DESCRIPTION
A SKIN PATCH WEARABLE BIOSENSOR FOR SIMULTANEOUS MONITORING
OF PHYSIOLOGICAL PARAMETERS IN INTERSTITIAL FLUID
TECHNICAL FIELD
Various aspects of this disclosure relate to a wearable device, in particular to a wearable device for analyzing physiological parameters in the interstitial fluid of a user wearing the wearable device.
BACKGROUND
The following discussion of the background art is intended to facilitate an understanding of the present disclosure only. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was published, known, or is part of the common general knowledge of the person skilled in the art in any jurisdiction as of the priority date of the disclosure.
In various scenarios, it may be desired and/or required to monitor a vital state (e.g., a wellness) of a user (e.g., a person), such as a driver or a patient. For example, in the case of a driver of a taxi, of public transport means (e.g., a bus) or a long range transport (e.g., a truck hauling goods across long distances) the vital state may be important for safety reasons since a deterioration of the wellness and awareness of the driver below optimal levels may have serious consequences that can lead to loss of life and significant material damages. Therefore, it may be desired and/or required to monitor the vital state (e.g., a psychological status and/or physiological states of the driver. Commonly, using a camera to monitor driver drowsiness is a valuable approach for enhancing driving safety. By analyzing facial cues and eye movements, the system can detect signs of fatigue or inattentiveness. Real-time alerts and interventions can then be initiated, promoting driver alertness and reducing the risk of accidents. However, camera-based technologies have limitations in some scenarios. For instance, in the case of a driver in low blood sugar situation, the camera can only detect abnormal conditions when the driver is about to faint, but it might be too late at that time. Thus, these approaches access the vital state of the driver by analyzing the physical effects resulting from a prior changed physiological status of the driver. As an example, there is a time gap between the consumption of alcohol and the resulting physical manifestation (of being drunk, such as having a slower eye reaction, unfocused eyes, less coordination, etc.). Therefore, alternative methods may be necessary to address this limitation and provide an early detection of abnormality in the driver's vital state. Other approaches monitor the vital state of the user using devices that detect biomarkers within sweat, tears, saliva, or interstitial fluid. This allows to predict the physical effects prior to its manifestation.
The emerging microneedle technology offers a promising solution for non-invasive monitoring of user's vital state. This innovative technology combines the advantages of microneedles and biosensors to extract interstitial fluid (ISF) and measure biomarkers in real-time. Hence, a wearable device adopting this technology may allow to predict physical effects prior to its manifestation. This may allow an early alertness to timely take precautionary measures to prevent any possible negative consequences. However, the existing microneedle biosensors also have limitations.
Some needle designs require an external source of power to draw the interstitial fluid and some biosensors have the detecting agents coated on the outside of the needle, which may lead to biosafety issue.
SUMMARY
Various aspects relate to a wearable device including a plurality of hollow needles for extracting interstitial fluid of a user when the wearable device is attached on skin of the user and one or more electrochemical sensors fluidly connected with the plurality of hollow needles and configured to detect one or more physiological parameters in interstitial fluid. This allows to (e.g., simultaneously) detect and monitor the one or more physiological parameters with high accuracy and in a minimally invasive manner.
In the exemplary scenario of the driver, the wearable device may be configured to detect an alcohol level as a physiological parameter of the driver, which allows to reduce the likelihood of accidents, endanger the lives of other road users, and also result in significant material damage resulting from drunk driving. Similarly, the wearable device may be configured to detect a drug level as a physiological parameter of the driver, which allows to reduce the above consequences. This invention does not require external power source to extract interstitial fluid and all the detecting agents are not in touch with skin to eliminate any biosafety risk.
Various aspects relate to a wearable device including: a substrate (e.g., a patch); a plurality of hollow needles extending from a first side of the substrate to a second side of the substrate opposite to the first side and protruding from the second side for extracting interstitial fluid of a user when the wearable device is attached on skin of the user; and an electrochemical sensor including a working electrode arranged on the first side of the substrate and fluidly connected with the plurality of hollow needles, wherein the electrochemical sensor is configured to detect a physiological parameter in interstitial fluid; wherein the plurality of hollow needles is configured to, when the wearable device is attached on skin of the user, extract the interstitial fluid of the user and transport the interstitial fluid to the working electrode by capillary effect.
Extracting the interstitial fluid by capillary effect has the effect that the wearable device does not require any external source (such as a pump or current/voltage source) for actuating the interstitial fluid.
According to various aspects, the hollow needles of the plurality of hollow needles may be coated with (e.g., one or more layer of) a hydrophilic material. This has the effect that the capillary effect is increased.
According to various aspects, the physiological parameter may be one of the following physiological parameters in interstitial fluid: an alcohol level within the interstitial fluid, a drug (e.g., opioid) level within the interstitial fluid, a glucose level within the interstitial fluid, or an oxygen level within the interstitial fluid.
