously supply the first and second fluids to the pores. The sensing element can comprise a translucent slab or element and possibly a reflective layer applied to the front side of the translucent slab. The translucent slab includes a plurality of pores, preferably small non-through pores, which can extend into the translucent slab from the front side, and when provided, through the reflective layer. A radiation source and a detector can be arranged to optically probe the contents of the pores and to generate corresponding signal outputs for use in determining the parameters of the fluid.

[0012] Each of the small holes preferably has an opening through which it can communicate with a fluid space, such as on the side of the translucent slab. Thus, the holes, if present, penetrate the reflective layer to enable fluid communication between the holes and the fluid space. The holes can extend into the translucent slab from each respective opening on the front side, such as in a direction towards the back side. When a hole is "non-penetrating", this means that the hole ends within the translucent slab and as a result, the hole does not continue through the entire translucent slab to the back side or to any common container or receptacle inside the slab. At this time, the hole can be in fluid communication only with the fluid space on the front side of the translucent slab. It should be noted that in some embodiments, the non-penetrating holes can be cross-shaped, so at least some of the holes can be connected to each other, forming an X-shape, Y-shape, V-shape, or similar interconnected shapes. Such a configuration is considered non-penetrating because no significant net mass transport occurs through the holes during operation, even if the holes are filled from the front side and the holes intersect each other. By appropriately sizing the openings of the holes on the front side, it is possible to prevent larger components of the fluid, such as red blood cells in a whole blood sample or debris in the fluid, from entering the holes at the front side of the sensing element while allowing relevant components in the plasma fraction of the whole blood sample to enter the holes. The relevant components are substances that are present in the plasma fraction of the whole blood sample and will be measured / detected using the sensor. In particular, proteins, bilirubin, and carbon dioxide are relevant components. The holes can extend from one of their surfaces into the sensing element or slab, and radiation is emitted towards the holes from a direction at a non-zero angle with respect to that surface and / or at a non-perpendicular angle with respect to the average direction of the holes. Similarly, or alternatively, the detector can be configured to receive radiation directed towards the detector along a non-zero angle with respect to its surface and / or at a non-perpendicular angle with respect to the average direction of the holes. In this way, the number of reflections / scatterings can be kept fairly low, allowing more radiation to reach the detector.

[0013]

[0014] ​During operation, in step a), the holes, such as on the front side of the translucent slab, can be brought into contact with a first fluid if no fluid is already present in the holes. While the first fluid is in the holes, it is optically probed, and as a result, a first optical signal is provided or detected. After measurement, the first fluid can be discharged from the holes, such as through the same openings.

[0015] Before or after that step, a second fluid is supplied to the holes and optically probed. The optical probe can include emitting radiation of at least a first and a second wavelength towards the holes, and / or the optical signal can be based thereon. The radiation can be reflected by the holes in different directions, including towards a detector such that a portion of the radiation is detected. The detected radiation can be reflected any number of times. The detected radiation can be reflected / scattered towards the detector by a second hole among a plurality of holes.

[0016] It may be preferred that the radiation is emitted towards a first hole among a plurality of holes and the detected radiation originates from a second hole among a plurality of holes. The first and second holes can be the same hole, or completely different holes, or some of the first holes can also be the second holes.

[0017] It may be preferred that there is a large overlap between the first and second holes, such as more than 50% of the first holes, for example more than 75%, for example more than 90% being also the second holes, and / or more than 50% of the second holes, for example more than 75%, for example more than 90% being also the first holes. It may be preferred that the overlap is smaller, such that 50% or less of the first holes are the second holes and / or 50% or less of the second holes are the first holes.

[0018] The detector can at this time be adapted to generate a signal representing the detected radiation and / or an optical signal. The optical signal can be reflected / scattered radiation towards the detector or radiation such as that detected by the detector. The optical signal can be regarded as the output of the detector based on such radiation. Finally, the optical signal can be the result of the analysis of such output or reflected radiation. The optical signal can represent the intensity change of the radiation due to absorption within the pore and scattering / reflection of the pore.

[0019] Preferably, the radiation is emitted towards the same pore and the detection is configured to receive radiation from the same pore throughout the useful life of the sensing element. Thus, the first and second pores are preferably the same during the method or the useful life of the sensing element as described above. Alternatively or additionally, it may be desired that the relative directions and positions of the radiation emitter (such as a radiation output element), the sensing element, and the detector (such as a radiation receiving element) are at least substantially the same. In this manner, the radiation is emitted towards the same pore from the same angle and the radiation is collected from the same pore and at the same angle. For example, note that changing the angle of incidence of the emitted radiation will change the optical structure seen by the radiation and as a result, the resulting detected radiation can vary for the same incident wavelength, intensity, and the same fluid within the pore.

[0020] The contents of the pore can be conveniently optically probed from the back side of a translucent slab opposite the surface where the opening of the pore is seen. If the sample contains larger components, the optical probe can be selectively performed only on the subsample (liquid) inside the pore.

[0021] The incident radiation can be directed / steered into the aperture to ensure that the radiation traverses the aperture and interacts with the fluid therein. Preferably, the probe radiation is sent into the aperture at an oblique incidence with respect to the longitudinal axis of the aperture and / or the surface normal on the plane of the surface where the aperture opening is seen, to ensure that the light traverses the aperture containing the fluid to be probed, thereby ensuring the maximum optical interaction path length.

[0022] The light exiting the aperture in response to the irradiation has interacted with the fluid within the aperture and thus carries information about the fluid. The exiting radiation, and / or the signal representing the exiting radiation, can then be analyzed for that information, for example, to develop a value representing the analyte content in a third fluid. The radiation can represent intensity changes including absorption caused by the analyte in the fluid, as well as "losses" or "gains" brought about by scattering / reflection of the radiation in the aperture. The analysis can include spectroscopic analysis of the exiting / detected radiation and / or, for example, signal / data processing for comparing the acquired signal with the signal acquired for a calibration / reference fluid such as a first fluid, for noise filtering, for applying corrections, and for removing artifacts.

[0023] In a particularly advantageous embodiment, it is the protein content in plasma, which is a third fluid optically probed, for example, by determining the refractive index of the third fluid. Proteins do not cause significant radiation absorption but are involved in defining the refractive index of plasma.

