Patent Description:
The present disclosure belongs to the technical field of sensors, in particular to a method to detect sweat by a sweat sensor and a method of determining sweat by a sweat sensing system.

The abnormal changes of sweat compositions in human body during exercise are related to the blood concentration level, or can directly indicate the health condition of a human body. For example, Na+ is the most electrolyte in human sweat, which is the important basis of sweat secretion. The concentration of Na+ can reflect different kinds of symptoms of water and salt metabolism disorder in human body. For example, athletes, soldiers, workers, etc. will suffer from hypernatremia due to severe dehydration when working in extreme environments (strenuous exercise, overheated fire rescue, etc.), and the Na+ concentration in their sweat and blood is far higher than the normal value. If water and electrolytes are not judged and supplemented timely, it is very likely to cause serious physiological threats or even death.

At present, the traditional sweat sensor cannot simultaneously and continuously detect the sweat volume and the electrolyte concentration in real time, and cannot prevent the mixture of old and new sweat from interfering with the detection of the electrolyte concentration. The patent document <CIT> discloses methods and apparatus for monitoring of fluid content that are suitable for in-situ, real time and/or continuous monitoring, especially of bodily fluids and in particular the content of sweat. The document also describes fabrication of such an apparatus. The apparatus comprises a multilayer structure comprising at least two electrode layers for detection of fluid content separated by at least one insulating layer. The multilayer structure defines at least one flow channel which provides a flow path for continuous flow of fluid in use, and the electrode layers form part of the sidewall of the flow channel(s). The flow channel(s) may run in a direction substantially perpendicular to the layers. The electrode layers may employ electrochemical detection and may comprise a reference electrode and an ion-sensitive electrode. The article titled "<NPL> mentions to use digital droplets to measure fluid flow rates and demonstrate their use for sweat rate monitoring, in a device called digital volume dispensing system (DVDS). The DVDS operates by electrically detecting the frequency of droplet generation. The fluid enters the device from the outlet of any pressure-driven channel into the DVDS where a droplet forms in the chamber. The droplet grows until it eventually shorts two electrodes before breaking onto a wick. Since the droplet volume is fixed by the chamber height, the droplet frequency directly measures the flow rate. The patent document <CIT> discloses sweat sensing devices configured to periodically measure sweat conductivity and galvanic skin response, devices to measure volumetric sweat flow rate, and devices that combine the three functions.

In order to solve the technical problems existing in the prior art, the present disclosure provides a method to detect swear by a sweat sensor and a method of determining sweat by a sweat sensing system which simultaneously and continuously detect the sweat volume and the electrolyte concentration in real time, and can prevent the mixture of old and new sweat from interfering with the detection of the electrolyte concentration.

The invention is defined by method claims <NUM> and <NUM>.

Compared with the prior art, the present disclosure has the following beneficial effect.

The methods of the present disclosure can simultaneously and continuously detect the sweat volume and the electrolyte concentration in real time, and can prevent the mixture of old and new sweat from interfering with the detection of the electrolyte concentration.

The above and other aspects, features and advantages of the embodiments of the present disclosure will become clearer from the following description taken in conjunction with the accompanying drawings, in which:.

Hereinafter, specific embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure can be implemented in many different forms, and the present disclosure should not be construed as limited to the specific embodiments set forth here. On the contrary, these embodiments are provided to explain the principles of the present disclosure and its practical application, so as to enable others skilled in the art to understand the various embodiments of the present disclosure and various modifications suitable for the specific intended application.

As used herein, the term "including" and its variants mean open terms with the meaning of "including but not limited to". The terms such as "based on" and "according to" mean "at least partially based on" and "at least partially according to". The terms "one embodiment" and "an embodiment" mean "at least one embodiment". The term "another embodiment" means "at least one other embodiment". The terms such as "first", "second", etc. can refer to different or identical objects. Other definitions, whether explicit or implicit, can be included below. Unless the context clearly indicates, the definition of a term is consistent throughout the specification.

