Device for monitoring the perspiration of a living being

Abstract

The invention relates to a device (1) for monitoring the perspiration of a living being, said perspiration causing the creation of a bodily fluid, said device comprising a support (10) having an active surface (100) intended to be applied against the skin (P) of a living being, said device comprising a processing unit (PU) and n sensors, with n greater than or equal to 2, each sensor (S1-Sn) being arranged on said active surface and connected to said processing unit (PU) to provide electrical measurement data, each sensor comprising an absorption element (2) capable of absorbing a volume of bodily fluid, the sensors being chosen with distinct bodily fluid absorption capacities such that a first sensor will reach saturation with bodily fluid more quickly than a second sensor. Figure to be published with the abbreviation: Figure 2

Description

Title of the invention: Device for monitoring the perspiration of a living being Technical field of the invention

[0001] The present invention relates to a device for monitoring the perspiration of a living being. State of the art

[0002] Various measurement sensors are now known to monitor certain physiological parameters of a living being in real time, such as blood glucose levels and heart rate. Recently, sweat sensors have also been developed to monitor the fluid losses experienced by a living being. These sensors can provide early warning of possible dehydration, for example during physical activity, or be used for other purposes, such as measuring the stress level of the living being.

[0003] US patent application 2022 / 257131A1 describes, in particular, the development of a wearable device in the form of a patch to be applied to the skin of a living being. The patch may be equipped with a measurement system capable of measuring physiological parameters of the living being by analyzing bodily fluids, i.e., sweat secreted by the living being. The parameters monitored include, for example, sodium levels, lactate levels, and glucose levels.

[0004] US patent 10405794B2 describes a sweat detector using in particular a coiled capillary capable of filling with body fluid, electrodes being distributed along the capillary to determine the volume of fluid captured and track the volume of sweat secreted.

[0005] Prior solutions often do not allow for accurate monitoring of the volume of sweat generated by the living organism. In document US10405794B2, once an initial volume plateau is reached, the proposed solution does not allow for monitoring the filling of the capillary over time.

[0006] The object of the invention is to propose a device for monitoring the perspiration of a living being, allowing in particular to track the volume of sweat secreted more precisely than in the prior art. Description of the invention

[0007] This objective is achieved by a device for monitoring the perspiration of a living being, said perspiration causing the creation of a bodily fluid, said device comprising a support having an active surface intended to be applied against the skin of a living being, said device comprising a processing unit and n sensors, with n greater than or equal to 2, each sensor being arranged on said active surface and connected to said processing unit to provide electrical measurement data, each sensor having an absorption element capable of absorbing a volume of body fluid, the sensors being chosen with distinct body fluid absorption capacities such that a first sensor will reach saturation with body fluid more quickly than a second sensor, the processing unit being configured to determine an ionic concentration of the body fluid, from the value of the electrical measurement data provided by the first sensor at saturation and the maximum volume of body fluid that the absorption element of the first sensor can absorb.

[0008] According to one particular feature, the processing unit is configured to track the volume filling of the second sensor over time, taking into account the electrical measurement data provided by this second sensor over time and the ionic concentration determined using the first sensor.

[0009] According to another feature, the processing unit is configured to determine the volume of body fluid absorbed by the first sensor taking into account the determined ionic concentration of the body fluid and the electrical measurement data provided by the first sensor over time.

[0010] According to another feature, the electrical measurement data are electrical impedance and / or electrical conductivity data of the body fluid.

[0011] According to another feature, the distinct absorption capacities of the sensors are achieved by playing on the type of absorbing material used and / or on the volume of absorbing material used and / or on the density of the absorbing material used.

[0012] The invention also relates to a method for monitoring the perspiration of a living being, said perspiration causing the creation of a bodily fluid, said method being implemented with a monitoring device as defined above, the method consisting of determining the ionic concentration of the bodily fluid, from the value of the electrical measurement data provided by the first sensor at saturation and the maximum volume of bodily fluid that the absorption element of the first sensor can absorb.

[0013] According to one particular feature, the method includes a step of monitoring the volume filling of the second sensor over time, taking into account the electrical measurement data provided by this second sensor over time and the ionic concentration determined using the first sensor.

[0014] According to another feature, the method includes a step of determining the volume of body fluid absorbed by the first sensor taking into account the ionic concentration of the body fluid determined and the electrical measurement data provided by the first sensor over time.

[0015] According to another feature, the electrical measurement data are electrical impedance and / or electrical conductivity data of the body fluid.

