Determining sweat parameters

Abstract

An apparatus (1) for determining a sweat parameter of a user is provided, the apparatus comprising a microfluidic structure (10) having a collection chamber (16) configured to collect sweat from a first skin area (i) and a sensor (12) configured to determine a sweat parameter from the sweat from the first skin area (i). The apparatus further comprises an evaporation control chamber (14) connected to the microfluidic structure (10) and configured to wet the microfluidic structure (10) with a fluid collected at a second area (ii). The wetting of the microfluidic structure (10) aims at increasing the available sweat for the sensor to determine the sweat parameter by increasing the humidity inside the microfluidic structure (10) and thereby reducing the evaporation of the sweat. A method for determining a sweat parameter of a user is also provided.

Description

Technical Field

[0001] This invention relates to an apparatus and method for determining a user's sweat parameters. Background Technology

[0002] There is a need for non-invasive, semi-continuous, and long-term monitoring of biomarkers indicating health and well-being. For example, such biomarker monitoring could be useful in assessing dehydration, stress, sleep, child health, and perioperative monitoring. Sweat is a poorly accessible biofluid and a rich source of information related to the physiology and metabolism of subjects.

[0003] Some examples of clinically relevant biomarkers in sweat are Na+, Cl-, or K+ ions for monitoring dehydration and cystic fibrosis diagnosis; lactic acid as an early warning sign of inflammation (which is associated with sepsis); glucose for diabetic patients and newborns; urea for monitoring skin condition and dehydration; ethanol for monitoring alcohol use; ammonium for monitoring metabolic disorders; and cortisol for monitoring stress.

[0004] Despite promising results from clinical studies as early as the 1940s and 1950s, the development of reliable sweat sensing technology has been hampered by several problems. To date, the effective application of sweat analysis has been primarily limited to the diagnosis of cystic fibrosis and drug and alcohol abuse testing.

[0005] As Mena-Bravo and de Castro summarized in “Sweat: A sample with limited present applications and promising future in metabolomics” (J. Pharm. Biomed. Anal. 90, 139–147 (2014)), it has been found that the results of sweat sensing can be highly variable, and there appears to be a lack of correlation between values ​​determined from blood and sweat samples for various biomarkers.

[0006] To address these issues, efforts have been made to enable wearable sensors to come into contact with sweat almost immediately as it is expelled from the skin. One example is the wearable patch proposed by Gao et al. in “Fully integrated wearable sensor arrays for multiplexed in situ perspiration analysis” (Nature 529, 509-514 (2016)). This patch includes an array of sensors for measuring Na+, K+, glucose, lactic acid, and skin temperature. However, this research focused on the development and integration of the sensors themselves, which, while clearly crucial, did not address the problems related to sweat collection. The latter primarily involves placing sensors with an area of ​​approximately a few centimeters between the skin and the sensor. 2 The absorbent pad is used to perform this task. The assumption is that if a large amount of sweat is produced (hence the test on someone engaging in strenuous exercise), the absorbent pad will absorb the sweat for analysis, and newly produced sweat will refill the absorbent pad and "wash away" the old sweat. However, due to the cumulative effect, the time-dependent response of the sensor is unlikely to directly reflect the actual level of the biomarker over time, making it difficult to reliably sense continuously over long periods. Such a patch may also not be designed to handle the small amounts of sweat typically produced by individuals at rest and in a thermally comfortable state, such as in the range of 0.03–0.1 nL / min / gland.

[0007] EP3649941A1 relates to an apparatus, system, and method for estimating the concentration of an analyte in sweat released from sweat glands. It also relates to a switching sensor device for sensing the concentration of an analyte in sweat released from sweat glands, and a trigger sensor device for sensing the concentration of an analyte in sweat released from sweat glands.

[0008] There is currently considerable interest in continuous sweat measurement. A major problem that needs to be addressed is the physiological mechanisms of temperature regulation that cause the rapid evaporation of tiny sweat droplets on the skin. Summary of the Invention

[0009] This invention is defined by the independent claims. Advantageous embodiments are defined in the dependent claims.