According to various aspects, the wearable device may further include: a processor configured to receive a signal from the electrochemical sensor, wherein the signal represents a concentration of the physiological parameter. This has the effect that the concentration of the physiological parameter can be determined directly by the wearable device itself. Thus, the processor may be configured to determine the concentration of the physiological parameter based on the signal.
According to various aspects, the wearable device may further include: a wireless communication interface coupled to the processor, wherein the processor is configured to transmit, via the wireless communication interface, a communication signal representing the determined concentration of the physiological parameter. By this, the wearable device can provide the detected concentrations to any suitable user device.
According to various aspects, the wearable device may further include: a current detection unit (e.g., including a current amplifier and a potentiostat), wherein the electrochemical sensor is configured to provide a reaction current representing the concentration of the physiological parameter to the current detection unit, and wherein the current detection unit is configured to provide a digital signal in accordance with the reaction current as the signal to the processor.
According to various aspects, the hollow needles of the plurality of hollow needles are arranged in an array of hollow needles.
According to various aspects, the hollow needles of the plurality of hollow needles are configured to, when the wearable device is attached on the skin of the user, extend through the stratum corneum of the skin for extracting interstitial fluid of the user. This allows to extract interstitial fluid being located below the stratum corneum of the skin.
According to various aspects, the hollow needles of the plurality of hollow needles may be made of biocompatible and/or a biodegradable material. Biocompatibility reduces the risk of any infection or the like and biodegradability avoids (e.g., nondegradable) trash.
According to various aspects, the hollow needles of the plurality of hollow needles have a length such that, when the wearable device is attached on the skin of the user, they protrude into the skin of the user in a range from about 300 pm to about 500 pm. This allows to extract interstitial fluid being located in that depth.
According to various aspects, each needle of the plurality of hollow needles may respectively include a pyramidal tip, a cuboid body, an opening within the pyramidal tip, and a channel within the cuboid body connecting the opening fluidly with the first electrochemical sensor and/or the second electrochemical sensor, respectively. Optionally the plurality of hollow needles may include a base on which the hollow needles are arranged. In some aspects, the base may be made of a same material as the hollow needles.
According to various aspects, the wearable device may further include: a reservoir fluidly connected with each of the plurality of hollow needles and with the electrochemical sensor, the reservoir being arranged between the plurality of hollow needles and the electrochemical sensor in flow direction, thereby providing a reservoir for extracted interstitial fluid.
According to various aspects, the wearable device may further include: one or more batteries configured to provide energy to the electrochemical sensor and optionally the processor. The one or more batteries allow that the wearable device does not require any external source of energy.
According to various aspects, the wearable device may further include: a first module including the substrate, the plurality of hollow needles, the electrochemical sensor, and a first holding structure; and a second module including the processor, the wireless communication interface, the one or more batteries, and a second holding structure; wherein the first holding structure and the second holding structure are configured to be releasably attachable to each other (e.g., by sliding the first holding structure into the second holding structure) such that the plurality of hollow needles are exposable, thereby allowing to releasably attach the first module to the second module.
According to various aspects, the wearable device may further include: a (e.g., flexible) fixing device coupled to the second module and allowing to attach the wearable device on the skin of the user such that the plurality of hollow needles extend through the stratum corneum of the skin for extracting interstitial fluid of the user. The fixing device includes at least one of a hook and loop fastener (e.g., a Velcro® fastener), a bracelet (e.g., for the wrist), and/or a patch configured to be wrappable around an (e.g., lower or upper) arm and/or a leg and/or a torso of the user.
According to various aspects, the first module may include further include a cover element being releasably attachable to the first module and configured to cover the plurality of hollow needles. This reduces the risk that the user comes into contact with needles prior to use, which may render the needles unsafe for subsequent use.
According to various aspects, the plurality of hollow needles is a first plurality of hollow needles, the electrochemical sensor is a first electrochemical sensor, the working electrode is a first working electrode, and the physiological parameter is a first physiological parameter; and the wearable device may further include: a second plurality of hollow needles extending from the first side of the substrate to the second side of the substrate and protruding from the second side for extracting interstitial fluid of the user when the wearable device is attached on skin of the user; and a second electrochemical sensor (comprising a second working electrode arranged on the first side of the substrate and fluidly connected with the second plurality of hollow needles, wherein the second electrochemical sensor is configured to detect a second physiological parameter different from the first physiological parameter in the interstitial fluid. This has the effect, that two (or more) physiological parameters (viz. the first physiological parameter and the second physiological parameter) can be determined simultaneously.
