Consumable device for sweat-based monitoring

Abstract

The invention relates to a consumable device for sweat-based monitoring, the consumable device comprising a proximal part configured to contact with a user, and further comprising: a) a sweat induction means on the proximal part, comprising: i. a sweat promoter configured to contact the skin of a user, and ii. a microfluidic structure; and b) a sweat interrogation means, located distally to the sweat induction means and comprising: i. a sample area; and ii. a passive fluid pump configured to induce the flow of the liquid through the sample area. The microfluidic structure is configured to convey fluid from the sweat promoter to the sample area. The invention also relates to a sweat-monitoring system comprising: a consumable device as above and a sweat-based monitoring device, the sweat-based monitoring device comprising sensing means and processing means.

Description

[0001] CONSUMABLE DEVICE FOR SWEAT-BASED MONITORING

[0002] Technical field of the invention

[0003] The present invention belongs to the field of medical devices. Particularly, the present invention relates to the field of wearable medical devices for monitoring in sweat, more particularly to a consumable device and to a sweat-monitoring system.

[0004] Background of the invention

[0005] Diabetes mellitus is a chronic metabolic disorder characterised by elevated blood glucose levels, which can lead to various complications affecting multiple organ systems. Effective management of diabetes requires frequent monitoring of blood glucose levels to adjust medication, diet, and lifestyle accordingly. Traditional methods of glucose monitoring involve invasive techniques such as finger-prick tests, which can be painful, inconvenient, and may discourage regular monitoring. State-of-the-art technologies monitor the glucose content in the blood by continuously or on-demand measuring glucose from interstitial fluids. Despite being invasive, these devices are largely adopted.

[0006] However, to draw a full picture of a patient's status and to provide relevant information to clinicians to advance the field of personalized medicine, the contemporary knowledge of other biomarkers information is fundamental. For example, lactate concentration can also be relevant in certain situations and levels can provide additional insights into the metabolic state of the patient and potential complications related to diabetes.

[0007] Lactate, a byproduct of glycolysis, is known to be significantly elevated in type 2 diabetes. An abnormal upregulation of monocarboxylate transporter 4 (MCT4) on the plasma membrane of cardiomyocytes in type 2 diabetes can lead to excessive lactate efflux from these cells. This disruption in lactate transport homeostasis can result in oxidative stress and inflammatory responses that exacerbate myocardial damage. In the context of diabetic ketoacidosis (DKA), a severe complication of diabetes, lactate levels can also be relevant. Elevated lactate levels may be an indication of a hypoinsulinemic state.

[0008] To date, to address the limitations of traditional glucose monitoring methods, various non- invasive approaches have been explored. Among these, monitoring glucose levels from sweat has gained significant attention due to its potential for continuous monitoring without the need for blood sampling. Sweat contains various analytes, including glucose, whose concentrations can reflect physiological changes in the body. However, the deployment of accurate and reliable wearable devices capable of monitoring glucose levels from sweat presents several challenges, including sensor sensitivity, selectivity, and biocompatibility. Furthermore, the lack of multiparametric devices able to detect different biomarkers sill poses a drawback in the deployment of personalized medicine. For instance, dehydration and glucose levels are interconnected. Dehydration can cause a person’s blood sugar levels to rise. This occurs when the water in their bloodstream decreases, resulting in a higher concentration of glucose being present in the blood.

[0009] Dehydration can occur due to various reasons such as excessive water loss from the skin due to heat, exercise, burns, severe skin disease, failure to replace water loss due to immobility or an impaired thirst mechanism, excess water loss from the kidneys due to medications, acute and chronic kidney disease, and excess water loss from the gastrointestinal tract due to vomiting, diarrhoea.

[0010] On the other hand, high blood sugar levels can reduce fluid levels in your body, which can lead to dehydration. Diabetes is a recognized risk factor for dehydration in the context of hyperglycaemia, given the osmotic effects of glucose. Therefore, by knowing a person’s glucose levels and hydration status, one can infer about their risk for conditions such as dehydration and hyperglycaemia. It is particularly important for a person with diabetes to monitor their blood sugars when they are ill, exercising, and in warmer climates. Over time, high blood sugar levels can cause long-term, serious health problems.

[0011] Prior art in the field of non-invasive glucose monitoring includes devices based on optical, electrochemical, and biochemical sensing principles. Optical methods utilize light absorption or reflection to measure glucose concentrations indirectly, while electrochemical methods rely on the detection of electrical signals produced by glucose oxidation reactions. Biochemical sensors incorporate enzymes or other bio-receptors to specifically detect glucose molecules.

[0012] In recent years, wearable health monitoring devices have gained considerable attention for their potential to offer continuous and non-invasive monitoring of various physiological parameters. This interest has led to extensive research and development. Prior art about sweat wearable sensors emphasizes features like optical modules for analyte detection, multiple sensor layers, the use of multiplexed electrochemical sensors. However, these devices imply a certain amount of sweat produced by the wearer that occurs normally during physical activities. Furthermore, to embrace robustness in the large adoption of wearable sensors there is a need to enhance analyte coverage, sensor specificity, data analysis methods.

[0013] There is therefore a need for a sweat-based monitoring device that does not need to rely on physical activity to obtain sweat and with enhanced analyte coverage, sensor specificity and data analysis capability. Summary of the invention

[0014] A first aspect of the invention refers to a consumable device for sweat-based monitoring, the consumable device comprising a proximal part configured to contact with a user. The consumable device further comprises: a. a sweat induction means on the proximal part. The sweat induction means comprises: i. A sweat promoter configured to contact the skin of a user, and ii. a microfluidic structure; and b. a sweat interrogation means, located distally to the sweat induction means. The sweat interrogation system comprises: i. a sample area; and ii. a passive fluid pump configured to induce the flow of the liquid through the sample area.

[0015] The microfluidic structure of the consumable device is configured to convey fluid from the sweat promoter to the sample area and the passive fluid pump is located after the sample area in the sense of the fluid.

[0016] In a preferred embodiment of any one of the embodiments of the first aspect of the invention, the sweat promoter comprises a hydrophilic layer embedded with a salt.

[0017] In another preferred embodiment of any one of the embodiments of the first aspect of the invention, the sweat promoter comprises a non-woven cloth layer with hydrophilic properties. In a more preferred embodiment, the sweat promoter comprises a non-woven cloth layer embedded with hydrophilic means. In another more preferred embodiment, the sweat promoter further comprises a methacrylate mesh layer.

[0018] In another preferred embodiment of any one of the embodiments of the first aspect of the invention, the sweat promoter comprises a sweat-inducing drug.

[0019] In another preferred embodiment of any one of the embodiments of the first aspect of the invention, the sweat promoter comprises a iontophoresis system.

[0020] In another preferred embodiment of any one of the embodiments of the first aspect of the invention, the consumable device further comprises a distal part configured to contact with a sweat-based monitoring device. Moreover, the sample area is a sample interrogation area distally accessible by the sweat-based monitoring device. In another preferred embodiment of any one of the embodiments of the first aspect of the invention the sweat promoter comprises a non-woven cloth layer with hydrophilic properties.

[0021] In another preferred embodiment of any one of the embodiments of the first aspect of the invention the microfluidic structure is spirally-shaped or fractal-shaped.

[0022] In another preferred embodiment of any one of the embodiments of the first aspect of the invention the sample area comprises a sample input and the microfluidic structure is configured to convey the fluid from the sweat promoter to the sample input of the sample interrogation area.