[0010] It would be advantageous if the device for determining a user's sweat parameters included features that reduce unwanted sweat evaporation. To better address one or more of these problems, in a first aspect of the invention, a device for determining a user's sweat parameters is provided, the device comprising:

[0011] A microfluidic structure includes a collection chamber and a sensor, the collection chamber being configured to collect sweat from a first skin region, and the sensor being configured to determine sweat parameters based on the sweat from the first skin region.

[0012] An evaporation control chamber, which is fluidly connected to the microfluidic structure, is configured to wet the microfluidic structure using fluid collected in a second region, wherein the second region is a second skin region and / or the surface of a condensing element configured to condense vapor released by the device.

[0013] The device is configured to collect sweat from a specific skin area (i.e., a first skin area) of the subject and to use sensors to determine the subject's sweat parameters based on the sweat collected from the first skin area.

[0014] The second region can be a second skin region. Any other skin region in the object that does not include the first skin region is a second skin region, and it may be adjacent to the first skin region. The first skin region is defined as the skin region in contact with the collection chamber of the device. Any other skin region that does not contact the collection chamber is a second skin region. Fluid (i.e., sweat or transepidermal water (TEW)) is discharged in the second skin region. The device is configured to utilize this sweat or TEW as a humidity source to wet its microfluidic structure, increase the vapor pressure within its microfluidic structure, and thus reduce the evaporation of sweat (i.e., sweat originating from the first skin region) used to determine sweat parameters.

[0015] By reducing sweat evaporation from the primary skin area, the amount of liquid sweat available reaching the sensor is increased, and the accumulation of dry components in the sweat can be prevented, thus avoiding hindering reliable and reproducible flow within the device. Furthermore, due to the reduced total volume of liquid sweat, sweat evaporation may alter the concentration of biomarkers in the liquid sweat reaching the sensor. Additionally, sweat evaporation may also impede the determination of sweat rate. Therefore, reducing sweat evaporation can also improve the measurement results of the sweat sensor.

[0016] The device can be a wearable device. Wearable devices can improve ease of use, are comfortable for the subject to wear for extended periods, and are suitable for continuous measurements over long periods (e.g., days or weeks).

[0017] According to embodiments of the invention, the fluid from the second skin region (i.e., sweat or TEW to be used to wet the microfluidic structure of the device) can be in a liquid or gaseous state. For example, the fluid can evaporate in an evaporation control chamber to increase humidity within the microfluidic structure, which is connected (i.e., fluid-connected) to the evaporation control chamber. In another example, the fluid is collected in the evaporation control chamber and delivered in a liquid state to the microfluidic structure to wet the sensor or other components of the microfluidic structure and maintain a humid environment within the device.

[0018] Sweat from the primary skin area is collected in a collection chamber. The collection chamber may include a conical column. The conical column reduces the overall volume within the collection chamber and the impact of fluid movement, thereby reducing the time required to fill the collection chamber. The collection chamber may include a hydrogel or wicking material.

[0019] Furthermore, the microfluidic structure may include a first absorber connected to the collection chamber and the sensor via a microfluidic channel. Sweat from a first skin region is collected in the collection chamber and, due to pressure from the sweat glands and capillary action, is transported along the sensor and ultimately into the first absorber. Alternatively, sweat may move along the microfluidic channel based on discrete droplet transport (e.g., based on passive chemical gradients or electrowetting techniques). Since the sweat received by the first absorber has already passed through the sensor, measurement is no longer required, and the sweat can be stored and evaporated. Wetting of the first absorber keeps the microfluidic channel moist, thus helping to reduce the evaporation of sweat from the first skin region that has not yet passed through the sensor. The gradual evaporation of sweat from the first absorber also helps to create a pressure gradient within the microfluidic channel, thereby facilitating the transport of sweat from the collection chamber to the sensor and ultimately into the absorber.

[0020] The wetting of the microfluidic structure by the evaporation control chamber reduces the evaporation rate of sweat from the first absorber. While it is desirable for sweat to evaporate from the first absorber, it is also desirable that this evaporation rate be limited, because rapid evaporation of sweat from the first absorber would also lead to rapid evaporation of sweat within the microfluidic channels, causing the sweat to evaporate before reaching the sensor.