According to various aspects, the wearable device may further include: a counter electrode; and a reference electrode; wherein the first working electrode, the counter electrode, and the reference electrode provide the first electrochemical sensor as a first three-electrode electrochemical sensor; and wherein the second working electrode, the counter electrode, and the reference electrode provide the second electrochemical sensor as a second three-electrode electrochemical sensor. By this, a single reference electrode and a single counter electrode can be used for simultaneously detecting two (or more) physiological parameters.
According to various aspects, the wearable device may further include: a third plurality of hollow needles and a fourth plurality of hollow needles extending from the first side of the substrate to the second side of the substrate and protruding from the second side for extracting interstitial fluid of the user when the wearable device is attached on the skin of the user, wherein the first plurality of hollow needles is fluidly connected with the first working electrode, wherein the second plurality of hollow needles is fluidly connected with the second working electrode, wherein the third plurality of hollow needles is fluidly connected with the counter electrode, and wherein the fourth plurality of hollow needles is fluidly connected with the reference electrode. By this, interstitial fluid can also be transported to the reference electrode and the counter electrode without requiring an external source of power.
Thus, a wearable device is provided capable to detect a vital state of a user (such as the driver in the above illustrative example) prior to physical effects resulting from the vital state. Hence, the wearable device allows to predict physical effects prior to its manifestation. This may allow an early alertness to timely take precautionary measures to prevent any possible negative consequences. For this, the wearable device is capable to detect physiological parameter(s) in interstitial fluid of the user. In the exemplary scenario of the driver, the wearable device may be configured to detect an alcohol level as a physiological parameter of the driver, which allows to reduce the likelihood of accidents, endanger the lives of other road users, and also result in significant material damage resulting from drunk driving. Similarly, the wearable device may be configured to detect a drug level as a physiological parameter of the driver, which allows to reduce the above consequences.
BRIEF DESCRIPTION OF THE DRAWINGS
The present disclosure will be better understood with reference to the detailed description when considered in conjunction with the non-limiting examples and the accompanying drawings, in which: FIG.1A to FIG.1 G each show aspects of a detection device according to various aspects; FIG.2 shows a detection module according to various aspects; and FIG.3A to FIG.3D each show a wearable device according to various aspects.
DETAILED DESCRIPTION
The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure. Other embodiments may be utilized and structural, and logical changes may be made without departing from the scope of the disclosure. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.
Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments. Features that are described in the context of an embodiment may correspondingly be applicable to the other embodiments, even if not explicitly described in these other embodiments. Furthermore, additions and/or combinations and/or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.
Various aspects relate to wearable device which allows to (e.g., simultaneously) detect and monitor one or more physiological parameters in interstitial fluid (of a user) with high accuracy, in a minimally invasive manner, and in a predictive manner prior to physical symptoms resulting from an unwellness.
FIG.1 A to FIG.1 G each show aspects of a detection device 100 according to various aspects. This detection device may also be referred to as skin patch.
FIG.1A shows a top view 108, a bottom view 110, and a sectional view in between 25 the top view 108 and the bottom view 110 of an exemplary configuration of the detection device 100.
The detection device 100 may include a (e.g., flexible) substrate (e.g., a patch) 102. The substrate 102 may have a first side (e.g., a top side) shown in the top view 108 and a second side (e.g., a bottom side) shown in the bottom view 110.
The detection device 100 may include plurality of hollow needles 106. The plurality of hollow needles 106 may extend from the first side of the substrate to the second side of the substrate 102 and protrude from the second side for extracting interstitial fluid of a user. The plurality of hollow needles 106 may be sized (viz. may have dimension such) that, when the detection device 100 is attached (e.g., worn or placed) on the skin of the user, the plurality of hollow needles 106 extend through the stratum corneum of the skin for extracting interstitial fluid of the user. For this, each hollow needle of the plurality of hollow needles 106 may be configured such that, when the detection device 100 is attached (e.g., worn or placed) on the skin of the user, the hollow needle extends through the skin of the user down to a depth in a range from about 300 pm to about 500 pm. As an example, each hollow needle of the plurality of hollow needles 106 may protrude from the substrate 102 with a length of about 1100 pm. In embodiments, in which there is a distance between the second side of the substrate 102 and the skin of the user when the detection device 100 is attached (e.g., worn or placed) on the skin of the user, the length of the hollow needles may be such that the hollow needles extend through the stratum corneum into the skin in a range from about 300 pm to about 500 pm. Due to the respective dimensions of the hollow needles, they may also be referred to as hollow microneedles. As illustratively shown in the bottom view 110, the plurality of hollow needles may be arranged in a square or circular array of hollow (micro-) needles. It is understood that such an array of hollow (micro-) needles is an exemplary arrangement of the hollow needles and that the hollow needles may be arranged in any other suitable arrangement.