[0016] According to another feature, the distinct absorption capacities of the sensors are achieved by playing on the type of absorbing material used and / or on the volume of absorbing material used and / or on the density of the absorbing material used. Brief description of the figures

[0017] Other features and advantages will become apparent in the detailed description that follows, given in relation to the accompanying drawings in which: - Figures IA and IB schematically represent the perspiration monitoring device according to the invention; Figure 2 illustrates the operating principle of the device with a diagram. monitoring of the invention, according to an advantageous implementation; - Figure 3 represents a diagram showing the variation curves of impedance as a function of the volume of fluid absorbed for sensors having distinct absorption capacities; - Figure 4 represents a diagram showing a curve of variation of the saturation impedance measured by a sensor used in the invention as a function of the ionic concentration; - Figure 5 shows a diagram illustrating the relationship between the volume absorbed by an absorption element depending on the ionic concentration of the fluid;

[0018] Detailed description of at least one embodiment

[0019] With reference to [Fig. 1A] and [Fig. 1B], the invention relates to a device 1 for monitoring the perspiration of a living being, for example a human being. Through perspiration, the living being releases a bodily fluid called sweat through the skin P.

[0020] The device may be in the form of a patch to be applied to the skin P of the living being.

[0021] The device may thus comprise a single support 10 that adheres to the skin of the living being. Without limitation, the support 10 may have a surface area of ​​between 5 cm² and 15 cm².

[0022] The support 10 is presented for example in the form of a strip or disc of flexible material, having an active surface 100 intended to be applied against the skin of the living being.

[0023] According to the invention, the device comprises several sensors SI, S2, S3, S4 (three or four sensors in the attached figures), these sensors being distributed over said active surface 100 of the support 10.

[0024] Device 1 also includes a processing unit UC.

[0025] The processing unit UC can be integrated into the support 10, mounted on the support 10, or located remotely from the support 10. Wired or wireless communication means can be integrated into the support 10 to send the data measured by each sensor to the processing unit UC (connection lines in Figures IA and IB). In [Fig. 2], the representation is schematic and illustrates the embodiment of the invention. A wired connection is used, for example, between each sensor and the processing unit UC.

[0026] The processing unit CU can be, for example, that of a smart portable object, such as, for example, a mobile phone, a computer or a smartwatch.

[0027] Each sensor includes an absorption element 2 made of at least one absorbing material. This element is responsible for absorbing the bodily fluid emitted by the living being when the device is positioned, with its active surface, against the skin of the living being.

[0028] The absorption element 2 has a determined saturation capacity, that is to say, it is capable of absorbing a maximum volume of body fluid.

[0029] According to a particular aspect of the invention, each sensor is used to measure an electrical parameter within its absorption element. This electrical parameter is, for example, the electrical impedance (denoted Z) and / or the electrical conductivity of the fluid and / or any other relevant electrical parameter. In the remainder of the description and in the drawings, the electrical impedance measurement Z will be used.

[0030] In conjunction with [Fig. 3], it can be seen that the impedance Z decreases as the volume absorbed by the absorption element of a sensor increases. In other words, the more body fluid absorption element 2 absorbs, the more the electrical impedance measured by the sensor will decrease, until it reaches a low plateau, indicating that absorption element 2 is saturated with fluid. In [Fig. 3], sensor S1 has a lower absorption capacity than sensor S2, which is lower than that of sensor S3. It can then be seen that the greater the saturation capacity of the absorption element (the slower it saturates with fluid), the later it reaches its impedance plateau.

[0031] The diagram in [Fig. 4] further shows that the impedance Z measured by a saturation sensor decreases as the ionic concentration (here, the NaCl concentration) of the captured fluid increases. In other words, in addition to the volume of body fluid captured, the ionic concentration of the captured fluid affects the measured impedance Z.

[0032] It follows that an absorption element 2 weakly soaked by a fluid having a high ionic concentration can return the same electrical signal as an absorption element 2 more strongly soaked by a fluid of lower ionic concentration.

[0033] The electrical measurement of the conductivity of the material (via impedance measurement or other) is therefore correlated both to the quantity of fluid present in the absorption element 2 and to its concentration.

[0034] Based on this, one of the features of the device of the invention is the use of a first sensor SI having an absorption element with a low saturation capacity. Thus, since this sensor SI saturates quickly with fluid, the processing unit UC can immediately deduce an ionic concentration of the captured fluid. Once the concentration is determined, it is possible to calculate the volume present in the absorption element at each measurement point from the diagram in [Fig. 5]. [Fig. 5] shows three curves, each for a distinct ionic concentration, each curve relating the measured impedance to the volume of absorbed fluid. In this figure, it can be seen in particular that three distinct volumes Vm_1, Vm_2, Vm_3 of fluid, at three distinct ionic concentration levels, allow the same impedance Zm to be measured.

[0035] The set of sensors in the device is also chosen so as to create a saturation range. By saturation range, it is understood that the sensors all have a distinct absorption capacity and a sufficient overlap area from one sensor to another. By overlap area, it is understood that all the sensors begin to fill at the same time, from the start of the device's use.