[0021] In addition, the sensor may include an vent for expelling sweat that has entered the sensor. The vent removes sweat, preventing it from accumulating inside the sensor and thus allowing space for new sweat to enter and be measured by the sensor. For the same reasons as with the first absorber, while it is desirable to remove sweat from the sensor through the vent, it is also desirable to limit the removal rate.

[0022] In one set of examples, the evaporation control chamber is directly connected to the first absorber or vent of the sensor in the microfluidic structure. In this example, fluid in the second skin region, in a vapor, liquid, or both state, can flow directly to the first absorber, or to the sensor's vent, or to both the first absorber's and sensor's vents. Directly wetting the first absorber or sensor's vent (as a component connected to the microfluidic channel) reduces the evaporation of sweat within the microfluidic channel, allowing sweat from the first skin region to travel through the microfluidic channel to the sensor.

[0023] In another example, the evaporation control chamber may include a second absorber configured to receive fluid collected from the second skin region and configured to wet the microfluidic structure. The evaporation control chamber may also include a fluid delivery device configured to deliver droplets of fluid to the second absorber.

[0024] Fluid transporters (e.g., those based on passive chemical gradients or electrowetting to move discrete droplets) provide faster fluid transport than capillary action. The advantage of a second absorber is that it is configured to stimulate fluid evaporation as quickly as possible, resulting in an increased wetting rate of the microfluidic structure.

[0025] In another example, the evaporation control chamber may include a fluid conveyor configured to deliver droplets of fluid to the first absorber.

[0026] In another example, the evaporation control chamber may also include a heater. Skin temperature may be sufficient to generate adequate evaporation within the evaporation control chamber. However, it may be beneficial for the heat generated from the heater to stimulate the evaporation of fluid originating from a second skin region.

[0027] In another example, the device may include a vent and a condensing element. The vent is configured to release vapor from the device, and the condensing element is connected to the vent and the microfluidic structure and configured to condense the vapor. Furthermore, the device is constructed of a first material having a first thermal resistance located at the collection chamber and the sensor, and a second material having a second thermal resistance located at the vent and the condensing element. Additionally, the first thermal resistance is configured to be higher than the second thermal resistance to condense the vapor before releasing it from the device.

[0028] A vent releases steam from the device to reduce internal pressure and allow fresh sweat from the first skin region to be collected and delivered to the sensor. To prevent rapid evaporation of sweat from the first skin region within the microfluidic structure and therefore within the microfluidic channels, humidity should be maintained at a high level. Therefore, a temperature gradient is created to promote condensation of steam before it leaves the device through the vent. To create this temperature gradient, the device is constructed of a first material that surrounds the portion of the device containing the collection chamber and the sensor. This first material has a first thermal resistance. The device is constructed using a second material in the portion surrounding the vent and the condensation element. This second material has a second thermal resistance, and the first thermal resistance is higher than the second thermal resistance.

[0029] The first material, having a greater thermal resistance than the materials used at the vent and condenser elements, generates a temperature gradient near the skin (i.e., at the collection chamber) with a higher temperature than at the vent and condenser elements. The lower thermal resistance of the second material at the vent and condenser elements causes them to have a temperature closer to ambient temperature, which is cooler than the steam. Contact between the steam and the cooler surface will cause some of the steam to condense. Therefore, the condensed steam will flow back into the equipment, reducing moisture loss from within the equipment.

[0030] In this example, the second region is the surface of the condensing element. In this example, the device does not need to collect fluid from the second skin region. Sweat from the first skin region, having passed through the sensor, increases the humidity inside the microfluidic structure in the form of vapor. This vapor condenses at the surface of the condensing element, flows back into the device, and reduces humidity loss from within the device.

[0031] The equipment may also include passive cooling elements such as cooling blocks or active cooling elements such as Peltier elements to increase the cooling of vents and condensing elements, thereby increasing the condensation of steam before it leaves the equipment.