The detection device 100 may include an electrochemical sensor 104. An electrode of the electrochemical sensor 104 may be firmly deposited on the first side of the substrate 102 and fluidly connected with the plurality of hollow needles 106. The electrochemical sensor 104 may be surface functionalized with detecting agents (e.g., enzyme, nanomaterials, chelating agents) to detect a physiological parameter in interstitial fluid of the user.
According to various aspects, the plurality of hollow needles 106 may be configured to extract and transport the interstitial fluid of the user to the electrochemical sensor 104 by capillary effect. Hence, the detection device 100 may include no external source (such as a pump or current/voltage source) for actuating the interstitial fluid.
As shown in FIG.1 B, the detection device 100 may include a reservoir 112 for interstitial fluid. The reservoir 112 may be fluidly connected with each hollow needle of the plurality of hollow needles and with the electrochemical sensor and, in flow direction, between them, thereby serving as the reservoir 112 for extracted interstitial fluid.
According to various aspects, the detection device 100 may include more than one electrochemical sensor and a corresponding plurality of hollow needles. Thus, the detection device 100 may include one or more electrochemical sensors 104 (n = 1 to N) (with N being any integer number equal to or greater than one) and a respective plurality of hollow needles 106(n) for each electrochemical sensor 104(n) of the one or more electrochemical sensors 104 (n = 1 to N). As described above, the detection device 100 shown in FIG.1A and FIG.1 B shows an embodiment for N =1. FIG.1C shows an exemplary configuration of the detection device 100 for N = 2. It is understood that these examples serve for illustration and that N may be greater than two. Using two or more electrochemical sensors allows for a simultaneous detection and continuous monitoring of several physiological parameters at the same time, such as glucose, oxygen, alcohol and/or drugs.
With reference to FIG.1C, the first electrochemical sensor 104(1) arranged on the first side of the substrate 102 and fluidly connected with a first plurality of hollow needles 106(1) as well as a second electrochemical sensor 104(2) arranged on the first side of the substrate 102 and fluidly connected with a second plurality of hollow needles 106(2). Each electrochemical sensor 104(n) of the one or more electrochemical sensors 104 (n = 1 to N) may be configured to detect a respective physiological parameter in interstitial fluid of the user. For example, the first electrochemical sensor 104(1) may be configured to detect a first physiological parameter of the user and the second electrochemical sensor 104(2) may be configured to detect a second physiological parameter of the user. The second physiological parameter may be different from the first physiological parameter such that the detection device 100 may be capable of simultaneously detect more than one physiological parameter of the user.
A physiological parameter, as described herein, may be any physiological parameter detectable from interstitial fluid, such as (but not limited to) an alcohol level within the interstitial fluid, a drug (e.g., opioid) level within the interstitial fluid, a glucose level within the interstitial fluid, an oxygen level within the interstitial fluid, etc. Combinations of other physiological parameters/biosignals of interest may also be monitored, depending on the specific application targeted depending on the type of the electrochemical sensor(s).
The detection device 100 may include a respective reservoir 112(n) for each of the pluralities of hollow needles 106 (n = 1 to N) (see FIG.1 D). Thus, the detection device 100 may include a plurality of N reservoirs.
As detailed above, a (e.g., each) plurality of hollow needles 106(n) may be configured (e.g., dimensioned) to extract interstitial fluid of the user. An exemplary configuration is shown in FIG.1 E. A hollow needle may include a pyramidal tip 6, a cuboid body 7, an opening 1 within the pyramidal tip 6, and a (interior) channel 2 within the cuboid body connecting the opening 1 fluidly with the corresponding electrochemical sensor 104(n), 4. As shown, the detection device 100 may, optionally, include the reservoir 112(n) provided in a gap 3 between a base 5 of the plurality of hollow needles 106(n) and the electrochemical sensor 104(n), 4. In some aspects, the base may be made of a same material as the hollow needles. The opening (also referred to as outer hole) 1 may be located outer holes of the central hollow spaces 1 of the interior channel 2 on skewed to a side of the pyramidal tip 6 (viz. not centrally). The pyramidal tip 6 may be sharp to allow for entering the skin of the user.
The dimensions of the hollow needles may be configured to, when the detection device 100 is worn on the skin, not draw blood from capillary blood vessels or reach underlying nerves. For example, the tip diameter may be about 0.05 mm and at the base a diameter of a hollow needle may be about 0.3 mm, but other variations in shape and dimensions may be used, as is known to those skilled in the art. Thus, when impinged into the user's skin, the microneedles can penetrate the outermost layer of the skin named stratum corneum down to a depth of about 0.3 mm to about 0.5 mm allowing to rapidly extract the interstitial fluid, e.g., by capillary effect, depending on the design and material of the respective plurality of hollow needles (also referred to as microneedle array). This is called a minimal invasive penetration since the microneedles reach neither the underlying capillary blood vessels nor the nerves and the user does not feel any pain.