[0023] In another preferred embodiment of any one of the embodiments of the first aspect of the invention the passive fluid pump is a hydrophilic pad, preferably a hydrophilic clotted salt- impregnated pad.

[0024] In another preferred embodiment of any one of the embodiments of the first aspect of the invention the passive pump is a hydrogel.

[0025] In another preferred embodiment of any one of the embodiments of the first aspect of the invention the consumable device further comprises a skin adhesive means.

[0026] In another preferred embodiment of any one of the embodiments of the first aspect of the invention wherein the consumable device further comprises a distal part configured to contact with a sweat-based monitoring device, the distal part is configured to contact with an optical sweat-based monitoring device and the sweat interrogation means further comprises: iii. an optical light diffuser located distally to the sample area.

[0027] In another preferred embodiment of any one of the embodiments of the first aspect of the invention wherein the consumable device further comprises a distal part configured to contact with a sweat-based monitoring device, the distal part is configured to contact with a sweatbased monitoring device through adhesive means.

[0028] A second aspect of the invention refers to a sweat-monitoring system. The sweat monitoring system comprises: a. a consumable device according to any one of the embodiments of the first aspect of the invention; and b. a sweat-based monitoring device comprising a proximal part and a distal part. The sweat-based monitoring device further comprises: i. sensing means configured to obtain data of the sample interrogation area through the proximal part of the sweat-based monitoring device; and ii. processing means configured to process the information acquired by the sensing means.

[0029] The consumable device and the sweat-based monitoring device are configured to be connected such that the sweat-based monitoring device contacts the distal part of the consumable device through its proximal part.

[0030] In another preferred embodiment of any one of the embodiments of the second aspect of the invention wherein the sweat-based monitoring device is an optical sweat-based monitoring device; the sensing means comprise: a photodetector sensor and a light source; and the sensing means are configured to directly access the proximal part of the consumable device. In a further preferred embodiment, the light source is configured to emit light in at least three different wavelengths. Even more preferably, the sensing means is a photoplethysmography (PPG) device.

[0031] Brief description of the drawings

[0032] To enable a better understanding of the present disclosure, and to show how the present disclosure may be carried out, reference will now be made, by way of example only, to the accompanying schematic drawings, wherein:

[0033] Figure 1 shows a perspective view of a sweat monitoring system according to one or more embodiments of the invention.

[0034] Figure 2 shows an exploded view of a sweat monitoring system according to one or more embodiments of the invention.

[0035] Figure 3 shows an exploded view of a consumable device according to one or more embodiments of the invention.

[0036] Figure 4 shows a cut-through view of a consumable device according to one or more embodiments of the invention.

[0037] Figure 5a shows a top view of an optical determination of the sweat rate according to one or more embodiments of the invention.

[0038] Figure 5b shows a graphical representation of the readings from an optical determination of the sweat rate according to one or more embodiments of the invention. Figure 6 shows a schematic view of an optical sweat-based monitoring setup according to one or more embodiments of the invention.

[0039] Figure 7 shows alternative implementations and uses of a consumable device according to one or more embodiments of the invention.

[0040] Figure 8 shows the evaluation of a salt-embedded pad for sweat collection during sedentary activity and identification of application site according to one or more embodiments of the invention. A.i Schematic of the two application sites A and B on the wrist. A.ii Illustration of the sedentary activity performed by participants during the wear time. B Comparison of sweat absorption between pads with and without embedded salt at sites A and B. C.i Time-course of sweat absorbed at site A (dorsal wrist). C.ii Time-course of sweat absorbed at site B (volar wrist).

[0041] Figure 9 shows a step-by-step protocol for sweat collection using a salt embedded consumable device according to one or more embodiments of the invention.

[0042] Figure 10 shows Sweat collection performance across 12 volunteers using a consumable device according to one or more embodiments of the invention.

[0043] Figure 11 shows the correlation of Sweat Glucose Concentration with Infrared, Green, and Red Channel Intensity.

[0044] Figure 12 shows an exploded view of sweat-monitoring system according to one or more embodiments of the invention used for in-vivo tests of Example 2,

[0045] Figure 13 shows examples of continuous glucose monitoring obtained with a consumable device according to one or more embodiments of the invention.

[0046] Figure 14 shows a Validation of non-invasive glucose monitoring using a sweat-monitoring system according to one or more embodiments of the invention.

[0047] Figure 15 shows an example of a multiparametric measurement by a sweat-monitoring system according to one or more embodiments of the invention.

[0048] Description of the invention

[0049] Definitions

[0050] It must be noted that, as used herein, the singular forms "a", "an", and "the", include plural references unless the context clearly indicates otherwise. Further, unless otherwise indicated, the term "at least" preceding a series of elements is to be understood to refer to every element in the series. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the present invention.

[0051] It is noted that the term “about”, as used herein, refers to + / - 30%, preferably + / - 20%, preferably + / - 15%, more preferably + / - 10%, of the indicated referred value.

[0052] As used herein, the conjunctive term "and / or" between multiple recited elements is understood as encompassing both individual and combined options. For instance, where two elements are conjoined by "and / or", a first option refers to the applicability of the first element without the second. A second option refers to the applicability of the second element without the first. A third option refers to the applicability of the first and second elements together. Any one of these options is understood to fall within the meaning, and therefore satisfy the requirement of the term "and / or" as used herein. Concurrent applicability of more than one of the options is also understood to fall within the meaning, and therefore satisfy the requirement of the term "and / or."

[0053] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integer or step. When used herein the term "comprising" can be substituted with the term "containing" or "including" or sometimes when used herein with the term "having". Any of the aforementioned terms (comprising, containing, including, having), whenever used herein in the context of an aspect or embodiment of the present invention may be substituted with the term "consisting of", though less preferred.

[0054] When used herein "consisting of' excludes any element, step, or ingredient not specified in the claim element. When used herein, "consisting essentially of does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim.

[0055] The term “fluid” in the context of the present invention refers to a liquid. More preferably, it refers to a water-based fluid, such as sweat. In the present invention, the term “sweat” may be used alternatively, although it shall not be understood as limited to sweat. Although the invention is directed at liquid fluids, it is noted that temporally or punctually, it may comprise gases, such as air, for example previous to its use.

[0056] The term "consumable" in the context of the present invention preferably refers to a device that is meant to be discarded after one cycle of use. More preferably, it refers to a patch or pad that is configured to be replaced after each monitoring session, or when saturated with fluid. The term "microfluidic" in the context of the present invention refers to a system that process or manipulate fluids at small volumes, typically in the range of microliters or nanoliters, using channels with dimensions of tens to hundreds of micrometers. These types of systems are configured to precisely control and manage the flow of fluids at such small scales.

[0057] The term "passive fluid pump" in the context of the present invention refers to a device that moves fluids without the use of active mechanical or electrical components. Instead, it relies on external forces or natural phenomena, such as gravity, capillary action, osmotic pressure, or thermal gradients, to induce fluid flow.

[0058] The term "hydrophilic" in the context of the present invention refers to a substance or material that has a strong affinity for water. Hydrophilic materials readily absorb water molecules, often through hydrogen bonding or other intermolecular forces. These materials can dissolve in water, attract water molecules, or become wetted easily when exposed to water.

[0059] The term "hydrogel" in the context of the present invention refers to a network of hydrophilic polymer chains that are capable of holding a large amount of water within their structure. These polymers can absorb and retain significant volumes of water, sometimes up to thousands of times their dry weight, resulting in a gel-like material.