[0036] From one sensor to another, distinct absorption capacities can be created by playing on the type of absorbing material and / or on the volume of absorbing material and / or on the density of absorbing material.

[0037] In [Fig.1B], without limitation, the sensors S1-S4 are chosen to differentiate themselves from each other by the thickness of absorbing material used for their absorption element 2.

[0038] The use of several sensors with distinct absorption capacities makes it possible, in particular, to extend the measurement range: - The absorption element of the first SI sensor (with the lowest absorption capacity) will allow an almost immediate measurement of the presence of fluid and will allow the sweat rate to be determined at the start of physical activity, as soon as the first drops of sweat appear. - The next sensor S2 (with a higher absorption capacity than the first) will take longer to start displaying sweat rate values, but as it will saturate later, it will allow the measurement range to be increased by continuing to give measurements while the first sensor is saturated. - This principle is duplicated for the other sensors in the device that follow in the series (up to n sensors). This allows us to measure the quantities of sweat. data is collected according to the collection capacity. This principle of multiple measurement sensors makes it possible to increase the measurement range.

[0039] Another advantage of using multiple sensors is the redundancy of measurements. Indeed, if the absorption capacity of the sensors differs from one sensor to another, overlapping areas exist, allowing measurements to be taken from several sensors simultaneously. This redundancy of measurements ensures that the measurements performed are reliable.

[0040] Another advantage of using multiple sensors with distinct absorption capacities is that each time a sensor becomes saturated, it is possible to determine the average sweat concentration collected in the sensor. This allows for regular monitoring of the variation in sweat concentration over time.

[0041] This measured concentration value can be used to refine the quantity (volume) of sweat collected according to its concentration.

[0042] The invention is described more precisely in connection with [Fig.2].

[0043] In [Fig.2], device 1 comprises a number n of sensors, with n greater than or equal to 2. The sensors are defined by their absorption element 2 of distinct capacities.

[0044] It should be noted that the more sensors device 1 has, the larger the sampling will be and therefore the more precise the monitoring of perspiration will be.

[0045] For n sensors, we have, for example: - The first SI sensor which has a first absorption capacity, corresponding to a maximum volume V1 of fluid that it can absorb. - The second sensor S2 which has a second absorption capacity, distinct from the first absorption capacity, therefore corresponding to a volume V2 chosen for example greater than VI and which corresponds to the maximum volume of fluid that this second sensor S2 can absorb. - The Sn sensor which has an nth absorption capacity, distinct from the absorption capacity of the Sn-1 sensor, therefore corresponding to a volume Vn chosen for example greater than Vn-1 and which corresponds to the maximum volume of fluid that the Sn sensor is capable of absorbing.

[0046] Throughout the process, the processing unit UC measures the impedance Z (or other relevant electrical parameter) within the absorption element 2. As shown by [Fig.3] and described above, when the impedance reaches a low plateau, this means that the sensor is reaching saturation.

[0047] From this, the operating principle is as follows (in [Fig.2], the grey area corresponds to the fill level of each Sl-Sn sensor):

[0048] A T0: Each absorption element 2 of the Sl-Sn sensors is empty and has not yet absorbed any fluid.

[0049] Between T0 and Tl: Physical activity has started and each absorption element 2 of the sensors gradually fills with body fluid.

[0050] At Tl: The absorption element of sensor SI reaches saturation first, and its volume VI, corresponding to its absorption capacity, is full. Since sensor SI is saturated, the processing unit UC therefore knows the volume VI of sweat absorbed by the sensor. At saturation, the processing unit UC determines, using a calculation module Ml, the ionic concentration Cl of the captured fluid from the measured impedance ZI and the volume VL

[0051] The determined Cl concentration can be used by the processing unit UC to monitor the volume filling V2(T) of the second sensor S2 over time and the volume filling of each other sensor in the device (Vn-l(T), Vn(T)), taking into account the impedances measured at each sensor over time (Z2(T), Zn-l(T), Zn(T)). The calculation modules M2, M3, and M4 are executed by the processing unit UC to perform these calculations.

[0052] Furthermore, the determined ion concentration Cl can be used retroactively to determine the volume filling kinetics (VI(T)) of the first SI sensor using each impedance measurement point acquired over time (Z1(T)). A calculation module M5 is executed by the processing unit to perform this calculation. Figure 5, already described above, illustrates the relationship between these different data points.

[0053] At T2: The absorption element of the second sensor S2 saturates in turn, by the volume V2. The processing unit UC can then again determine, via a calculation module M10, the ionic concentration C2 of the fluid captured by the sensor S2, taking into account the measured impedance Z2 at saturation.