According to various aspects, the hollow needles may be coated with (e.g., one or more layer of) a hydrophilic material. This may increase the capillary effect for extracting the interstitial fluid. The hydrophilic material may be a hyaluronic acid. The hydrophilic material may create a (super) hydrophilic surface for increasing the capillary effect. The (super) hydrophilic surface may have a contact angle (to interstitial fluid) equal to or less than 30°.
Such a (e.g., array) of hollow (micro-) needles may, for example, be manufactured using high-resolution photo-cure 3D printing.
According to various aspects, each electrochemical sensor 104(n) may be a three-electrode sensor. A three-electrode sensor may include a working electrode, a counter electrode, and a reference electrode. Therefore, as shown in FIG.1 F, the reference sign 104(n) may refer to a working electrode of a respective electrochemical sensor 104(n) and the detection device 100 may further include a counter electrode 114, and a reference electrode 116. Similarly as described herein with reference to a respective plurality of hollow needles 106(n) and the corresponding (working electrode of the corresponding respective) electrochemical sensor 104(n), the detection device 100 may include a counter plurality of hollow needles 118 for extracting interstitial fluid and fluidly connected with the counter electrode 114 as well as a reference plurality of hollow needles 120 for extracting interstitial fluid and fluidly connected with the reference electrode 120 (each may also include a respective (or common) reservoir).
Thus, the first working electrode 104(1), the counter electrode 114 and the reference electrode 116 may form the first electrochemical sensor and the second working electrode 104(2), the counter electrode 114 and the reference electrode 116 may form the second electrochemical sensor. Hence, the detection device 100 may include a plurality of N working electrodes, the counter electrode, and the reference electrode. Thus, a total number of electrodes for detecting N parameters may be N+2. For example, in order to detect alcohol and opioid, four electrodes may be used, namely (n=1) alcohol working electrode, (n=2) opioid working electrode, (3) the counter electrode, and (4) the reference electrode.
Each electrode described herein may be made of carbon and/or noble metals. Each working electrode 104(n) may be configured for specific detecting agent(s) with selective affinity towards the desired biochemical (indicating the corresponding physiological parameter) so that they can detect it as well as measure its concentration in the interstitial fluid.
The topmost layer of each working electrode 104(n) may be made of a substance which has strong chemical affinity towards the biochemical of interest for the physiological parameter to be monitored. Hence, only the molecules of the biochemical of interest will be selectively trapped at the surface of the working electrode 104(n), and this will trigger their detection and generate an output signal proportional to their concentration by an electrochemical mechanism, e.g. modification of impedance or inducing a local redox reaction that can generate a small current, or any other electrochemical mechanism suitable for the specific structure of the chosen electrochemical sensors, as known to those skilled in the art. FIG.1G shows an exemplary configuration of the detection device 100 with a view on the hollow needle arrays (upper image) and a view on the electrodes (lower image).
The detection device 100 may include a respective working electrode contact 122(n) for each of the one or more working electrodes 104(n), a counter electrode contact 124 for the counter electrode 114, and a reference electrode contact 126 for the reference electrode 116.
The detection device 100 can be fabricated with low costs and does not require any complex manufacturing processes. Detecting the physiological parameter(s) within the interstitial fluid is advantageous over other methods since the interstitial fluid may include similar biomarkers as blood; however, is less invasive. Further, there is only a short lag time between the biomarkers being in the blood and later on in the interstitial fluid. As compared to detecting biomarkers within sweat, tears or saliva, the present approach has a higher accuracy/precision. Also, in sweat, tears or saliva based biodetection there is a much larger variability in the concentration of the biochemicals of interest that is caused or at least influenced by many other factors, e.g., the state of hydration.
Further, the detection device 100 allows to, when being arranged on the skin of the user, to detect (e.g., monitor) the one or more physiological parameters continuously.
FIG.2 shows a detection module 200 (also referred to as first module) according to various aspects. The detection module 200 may include the detection device 100. The detection module 200 may include a needle element 202 including the plurality of hollow needles and a sensor element 204 including the one or more electrochemical sensors. The needle element 202 and the sensor element 204 may provide the detection device 100. The detection module 200 may include a first frame layer 206 and a second frame layer 208 sandwiching the detection device 100 in between. The substrate 102 of the detection device 100 may include a flexible sheet having first and second surfaces and the needles provided on the first surface of the flexible sheet. An adhesive sheet may be adhered to the second surface of the flexible sheet. A protective release sheet may include one or more holes, wherein the needle array may be held in the hole. A case holding may hold the protective release sheet so that the protective release sheet is sandwiched from above and below.