[0060] The term "light diffuser" in the context of the present invention refers to a material or device used to spread or scatter light evenly, reducing glare and softening the illumination.

[0061] The term "biomarker" in the context of the present invention refers to a measurable indicator of some biological condition or state. Biomarkers can be used to detect or monitor diseases, track the progress of treatment, or even predict the risk of future health issues.

[0062] The term "sensing means" in the context of the present invention refers to any means capable of measuring a parameter of the environment. It may comprise any type of parameter and many different technologies such as optical sensors, chemical sensors, electrochemical sensors, enzymatic sensors, conductivity sensors or capacitance sensors. It may comprise emitting and receiving subassemblies for measuring certain parameters.

[0063] The term " processing means" in the context of the present invention refers to any component, system, or apparatus that is designed to perform data processing functions. In a broad sense, it encompasses hardware and software elements that are responsible for executing instructions, managing data flow, and performing computations. It. may comprise one or more processing units, such as a microprocessor, GPU, CPU, multi-core processor or the like.

[0064] The term “sense of the fluid” refers to the sense a fluid is configured to travel through the consumable device. Description

[0065] Each embodiment disclosed herein is contemplated as being applicable to each of the other disclosed embodiments. Thus, all combinations of the various elements described herein are within the scope of the invention.

[0066] A pivotal issue of current sweat monitoring devices is the biofluid availability. Most existing technologies relying upon sweat as biofluid for biomarker detection need the wearer to perform sports activities to generate enough volume of samples that can be read from the sensor system used, whether it be colorimetric, optical, electrochemical or else.

[0067] This represents a drawback in adopting sweat as a biofluid for target applications that are not sport-related. For instance, in the field of glucose monitoring, most forms of physical activities based on aerobic exercise lower the glucose levels, while more intensive training based on weightlifting can raise the glucose concentration. Thus, the issue of sweat availability hinders its large adoption as a sample for biomarker detection.

[0068] A first aspect of the invention relates to a consumable device 100 for sweat-based monitoring. As it will be explained herein, the consumable device 100 does not need to rely on physical activity to obtain sweat. This means that the consumable device is able to function even when natural perspiration is insufficient or non-existent.

[0069] The consumable device 100 may be any type of consumable device as above-defined. The consumable device 100 comprises a proximal part configured to contact with a user. As shown for example in Fig. 7, it is understood that the consumable device is configured to contact the skin 0 of a user, be it any part of his / her body, such as a wrist, an arm or the chest. The skilled person may envisage many other locations wherein the consumable may be configured to contact the skin 0 for the user, all of which are deemed to be comprised within the present embodiment. As shown in Figs. 3 and 4, the consumable device further comprises a sweat induction means 20 on the proximal part and a sweat interrogation means 30, located distally to the sweat induction means 20. The sweat induction means 20 is therefore the most proximally located element of the consumable device 100.

[0070] The sweat induction means 20 comprises a sweat promoter 1 and a microfluidic structure 2. The sweat promoter 1 may be any type of element configured to promote the formation of sweat when in contact with the skin surface 0 of a user. For example, it may be a layer with hydrophilic properties by comprising hydrophilic means, such as biocompatible skin-gentle hydrophilic liquids, salts (e.g. NaCI, KCI, CaCh, MgSOt) or polymers (e.g. Polyethylene glycol (PEG) or Polyvinyl alcohol (PVA)). As described in Example 2 with respect Fig. 8 B, there is an enhanced sweat collection with salt relative to no salt. The sweat promoter 1 may also be a sweat-inducing molecule including sweat-inducing drugs. Sweat-inducing molecules may include: acetylcholine and cholinergic agents, which are known to stimulate muscarinic receptors in sweat glands when applied topically; pilocarpine, which is a particular cholinergic agonist that is known to stimulate muscarinic receptors when applied topically and inducing sweating; capsaicin which activates transient receptor potential vanilloid 1 (TRPV1) channels, inducing sweating through neurogenic inflammation; menthol, which activates TRPM8 receptors, which can cause a cooling sensation followed by reflex sweating methyl salicylate which, when applied topically, it can induce localized warming and sweating through vasodilation and irritation; or any other molecule known by the person skilled in the art (i.e. , that pertains to the common general knowledge) as being able to promote the formation of sweat when in contact with the skin surface. In other words, the contribution made by the present invention is the inclusion of a sweat promoter together with a microfluidic structure 2 as will be explained later, to gather sweat for sweat-based monitoring irrespective of the way or strategy used to promote sweat production.

[0071] Alternatively or additionally, the sweat promoter 1 may be an iontophoresis system. Iontophoresis is a known sweat induction technique that allows the acquisition of sweat samples while the body is sedentary. In iontophoresis a current is generated under the skin surface by applying a voltage between the iontophoretic electrodes, leading to an increase on the permeability of the skin, through which molecules can be introduced and an increase in the secretion of sweat induced.

[0072] The sweat promoter is configured to contact the skin 0 of a user. The microfluidic structure 2 may be of different types as above-described and as it will be developed below.

[0073] The sweat interrogation means 30 comprises a sample area 5 and a passive fluid pump 7. The sample area 5 may be any area suitable for collecting a fluid or sweat sample. It is no9ted Figs. 3 and 4 show a determined sample area 5, but the sample area 5 may take different shapes and sizes, as the skilled person may envisage. The passive fluid pump 7 may be of different types, as above described. For example it may comprise a hydrogel or an hydrophilic pad. The passive fluid pump 7 is configured to induce the flow of the liquid through the sample area 5. This may be achieved by locating the passive fluid pump 7 strategically either before or after the sample area 5 in the sense of the fluid. In a particular embodiment, as shown in Fig. 3, the passive fluid pump 7 is located after the sample area 5 in the sense of the fluid. Advantageously, having the passive fluid pump 7 located after the sample area 5 in the sense of the fluid provides for a more controlled and uniform flow through the entire sample area 5, minimizing issues like sample stagnation or bypassing, which is particularly important for continuous and quantitative analysis. This configuration ensures that the sensors in the sample area are constantly exposed to fresh sample.

[0074] In the first aspect of the invention, the microfluidic structure 2 is configured to convey fluid from the sweat promoter 1 to the sample area 5. Therefore, the fluid from the sweat promoter 1 is able to fill the sample area 5 with the help of the microfluidic system 2 and the passive fluid pump 7, wherein the microfluidic system conveys fluid from the sweat promoter 1 to the sample area 5 and the passive fluid pump 7 ensures the liquid flows through the sample area 5.

[0075] The microfluidic structure 2 may be configured to convey fluid from the sweat promoter 1 to the sample area 5 through capillarity or through any design means configured to facilitate a flow gradient from the sweat promoter towards the sample area, as the skilled person may envisage.

[0076] As shown in Figs 3 and 4 the consumable device 100 may comprise further other features that will be explained later on. These features are considered optional but preferred in some embodiments and / or applications It is also noted the consumable device 100 and its sweat promoter 1 , microfluidic structure 2, sample interrogation area 5, and passive fluid pump 7 from Figs. 3 and 4 have a determined shapes, proportions, locations and sizes that may differ in other embodiments of the present aspect of the invention. Also the order and configurations of the elements conforming the consumable device may differ from those depicted in Figs. 3 and 4 as long as they are within the claimed subject matter.