[0024] The cross-sectional area of the aperture may desirably correspond to a circle with a diameter within 50% of the wavelength of the radiation, for example, within 25% of the wavelength, so that the aperture can act like a particle-like element that scatters. The wavelength of the radiation can be, for example, the minimum wavelength, the maximum wavelength, or the average wavelength used in the determination. Thus, the scattering efficiency of the aperture will depend on the difference in refractive index between the fluid within the aperture and the material of the sensing element forming the aperture. The greater the difference in refractive index, as in the case where the fluid is a gas such as air, the higher the scattering.

[0025] The first and second fluids have different predetermined refractive indices. Therefore, the scattering caused by the pores is different. This is utilized as a calibration for the determination of the refractive index of the third fluid. The radiation loss, i.e., the intensity change, between the radiation emitter and the detector is due to absorption and scattering / reflection. Therefore, when the absorption of the first and second fluids at at least two wavelengths is known, the contribution caused by scattering / reflection due to the refractive index of the fluid can be determined and calibrated.

[0026] The radiation loss can also be a radiation gain if the absorption is smaller than the gain from the RI change. When the absorption of one fluid is known at the first and second wavelengths, when the refractive index of that fluid is known, and when the absorption of another fluid is known at the first and second wavelengths and the refractive index of that fluid is known, the relationship at the first wavelength between the received radiation scattered / reflected and the radiation absorbed can be determined. Also, the same relationship can be determined at the second wavelength. From these relationships, the amount of scattered radiation and / or the amount of absorbed radiation can be determined for the third fluid, thereby making it possible to determine both the absorption from a number of compounds and the refractive index of the third fluid. This may require just as many wavelengths (and data on the compound absorption spectrum as a function of wavelength) as there are compounds being investigated plus one (for RI determination).

[0027] Therefore, each of steps a), b), and c) - preferably includes emitting radiation at each of the first and second wavelengths to a detection element, and - determining the intensity of the radiation at each of the first and second wavelengths from the detection element, and step d) is performed further based on the determined intensities.

[0028] Generally, the wavelength can be the wavelength interval at which the wavelength is provided. In many cases, a single wavelength is not desired or achievable, and the radiation is then emitted and / or received within the desired wavelength interval, such as after being filtered.

[0029] Of course, more wavelengths than the first and second wavelengths can be used. Thus, radiation including a third wavelength can be emitted to the sensor element, and radiation at or within that wavelength can also be detected, and the result of that detection is used in the determination.

[0030] In fact, this calibration can be even more general. In a normal spectrometer or sensing element for determining concentration based on the radiation absorption of components of a sample / fluid or the like, the calibration is based on the absorption of the calibration fluid at different wavelengths. The wavelengths are selected based on the component to be determined. The calibration fluid is desired to absorb at each wavelength. However, on the other hand, it is desired to reduce the number of calibration fluids.

[0031] The present invention makes such calibration easier. From the calibration, intensity changes, such as the total effect of absorption and scattering, can be determined at all relevant wavelengths. The contribution from scattering can be determined from fluids having significant absorption or no significant absorption at these wavelengths. Absorption can be converted into sensitivity, which is the absorption divided by the concentration of the absorbing component and the molar absorption coefficient of the component. Thus, from the determination of the scattering contribution, for example, the intensity change brought about thereby, at two wavelengths, and the determination of absorption at one of the wavelengths, the absorption at other wavelengths can be assumed or determined from the scattering contribution. It can be assumed that the relative difference between the absorption contributions is the same as that observed between the scattering contributions.

[0032] The first fluid can be used to calibrate the method and can be a specific calibration fluid, but can also have other functions, such as a rinse fluid used before contacting the front side with the second or third fluid. The third fluid is, in some embodiments, the actual unknown fluid that is the whole blood sample or fluid to be analyzed. In practice, the first fluid can be a gas, and the second fluid can be a fluid having the above properties. Thereby, the pores can be 'primed' by pre-filling with a liquid that is affinity with the second / third fluid such as whole blood, and in particular, a liquid that is affinity with the plasma phase when the fluid is whole blood, such as an aqueous solution commonly used for rinsing, calibration, and / or quality control purposes in a blood analyzer. For example, a typical rinse solution used for flushing in a whole blood analyzer system can be used as such a liquid. The rinse solution is an aqueous solution containing K+, Na+, Cl−, Ca2+, O2, pH, CO2, and HCO3− at concentrations corresponding to human plasma. Non-limiting examples of suitable solutions commonly used for rinsing, calibration, and / or quality control purposes are further listed below. When the whole blood sample or fluid is contacted with the front surface primed with the plasma-affinity liquid / fluid-affinity fluid, representative sub-samples (fluids) of the components in the plasma phase of the whole blood sample or of the fluid are extracted and transferred in a very efficient and gentle manner by diffusion of the relevant components into the pre-filled pores. In particular, any concentration gradient in the analyte content between the latter and the former fluid in the pores results in a diffusive movement, thereby producing in the pores a sub-sample (fluid) having an analyte concentration representative of the analyte concentration in the fluid.

[0033] As described, the first fluid can desirably be a gas such as ambient air. Air has a low refractive index, which may be desirable in calibration. At this time, the pores, such as the front side of the sensing element, may be dry. In addition, the inner surface of the pores can desirably be hydrophilic, thereby enabling the next fluid to be extracted into the pores by capillary forces when it is aqueous.

[0034] The sensing element can be disposable in the sense that once all fluids have been introduced into it, the sensing element is not reused. This is particularly the case when one fluid is a gas and the other is a liquid, as complete removal of all liquid from the pores is required before reuse is possible, and it may be desirable not to reuse the sensing element.

[0035] However, it should be noted that the optical signals from the first and second fluids can be reused for some third fluid, and as a result, the sensing element can be used for two or more third fluids.

[0036] Obviously, other parameters of the third fluid can also be determined when the third fluid contains a substance at a certain concentration, and step d) further includes determining the concentration of the substance in the third fluid. This determination can be made in the same manner as further described below in connection with the second aspect of the present invention.

[0037] Furthermore, according to one embodiment of the sensing element, the cross-sectional dimension of the opening of the pore is about 1 μm or less, about 800 nm or less, preferably about 500 nm or less, or even about 400 nm or less, and / or the length of the pore in the axial direction along the pore is less than 100 μm, less than 50 μm, preferably less than 30 μm, or about 25 μm.

[0038] By using a pore having an opening in the front plane of a translucent slab having a maximum cross-sectional dimension of about 1 μm or less, or preferably within the submicron range, such as about 800 nm or less, such as about 500 nm or less, or about 400 nm or less, when the first or second fluid is whole blood, any cellular components including red blood cells, white blood cells, and thrombocytes / platelets are prevented from entering the pore.