The detection module 200 may include or may be attachable to a cover element 210. The cover element 210 may be configured to releasably attach to the detection module 200 and configured to cover the one or more pluralities of hollow needles. Thus, the cover element 210 can be used to protect the one or more pluralities of hollow needles from damage and/or reducing the risk of contamination. Hence, the detection module 200 may include a housing (e.g., a casing) for housing the detection device 100.
FIG.3A shows a wearable device 10 according to various aspects. The wearable device 10 may be modular. The wearable device 10 may include the detection module 200. The wearable device 10 may include a read-out module 300 (also referred to as second module).
The detection module 200 may be couplable to the read-out module 300. For this, the read-out module 300 may include a suitable interface 302 to the detection module 200. According to various aspects, the detection module 200 and the readout module 300 may be releasably attachable to each. For example, the detection module 200 may include a first holding structure and the read-out module 300 may include a second holding structure which may be configured releasably attachable to each. As an example, the read-out module 300 may include a guiding structure into which the detection module 200 can slide in (and out) to releasably attach the detection module 200 and the read-out module 300 with each other. Optionally, the detection module 200 and/or the read-out module 300 may include a lock mechanism allowing to lock the position of the detection module 200 when attached to the read-out module 300. In either case, when the detection module 200 is attached to the read-out module 300, they may be arranged such that the one or more pluralities of hollow needles are exposable (e.g., by removing the cover element 210 when used). As an example, the detection module 200 may include a slidable feature and a lockable slot to hold the detection module 200 within the read-out module 300.
The read-out module 300 may include a processor 304 (e.g., a microprocessor). According to various aspects, the detection module 200 may be configured to provide one or more signals representing the detected one or more physiological parameters. For example, the detection module 200 may be configured to provide (directly or indirectly) (when attached to the read-out module 300) a respective signal from each electrochemical sensor 104(n) representing a concentration of the corresponding detected physiological parameter to the processor 304.
In an exemplary configuration, the detection module 200 may be configured to provide a respective current from the working electrode(s), the counter electrode, and the reference electrode, described herein, via the above-described electrode contacts (e.g., the working electrode contact 122(n) for each of the one or more working electrodes 104(n), the counter electrode contact 124 for the counter electrode 114, and the reference electrode contact 126 for the reference electrode 116). The interface 302 may be configured to receive the currents. The read-out module 300 may include a current amplifier 306 for amplifying the currents and a potentiostat 308 for measuring and digitizing the amplified currents. The processors 304 may be configured to receive the digitized amplified current values representing the respective concentration of the one or more physiological parameters.
Hence, output signals from all of the one or more electrochemical sensors may be directed to the read-out module 300 which may perform signal processing, conversion of the sensor's output analog signals into an appropriate digital format, process the obtained data and then transmit them wirelessly to a nearby user device.
In some examples, the detection module 200 may include three ports, two for data transfer and one as power source.
The processor 304 may be configured to determine the respective concentration of the one or more physiological parameters based thereon.
The read-out module 300 may include a wireless communication interface 310. The wireless communication interface 310 may be coupled to the processor 304. The processor 304 may be configured to transmit, via the wireless communication interface 310, a signal representing the respectively determined concentration of the one or more physiological parameters. The wireless communication interface 310 may be any suitable interface for providing a corresponding wireless communication connection. The processor 304 may be configured to transmit the signal via the wireless communication interface 310 to one or more user devices 20 capable to receive the signal (e.g., depending on the type of the wireless communication connection). A user device, as described herein, may be any suitable device capable to interact with a user via one or more user interfaces (e.g., including a speaker, a display (e.g., a touchscreen), etc. The user device may be, for example, a smartphone, a tablet, a laptop, a smartwatch, a TV, a head-mounted display, augmented reality glasses, etc. The transmission to the user device may be a direct transmission or an indirect transmission (e.g., via a cloud server).
The read-out module 300 may include one or more batteries 312 for powering one or more elements or devices of the read-out module 300, such as the interface 302, the processor 304, the current amplifier 306, the potentiostat 308, and/or the wireless communication interface 310.
According to various aspects, the read-out module 300 may be configured such that 25 respective one or more threshold values of parameters described herein can be set via the wireless communication interface 310.
According to various aspects, the read-out module 300 may be configured such that configuration settings can be set via the wireless communication interface 310.
According to various aspects, the detection module 200 and the read-out module 300 may be configured such that respective one or more threshold values of detection parameters and/or configuration settings of the detection module 200 can be set via the wireless communication interface 310.