[0077] Advantageously, a consumable device 100 comprising a sweat induction means 20 and a sweat interrogation means (30) according to the first aspect of the invention can induce sweat and collect it for further analysis. This analysis may be in situ through a further monitoring device as will be explained further below, or remotely, though an analysis of the contents of the sample area in a dedicated separate system, such as a laboratory or a dedicated independent device. Therefore, this consumable device 100 does not need to rely on physical activity to obtain sweat. This is particularly important when natural perspiration is insufficient or non-existent. Moreover, the analysis can be performed continuously thanks to the passive fluid pump.

[0078] In a preferred embodiment of any one of the embodiments of the first aspect of the invention, the consumable device further comprises a distal part configured to contact with a sweat-based monitoring device 200. The distal part may be configured in different ways, as the skilled person may note. For example, it may comprise a dedicated connection means on its distal part, configured to match corresponding connection means of a sweat-based monitoring device 200, or it may comprise adhesive means configured to attach to a dedicated area of said sweat-based monitoring device 200. The sweat-based monitoring device 200 may be of different types, such as optical, chemical, electrochemical or enzymatic monitoring.

[0079] In this preferred embodiment, the sample area 5 is a sample interrogation area 5 distally accessible by the sweat-based monitoring device.

[0080] The sample interrogation area may be distally accessible by the sweat-based monitoring device in different ways. For example, an optical sweat-based monitoring device 200 only requires optical access to the sample interrogation area, particularly at least only on the wavelength it is configured to measure. However, a chemical sweat-based monitoring device 200 may require physical access to the sample interrogation area.

[0081] For electrochemical sweat-based monitoring devices 200 the sample interrogation area 5 would need to provide direct access contact with electrodes that can measure the electrical properties of the sweat, such as ion concentration or conductivity, requiring the area to be designed for optimal electrode placement and contact. The electrodes may be comprised in the consumable device 100 and electrical component be provided on the distal part of the consumable device for its access by a sweat-based monitoring device 200.

[0082] Advantageously, a consumable device 100 which comprises a distal part configured to contact with a sweat-based monitoring device 200 can be used to monitor biomarkers in the sweat locally when said sweat-based monitoring device 200 is attached to its distal end.

[0083] In another preferred embodiment of any one of the embodiments of the first aspect of the invention, the sweat promoter 1 comprises a non-woven cloth layer with hydrophilic properties. This layer amplifies the osmotic effect, ensuring efficient sweat transport. Its porous structure facilitates the swift movement of sweat, avoiding any potential blockages.

[0084] The hydrophilic properties may be achieved through different means as the skilled person may envisage. For example it may be embedded with a hydrophilic means, such as salts (e.g. NaCI, KCI, CaCh, MgSOt) or polymers (e.g. Polyethylene glycol (PEG) or Polyvinyl alcohol (PVA)) or any other type of hydrophilic substance the skilled person may envisage capable of inducing dehydration of the skin. It is noted that as long as the non-woven cloth layer has hydrophilic properties it will work as a sweat promoter 1.

[0085] In a further preferred embedment, the sweat promoter further comprises a methacrylate mesh layer. Advantageously, a methacrylate mesh layer facilitates conveying the fluid obtained by the non-woven cloth into a single place, preferably to a preferred place wherein the microfluidic structure 2 can receive said fluid to convey it to the sample interrogation area. The methacrylate mesh layer can be also embedded with a hydrophilic means to ensure the hydrophilic properties are maintained, or to further create a hydrophilic gradient. This serves a dual purpose. It creates an osmotic gradient through embedded hydrophilic means, which draw sweat through the mesh via osmotic flow. Additionally, the mesh features a design for hassle- free removal and replacement of the collector.

[0086] As shown in Figs. 3 and 4, in another preferred embodiment of any one of the embodiments of the first aspect of the invention, the microfluidic structure 2 is configured to passively convey the fluid from the sweat promoter 1 to the sample interrogation area 5. In a more particularly preferred embodiment, the microfluidic structure 2 is spirally-shaped or fractal-shaped.

[0087] It has been found that a spiral shaped microfluidic structure 2, as shown in Figs. 3 and 4, wherein the spiral goes from the centre of the sweat promoter towards an extreme of the consumable device in a spiral pattern, enables the passive movement of the fluid towards the sample area 5, even if moving towards said sample area 5 involves fighting gravity. The skilled person may envisage many other shapes, such as fractals that likewise enables a passive movement towards the sample area 5. It is therefore submitted all of these other alternatives are also comprised within this particular embodiment, including different types of spirally- shapes and fractal-shaped microfluidic structures.

[0088] In another preferred embodiment of any one of the embodiments of the first aspect of the invention, as shown in Figs 3 and 4, the sample area 5 comprises a sample input 4 and the microfluidic structure 2 is configured to convey the fluid from the sweat promoter 1 to the sample input of the sample interrogation area 5.

[0089] Advantageously, this allows for a controlled input of the fluid into the sample area (5).

[0090] In a more preferred embodiment, as shown in Fig. 4, the sweat promoter 1 comprises a fluid dense area, such as in the centre of the sweat promoter 1 and the microfluidic structure 2 is further configured to convey the fluid from the fluid dense area of the sweat promoter 1 to the sample input of the sample interrogation area 5.

[0091] In another preferred embodiment of any one of the embodiments of the first aspect of the invention, the passive fluid pump 7 is a hydrophilic pad, preferably a hydrophilic clotted salt- impregnated pad.

[0092] A hydrophilic pad can allow for a simple passive way of inducing the flow of the liquid through the sample area 5 by leveraging its inherent properties to attract and absorb water. Hydrophilic materials have an affinity for water molecules, which causes them to draw in and retain moisture from their surroundings. When the hydrophilic pad is placed in contact with the sample area 5, it begins to absorb sweat or other liquid samples through capillary action. This natural wicking effect pulls the liquid from the sample area into the pad without the need for any external power source or active pumping mechanism.

[0093] In the case of a hydrophilic clotted salt-impregnated pad, the presence of salts enhances this process by further attracting water molecules due to osmotic pressure differences. The salts create a high osmotic potential within the pad, which promotes the movement of water from areas of lower solute concentration, such as the sample area, to areas of higher solute concentration within the pad. This efficient absorption mechanism ensures that the liquid sample is continuously drawn through the sample area 5, facilitating consistent and reliable monitoring.

[0094] By utilizing a hydrophilic pad, the system benefits from a passive and maintenance-free method for of inducing the flow of the liquid through the sample area 5, making the design simpler, more cost-effective, and reliable for continuous operation.

[0095] In another preferred embodiment of any one of the embodiments of the first aspect of the invention, the passive fluid pump 7 is a hydrogel.

[0096] Hydrogels are networks of polymer chains that are highly absorbent and can retain a significant amount of water while maintaining their structure. Using a hydrogel as the passive fluid pump 7 has the advantage of providing a highly efficient, biocompatible, and self-regulating mechanism for inducing the flow of liquid through the sample area 5.

[0097] In another preferred embodiment of any one of the embodiments of the first aspect of the invention, as shown for example in Figs. 3 and 4 the consumable device further comprises a skin adhesive means 3.

[0098] Advantageously, the skin adhesive means allows to attach the consumable in an easy way to the skin of the patient in different surfaces of the body without requiring additional complex attaching means such as straps.

[0099] In another preferred embodiment of any one of the embodiments of the first aspect of the invention wherein the consumable device 100 further comprises a distal part configured to contact with a sweat-based monitoring device, as shown for example in Fig. 3, the distal part is configured to contact with an optical sweat-based monitoring device, and the sweat interrogation means further comprises an optical light diffuser 8 located distally to the sample area 5.