[0039] Furthermore, a pore with an opening having a cross-sectional dimension of about 500 nm or less has an increased sensitivity compared to larger pores, such as a pore having an opening with a cross-sectional dimension of about 800 nm or more but having the same total pore volume / volume porosity.

[0040] Most preferably, the pores have minimum apertures with respective minimum pore volumes to enable efficient extraction of a sufficiently large sub-sample that can still be probed with an acceptable signal-to-noise ratio. Advantageously, the pores have apertures of about 30 nm or greater, or 50 nm or greater, or 100 nm or greater, or about 200 nm or greater.

[0041] Suitable pores can be produced, for example, from a transparent polymer membrane having so-called track-etched pores similar to those commercially available from IT4IP (IT4IP s.a. / avenue Jean-Etienne Lenoir 1 / 1348 L ouvain-la-Neuve / Belgium), with improvements such as the pores being closed at one end. The through-holes in the membrane can be closed, for example, by laminating a backsheet to the back side of the porous membrane, or by decelerating the ions such that the ion impact tracks, and thus the etched pores following these tracks, stop within the transparent polymer membrane to form non-through holes. The membrane is typically backed by a rigid transparent element to provide adequate mechanical strength for a translucent slab or sensing element.

[0042] The sensing element is preferably made of a material that does not absorb radiation at one or more wavelengths and can simultaneously preferably produce non-through holes in the material, for example by track etching the material. Suitable materials for this are polyethylene terephthalate (PET or PETE), or a PET analogue (polyethylene terephthalate polyester (PETP or PET-P)), or polycarbonate (PC). The sensing element may include a hydrophilic coating, such as polyethylene glycol (PEG), to increase diffusion into the pores. The hydrophilic coating can be selected according to the use of the sensing element. In some applications, once the sensing element is used, it never dries out, so it only needs to be hydrophilic at startup. In other uses of the sensing element, it requires a coating that keeps it permanently hydrophilic so that the sensing element remains usable when it dries and then is re-wetted for further use.

[0043] According to yet another embodiment of the sensing element, the porosity of a given volume of the translucent slab containing the pores is 50% to 5% by volume, 30% to 10% by volume, or about 15% by volume. The pores create porosity within the sensing element (or within a given region of the sensing element) with a corresponding front surface area over which the pore openings are distributed. The porosity can be characterized in terms of the volume of voids created within the sensing element by the pores, i.e., the pore volume, which is referred to as the volume of the sensing element penetrated by the pores. This volume is here defined as the volume between the front region where the pores are distributed and the same parallel region shifted into the sensing element by the maximum depth of penetration of the pores into the sensing element as seen in the axial direction perpendicular to the front side of the sensing element.

[0044] In addition, the porosity can be further characterized in terms of an integrated pore volume equal to the fluid volume in which the optical probe is available. The pore volume can be conveniently expressed as an equivalent pore volume depth DELTA which is the pore volume referred to for the corresponding front side on which the pore openings are distributed. Thus, the porosity of the sensing element can be converted to the equivalent pore volume depth DELTA as follows. Pores having openings within a given front area A have a total pore volume V. The equivalent pore volume depth is then calculated as the total pore volume divided by the given front area: DELTA = V / A.

[0045] Advantageously, according to some embodiments, the equivalent pore volume depth DELTA is less than 20 μm, or less than 15 μm, or less than 10 μm, or in the range of 3 μm to 5 μm, and the equivalent pore volume depth DELTA is defined as the total volume V of the pores divided by the front area A on which the pore openings are distributed.

[0046] In situations where the fluid is whole blood and only the serum is of interest, a small subsample with representative concentrations of the relevant components is obtained. A small subsample volume is desirable to facilitate rapid subsample exchange and thus reduce the response time of the sensing element and the cycle time of the measurements using the sensing element. A small subsample volume is further desirable to avoid the effect of the depletion of the plasma fraction boundary layer in the whole blood sample close to the front side of the sensing element. Such a depletion effect could otherwise occur in a small static sample, in which, for example, if the equivalent pore volume depth exceeds a critical value, red blood cells can interfere with the efficient diffusion exchange of the relevant components from the volume of the whole blood sample towards the boundary layer at the front side of the sensing element.

[0047] Preferably, the equivalent pore volume depth DELTA is at least 1 μm, alternatively at least 2 μm, or in the range of 3 μm to 5 μm, and the equivalent pore volume depth is defined as above. A larger fluid volume may be desirable to achieve a better signal-to-noise level since a larger fluid volume contributes to the optically probed information regarding the relevant components in the second fluid.

[0048] Furthermore, according to some embodiments, on the one hand, reducing response time, reducing cycle time, and / or avoiding a diminishing effect in small standing volumes of fluid, and on the other hand, a useful trade-off with the required or desired signal-to-noise ratio, is found for pore volume depths DELTA in the range of 1 μm to 20 μm, preferably in the range of 2 μm to 10 μm, or an equivalent of about 4 μm to 5 μm.

[0049] As described above, the method can be used to determine the concentration of the components, rather than the refractive index of the third fluid, from absorptions etc. determined for this component in step c) thereof. At this time, step d) can instead determine the concentration taking into account the contribution by the refractive index of the third fluid.

[0050] Aspects of the invention thus relate to a method of determining the concentration of a fluid, the method comprising a) obtaining a first optical signal from a sensing element having a plurality of pores containing a first fluid having a first predetermined refractive index and a first predetermined absorption at at least a first and a second wavelength; b) obtaining a second optical signal from the sensing element, the pores containing a second fluid having a second predetermined absorption at at least the first and second wavelengths and a second predetermined refractive index, the second refractive index being different from the first refractive index; c) obtaining a third optical signal from the sensing element, the pores containing a third fluid; d) determining the concentration of a component of the third fluid based on the first, second, and third optical signals, the first and second predetermined absorptions, and the first and second refractive indices; and comprising.

[0051] The determination may include determining the refractive index of a third fluid. Alternatively, the refractive index contribution may be compensated for. The component may absorb radiation at one of the first and second wavelengths, and step c) may include determining the absorption at the first and / or second wavelengths, which absorption may be utilized in step d).

[0052] As described above and below, steps a) and b) may include emitting radiation including the first and second wavelengths to a sensor element and determining the intensity of the radiation at or around the first and second wavelengths received from the sensor element, and the determined intensity is used in step c).