[0032] The present invention also provides a method for determining a user's sweat parameters, the method comprising:

[0033] Collects sweat originating from the first skin area;

[0034] Fluid originating from a second region is collected to wet the microfluidic structure of the device, which has a sensor configured to determine sweat parameters based on sweat from a first skin region. The evaporation control chamber is fluidly connected to the microfluidic structure and configured to wet the microfluidic structure using the fluid collected in the second region, wherein the second region is a second skin region and / or the surface of a condensation element configured to condense vapor released by the device.

[0035] The sensor is used to determine sweat parameters based on sweat originating from the first skin region.

[0036] This method aims to increase the amount of sweat available for the sensor to determine sweat parameters by increasing the humidity inside the device, including the sensor, and thus reducing sweat evaporation.

[0037] These and other aspects of the invention will be apparent and explained with reference to the embodiments described below. Attached Figure Description

[0038] To better understand the invention and to more clearly illustrate how to implement it, reference is now made to the accompanying drawings by way of example only, wherein:

[0039] Figure 1a and 1b A first example of a device according to the present invention is shown.

[0040] Figure 2 A second example of the device according to the invention is shown.

[0041] Figure 3 A third example of the device according to the invention is shown.

[0042] Figure 4 A fourth example of a device according to the present invention is shown.

[0043] Figure 5a and 5b A fifth example of a device according to the invention is shown.

[0044] Figure 6 A flowchart illustrating an example of the method according to the present invention is shown. Detailed Implementation

[0045] This invention will be described with reference to the accompanying drawings. The detailed description and specific examples are for illustrative purposes only, indicating exemplary embodiments of the apparatus and methods, and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus and methods of the invention will be better understood from the following description, claims, and drawings. It should be understood that the drawings are merely schematic and not to scale. It should also be understood that the same reference numerals are used in the drawings to indicate the same or similar parts.

[0046] Figure 1a and 1bAn example of the invention is shown. Device 1 includes a microfluidic structure 10 having a collection chamber 16 and a sensor 12, in which sweat from a first skin region i is collected, and the sensor 12 is used to determine sweat parameters from the first skin region i. Device 1 also includes an evaporation control chamber 14 connected to the microfluidic structure 10 and collecting fluid from a second region ii. Figure 1a In the middle, the second region ii is the second skin region. Figure 1b The second area is a region within the equipment.

[0047] Evaporation of sweat from the first skin region 1 may limit the availability of sweat required by the sensor 12. The humidity in the microfluidic structure 10 is controlled by the evaporation control chamber 14, which maintains a relatively high humidity so that only a small portion of the sweat collected from the first skin region 1 in the collection chamber 16 will evaporate.

[0048] The fluid collected from the second region can be in a liquid or gaseous state. It can flow directly to the microfluidic structure 10, or, for example, in the case of vapor, it will fill the space within the device, and when the evaporation control chamber 14 is connected to the microfluidic structure 10, it will also fill the space of the microfluidic structure 10. Therefore, a humid environment is maintained within the microfluidic structure 10, and the evaporation of sweat originating from the first skin region i for determining sweat parameters is reduced. The humid environment in the microfluidic structure can, for example, have a relative humidity (RH) higher than the typical relative humidity (RH) value in an indoor environment, and for example, can be 80-90%.

[0049] The sweat parameter determined by sensor 12 is the concentration of a biomarker in sweat, and optionally, the sweating rate. The sensor used to determine the biomarker concentration can operate, for example, based on electroanalytical techniques (e.g., chronoamperometry, potentiometry, voltammetry, electrochemical impedance spectroscopy, piezoelectricity) or optical techniques (e.g., colorimetry, fluorescence). Examples of sensors capable of sensing parameters indicating a person's sweating rate include, for example, a skin response (GSR) sensor, a calorimetric flow sensor, a microbalance, or a resonance-based sensor.

[0050] Despite Figure 1a and 1b Not shown, but device 1 may include an output (e.g., a display) for transmitting the determined sweat parameters to a user and / or a communication component for connecting to an external output device to transmit the determined sweat parameters to a user.

[0051] Figure 2 Another exemplary embodiment of the invention is shown. Device 2 includes a microfluidic structure 10 and an evaporation control chamber 14. The microfluidic structure 10 includes a collection chamber 16 and a sensor 12 connected via a microfluidic channel 22.