[0100] The optical light diffuser 8 can vary in type depending on the specific application and desired outcomes. For instance, it may utilize diffraction, scattering, or reflection mechanisms to achieve uniform illumination of the sample area 5, enhancing the accuracy and reliability of sweat analysis. Different types of optical light diffusers can be employed based on factors such as the nature of the optical sensors used and the characteristics of the sweat-based monitoring device.

[0101] It is noted that the optical light diffuser 8 may cover the entire sample area 5 or only a portion thereof, ass the skilled person may envisage. Moreover, the optical light diffuser 8 can be manufactured in various other shapes, which may vary according to the shape of the sample interrogation area 5.

[0102] In another preferred embodiment of any one of the embodiments of the first aspect of the invention wherein the consumable device 100 further comprises a distal part configured to contact with a sweat-based monitoring device 200, as shown for example in Figs. 3 and 4 the distal part is configured to contact with a sweat-based monitoring device through adhesive means 6. Advantageously, providing an adhesive means to conform the contact with a sweatbased monitoring device 200 provides for an easy connection between the consumable device 100 and a sweat-based monitoring device 200 that is reliably constant throughout the lifespan of said sweat-based monitoring device 200, since each consumable device 100 would comprise fresh adhesive means 100.

[0103] In a more preferred embodiment of any one of the embodiments of the first aspect of the invention, the adhesive means 6 configured to contact with a sweat-based monitoring device 200, and the skin adhesive means 3 are comprised in the same layer.

[0104] As shown in Figs. 3 and 4 the same layer can be adapted to comprise both the adhesive means 6 configured to contact with a sweat-based monitoring device 200 on one side and the skin adhesive means 3 on the other side of the same layer, the layer covering the rest of the consumable device. However, it is noted that the layer and each adhesive means 3, 6 may take different shapes and sizes depending on the skin surface and the sweat-based monitoring device 200 the consumable device 100 is configured to contact.

[0105] In another preferred embodiment of any one of the embodiments of the first aspect of the invention the sweat promoter 1 comprises fluorescently labelled markers of a biomarker.

[0106] Advantageously, when the sweat promoter 1 comprises fluorescently labelled markers of a biomarker, if the fluid comprises the biomarker, said fluorescently labelled markers are dragged through the microfluidic structure 2 to the sample area 5, where they can be detected.

[0107] This may be done by a further analysis if the contents of the sample area 5, for example in a laboratory, or through a sweat-based monitoring device, such as an optical sweat-based monitoring device. In a preferred embodiment, the biomarker is one or more selected from the following list: glucose, lactate, urea, cortisol, creatinine, iron, copper, chloride, sodium, mercurous ion tyrosine, neuropeptides, cytokines.

[0108] In another preferred embodiment, the consumable device is configured to contact the skin 0 of a wrist of a user, an arm or the chest of a user as shown in Fig. 7. This configuration may involve appropriate shape, dimensions and ergonomic changes to account for the placement on the skin 0 of the user.

[0109] In a more preferred embodiment, the proximal part of the consumable device is configured to contact the skin 0 of a wrist of a user. This may comprise the dorsal wrist and / or the volar wrist. Even further preferably, the proximal part of the consumable device is configured to contact the skin 0 of the volar wrist of the user. Advantageously, and as explained in Example with reference to Fig. 8, the volar wrist shows a significantly higher sweat uptake. More preferably, when the sweat promoter 1 is a salt-embedded sweat promoter 1 , the sweat uptake is even higher, as shown in Fig. 8.

[0110] A second aspect of the invention relates to a sweat-monitoring system, as shown for example in Figs. 1 and 2, the sweat monitoring system comprising a consumable device 100 according to any of the consumable devices of the first aspect of the invention; and a sweat-based monitoring device 200 comprising a proximal part and a distal part. The sweat-based monitoring device 200 further comprises: sensing means 13 and processing means 11.

[0111] The sensing means 13 are configured to obtain data from the sample interrogation area 5 through the proximal part of the sweat-based monitoring device 200. The sensing means 13 can utilize various technologies, such as chemical, electrochemical, enzymatic or optical sensors, to capture and analyse sweat composition and biomarkers. Chemical sensors may include electrochemical sensors capable of detecting ions or molecules in sweat, while optical sensors may employ spectroscopic techniques to measure analyte concentrations non- invasively. The choice of sensing means depends on factors such as the targeted analytes, sensitivity requirements, and desired application scenarios.

[0112] The processing means are 11 configured to process the information acquired by the sensing means. The processing means 11 can encompass different types of electronic circuits, algorithms, or software designed to interpret and analyse the data obtained from the sensing means. For instance, it may comprise one or more processing units, such as a microprocessor, GPU, CPU, multi-core processor or the like. The consumable device 100 and the sweat-based monitoring device 200 are configured to be connected such that the sweat-based monitoring device 200 contacts the distal part of the consumable device 100 through its proximal part.

[0113] As shown in Figs. 1 and 2 the sweat monitoring system may comprise further other features, such as an outer housing 12 for the sweat-based monitoring device 200 as will be explained later on. It is also noted the sweat monitoring system from Figs. 1 and 2 have a determined shapes, proportions and sizes that may differ in other embodiments of the present inventions. Also the order and configurations of the elements conforming the consumable device may differ as long as they are within the claimed subject matter.

[0114] Advantageously, a sweat monitoring system of the second aspect of the invention, allows for monitoring sweat biomarkers in situ even in conditions wherein the user would normally not sweat, for example when the user is not doing exercise, or where ambient conditions are not propitious for sweating.

[0115] In a preferred embodiment of the second aspect of the invention, the biomarker is one or more selected from the following list: glucose, lactate, urea, cortisol, creatinine, iron, copper, chloride, sodium, mercurous ion tyrosine, neuropeptides, or cytokines.

[0116] In another preferred embodiment of the second aspect of the invention, the sweat-based monitoring device 200 is an optical sweat-based monitoring device. In this embodiment, the sensing means comprise: at least one photodetector sensor and one light source. The photodetector sensor may be a photodiode, a phototransistor, photomultiplier Tubes (PMTs), or even a complementary metal-oxide-semiconductor (CMOS) sensor, as the skilled person ay envisage. All of these and other alternatives are comprised within the present disclosure. Regarding the light source it may be a Light Emitting Diode (LED) but it is not limited to such, and may be a Laser diode or any other light source that the skilled person may envisage for a wearable.

[0117] Moreover, the sensing means are configured to directly access the proximal part of the consumable device 100. If the sweat-based monitoring device 200 comprises a housing 12, the housing may comprise an opening to allow the photodetector sensor and light source to directly access the proximal part of the consumable device 100.

[0118] Advantageously, the fluid comprised in the sample interrogation area 5 can be optically analysed. For example, fluorescently labelled markers can be identified in the sample interrogation area 5 if the fluid comprises the biomarker said fluorescently labelled markers are configured to mark. In a more preferred embodiment of the second aspect of the invention, as shown in Fig. 6, the light source is configured to emit light in at least three different wavelengths. In a particularly more preferred embodiment, the light source is configured to emit light at least in 880 nm, 660nm and 537 nm wavelengths.

[0119] In an even more preferred embodiment of the second aspect of the invention, the sensing means is a photoplethysmography (PPG) device.