<FIG> is a schematic structural diagram of a sweat sensor according to a first embodiment of the present disclosure. In <FIG>, the diagram (B) shows a top view of a sweat sensor according to a first embodiment of the present disclosure. It is noted that in the diagram (B), in order to clearly show the electrode structure, the adhesive layer <NUM> and the water-absorbing diffusion layer <NUM> are not shown. The diagram (A) shows a cross-sectional view of a sweat sensor according to a first embodiment of the present disclosure taken along the line a-a' in the diagram (B). Of course, the diagram (A) additionally shows a human skin system.

As shown in <FIG>, a sweat sensor according to a first embodiment of the present disclosure comprises a sweat-guiding electrode layer <NUM>, an adhesive layer <NUM>, and a water-absorbing diffusion layer <NUM>.

Specifically, the sweat-guiding electrode layer <NUM> comprises an insulating layer <NUM>, a conductive electrode (not labeled) provided in the insulating layer <NUM>, and a first through hole (not labeled), wherein the first through hole goes through the insulating layer <NUM> and the conductive electrode. In one example, the conductive electrode comprises a first electrode <NUM> and a second electrode <NUM>, wherein the first electrode <NUM> and the second electrode <NUM> are located on the same plane, and the central axis of the electrode through hole (not labeled) of the first electrode <NUM>, the central axis of the electrode through hole (not labeled) of the second electrode <NUM> and the central axis of the first through hole coincide with each other.

In one example, the insulating layer <NUM> is mainly made of a flexible insulating polymer material, which may be polydimethylsiloxane, silicone rubber, thermoplastic polyester, etc. The thickness of the insulating layer <NUM> is between <NUM> and <NUM>.

The first electrode <NUM> and the second electrode <NUM> are embedded inside the insulating layer <NUM> and located at the middle part in the thickness direction. The first electrode <NUM> and the second electrode <NUM> can be thin-film electrodes with certain thickness and width made of carbon nanotubes, graphene, carbon black, carbon fiber, etc., or thin-film electrodes with certain thickness and width made of other materials such as conductive testing metals such as gold, platinum, copper, etc. The thickness of the first electrode <NUM> and the second electrode <NUM> is between <NUM> and <NUM>, and the width (line width) of the first electrode <NUM> and the second electrode <NUM> is smaller than the diameter of each through hole (e.g., an electrode through hole, a first through hole, etc.).

Here, the embedding method of the first electrode <NUM> and the second electrode <NUM> in the insulating layer <NUM> is not particularly limited. For example, in one example, first, an insulating layer <NUM> is prepared, and the first electrode <NUM> and the second electrode <NUM> located on the same level are prepared on the insulating layer <NUM> using a method such as screen printing. Finally, another insulating layer <NUM> is prepared on the insulating layer <NUM>, the first electrode <NUM> and the second electrode <NUM>, and the first electrode <NUM> and the second electrode <NUM> are embedded in the position inside the insulating layer <NUM>. In another example, first, an electrode-shaped mold template is prepared using a machining method. The prepolymer, of which the insulating layer <NUM> is made, is then poured into the mold template using a template replication method, and after the prepolymer is peeled off after being cured and molded, a groove with an electrode shape is formed. The first electrode <NUM> and the second electrode <NUM> are filled and prepared in the groove, and then another insulating layer <NUM> is prepared on the first electrode <NUM> and the second electrode <NUM>. Finally, the first electrode <NUM> and the second electrode <NUM> are embedded in the position inside the insulating layer <NUM>.