[0054] Similarly, the ion concentration C2 is used by the processing unit UC to monitor the volume filling (Vn-l(T) and Vn(T)) of the other, still unsaturated sensors, S3 to Sn, using impedance measurements over time (Zn-l(T) and Zn(T)). The M20 and M30 calculation modules are executed by the processing unit UC to perform these calculations.

[0055] As with T1, it is also possible to determine the volumes V2(T) of body fluid absorbed over time by the second sensor S2 from the impedance measurement points Z2(T) and the determined ionic concentration C2. The calculation module M40 is executed by the processing unit UC to perform this operation.

[0056] At Tx: The Sn-1 sensor reaches saturation. The principle described above is reproduced to determine, using an M100 calculation module, the ionic concentration Cn-1 of the fluid using the volume of the Sn-1 sensor and the impedance Zn-1 measured at saturation of the Sn-1 sensor. The processing unit is also configured to track the filling volume of the Sn sensor over time (Vn(T)), via the M200 calculation module which receives as input the ionic concentration Cn-1 and the impedance Zn(T) measured over time at the Sn sensor.

[0057] As with T1 and T2, it is also possible to go back to the volumes Vn-l(T) of body fluid absorbed over time by the Sn-1 sensor from the impedance measurement points Zn-1 (T) and the determined ionic concentration Cn-1. The M300 calculation module is executed by the processing unit to perform this operation.

[0058] A Tf: All the Sl-Sn sensors are filled with body fluid and therefore reach saturation.

[0059] The principle of the invention thus presents numerous advantages, including: - A solution allowing reliable monitoring of perspiration, from the first moments of physical activity; - A reliable and easy-to-implement solution; - A solution enabling monitoring of perspiration over a wide range of measurements;

Claims

Demands

1. Device (1) for monitoring the perspiration of a living being, said perspiration causing the creation of a bodily fluid, said device comprising a support (10) having an active surface (100) intended to be applied against the skin (P) of a living being, said device comprising a processing unit (PU) and being characterized in that it comprises n sensors, with n greater than or equal to 2, each sensor (Sl-Sn) being arranged on said active surface and connected to said processing unit (PU) to provide electrical measurement data, each sensor comprising an absorption element (2) capable of absorbing a volume of bodily fluid, and in that the sensors are chosen with distinct bodily fluid absorption capacities such that a first sensor will reach saturation with bodily fluid more quickly than a second sensor, the processing unit (PU) being configured to determine an ionic concentration of the bodily fluid,based on the value of the electrical measurement data provided by the first sensor (SI) at saturation and the maximum volume of body fluid that the absorption element (2) of the first sensor (SI) can absorb.

2. Device according to claim 1, characterized in that the processing unit (CU) is configured to track the volume filling of the second sensor (S2) over time taking into account the electrical measurement data provided by this second sensor (S2) over time and the ionic concentration determined using the first sensor (SI).

3. Device according to claim 1 or 2, characterized in that the processing unit (CU) is configured to determine the volume of body fluid absorbed by the first sensor (SI) taking into account the determined ionic concentration of the body fluid and the electrical measurement data provided by the first sensor (SI) over time.

4. Device according to any one of claims 1 to 3, characterized in that the electrical measurement data are electrical impedance and / or electrical conductivity data of the body fluid.

5. A device according to any one of claims 1 to 4, characterized in that the distinct absorption capacities of the sensors are achieved by varying the type of absorbing material used and / or the volume of the absorbent material used and / or on the density of the absorbent material used.

6. A method for monitoring the perspiration of a living being, said perspiration causing the creation of a body fluid, said method being characterized in that it is implemented with a monitoring device (2) as defined in any one of the preceding claims, and in that it consists of determining the ionic concentration of the body fluid, from the value of the electrical measurement data provided by the first sensor (SI) at saturation and the maximum volume of body fluid that the absorption element of the first sensor can absorb.

7. Method according to claim 6, characterized in that it comprises a step of monitoring the volume filling of the second sensor (S2) over time taking into account the electrical measurement data provided by this second sensor (S2) over time and the ionic concentration determined using the first sensor.

8. A method according to claim 6 or 7, characterized in that it comprises a step of determining the volume of body fluid absorbed by the first sensor (SI) taking into account the determined ionic concentration of the body fluid and the electrical measurement data provided by the first sensor (SI) over time.

9. A method according to any one of claims 6 to 8, characterized in that the electrical measurement data are electrical impedance and / or electrical conductivity data of the body fluid.

10. A method according to any one of claims 6 to 9, characterized in that the distinct absorption capacities of the sensors are achieved by playing on the type of absorbing material used and / or on the volume of absorbing material used and / or on the density of the absorbing material used.

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