According to various aspects, the wearable device 10 may include a fixing device 400. The fixing device 400 may be coupled to the read-out module 300. The fixing device 400 may allow to attach the wearable device 10 on the user. For example, the at least one of a hook and loop fastener (e.g., a Velcro® fastener), a bracelet (e.g., for the wrist), and/or a patch configured to be able to wrap around an (e.g., lower or upper) arm and/or a leg and/or a torso of the user. Hence, the wearable device 10 may be wearable at any suitable position on the user e.g., similar to a watch in the case of the wrist. The wearable device 10 may be configured such that, when the fixing device 400 is attached (e.g., fixed) to the user, the one or more pluralities of hollow needles are arranged in direction of the skin of the user and protrude through into the skin for extracting interstitial fluid.
In an embodiment, a casing of the read-out module 300 may be attached to a flexible bracelet or watch-like band. This casing may expose the (micro-) needle arrays on the underlying side of the casing, so that they can easily penetrate the skin when the wearable device 10 is attached to the wrist and firmly secured onto the skin. In a further embodiment, the casing may be attached to a flexible body patch that can applied or wrapped onto/around the torso. In an even further embodiment, the casing may be embedded into a flexible patch that can be wrapped around parts of the bodies, depending on its specific design.
It is understood that the read-out module 300 may include a housing (e.g., a casing) for housing the elements of the read-out module 300.
FIG.3B to FIG.3D each show an exemplary configuration of the wearable device 10. The exemplary configuration shown in FIG.3C and FIG.3D refer to an embodiment in which the detection module 200 is slidable into the read-out module 300. This sliding method may not require any adhesive, thereby providing an easy and user-friendly approach. Further with reference to in FIG.3C and FIG.3D, the housing of the read-out module 300 may include a battery cover 314 releasably attachable to one or more other parts of the housing, thereby allowing to change an empty one of the one or more batteries 312 with a new one.
Optionally, the read-out module 300 may include an indicator 316 (e.g., a button, an !HMI-Human Machine Interface, etc.) configured to indicate a status of the wearable device 10. For example, the indicator 316 may include one or more light emitting diodes (LEDs) for indicating the status of the wearable device 10 depending on a shown color. For example, the indicator 316 may be configured to indicate a battery status, a connectivity (of the wireless communication interface 310), and/or a working or non-working status.
For example, a method for using the wearable device 10 may include removing the cover element 210 (when used). The method may further include attaching the detection module 200 to the read-out module 300 (e.g., by sliding the detection module 200 into the read-out module 300). The method may include checking the indicator 316 indicating whether the wearable device 10 is working or not. The method may include checking the indicator 316 indicating whether there is connectivity of the wireless communication interlace 310. The method may include, in the case that the wearable device 10 is working and that there is connectivity, the user pressing a start button (provided at the read-out module 300) to start transferring data to the one or more user devices 20. Optionally, the method may include attaching the fixing device 400 on the read-out module 300 (prior or after one or more of the above-described steps). The method may include fixing the fixing device 400 on the user to attach the wearable device 10 to the user.
The modularity of the wearable device 10 as described herein may allow to reduce costs for detecting and monitoring one or more physiological parameters of a user (viz. in interstitial fluid of the user). For example, the detection module 200 may be for one-time use, whereas the read-out module 300 and the fixing device 400 may be for long-time use. The releasable attachment of a detection module 200 to the read-out module 300 may be in a plug-and-play type. Further, the modular approach of the detection module 200 further reduces the risk of biological contamination and/or fouling as no enzymes/chemicals are entering the skin together with microneedles. The wearable device 10 as described herein allows a data processing of the wearable device itself making the wearable device available to all kind of users since no special analyzing and/or processing knowledge is required. The wearable device disclosed herein allows to conduct a (e.g., simultaneous) real time in situ measurement of one or more biochemicals expressing physiological parameters in interstitial fluid using a minimally invasive approach.
Hence, the wearable device 10 described herein may allow to simultaneously monitor several physiological parameters.
The microneedles are minimally invasive so that the user does not feel any pain. The microneedles may be made of a biocompatible and biodegradable material, e.g. synthetic resin, making them environmentally friendly.
The wearable device allows for a real-time and continuous monitoring (e.g., depending on the one or more batteries the wearable device may be functional for more than 12 hours).
The one or more electrochemical sensors (e.g., their electrodes and other elements) may be located right behind the substrate (e.g., patch) and, therefore, do not enter or contact the skin. Further, the wearable device allows for a fast detection time (e.g., less than 5 minutes) and -in the case of alcohol-with better accuracy when compared to normal transdermal alcohol sensors.
According to various aspects, a wearable microneedle-based biosensor for simultaneous continuous monitoring of physiological parameters is provided. The wearable may be used by vehicle fleet operators, by insurance companies, in telemedicine, in hospitals, in the aviation sector, in a factory setup, etc. In the following, various aspects of this disclosure will be illustrated. It is noted that aspects described with reference to control device or a vehicle may be accordingly 20 implemented in a method, and vice versa.