At the middle of the insulating layer <NUM>, the first electrode <NUM> and the second electrode <NUM>, a through hole <NUM> (consisting of the first through hole, the electrode through hole, etc.) is prepared by a laser cutting method, a template method or a mechanical punching method, and the diameter of the through hole <NUM> is between <NUM> and <NUM>. The effective test surfaces of the first electrode <NUM> and the second electrode <NUM> are exposed to the inner wall surface of the through hole <NUM>. Preferably, the cylindrical inner wall of the through hole <NUM> and the surfaces of the first electrode <NUM> and the second electrode <NUM> exposed to the through hole show hydrophobic properties. Therefore, the hydrophobic materials can be selected according to the properties of the materials of the insulating layer <NUM> and the electrode, and the hydrophobic through hole can also be realized by post-treatment methods, such as silane reagent treatment.

The adhesive layer <NUM> is provided on the insulating layer <NUM>, and the adhesive layer <NUM> is provided with a second through hole (not shown) communicated with the first through hole. That is, the through hole <NUM> goes through the insulating layer <NUM>, the adhesive layer <NUM>, the first electrode <NUM> and the second electrode <NUM>. The part of the through hole <NUM> in the insulating layer <NUM> is set as the first through hole, the part of the through hole <NUM> in the adhesive layer <NUM> is set as the second through hole, the part of the through hole <NUM> in the first electrode <NUM> is set as the electrode through hole of the first electrode <NUM>, and the part of the through hole <NUM> in the second electrode <NUM> is set as the electrode through hole of the second electrode <NUM>.

The adhesive layer <NUM> is a viscous film fixedly connected between the sweat-guiding electrode layer <NUM> and the water-absorbing diffusion layer <NUM>, and comprises an ultra-thin double-sided adhesive tape with a fixed thickness (<NUM> to <NUM> in thickness), a prepolymer of viscoelastic polymer, etc. In one example, the adhesive layer <NUM> prepares a second through hole with the same size as the first through hole at the overlapping position of the first through hole of the sweat-guiding electrode layer <NUM> by a laser cutting method, a template method or a mechanical punching method, so that sweat flows through the first through hole and the second through hole. Further, the central axis of the first through hole coincides with the central axis of the second through hole.

The water-absorbing diffusion layer <NUM> is provided on the adhesive layer <NUM> and covers the second through hole. In one example, the water-absorbing diffusion layer <NUM> is a film made of a hydrophilic material, including but not limited to water-absorbing materials such as clothing fabrics, paper-based cellulosic films, gels and the like. In this embodiment, the water-absorbing diffusion layer <NUM> can take clothing itself as the water-absorbing layer, and preferably take breathable sweat-permeable sports tights, wrist guards, palm guards, elbow guards, sweat-absorbing belts and the like as the water-absorbing layer. The thickness of the water-absorbing diffusion layer <NUM> is not limited. The water-absorbing diffusion layer <NUM> is integrated with the sweat-guiding electrode layer <NUM> through the adhesive layer <NUM> to form a sweat sensor.

<FIG> is a schematic diagram of the state in which a wearable device with a sweat sensor according to a first embodiment of the present disclosure is placed on the surface of human skin. As shown in <FIG>, a sweat sensor according to the first embodiment of the present disclosure is wrapped and fixed by a belt made of elastic fabrics and elastic materials to form a wearable device. Furthermore, the wearable device can be integrated and compatible with sports tights, wrist guards, palm guards, elbow guards, sweat-absorbent belts and other fabrics to form an elastic water-absorbing fixing belt device <NUM>.

When the sweat sensor according to the embodiment of the present disclosure is provided on the human skin <NUM>, sweat <NUM> is secreted by sweat glands <NUM> in the hypodermis <NUM>. When being secreted from sweat glands <NUM>, sweat <NUM> has a certain pressure up to <NUM>,<NUM>-<NUM>, which is enough to pump sweat <NUM> into the through hole <NUM> to be quickly absorbed by the water-absorbing diffusion layer <NUM>. When sweat <NUM> passes through the inner wall of the through hole <NUM>, the parallel electrodes (i.e., the first electrode <NUM> and the second electrode <NUM>) exposed to the through hole <NUM> will record the conductance value of the sweat liquid or the sweat droplet in real time. <FIG> is a schematic diagram of the detection principle of a conductance square wave curve, where ΔT<NUM> represents the duration of a first conductance square wave and ΔT<NUM> represents the duration of a second conductance square wave. <FIG> is a conductance square wave curve diagram obtained by a sweat sensor under the micro-flow injection pump test according to an embodiment of the present disclosure.