[0053] Of course, all considerations, embodiments, and the like of all other aspects of the present invention may be equally relevant in relation to this aspect. Another aspect of the present invention relates to a method for determining a parameter of a fluid, the method comprising a) obtaining a first optical signal from a sensing element having a plurality of holes containing a first fluid having a first predetermined refractive index and a predetermined absorption at at least one of one or more wavelengths; b) obtaining a second optical signal from the sensing element, wherein the holes contain a second fluid having a second predetermined refractive index, the second refractive index being different from the first refractive index; and c) determining the concentration of a component of the second fluid based on the first and second optical signals, the first and second refractive indices, and the predetermined absorption, the component absorbing radiation at at least one of one or more wavelengths; including.

[0054] In this context, a parameter can be any parameter of the fluid, such as the concentration of a component of the fluid or the refractive index, which can be determined using radiation, for example, based on the absorption of the component at a wavelength different from one wavelength. Conventional parameters are the concentrations of the components of the liquid, such as molecules, drugs, constituent substances, or the like. As is well known, the concentration can be determined based on the absorption of radiation at one or more specific wavelengths.

[0055] On the other hand, the refractive index of the fluid can also affect the manner in which the radiation travels through the detection environment and can thus be compensated for. In a particularly advantageous embodiment, the coloring of the plasma, which is the second fluid, is by means of hemoglobin that is optically probed, for example, by using spectrally resolved absorption measurements, or within a spectral range indicative of the presence of bilirubin in the second fluid, for example, within a spectral range from 380 nm to 750 nm, for example, within a spectral range from 400 nm to 540 nm, or by measuring the absorption spectrally integrated over a predefined bandwidth of approximately 416 nm and / or approximately 455 nm and / or approximately 525 nm.

[0056] The first and second fluids have different predefined refractive indices. Therefore, the scattering caused by the pores will be different. This is desired to be taken into account in determining the concentration of the components of the second fluid, because this concentration is often determined based on the intensity of radiation within different wavelengths. At this time, greater scattering will result, to a greater or lesser extent depending on the actual optical environment, in the radiation being detected for the same sample or fluid.

[0057] It should also be noted here that scattering and reflection are wavelength-independent within a reasonable range, at least to the extent that wavelength sensitivity does not need to be considered in the determination in some cases. If the wavelengths used are too different, or if the desired accuracy is too high, the wavelength dependence of scattering / reflection at different refractive indices can be determined and considered for individual wavelengths.

[0058] When first and second optical signals are determined, such as by detecting radiation from first and second fluid optical probes, the concentration of a component of the second fluid can be determined based on the detected radiation and the refractive indices of the first and second fluids.

[0059] Steps a) and b) comprise - emitting radiation at at least one wavelength and another wavelength to a sensing element, and - determining the intensities of the radiation at at least one wavelength and another wavelength from the sensing element and are preferably included, and step c) is further based on the determined intensities.

[0060] Typically, absorption at two wavelengths is desired to determine the concentration of a component. For some components, often, in order to be able to solve the matrix that results in the concentration of the individual components, it is desired to have at least as many wavelengths as the components to be determined, and in many cases more.

[0061] The wavelengths can be selected such that some components absorb more at some wavelengths than at others, which is standard for those skilled in the art. The first fluid, the sensing element, and the aperture, and the fluid provision, radiation emission, and radiation detection may be as described in connection with the first aspect of the invention. Small non-penetrating apertures allow for very efficient and fast fluid uptake and, when the fluid contains larger molecules or parts, allow for immediate extraction of a subsample for the optical probe by capillary forces and / or diffusion.

[0062] All embodiments, situations, examples, and the like of the first aspect of the invention are equally relevant to the second aspect of the invention. In this aspect of the invention, the refractive indices of the first and second fluids are predetermined and different. The first and second fluids can be selected based on several parameters such as their refractive indices, any absorption at one or more wavelengths, their type (liquid, gas, suspension), whether they are homogeneous or contain undesired large components in the pores, and the like.

[0063] Also, the wavelength can be selected based on any absorption of the wavelength of the sensing element and the fluid. Also, as described above, the wavelength can be adapted to the pore size or vice versa. As also mentioned in connection with the first aspect, it is preferred that the same pore can receive radiation from the radiation emitter and scatter / refract the radiation towards the detector, and that the angles of the emitted radiation and the detected radiation are the same regardless of which fluid is in the pore.

[0064] Generally, it may be desired that the first and second refractive indices are sufficiently different. Thus, the second refractive index may desirably be at least 1.05 times, for example at least 1.1 times, for example at least 1.15 times, for example at least 1.2 times, for example at least 1.25 times, for example at least 1.3 times the first refractive index.

[0065] As mentioned above, the first fluid may desirably be a gas. In such a manner, a large refractive index difference can be obtained between the first fluid and the second fluid. This gas can be ambient air or a gas having non-zero absorption at at least one of the wavelengths. In such a manner, it is possible to determine both the refractive index sensitivity and the absorption sensitivity of the system without activating (wetting) the sensor unit. Since water vapor in the ambient air can cause undesirable absorption at some radiation wavelengths, it may also be desired to determine or control any humidity of the ambient air.

[0066] Surprisingly, for whole blood and plasma samples as well as many other samples, the large RI difference between air and water / sample / fluid enables the assignment of known RIs to the sample / fluid, even if the RI of the sample / fluid, which is usually 1.33 - 1.35 (corresponding to normal protein concentration variations in blood), is not known more precisely than that. This is due to the RI difference with water (RI = 1) being much larger than that of the sample / fluid (RI = 1.33 - 1.35). At this time, since it is known that the RI of the sample is within 1 / 33 of the difference from water and the sample / fluid, more accurate calibration can be obtained.

[0067] A third aspect of the present invention relates to a system for determining the refractive index of a fluid, the system comprising - a sensing element having a plurality of holes, - a controllable radiation providing device configured to emit radiation of one or more wavelengths towards the holes, - a detector configured to detect the emitted radiation reflected / scattered by the holes and output corresponding information, - a controllable fluid providing element configured to provide fluid to the holes, - a controller, which controls the radiation providing device and the fluid providing element, and - when the hole contains a first fluid having a predetermined first refractive index and a predetermined first absorption at least at the first and second wavelengths, controlling the detector to obtain a first optical signal, - when the hole contains a second fluid having a predetermined second absorption at least at the first and second wavelengths and a second predetermined refractive index, controlling the detector to obtain a second optical signal, wherein the second refractive index is different from the first refractive index, - when the hole contains a third fluid, controlling the detector to obtain a third optical signal, - determining the refractive index of the third fluid based on the first, second, and third optical signals, the first and second absorptions, and the first and second refractive indices and a controller configured to perform Comprises.