[0120] Traditional photoplethysmography (PPG) involves illuminating the skin with light and measuring the variations in light absorption or reflection caused by blood flow. PPG allows for physiological monitoring, including heart rate monitoring, blood oxygen saturation (SpO2) measurement, and assessment of vascular health.

[0121] Therefore, integrating the PPG technology as the sensing means in the preferred embodiment of the optical sweat-based monitoring device enhances the versatility and functionality of the sweat-monitoring system, enabling real-time assessment of biomarker in sweat with high accuracy and reliability.

[0122] In another preferred embodiment of the second aspect of the invention, and as shown in Figs. 1 ,2 and 7 the sweat-monitoring system is a wearable system.

[0123] All of the above are fully within the scope of the present disclosure, and are considered to form the basis for alternative embodiments in which one or more combinations of the above described features are applied, without limitation to the specific combination disclosed above.

[0124] In light of this, there will be many alternatives which implement the teaching of the present disclosure. It is expected that one skilled in the art will be able to modify and adapt the above disclosure to suit its own circumstances and requirements within the scope of the present disclosure, while retaining some or all technical effects of the same, either disclosed or derivable from the above, in light of his common general knowledge in this art. All such equivalents, modifications or adaptations fall within the scope of the present disclosure.

[0125] EXAMPLES

[0126] Example 1

[0127] The present sweat monitoring system (see Figs. 1 and 2) aims to overcome the limitations of existing glucose-monitoring wearable technologies measuring biomarkers in sweat by integrating in a compact solution: I. a non-invasive sweat-inducing and collection consumable patch 100;

[0128] II. a compact optical system for sample interrogation;

[0129] III. an electronic system to collect, analyse, and communicate the data;

[0130] IV. an algorithm to convert the raw data into biomarker concentration and nature by means of machine learning to distinguish the composition of the signal related to each biomarker, increasing specificity.

[0131] By leveraging recent advancements in wearable sensor technology, materials science, optoelectronics, microfluidic, and sustainability, the proposed device achieves high sensitivity and selectivity for biomarkers detection in sweat including glucose and lactate detection while at the same time ensuring long-term wearability and life of the device. The device's compact and ergonomic design allows for discreet and comfortable wearing, enabling users to monitor their glucose and lactate levels seamlessly throughout the day.

[0132] The sweat monitoring system is composed of a durable sweat-based monitoring device 200 comprising the optoelectronic, data analysis and transmission components, and a consumable device 100 for non-invasive sweat induction, and collection (see Fig. 1).

[0133] The proposed integrated technology is now depicted by explaining the functionality and structure of its core components.

[0134] The non-invasive sweat-inducing and collection consumable patch 100 is a multi-layered microfluidic patch composed of different materials with different properties (see Fig. 3).

[0135] In combination they:

[0136] 1) help raise skin temperature of about 2 C

[0137] 2) Combine a sweat promoter made of a non-woven osmotic membrane and a flow promoter made of a non-woven salt-impregnated pad to facilitate the sweat withdrawal from the skin and its meter to the sensor area;

[0138] 3) Provide an optical window for continuous optical interrogation of the sweat.

[0139] In the specific, the patch 100 is a wearable, skin-contactable device that collects sweat from the user's skin. It incorporates microfluidic channels 2, sweat and flow promoters 1 to induce sweating and meter the sweat to the sensor area with the optical window. It comprises:

[0140] Skin Adhesive Layer 3: An ultra-thin, hypoallergenic adhesive layer that comfortably adheres to the skin, ensuring consistent contact without causing irritation or discomfort. It is designed to prevent sweat leakage, maintaining its integrity even during intense physical activity.

[0141] • A sweat promoter 1 : composed of a composite material made of methacrylate mesh layer embedded with NaCI. This is positioned directly above the adhesive layer; this biocompatible methacrylate mesh serves a dual purpose. It creates an osmotic gradient through embedded NaCI particles, which draw sweat through the mesh via osmotic flow. Additionally, the mesh features a design for hassle-free removal and replacement of the collector. Below the methacrylate mesh lies a non-woven cloth layer impregnated with NaCI. This layer amplifies the osmotic effect, ensuring efficient sweat transport. Its porous structure facilitates the swift movement of sweat, avoiding any potential blockages.

[0142] • A structured architecture to provide a conical scaffold to the Sweat promoter. This configuration will aid the fluid to concentrate from the border of the sweat promoter to the input of the microfluidic path and will provide tick marks for the optical determination of a person's sweat rate and dehydration levels.

[0143] • Vertical Microfluidic Path 2: The core component of the collector is the vertical microfluidic path. This complex arrangement of capillaries and channels meticulously directs the flow of sweat downward.

[0144] • A sample area 5 for optical detection of the analyte of choice;

[0145] • A passive fluid pump 7 composed of a super-hydrophilic clotted salt-impregnated pad that acts as a passive pump to aid the sweat to flow from the skin, through the optical window to the outlet.

[0146] The ability to monitor targeted biomarkers accurately and continuously from the collected sweat is performed by means of a miniaturized optoelectronic setup. This is composed of:

[0147] • Internal LEDs to emit light at different wavelengths of 880, 660, and 537 nm;

[0148] • Photodetectors that detect the light reflected from the sweat sample within the optical window;

[0149] • Optical elements to optimize the transmission of light;

[0150] • Low-noise electronics to process the detected signals;

[0151] • CMOS sensor to monitor fluid transport and sweat rates;

[0152] • Ambient Light Rejection to minimize interference from external light sources;

[0153] • Hardware electronic element, encapsulated in a bio-compatible plastic injection housing 12 and a hypoallergenic band. The collection, analysis, and data transmission are performed by means of firmware. It works in real-time, and continuous using an integrated solid memory, a multiplexed design of I2C signal input ports, and a serial digital communication system for the photodetectors integrated into the device. The real-time capability of the physical sensors and firmware in parallel enables the capture of different biomarker information at the same time as the overall absorbed signals from which they are extracted are acquired.

[0154] In addition to the measurement and signal processing systems, the integrated system includes elements for its correct operation: a rechargeable battery and operation commands (for example start, stop, connect). There is an in-memory data storage protocol to avoid its loss in case of disconnection from the communication network and embedded algorithms to process the data obtained from the different sensors. The embedded algorithm uses the digitised electrical response and applies supervised learning algorithms such as multivariate signal regression to correlate the signal composition generated from different LEDs with the biomarker concentration. Furthermore, to increase the prediction's sensitivity and specificity, the algorithm can apply Neural-Network by means of frequency and temporal spectrum analysis. The collected, and analysed data are then transmitted in near real-time for sufficient functionality and operability through an associated mobile application to a cloud-based platform, where Support Vector Regression or Random Forest Regression might be performed for further increase of performance.

[0155] As shown in Figs. 5A, the optical determination of the sweat rate can be performed through image processing. The CMOS sensor is set up to record the field of view where the liquid and tick marks are visible. Frames are captured from the video stream at regular intervals (e.g., every second). Image processing techniques are applied to detect the liquid and the tick mark and to convert this info in sweat rate, as shown in Fig. 5B

[0156] Example 2

[0157] Non-invasive sweat monitoring holds promise for tracking metabolic health, but existing technologies require physical exertion to generate analyzable sweat volumes, limiting utility for sedentary or chronically ill users. In the present example, we present a wearable system combining a consumable osmotic patch and optical reader that enables exercise-free, multianalyte sweat monitoring. The patch employs a salt-impregnated composite promoter to induce sweat via passive osmotic gradients, while spiral microfluidics and a distal hydrophilic pump ensure continuous flow through an optical interrogation zone. A photoplethysmography (PPG)-based diffuse reflectance spectrometer analyzes biomarkers (glucose, lactate, electrolytes) in microliter volumes. Clinical validation in diabetic cohorts demonstrated a Mean Absolute Relative Difference (MARD) of 12% against capillary blood glucose, outperforming commercial electrochemical sensors. This system resolves the "sedentary sweat paradox," enabling reliable monitoring without physical activity, and represents a paradigm shift toward passive, personalized metabolic health tracking.