As shown in <FIG>, the height or amplitude of the conductance square wave curve is correlated with the real-time total sweat electrolyte concentration in the through hole <NUM>, and the sweat volume and sweat rate of sweat droplets passing through the through hole <NUM> are correlated with the time difference between the conductance square wave curve and the next conductance square wave curve. Therefore, the sweat sensor according to the embodiment of the present disclosure can successfully distinguish the sweat electrolyte concentration from the sweat volume through a real-time continuous conductance square wave curve. At the same time, the sweat sensor has the advantage that the accuracy is not interfered by the mixture of old and new sweat.

<FIG> is a schematic structural diagram of a sweat sensor according to a second embodiment of the present disclosure. In <FIG>, the diagram (B) shows a top view of a sweat sensor according to a second embodiment of the present disclosure. It is noted that in the diagram (B), in order to clearly show the electrode structure, the adhesive layer <NUM> and the water-absorbing diffusion layer <NUM> are not shown. The diagram (A) shows a cross-sectional view of a sweat sensor according to a second embodiment of the present disclosure taken along the line b-b' in the diagram (B). Of course, the diagram (A) additionally shows a human skin system. The diagram (C) shows a schematic structural diagram of the first electrode and the second electrode in the sweat sensor according to the second embodiment of the present disclosure.

As shown in <FIG>, the structure here is different from the structure of the sweat sensor of the first embodiment shown in <FIG> in that the first electrode <NUM> and the second electrode <NUM> are not located on the same plane. For example, the second electrode <NUM> is above the first electrode <NUM>, so that the electrode through hole of the second electrode <NUM> overlaps with the electrode through hole of the first electrode <NUM> from top to bottom.

<FIG> is a schematic structural diagram of a sweat sensor according to a third embodiment of the present disclosure. In <FIG>, the diagram (B) shows a top view of a sweat sensor according to a third embodiment of the present disclosure. It is noted that in the diagram (B), in order to clearly show the electrode structure, the adhesive layer <NUM> and the water-absorbing diffusion layer <NUM> are not shown. The diagram (A) shows a cross-sectional view of a sweat sensor according to a third embodiment of the present disclosure taken along the line a-a' in the diagram (B). Of course, the diagram (A) additionally shows a human skin system.

As shown in <FIG>, the structure here is different from the structure of the sweat sensor of the first embodiment shown in <FIG> in that the sweat sensor according to the third embodiment of the present disclosure further comprises a contact layer <NUM>, which is provided on the surface of the insulating layer <NUM> facing away from the adhesive layer <NUM>. The contact layer <NUM> is provided with a third through hole (not shown) communicated with the first through hole. Further, the central axis of the first through hole coincides with the central axis of the third through hole, that is, the through hole <NUM> goes through the contact layer <NUM>.

The contact layer <NUM> has two functions: first, it is convenient to adjust the thickness of the sweat-guiding electrode layer <NUM>; second, when the hardness of the insulating layer <NUM> is not suitable for direct contact with the skin, the contact layer <NUM> can achieve good contact and attachment with the skin. The material of the contact layer <NUM> includes, but is not limited to, polydimethylsiloxane, silicone rubber, thermoplastic polyester, etc. The close bonding between the contact layer <NUM> and the insulating layer <NUM> can be achieved by common techniques such as cross-linking and bonding.

<FIG> is a schematic structural diagram of a sweat sensing system according to an embodiment of the present disclosure. For the convenience of description, only conductive electrodes and insulating layers are shown in <FIG>.

As shown in <FIG>, the sweat sensing system according to the embodiment of the present disclosure comprises a plurality of sweat sensors according to the second embodiment of the present disclosure shown in <FIG>. The plurality of sweat sensors are arranged in an array.