[0068] The third aspect relates to the first aspect of the present invention, and all considerations regarding fluids, wavelengths, refractive indices, holes, detection elements, and the like are equally relevant in this context. The radiation providing device is controllable. In this context, this may be for selecting the wavelength or wavelength interval to be emitted as desired. Alternatively, the intensity emitted within one wavelength, some of the wavelengths, or all of the wavelengths can be controlled. Further alternatively, the emission of radiation onto the holes, such as which holes, the position of the holes within the detection element, the area or volume of the holes receiving the radiation, the angle of incidence, or the like, can be controlled.

[0069] The radiation providing device may comprise one or more radiation emitters such as a laser, laser diode, LED, OLED, or the like, and one or more optical elements for transporting the radiation to the first hole. The optical elements may comprise a filter, collimator, lens, optical guide, or the like. In many cases, these optical elements will define which hole is the first hole.

[0070] The detector may comprise one or more detection elements such as a photodiode, and optical elements for transporting the radiation from the second hole to the detection element. These optical elements may comprise a lens, collimator, filter, radiation guide, or the like. In many cases, these optical elements will define which hole is the second hole. The filter may be used to split the received radiation into different wavelengths or wavelength intervals that can later be individually detected. Alternatively, the detector may be configured to determine the spectrum of the received radiation.

[0071] Preferably, the radiation providing device and the detector maintain a fixed relationship with respect to the detection element during detection and between optical probes of different fluids. In such a manner, the detection element can be configured to receive radiation from the same hole over time.

[0072] The detector is configured to output information corresponding to the received radiation. This corresponding radiation may correspond to the total intensity received, the intensity determined at different wavelengths such as one or more wavelengths or the like. This may be, for example, in the form of individual values or spectra of the received radiation.

[0073] The fluid providing element is controllable to provide a desired fluid to the pore. As described above, some fluids may already be provided in the pore, for example, from the manufacture of the sensing element. The fluid providing element may comprise individual containers for individual fluids. Alternatively, a common container may be provided, in which case the operator continuously supplies the desired fluid to the fluid providing element, and then the fluid providing element can supply the selected fluid to the pore. The fluid supply element may also remove the former fluid from the pore in the same step or a previous step.

[0074] The controller can be any type of controller, such as a processor, FPGA, DSP, software control, hardwired, or any combination thereof. The processor can be remote from the sensing element or an integral part of the system. The processor can be divided into different parts that perform different tasks. The processor can communicate with the radiation emitter, detector, and fluid supply element in any manner, for example, via wires or wirelessly.

[0075] The controller can then control the system to implement the above method and / or the method of the first aspect of the present invention. As described in connection with the first aspect of the present invention, the refractive index of the third fluid can be determined based on the first, second, and third information, the first and second absorptions, and the first and second refractive indices.

[0076] As shown above, it may be desired for the controller to be configured to determine the concentration of a substance in a third fluid in the determination. In this context, the controller may be configured to control a fluid providing element to supply a third fluid containing a substance at a certain concentration. Then, the controller may be configured to determine the concentration of the substance in the third fluid in the determination.

[0077] The controller is preferably - controlling a radiation providing device to emit radiation at each of the first and second wavelengths to a detection element, - the detector, - as at least a part of the first optical signal, the first intensity of the radiation at each of the first and second wavelengths from the detection element, and - as at least a part of the second optical signal, the second intensity of the radiation at each of the first and second wavelengths from the detection element to control to determine, - determining a refractive index further based on the determined first and second intensities and is configured to perform.

[0078] A fourth aspect of the present invention relates to a system for determining a parameter of a fluid, the system comprising - a detection element having a plurality of holes, - a controllable radiation providing device configured to emit radiation of one or more wavelengths towards the holes, - a detector configured to detect the emitted radiation reflected by the holes and output corresponding information, - a controllable fluid providing element configured to supply fluid to the holes, - a controller, to control the radiation providing device and the fluid providing element, and - when the holes contain a first fluid having a predetermined first refractive index and a predetermined first absorption at at least one of one or more wavelengths, controlling the detector to acquire a first optical signal, - When the hole contains a second fluid having a second predetermined refractive index, controlling the detector to acquire a second optical signal, the second refractive index being different from the first refractive index, and controlling the detector - Based on the first and second optical signals, a predetermined first absorption, and the first and second refractive indices, determining the concentration of a component of the second fluid, the component absorbing radiation at at least one of a plurality of wavelengths and determining a controller configured to perform and comprising

[0079] This aspect corresponds to a second aspect of the present invention, and all considerations made in this regard are equally relevant to this aspect. Of course, all considerations made with respect to a third aspect of the present invention relating to the controller, the fluid, the fluid providing element, the radiation providing device, the detector, the sensing element, and the like are equally relevant in this context.

[0080] The controller is preferably - controlling the radiation providing device to emit radiation at at least one wavelength and another wavelength to the sensing element, - controlling the detector to - as at least a part of the first optical signal, the first intensity of radiation at at least one wavelength and another wavelength from the sensing element, and - as at least a part of the second optical signal, the second intensity of radiation at at least one wavelength and another wavelength from the sensing element and determining, - further determining the component based on the determined intensities and being configured to perform.

[0081] When receiving information related to the radiation received when the first, second, and third fluids are in the pores, the concentration can be determined based on the first and second information, the first and second absorptions, and the first and second refractive indices, and the concentration is the concentration of the components of the second fluid, and the components absorb radiation at at least one of one or more wavelengths. This is further explained above.

[0082] The first refractive index may desirably be at least 1.05 times the second refractive index. The fluid providing element may desirably comprise a plurality of fluid containers and flow paths from each fluid container to the pores. In such a manner, the fluid providing element may control the flow of at least some of the fluids.

[0083] The system may also comprise a plurality of sensing elements such that the sensing element can be discarded after the determination of the refractive index or the concentration of the component, and a new sensing element is used for subsequent determinations. The sensing element may desirably have a gas such as ambient air in the pores as the first fluid.

[0084] As described above, the radiation emitter preferably emits radiation towards the same pores with at least 10% within, and the detector is configured to receive radiation from the pores.