[0052] Optionally, the device 2 includes a first absorber 20 connected to a microfluidic channel and receiving sweat from a first skin region i that has passed through the sensor 12.

[0053] Optionally, the sensor 12 includes an exhaust port 21 configured to expel sweat from the sensor 12 and into the microfluidic structure 10.

[0054] Optionally, the collection chamber 16 includes conical columns 24. The conical columns 24 are configured such that they do not obstruct the movement of sweat toward the sensor 12 within the collection chamber 16.

[0055] exist Figure 2 In this process, sweat from the first skin region i is collected in the collection chamber 16, where it is expelled from the sweat glands onto the skin. With the aid of capillary action in the microfluidic channel 22, the pressure from the sweat glands propels the sweat collected from the first skin region i through the microfluidic channel 22 to the sensor 12, and ultimately into the optional first absorber 20. As it passes through the sensor 12, the sensor measures sweat parameters. Fluid from the second skin region ii is collected in the evaporation control chamber 14, which is used to wet the microfluidic structure 10.

[0056] In another example, the collected fluid is directly connected to an optional vent 21 of an optional first absorber 20 or sensor 12. This direct wetting of the vent 21 of the first absorber 20 or sensor 12 can accelerate the reduction of sweat evaporation within the microfluidic channel 22, through which sweat from the first skin region i moves to the sensor 12.

[0057] Figure 3 Another exemplary embodiment of the invention is shown. Similar to Figures 1 and 2, device 3 includes a microfluidic structure 10 and an evaporation control chamber 14 connected to the microfluidic structure 10. The microfluidic structure 10 includes a collection chamber 16 (optionally including a conical column 24), a sensor 12 (optionally having an exhaust port 21), and a first absorber 20 connected via a microfluidic channel 22. Figure 3 In this device, the evaporation control chamber 14 may include heaters 28a, 28b, or 28c. The device 3 also includes a vent 26. Optionally, heater 28b is configured to allow moisture to be transferred to the microfluidic structure 10.

[0058] Evaporation control chamber 14 evaporates fluid, i.e., sweat or TEW, from the second skin region ii, and this localized evaporation of the fluid produces moisture, which is dispersed within the microfluidic structure 10, thereby minimizing evaporation within the microfluidic structure 10. Excess moisture is discharged from the device through vent 26. Vent 26 may include a moisture-permeable membrane.

[0059] Skin temperature is sufficient to generate enough evaporation in the evaporation control chamber 14; however, it may be beneficial to stimulate the generation of moisture when using optional heaters 28a, 28b and / or 28c.

[0060] Figure 4 Another exemplary embodiment of the invention is shown. Figure 4 In the process, the microfluidic structure 10 of device 4 includes... Figure 3 The same features and operation are shown in the illustrated embodiment. The evaporation control chamber 14 includes a fluid delivery unit 34, a second absorber 30, and an optional heater 32. The fluid delivery unit 34 delivers sweat and / or TEW originating from the second skin region ii to the second absorber 30. The sweat and / or TEW accumulated in the second absorber 30 evaporates, optionally with the assistance of the heater 32. The resulting moisture is dispersed within the microfluidic structure 10, thereby reducing evaporation within the microfluidic structure 10.

[0061] Figures 5A and 5B illustrate another exemplary embodiment of the invention. Device 5 includes a microfluidic structure 10 with a sensor 12 that receives sweat from a first skin region i via a microfluidic channel 22. Sensor 12 includes an exhaust port 21 configured to expel sweat from sensor 12 and into the microfluidic structure 10. Microfluidic structure 10 may include a first absorber 20 that receives sweat that has passed through sensor 12. Device 5 includes a vent 26, a condensation element 42, and an optional cooling element 44. An evaporation control chamber 14 is connected to microfluidic structure 10. The vent is connected to the microfluidic structure via condensation element 42.

[0062] In Figure 5B, the second region ii is the surface of the condensing element 42. The evaporation control chamber 14 is the condensing element 42. In another example, the device may include two second regions ii, namely the second skin region and the surface of the condensing element 42.