[0158] Introduction

[0159] Sweat is a rich source of biomarkers, including glucose, lactate, and electrolytes, offering a non-invasive window into metabolic health. However, most wearable sweat sensors rely on physical activity to generate sufficient sample volumes, limiting use cases for sedentary individuals or patients with limited mobility. Prior solutions, such as iontophoresis or thermal stimulation, require external power or risk skin irritation. Microfluidic systems improve sample handling but lack integrated mechanisms to induce sweat at rest.

[0160] We address these limitations through a passive osmotic-driven wearable system. Our consumable patch combines a NaCI-embedded composite promoter to induce sweat via osmotic gradients and fractal microfluidics to guide sweat to an optical interrogation zone. Unlike prior art, which focuses on passive collection or evaporation-driven pumps, our design ensures continuous flow without external energy. Paired with a PPG-based optical reader, the system enables multi-analyte detection in sedentary users, a critical advance for chronic disease management.

[0161] 1. Osmotic Sweat Induction and Microfluidic Transport

[0162] The consumable patch features a sweat induction layer comprising a non-woven cotton pad (85% NaCI w / w) and a methacrylate mesh. Upon skin contact, hydration triggers osmotic extraction, generating 15 ± 3 pL / h of sweat in resting volunteers (n=12), a 3* improvement over unmodified controls (p<0.01). Spiral microfluidic channels (1 .2 ± 0.3 pL / s flow rate) and a distal hydrophilic pump sustain flow through the interrogation chamber, avoiding stagnation.

[0163] Evaluation of a salt-embedded pad for sweat collection during sedentary activity and identification of application site can be seen in Figure 8. A.i Schematic of the two application sites on the wrist: site A (dorsal wrist) and site B (volar wrist). A.ii Illustration of the sedentary activity performed by participants during the wear time. B Comparison of sweat absorption between pads with and without embedded salt at sites A and B, showing enhanced sweat collection with salt (light grey bars) relative to no salt (dark grey bars). C.i Time-course of sweat absorbed at site A (dorsal wrist) across various wear durations, with relatively low sweat accumulation and minimal change over time. C.ii Time-course of sweat absorbed at site B (volar wrist), demonstrating significantly higher sweat uptake, especially with salt-embedded pads. The shaded region indicates the average absorbed sweat volume across trials at each time point.

[0164] A Step-by step protocol for sweat collection using the salt embedded patch can be seen in Figure 9:

[0165] (i) Remove the patch and bag from storage.

[0166] (ii) Record the serial number on the label and match it with the anonymized volunteer ID.

[0167] (iii) Attach the label to the patch while still in the bag.

[0168] (iv) Weigh the patch before application to establish the baseline mass.

[0169] (v) Remove the release liners.

[0170] (vi) Apply the patch to the anterior (volar) wrist, preferably the left arm, with the absorptive side facing the skin.

[0171] (vii) Allow the patch to remain on the skin for 1 hour during sedentary activity.

[0172] (viii) Weigh the patch again after removal to determine the mass difference.

[0173] (ix) Place the used patch back into a new labelled bag and store it in a refrigerator for subsequent analysis.

[0174] Note: Sweat volume was calculated based on the difference in patch mass before and after application, assuming the density of sweat to be approximately equal to water (1 mg = 1 pL)

[0175] Figure 10 shows the sweat collection performance across 12 volunteers:

[0176] - A.i Pie chart showing the gender distribution of participants and their corresponding average sweat absorbed using the salt-embedded pad. Men (light grey) produced an average of 13.4 pL of sweat, while women (black) produced an average of 7 pL.

[0177] - A.ii Bar graph displaying individual sweat absorption values for each of the 12 volunteers. The dashed grey line indicates the overall average (mean), and the solid blue line represents the median sweat volume collected across all participants. Considerable variability is observed among individuals, with some outliers exhibiting substantially higher sweat absorption.

[0178] 2. Optical Interrogation and Biomarker Detection

[0179] The optical reader employs three LEDs (537 nm, 660 nm, 880 nm) and a photodetector to perform diffuse reflectance spectroscopy. In a pilot study (n=11), glucose detection achieved a MARD of 16% (850 data points) against capillary blood. Post-firmware optimization reduced MARD to 12%.

[0180] The graphs presented in Figure 11 illustrate the relationship between glucose concentration in sweat and the normalized intensity of photoplethysmography (PPG) signals across three different channels: infrared (IR), green, and red. Each graph plots the normalized intensity against glucose concentrations of 0.1018 mg / dL, 0.3036 mg / dL, 1.2815 mg / dL, and 1.8018 mg / dL. Artificial sweat solution has been prepared to cover the largest possible range of glucose concentrations that can be found in humans, according to scientific literature.

[0181] IR Channel: The scatter plot for the IR channel shows a clear trend where the normalized intensity increases with higher glucose concentrations. This suggests a positive correlation between glucose levels and the IR PPG signal, indicating the potential of IR light for glucose detection in sweat.

[0182] Green Channel: The green channel plot also demonstrates an increasing trend in normalized intensity with rising glucose concentrations. However, the correlation appears to be less pronounced compared to the IR channel, suggesting that while green light can detect glucose, it may be less sensitive than IR light.

[0183] Red Channel: Similar to the IR and green channels, the red channel plot shows an upward trend in normalized intensity with increasing glucose concentrations. The data points indicate a moderate correlation, positioning the red channel as a viable option for glucose detection, albeit with potential limitations in sensitivity.

[0184] To perform the calibration curve three different sweat patches have been used and 5 measurements per concentration per patch have been performed for a total of 45 data points. This test has led to a preliminary algorithm for the prediction of the blood glucose starting from the measurement of the intensity of light generated from the glucose in sweat.

[0185] The Proposed invention is applied building a system that begins with a pre-wetted, non-woven pad embedded with salts (Figure 12 from bottom to top) , placed to induce and sustain non- invasive sweat extraction through osmotic pressure. This encourages consistent sweat generation directly from the eccrine glands, even in the absence of physical exertion. The sweat then travels through hydrophilic microfluidic channels, which use capillary action to efficiently guide the fluid toward the optical detection zone.

[0186] Once inside the detection chamber, sweat — containing glucose and other biomarkers — is optically interrogated by the Optical Reader, a miniaturized system based on diffuse reflectance spectroscopy. The chamber’s interior includes a highly reflective white background, with the aim to enhance light scattering and improve detection sensitivity. The optical reader itself employs a multi-wavelength light source, typically using red, green, and infrared LEDs adapted from photoplethysmography (PPG) technology. As the light passes through the migrating sweat sample, specific wavelengths are absorbed by glucose molecules, while others are reflected or scattered. At the distal end of the interrogation chamber lies the outlet of the microfluidic path, which is connected to the nonwoven skin-adhesive pad. This interface both encourages sweat extraction and functions as a passive pump, sustaining fluid flow into the sensing region.