[0085] The final aspect relates to a method for determining fluid parameters, and the method is a) obtaining a first optical signal from a sensing element having a plurality of pores containing a first fluid having a first predetermined refractive index and a first predetermined absorption at at least one of one or more wavelengths; b) obtaining a second optical signal from the sensing element, the pores containing a second fluid having a second predetermined absorption at at least one of one or more wavelength indices; c) based on the first and second optical signals, the first and second absorptions, and the predetermined refractive indices Subsequently, a step of determining the refractive index of the second fluid is included. This includes.

[0086] Obviously, all embodiments, situations, and considerations related to all other aspects of the present invention are equally effective in relation to this aspect of the present invention. In this aspect, knowledge of the scattering caused by radiation absorption and the refractive index of the fluid in the pores can be used to determine the refractive index of an unknown fluid. As described above, the refractive index can represent a component that may not absorb radiation at least at the wavelength used for determination, and as a result, the refractive index can be used to obtain knowledge about this component.

[0087] In the following, preferred embodiments will be described with reference to the drawings.

Brief Description of the Drawings

[0088]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Best Mode for Carrying Out the Invention

[0089] In FIG. 1, a measurement environment 10 is shown comprising a sensing element 12 which can be a translucent slab containing a plurality of non-through holes 122, and fluid can proceed from a flow channel or flow F into the non-through holes 122.

[0090] The holes can be provided in any manner, such as by etching. When providing a material in an etching solution or fluid, the material is etched and holes are formed in these locations while the surface is maintained, and there are ways in which the surface of element 12 is altered in some locations so that substantial etching is not seen in other locations. In some ways, the position of the holes is probabilistic, such as when the action of the surface is provided using charged particles or ions. In other ways, such as using lithography, the surface can be acted upon at the locations provided by the pattern, whereby the holes can be positioned in the pattern.

[0091] The depth and width of the holes can be controlled by the etching parameters. In one embodiment, the translucent slab or element 12 is made of a translucent, preferably transparent, polymeric material and has track-etched non-through holes 122 with an essentially circular cross-section. The holes have openings 126 with a diameter of 400 nm and a depth of 25 μm and are distributed with a porosity of 15% by volume. Together, the holes distributed over a given front-side 124 surface area A have a total volume V and an equivalent hole volume depth DELTA = V / A which can be 1 to 100 μm, such as 1 to 50 μm, such as 1 to 25 μm, such as 1 to 10 μm, such as 2 to 6 μm, such as about 4 μm.

[0092] In one embodiment, a mirror surface is further provided on the front side 124. For example, this surface can be obtained by the directional sputter evaporation of Pd on the front side of the translucent polymer slab 12 using the evaporation direction at an incident angle of 25 degrees with respect to the surface normal on the front side 124 until a reflective layer (not illustrated) having a thickness of 30 nm is obtained on the front side 124 of the translucent slab 12. Then, holes can be formed as described.

[0093] In some embodiments, the holes can be cross - intersecting, so that at least some of the holes can be connected to each other, forming an X - shape, Y - shape, V - shape, or similar interconnected shapes. In other embodiments, the holes, or most of the holes, extend from one surface more or less parallel to each other and into the material of the element 12.

[0094] The radiation emitter 14 is provided to direct and emit radiation into and through the holes 122, and the radiation interacts with the fluid within the holes 122. This radiation also interacts with the fluid at the interface between the holes and the fluid. Thus, the refractive index of the fluid is involved in the interaction between the radiation and the fluid.

[0095] One or more radiation receivers or detectors 16 are provided to receive the emitted radiation that has interacted with the fluid within the holes. Preferably, the radiation emitted into the element 12 is perpendicular to the upper or lower surface 124 / 125 or at a non - zero angle with respect to the common direction of the holes. Additionally, or alternatively, the radiation detected by the detector can be received from a direction that is perpendicular to the upper or lower surface or at an angle with respect to the common direction of the holes.

[0096] The holes that receive radiation from the emitter and the holes that finally reflect or direct the radiation towards the detector can be the same, have an overlap, or form different groups of holes. It may be desired for the radiation to be reflected by a plurality of holes before being detected. This can be achieved by ensuring that the hole from which the radiation is emitted by the emitter is not within the field of view of the detector.

[0097] The hole 122 opens to the surroundings on the first side 124 of the element 12. Radiation can be emitted into the element 12 on the opposite side 125. Also, the detector 16 can be positioned to receive the radiation exiting the element 12 at the surface 125, and as a result, for example, fluid can be introduced into the hole from the first side 124. This surface can form part of the fluid flow path, whereby fluid can be provided into the hole and can be removed from the hole again, such as when the fluid is replaced by another fluid.

[0098] As is normal, when the fluid absorbs part of the radiation, the radiation received by the detector 16 can be reduced. From the attenuation or absorption of the radiation, the concentration of the absorbing element in the hole can be determined.

[0099] However, other parameters of the fluid can be determined. It should be noted that the difference in refractive index between the material of the sensing element forming the hole 122 and the fluid will convert the hole into a lens-like structure. Then, the parameters of these lens-like structures will change with the change in the refractive index of the fluid.

[0100] Therefore, the beam of radiation emitted through the lens-like structure will undergo different focusing, scattering, reflection, and dispersion at the different refractive indices of the lens-like structure caused by the different refractive indices of different fluids.

[0101] The radiation received by the detector can thus depend on both the refractive index of the fluid and any absorption. exist. The holes are provided within the sensing element 12. Thus, portions of the sensing element 12 are provided between adjacent holes. At the opening 126, the sensing element may form a flat, yet porous, surface 124, as illustrated by the dashed line. These flat outer portions between the holes may act to reflect radiation impinging thereon from the sensing element 12, such that this radiation (or a portion thereof) is reflected back into the sensing element 12. As described above, a reflective surface may further be provided on this surface to increase such reflection. However, it may be preferred in some cases that the detector 16 is not positioned to receive any radiation from such a direct reflection of the radiation directly from the emitter 14.

[0102] In addition, or alternatively, a first region or volume of the sensing element 12 may receive radiation directly from the light source 14. The first region or volume of the sensing element 12 may be a region or volume that is within the field of view of an optical element that emits or directs radiation onto and into the element 12. Similarly, a second region or volume of the sensing element 12 may be a region or volume from which the detector 16 directly receives radiation. The second region or volume may be a region or volume of the sensing element 12 that is within the field of view of an optical element that collects or directs radiation towards the element detector 16.

[0103] Since the light rays of the radiation may cross without interfering, the region or volume may be positioned such that the radiation supplied towards one volume may pass through the radiation from another region that is directed towards the detector.