[0063] Device 5 is constructed from a first material 46 having a first thermal insulation and a second material 48 having a second thermal insulation. The first thermal insulation is superior to the second thermal insulation. The first material 46 is used in the portion of device 5 that includes the microfluidic channel 22, the sensor 12, and an optional first absorber 20. The second material 48 is used in the portion of the device that includes the device's vent 26, the condensing element 42, and an optional cooling element 44. Optionally, the first material 46 and the second material 48 are used only in the aforementioned portions of the housing, while the remaining portions of the housing comprise a third material. In the example shown in FIG5A, the first material 46 is used in the portion of device 5 that includes the microfluidic structure 10 and the evaporation control chamber 14, while the second material 48 is used in the portion of device 5 where the vent 26, the condensing element 42, and the optional cooling element 44 are located.

[0064] To reduce the evaporation of sweat from the first skin region i within the microfluidic structure 10, the humidity within the microfluidic structure 10 should be high. To increase the humidity within the microfluidic structure, in Figure 5a In the process, fluids from the second skin region ii (e.g., sweat and / or transepidermal water (TEW)) are evaporated, and Figure 5b In this process, sweat from the first skin area i evaporates, therefore the temperature should be increased. However, the increase in temperature will also cause sweat to evaporate more quickly from the optional first absorber 20 and / or from the sensor 12, escape from the exhaust port 21, and eventually be discharged from the device through the exhaust port 26.

[0065] To prevent moisture loss from the device due to liquid loss through the microfluidic channel 22 caused by evaporation from the first absorber 20 and / or vent 21, a high humidity level should be maintained. Therefore, a temperature gradient is created from the skin surface (higher temperature) towards the device's vent (lower temperature) to promote condensation. This temperature gradient is created by using a first material 46 with higher thermal insulation than the second material 48. Consequently, heat transfer between the device and the external environment is reduced near the skin, while it is higher at the vent 26 and condensing element 42. Therefore, the device temperature near the skin is higher than the device temperature near the vent 26 and condensing element 42. Contact between vapor and the cooler surface of the condensing element 42 will cause partial condensation of the vapor, and the condensed vapor will flow back into the device, thereby reducing moisture loss within the microfluidic structure 10.

[0066] The cooling of the vents and condenser element 42 can be increased by optionally adding passive cooling elements (i.e., cooling blocks) or active cooling elements (such as Peltier).

[0067] Figure 6 An example of a method 600 for determining a user's sweat parameters is shown. The method includes the steps of: collecting sweat 610 originating from a first skin region i, collecting fluid 620 to be used for wetting a microfluidic structure 10 in a second region ii, and determining sweat parameters 630 based on the sweat originating from the first skin region i. The microfluidic structure 10 includes a sensor 12 for determining sweat parameters based on the sweat originating from the first skin region i.

[0068] The determined sweat parameters are the concentrations of biomarkers in the sweat from the first skin region i, and optionally the sweating rate.

[0069] The second region ii can be a second skin region ii. In another example, the second region is formed by a condensing element configured to condense vapor released by the device used to implement the method.

[0070] The method may also include providing the user with an output having the determined sweat parameters.

[0071] In summary, the present invention provides a device 1 for determining a user's sweat parameters, the device comprising a microfluidic structure 10 having a collection chamber 16 and a sensor 12, the collection chamber 16 being configured to collect sweat from a first skin region i, and the sensor 12 being configured to determine sweat parameters based on the sweat from the first skin region i. The device also includes an evaporation control chamber 14 connected to the microfluidic structure 10 and configured to wet the microfluidic structure 10 using fluid collected at a second region ii. The wetting of the microfluidic structure 10 aims to increase the amount of sweat available for the sensor to determine sweat parameters by increasing the humidity inside the microfluidic structure 10, thereby reducing sweat evaporation. A method 600 for determining a user's sweat parameters is also provided.

[0072] It should be noted that the above embodiments are illustrative and not limiting of the invention, and those skilled in the art can devise many alternative embodiments without departing from the scope of the claims. Any reference numerals placed in parentheses in the claims should not be construed as limiting the claims. The use of "comprising" and its variations do not exclude the presence of other elements or steps besides those listed in the claims. The quantifier "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by hardware comprising several different elements and / or by means of a suitably programmed processor. In device claims enumerating several devices, several of these devices may be specifically implemented by the same hardware. Measures recited in mutually different dependent claims can be advantageously combined.