[0187] This compact, low-power setup allows the present invention to function as a wearable diffuse reflectance spectrophotometer — capable of detecting potentially not only glucose but also other analyte-related shifts, all in real-time as sweat transitions from the skin into the sensing layer.

[0188] Figure 13 shows an Example of continuous glucose monitoring obtained with the proposed invention (clear grey), black dots represents control points of direct blood glucose measurement, dark grey lines represent control points measuring glucose values in the interstitial fluid with commercially available CGM devices (Abbott Freestyle Libre 2).

[0189] Figure 14 shows the validation of non-invasive glucose monitoring using a wearable sweat sensor. The study included two cohorts:

[0190] 1) continuous monitoring of 12 volunteers (10 healthy, 1 with type 1 diabetes, and 1 with type 2 diabetes) at the Onalabs InnoHub (blue), and

[0191] 2) on-demand measurements from 30 type 2 diabetic patients at a Primary Care Center (orange, 51% women, 49% men).

[0192] Glucose was monitored non-invasively through sweat with potential of perspiration tracking. The system might connect with ONAVITAL to provide real-time wellness and precision data. The Consensus Error Grid compares predicted blood glucose levels from the ONAMED system against reference blood glucose values, showing most points within clinically acceptable zones A and B.

[0193] A total of 983 paired data points were analyzed, yielding a Mean Absolute Relative Difference (MARD) of -20%, indicating promising accuracy. The lower panel shows an example of a 12- hour trace comparing ONAMED-predicted glucose (blue) with a commercial continuous glucose monitor (CGM) (green), highlighting alignment and temporal trends. 3. Clinical Validation in Diabetic Cohorts

[0194] A 60-patient trial (Type 2 diabetes) demonstrated 95% concordance with conventional blood analysis performed in the laboratory setting of a primary care center unit.

[0195] Discussion The proposed system has the potential to resolve critical limitations in non-invasive monitoring. By decoupling sweat generation from physical activity, it enables reliable tracking in sedentary users — a population often excluded from existing solutions. The osmotic induction mechanism, consuming no external power, is biocompatible and scalable, addressing safety concerns of iontophoresis. The PPG-based optical system offers advantages over electrochemical sensors, including immunity to biofouling and simultaneous multi-analyte detection. Clinical validation in diabetic cohorts confirms viability for chronic disease management, with accuracy rivaling invasive glucometers. Furthermore given the application site, it has strong potential to be coupled with smart watches or other medical wearable devices such as the ONAVITAL, providing so a more comprehensive overview of the person status. In figure 15, it can be seen example of a diabetic type 2 volunteer that wore the two devices in a bracelet fashion to monitor non- invasively and continuously glucose, pulse rate, diastolic pressure, systolic pressure, oxygen saturation and skin temperature.

Claims

CLAIMS1. A consumable device (100) for sweat-based monitoring, the consumable device comprising a proximal part configured to contact with a user, the consumable device further comprising: a. a sweat induction means (20) on the proximal part, the sweat induction means (20) comprising: i. A sweat promoter (1) configured to contact the skin (0) of a user and to promote the formation of sweat when in contact with the skin (0), and ii. a microfluidic structure (2); b. a sweat interrogation means (30), located distally to the sweat induction means (20), the sweat interrogation system comprising: i. a sample area (5); and ii. a passive fluid pump (7) configured to induce the flow of the liquid through the sample area (5); wherein the microfluidic structure (2) is configured to convey fluid from the sweat promoter (1) to the sample area (5); and wherein the passive fluid pump (7) is located after the sample area (5) in the sense of the fluid.

2. The consumable device according to claim 1 , wherein the sweat promoter (1) comprises a hydrophilic layer embedded with a salt.

3. The consumable device according to any one of claims 1 or 2, wherein the sweat promoter (1) comprises a non-woven cloth layer with hydrophilic properties.

4. The consumable device according to claim 3, wherein the sweat promoter (1) comprises a non-woven cloth layer embedded with hydrophilic means.

5. The consumable device according to any one of claims 3 or 4, wherein the sweat promoter (1) further comprises a methacrylate mesh layer.

6. The consumable device according to any one of claims 1 to 5, wherein the sweat promoter (1) comprises a sweat-inducing drug.

7. The consumable device according to any one of claims 1 to 6, wherein the sweat promoter (1) comprises a iontophoresis system.

8. The consumable device according to any one of claims 1 to 7, wherein the consumable device (100) further comprises a distal part configured to contact with a sweat-based monitoring device (200), and wherein the sample area (5) is a sample interrogation area (5) distally accessible by the sweat-based monitoring device (200).

9. The consumable device according to any one of claims 1 to 8, wherein the sweat promoter (1) comprises: a. a non-woven cloth layer with hydrophilic properties.

10. The consumable device according to any one of claims 1 to 9, wherein the microfluidic structure (2) is spirally-shaped or fractal-shaped.

11. The consumable device according to any one of claims 1 to 10, wherein the sample area (5) comprises a sample input (4) and wherein the microfluidic structure (2) is configured to convey the fluid from the sweat promoter (1) to the sample input (4) of the sample interrogation area (5).

12. The consumable device according to any one of claims 1 to 11 , wherein the passive fluid pump (7) is a hydrophilic pad.

13. The consumable device according to an claim 12, wherein the passive fluid pump (7) isa hydrophilic clotted salt-impregnated pad.

14. The consumable device according to any one of claims 1 to 13, wherein the passive pump (7) is a hydrogel.

15. The consumable device according to any one of claims 1 to 14, wherein the consumable device further comprises a skin adhesive means (3).

16. The consumable device according to any one of claims 8 to 15, wherein the distal part is configured to contact with an optical sweat-based monitoring device, and wherein the sweat interrogation means (30) further comprises: iii. an optical light diffuser (8) located distally to the sample interrogation area (5).

17. The consumable device according to any one of claims 7 to 16, wherein the distal part is configured to contact with a sweat-based monitoring device (200) through adhesive means (6).

18. The consumable device according to any one of claims 1 to 17, wherein the sweat promoter (1) comprises fluorescently labelled markers of a biomarker.

19. The consumable device according to any one of claims 1 to 18, wherein the proximal part is configured to contact with a wrist of the user.

20. The consumable device according to any one of claims 1 to 19, wherein the proximal part is configured to contact with a volar wrist of the user.

21. A sweat-monitoring system, the sweat monitoring system comprising: a. a consumable device (100) according to any one of claims 1 to 20; and b. a sweat-based monitoring device (200) comprising a proximal part and a distal part, the sweat-based monitoring device (200) further comprising;i. sensing means (13) configured to obtain data of the sample interrogation area (5) through the proximal part of the sweat-based monitoring device (200); ii. processing means (11) configured to process the information acquired by the sensing means; wherein the consumable device (100) and the sweat-based monitoring device (200) are configured to be connected such that the sweat-based monitoring device (200) contacts the distal part of the consumable device (100) through its proximal part.

22. The sweat monitoring system according to claim 21 wherein the sweat-based monitoring device is an optical sweat-based monitoring device; wherein the sensing means comprise: a photodetector sensor and a light source; and wherein the sensing means are configured to directly access the proximal part of the consumable device.

23. The sweat monitoring system according to claim 22, wherein the light source is configured to emit light in at least three different wavelengths.

24. The sweat monitoring system according to claim 21 or 23, wherein the sensing means is a photoplethysmography (PPG) device.

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