[0104] It may be desired that the first and second regions or volumes are different, for example, having little or no overlap. It may be desired that less than 25%, for example less than 10%, for example less than 5%, for example less than 1% of all the surfaces of the holes 12 within the first region / volume are also present within the second region / volume. Alternatively, the first and second regions / volumes may have a large overlap, such as one being completely contained within the other.

[0105] Calibration can, from here on, be done in a new manner. In one manner, the present structure can be used to determine the refractive index of an unknown fluid. In another manner, the present structure can use the refractive index to calibrate the absorption determination of a fluid with a known refractive index, and thus, the determination of the concentration of the absorption component.

[0106] Generally, a first fluid or reference fluid having a first refractive index is supplied into the pores. The fluid can be a gas or a liquid. It may be preferable to use ambient air. Ambient air has a refractive index far from that of a liquid, which can be advantageous.

[0107] When the first fluid / reference fluid is in the pores, a first detection of the radiation intensity, for example, at a first wavelength or within a first wavelength interval, is performed. If the reference fluid has little or no absorption at the first wavelength, the detected contribution is solely or mainly due to the refractive index of the fluid and its effect on the lens-like structure defined by the fluid in the pores. If the reference fluid absorbs at that wavelength, its contribution can be taken into account.

[0108] Of course, radiation at a plurality of wavelengths or within a plurality of wavelength intervals can be emitted into element 12. The effect of the refractive index of the reference fluid can be assumed to be the same for all wavelengths, even if it changes slightly. As a result, the effects of absorption at different wavelengths / intervals can be used to determine and separate the contributions from absorption and refractive index.

[0109] Then, or before supplying the first fluid / reference fluid to the pores, a second fluid is introduced into the pores and the radiation is emitted into the pores again and the radiation is detected. If the refractive index of the second fluid is predetermined or known, the first and second fluids can here form a calibration set for the determination of the refractive index of a third fluid supplied to the pores.

[0110] Obviously, the fluid may also exhibit absorption at one or more of the wavelengths, but such contributions can be compensated for in the calibration as long as a sufficient determination is made (such as at a sufficient number of wavelengths).

[0111] On the other hand, if the refractive index of the second fluid is known and the absorption of the first fluid at one or more wavelengths is known, even the second fluid can be a fluid with an absorption element of unknown concentration. In this situation, when a sufficient number of wavelengths are used that allow determination of both the absorption of the components and the refractive index of the second fluid, calibration using the first fluid can also be sufficient here. When wavelengths at which the loss of radiation due to absorption can be determined are used, the effect of the refractive index of the fluid can be determined. This effect can be an increase or decrease in the received radiation intensity, and this effect can be assumed to be the same for at least all wavelengths within a fairly wide range. Refraction at the interface between two materials with different refractive indices is wavelength-dependent, but does not reach any significant degree within a wavelength range of several hundred nm.

[0112] The concentrations of multiple components can be determined when a sufficient number of wavelengths are used that are selected such that the components absorb differently within the wavelength.

Example

[0113] In a sensing element as described above, different reference fluids were tested for a set of measurements at four different wavelengths WL1, WL2, WL3, and WL4 used to determine plasma parameters. Three replicates of each sample type were used, and two calibrations were compared, which were performed on the same 10 analyzers and flowed four fluids with different degrees of hemolysis.

[0114] The first calibration fluid (marked with O in Figure 2) is a calibrated fluid with a standard color. The refractive index of the normal calibration fluid is close to that of plasma (1.33). The second calibration fluid (marked with a + in FIG. 2) has very little absorption at these wavelengths, but is a 1500 mM glucose solution that causes scattering / reflection due to its refractive index of 1.41.

[0115] In FIG. 2, it can be seen that the signal increases until it reaches a steady-state value. This is due to the fact that diffusion is used in this analyzer, so it takes very little time for the fluid to enter the pores.

[0116] The change in radiation intensity is determined in units of normal mAbs of pure absorption. From the very low intensity changes, it can be seen that the total scattering and absorption of the normal calibration fluid is very low at two of the wavelengths (WL3 and WL4). This is due to the calibration fluid not absorbing or scattering any of this radiation. Therefore, the calibration at wavelengths WL3 and WL4 can historically be performed based on measurements at WL1 and / or WL2. The sensitivity of WL3 and WL4 can be assumed to be, for example, that of WL2.

[0117] In contrast, the second calibration fluid has high intensity changes at all four wavelengths. Here, the contribution is mainly caused by the change in the interaction of the radiation at the interface between the pore and the fluid, and thus by the difference in refractive index between the fluid and the reference fluid (in this case, the fourth fluid).

[0118] In this situation, it is worth noting that the cross-section of the hole perpendicular to the longitudinal axis of the hole is comparable to the wavelength of the radiation such that the interaction between the radiation and the hole includes scattering. The radiation will thus be scattered from hole to hole until it is directed out of element 12. When interacting in the hole, the radiation will also pass through the fluid and thus, if the fluid absorbs the radiation, through absorption. The lower intensity change of the second fluid at WL1 compared to the same fluid intensity change at WL2 is caused by a lower refractive index change sensitivity at WL1 compared to WL2. The same ratio is observed when using the optically absorbing calibration fluid (Cal2), which is not directly obvious in Figure 2 but is caused by a dissipation coefficient approximately 1.25 times higher for tartrazine at WL1 compared to WL2. Thus, surprisingly, the absorption sensitivity ratio between the WLs can be converted to the scattering sensitivity ratio between the same WLs and vice versa.

[0119] In addition to the absorption by the normal calibration fluid, the radiation will also be lost due to scattering by the hole. This effect depends on the refractive index of the fluid. Thus, a comparison can be made between calibrating the five analyzers using the first calibration fluid, using the second calibration fluid, and using both fluids.

[0120] Figure 3 illustrates the calibration of five analyzers (each illustrated by one of the symbols on the right) using a standard calibration fluid after four fluids (RPP0, RPP165, RPP330, and RPP1000) have been measured three times in each analyzer, resulting in each of the marks under each fluid.

[0121] RPP is the so-called "Reference Plasma Pool" based on a blood sample in which hemolysis has released all colors from the red blood cells. Thus, the RPP1000 sample has 1000 mg / dl of free hemoglobin (also called ccfHb) dissolved in the plasma. Since the fluid is blood-based, the protein concentration and its RI are the same for all RPP fluids.

[0122] The RPP0 measurement is found not to be zero when it should be zero. This is caused by scattering induced by the refractive index of the fluid. Also, it is found that the performance at RPP1000 in mg / dL ccfHb is lower.