In this case, the insulation layer <NUM>, the adhesive layer <NUM>, the water-absorbing diffusion layer <NUM> and/or the contact layer <NUM> (if provided) of each sweat sensor are integrated. That is, a plurality of conductive electrodes are provided in an insulating layer <NUM>. An adhesive layer <NUM> and a water-absorbing diffusion layer <NUM> are laminated on the insulating layer <NUM> at a time, and a contact layer <NUM> is provided on the surface of an insulating layer <NUM> facing away from an adhesive layer <NUM>.

Of course, each through hole <NUM> also goes through an adhesive layer <NUM> to form a plurality of second through holes, and also goes through a contact layer <NUM> to form a plurality of third through holes. That is, the first through hole (including each electrode through hole), the second through hole and the third through hole are communicated with each other in one-to-one correspondence.

When the plurality of sweat sensors are distributed in an array, the first electrodes of various conductive electrode are located on the same plane, the second electrodes of various conductive electrode are located on the same plane, and the first electrodes and the second electrodes are located on different planes. Therefore, all the first electrodes of the conductive electrodes of each column are connected together and connected to the column conductive terminals, while all the second electrodes of the conductive electrodes of each row are connected together and connected to the row conductive terminals. For example, in <FIG>, all the first electrodes of a first column of conductive electrodes are connected together and connected to the column conductive terminal <NUM>, all the first electrodes of a second column of conductive electrodes are connected together and connected to the column conductive terminal <NUM>, and all the first electrodes of a third column of conductive electrodes are connected together and connected to the column conductive terminal <NUM>. All second electrodes of a first row of conductive electrodes are connected together and connected to the row conductive terminal <NUM>, all second electrodes of a second row of conductive electrodes are connected together and connected to the row conductive terminal <NUM>, and all second electrodes of a third row of conductive electrodes are connected together and connected to the row conductive terminal <NUM>.

With the sweat sensing system provided above, the data of a plurality of sampling points can be obtained by arranging a plurality of conductive electrodes in an array, so that the accuracy of analysis of sweat volume per unit area and sweat electrolyte concentration can be further improved.

The specific embodiments of the present disclosure have been described above. Other embodiments are within the scope of the appended claims.

The terms "exemplary" and "example" used throughout this specification mean "serving as an example, instance or illustration", rather than mean "preferable to" or "advantageous over" other embodiments. For the purpose of providing an understanding of the described technology, the detailed description comprises specific details. However, these techniques may be practiced without these specific details. In some instances, in order to avoid obscuring the concepts of the described embodiments, well-known structures and devices are shown in the form of a block diagram.

Claim 1:
A method to detect sweat by a sweat sensor, the sweat sensor comprising:
a sweat-guiding electrode layer (<NUM>) comprising an insulating layer (<NUM>), a conductive electrode provided in the insulating layer (<NUM>), and a first through hole, wherein the first through hole goes through the insulating layer (<NUM>) and the conductive electrode, and the conductive electrode comprises a first electrode (<NUM>) and a second electrode (<NUM>);
an adhesive layer (<NUM>) provided on the insulating layer (<NUM>), wherein the adhesive layer (<NUM>) is provided with a second through hole communicated with the first through hole; and
a water-absorbing diffusion layer (<NUM>) provided on the adhesive layer (<NUM>), wherein the water-absorbing diffusion layer (<NUM>) covers the second through hole;
characterized in that
conductance values of sweat passing through the first through hole are recorded by the conductive electrode,
a conductance square wave curve is obtained according to the conductance values,
a real-time total sweat electrolyte concentration and a total sweat volume are simultaneously obtained through the conductance square wave curve; and
an amplitude of the conductance square wave curve is correlated with the real-time total sweat electrolyte concentration in the first through hole, and
the total sweat volume and a sweat rate of sweat passing through the first through hole are correlated with a time difference between conductance square waves in the conductance square wave curve.