Claims

1. A device (1) for determining a user's sweat parameters, the device comprising: A microfluidic structure (10) includes a collection chamber (16) and a sensor (12), the collection chamber being configured to collect sweat from a first skin region (i), and the sensor being configured to determine sweat parameters based on the sweat from the first skin region (i). The microfluidic structure (10) includes a first absorber (20) connected to the collection chamber (16) and the sensor (12) via a microfluidic channel (22). The first absorber (20) is configured to receive sweat from the first skin region (i) that has passed through the sensor (12), and... An evaporation control chamber (14), which is fluidly connected to the microfluidic structure (10) and configured to wet the microfluidic structure (10) using fluid collected at a second region (ii), wherein the second region (ii) is Second skin area, and / or The surface of a condensing element (42), configured to condense vapor released by the device (1), has a vent (26) connected to the microfluidic structure via the condensing element (42), and the sensor (12) includes an exhaust port (21) configured to expel sweat from the sensor (12) and into the microfluidic structure (10). The evaporation control chamber (14) is directly connected to the first absorber (20) and is configured to wet the first absorber.

2. The device according to claim 1, wherein: The second region (ii) is the second skin region, and wherein, The sensor (12) includes an exhaust port (21) configured to expel sweat from the sensor (12).

3. The device according to claim 2, wherein: The evaporation control chamber (14) is directly connected to the exhaust port (21) of the sensor (12) and is configured to wet the exhaust port of the sensor.

4. The device according to any one of claims 1-3, wherein: The second region (ii) is the second skin region, and The evaporation control chamber (14) includes a second absorber (30) configured to receive fluid collected from the second skin region (ii) and configured to wet the microfluidic structure (10). A fluid delivery device (34) configured to deliver droplets of fluid from the second skin region (ii) to the second absorber (30).

5. The device according to any one of claims 1-4, wherein: The evaporation control chamber (14) is configured to evaporate the fluid collected from the second skin region (ii).

6. The device according to claim 5, wherein: The evaporation control chamber (14) is configured to use heaters (28a, 28b, 28c, 32) to evaporate the fluid collected from the second skin region (ii).

7. The device according to any one of the preceding claims, wherein, The device includes: The vent (26) is configured to release steam out of the device; The condensing element (42), which is connected to the vent and the microfluidic structure (10) and is configured to condense vapor, wherein the device is constructed of the following materials: A first material (46) at the collection chamber (16) and the sensor (12), the first material (46) having a first thermal resistance; A second material (48) at the vent (26) and the condenser element (42), the second material (48) having a second thermal resistance, wherein: The first thermal resistance is higher than the second thermal resistance so that the steam is condensed at the condensing element (42) before being released from the device through the vent (26).

8. A method (500) for determining a user's sweat parameters, the method comprising: Collect sweat originating from the first skin region (i) (510); Fluid (520) is collected in a second region (ii) to wet the microfluidic structure (10) of the device (1), the device having: A sensor (12) configured to determine sweat parameters based on sweat from a first skin region (i), wherein the microfluidic structure (10) includes a first absorber (20) connected via a microfluidic channel (22) to a collection chamber (16) and the sensor (12), wherein the first absorber (20) is configured to receive sweat from the first skin region (i) that has passed through the sensor (12), and An evaporation control chamber (14), which is fluidly connected to the microfluidic structure (10) and configured to wet the microfluidic structure (10) using fluid collected at a second region (ii), wherein the second region (ii) is Second skin area, and / or The surface of a condensing element (42), configured to condense vapor released by the device (1), has a vent (26) connected to the microfluidic structure via the condensing element (42), and the sensor (12) includes an exhaust port (21) configured to expel sweat from the sensor (12) and into the microfluidic structure (10). The evaporation control chamber (14) is directly connected to the first absorber (20) and configured to wet the first absorber. The sensor (12) is used to determine sweat parameters (530) based on sweat originating from the first skin area (i).

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