[0123] In Figure 4, the same fluid is being analyzed using a second calibration fluid. The RPP0 measurement is found here to be provided with a zero value as expected. It is also found that calibration functions well for RPP165 and RPP330 fluids, which is not improved in RPP1000 fluid since RI calibration is not ideal for calibrating the color signal from cfHb.

[0124] In Figure 5, five analyzers are calibrated using both the first and second calibration fluids, and it is found that the best of the two calibrations is obtained. Better performance for RPP0, RPP165, and RPP330 fluids is seen from the second calibration fluid, and better performance in RPP1000 fluid is seen from the first calibration fluid.

[0125] Instead of measurements that use radiation absorption to determine the concentration of a component, the concentration of the component can be estimated from the refractive index of the fluid. For example, proteins in plasma do not absorb at any significant degree in any of WL1 - WL4, but the concentration of proteins in plasma will define its refractive index.

[0126] In Figure 6, five analyzers calibrated using the first calibration fluid are used to estimate the total protein in each of the fluids RPP0, RPP 165, RPP330, and RPP1000. For comparison, Figure 7 illustrates the same analyzers analyzing the same fluids, but here calibrated using the second calibration fluid. The measurements are found to have better performance when using both calibrations.

Claims

1. 1. A method for determining the refractive index of a fluid, comprising the steps of: a) acquiring a first optical signal from a sensing element having a plurality of pores containing a first fluid having a first predetermined refractive index and a first predetermined absorption at at least a first and a second wavelength; b) acquiring a second optical signal from the sensing element, the bore including a second fluid having a second predetermined absorption at the at least first and second wavelengths and a second predetermined refractive index, the second refractive index being different from the first refractive index; c) acquiring a third optical signal from the sensing element, the bore containing a third fluid; and d) determining a refractive index of the third fluid based on the first, second, and third optical signals, the first and second predetermined absorptions, and the first and second refractive indices; The method includes:

2. 1. A method for determining a parameter of a fluid, comprising the steps of: a) acquiring a first optical signal from a sensing element having a plurality of pores containing a first fluid having a first predetermined refractive index and a predetermined absorption at at least one of one or more wavelengths; b) acquiring a second optical signal from the sensing element, the bore containing a second fluid having a second predetermined refractive index, the second refractive index being different from the first refractive index; c) determining a concentration of a component of the second fluid based on the first and second optical signals, the first and second refractive indices, and the predetermined absorption, the component absorbing radiation at at least one of the one or more wavelengths; The method includes:

3. The method of claim 1 , wherein the third fluid comprises a concentration of a substance, and step d) further comprises determining the concentration of the substance in the third fluid.

4. 4. The method of claim 1, wherein the second refractive index is at least 1.05 times the first refractive index.

5. The method of claim 1 , wherein the first fluid is a gas.

6. Each of steps a), b), and c) comprises: - emitting radiation at each of said first and second wavelengths to said sensing element; and - determining the intensity of radiation at each of said first and second wavelengths from said sensing element; Including, The method of claim 1 , wherein step d) is performed further based on the determined intensity.

7. Steps a) and b) include - emitting radiation at at least one wavelength and another wavelength to said sensing element; and - determining the intensity of radiation at said at least one wavelength and at said other wavelengths from said sensing element; Including, The method of claim 2 , wherein step c) is further based on the determined intensity.

8. 1. A system for determining the refractive index of a fluid, comprising: a sensing element having a plurality of holes; - a controllable radiation providing device configured to emit radiation of one or more wavelengths towards the aperture; a detector configured to detect the emitted radiation reflected / scattered by said hole and to output corresponding information; - a controllable fluid providing element configured to provide a fluid to said hole; a controller configured to control the radiation providing device and the fluid providing element; and - controlling said detector to obtain a first optical signal when said hole contains a first fluid having a first predetermined refractive index and a first predetermined absorption at at least a first and a second wavelength; - controlling the detector to obtain a second optical signal when the hole contains a second fluid having a second predetermined absorption at at least the first and second wavelengths and a second predetermined refractive index, the second refractive index being different from the first refractive index; - controlling said detector to obtain a third optical signal when said hole contains a third fluid; determining a refractive index of the third fluid based on the first, second, and third optical signals, the first and second absorptions, and the first and second refractive indices; a controller configured to: A system comprising:

9. 1. A system for determining a parameter of a fluid, comprising: a sensing element having a plurality of holes; - a controllable radiation providing device configured to emit radiation of one or more wavelengths towards the aperture; a detector configured to detect the emitted radiation reflected by said hole and to output corresponding information; a controllable fluid providing element configured to provide a fluid to said hole; a controller configured to control the radiation providing device and the fluid providing element; and - controlling said detector to obtain a first optical signal when said hole contains a first fluid having a first predetermined refractive index and a first predetermined absorption at at least one of one or more wavelengths; - controlling the detector to obtain a second optical signal when the hole contains a second fluid having a second predetermined refractive index, the second refractive index being different from the first refractive index; determining a concentration of a component of the second fluid based on the first and second optical signals, the predetermined first absorption, and the first and second refractive indices, the component absorbing radiation at at least one of the one or more wavelengths; a controller configured to: A system comprising:

10. The system of claim 8 , wherein the controller is configured to determine, in the determining, a concentration of a substance in the third fluid.

11. 11. The system of claim 8, wherein the second refractive index is at least 1.05 times the first refractive index.

12. The system of claim 8 , wherein the fluid providing element comprises a plurality of fluid reservoirs and a flow path from each fluid reservoir to the hole.

13. The system of claim 8 , wherein the first fluid is a gas.

14. The controller includes: - controlling the radiation providing device to emit radiation at each of the first and second wavelengths towards the sensing element; - said detector, a first intensity of radiation at each of the first and second wavelengths from the sensing element as at least a portion of the first optical signal; and a second intensity of radiation at each of the first and second wavelengths from the sensing element as at least a portion of the second optical signal; and controlling the control to determine determining the refractive index further based on the determined first and second intensities; and The system of claim 8 , configured to:

15. The controller includes: - controlling a radiation providing device to emit radiation at said at least one wavelength and at said further wavelength to said sensing element; - said detector, a first intensity of radiation at the at least one wavelength and at the other wavelengths from the sensing element as at least a portion of the first optical signal; and a second intensity of radiation at said at least one wavelength and at said other wavelengths from said sensing element as at least a portion of said second optical signal; and controlling the control to determine - determining said components further based on said determined intensities; The system of claim 9 , configured to:

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