Example 1 is a wearable device including: a substrate (e.g., a patch); a first plurality of hollow needles and a second plurality of hollow needles extending from a first side of the substrate to a second side of the substrate opposite to the first side and protruding from the second side for extracting interstitial fluid of a user when the wearable device is attached on skin of the user; a first electrochemical sensor arranged on the first side of the substrate and fluidly connected with the first plurality of hollow needles, wherein the first electrochemical sensor is configured to detect a first physiological parameter in interstitial fluid of the user; and a second electrochemical sensor arranged on the first side of the substrate and fluidly connected with the second plurality of hollow needles, wherein the second electrochemical sensor is configured to detect a second physiological parameter different from the first physiological parameter in interstitial fluid of the user.
In Example 2, the subject matter of Example 1 can optionally include that the first plurality of hollow needles and the second plurality of hollow needles are configured to, when the wearable device is attached on the skin of the user, extract the interstitial fluid and transport the interstitial fluid to the first electrochemical sensor and the second electrochemical sensor, respectively, by capillary effect. Hence, the wearable device may include no external source (such as a pump or current/voltage source) for actuating the interstitial fluid.
In Example 3, the subject matter of Example 1 or 2 can optionally include that the first plurality of hollow needles and the second plurality of hollow needles are internally coated with (e.g., one or more layer of) a hydrophilic material (e.g., to increase the capillary effect). The hydrophilic material may be a hyaluronic acid. The hydrophilic material may create a (super) hydrophilic surface for increasing the capillary effect. The (super) hydrophilic surface may have a contact angle (to interstitial fluid) equal to or less than 30°.
In Example 4, the wearable device of any one of Examples 1 to 3 can optionally further include: a first working electrode for detecting the first physiological parameter; a second working electrode for detecting the second physiological parameter; a counter electrode; and a reference electrode; wherein the first working electrode, the counter electrode, and the reference electrode provide the first electrochemical sensor as a first three-electrode electrochemical sensor; and wherein the second working electrode, the counter electrode, and the reference electrode provide the second electrochemical sensor as a second three-electrode electrochemical sensor.
In Example 5, the wearable device of Example 4 can optionally further include: a third plurality of hollow needles and a fourth plurality of hollow needles extending from the first side of the substrate to the second side of the substrate and protruding from the second side for extracting interstitial fluid of the user when the wearable device is attached on the skin of the user, wherein the first plurality of hollow needles is fluidly connected with the first working electrode, wherein the second plurality of hollow needles is fluidly connected with the second working electrode, wherein the third plurality of hollow needles is fluidly connected with the counter electrode, and wherein the fourth plurality of hollow needles is fluidly connected with the reference electrode.
In Example 6, the subject matter of any one of Examples 1 to 5 can optionally include that the first physiological parameter and/or the second physiological parameter are one of the following physiological parameters in interstitial fluid: an alcohol level within the interstitial fluid, a drug (e.g., opioid) level within the interstitial fluid, a glucose level within the interstitial fluid, or an oxygen level within the interstitial fluid.
In Example 7, the wearable device of any one of Examples 1 to 6 can optionally further include: a processor configured to receive a first signal from the first electrochemical sensor and a second signal from the second electrochemical sensor, wherein the first signal represents a concentration of the first physiological parameter and wherein the second signal represents a concentration of the second physiological parameter.
In Example 8, the subject matter of Example 7 can optionally include that the processor is configured to determine the concentration of the first physiological parameter based on the first signal and the concentration of the second physiological parameter based on the second signal.
In Example 9, the wearable device of Example 8 can optionally further include: a wireless communication interface coupled to the processor, wherein the processor is configured to transmit, via the wireless communication interface, a signal representing the determined concentration of the first physiological parameter and/or the determined concentration of the second physiological parameter.
In Example 10, the wearable device of any one of Examples 7 to 9 can optionally further include: a first current detection unit (e.g., including a current amplifier and a potentiostat), wherein the first electrochemical sensor is configured to provide a reaction current representing the concentration of the first physiological parameter to the first current detection unit, and wherein the first current detection unit is configured to provide a digital signal in accordance with the first reaction current as the first signal to the processor; and/or a second current detection unit (e.g., including a current amplifier and a potentiostat), wherein the second electrochemical sensor is configured to provide a second reaction current representing the concentration of the second physiological parameter to the second current detection unit, and wherein the second current detection unit is configured to provide a digital signal in accordance with the second reaction current as the second signal to the processor.
In Example 11, the subject matter of any one of Examples 1 to 10 can optionally include that the hollow needles of the first plurality of hollow needles are arranged in an array of hollow needles and/or wherein the hollow needles of the second plurality of hollow needles are arranged in an array of hollow needles.
In Example 12, the subject matter of any one of Examples 1 to 11 can optionally include that the first plurality of hollow needles and the second plurality of hollow needles are configured to, when the wearable device is attached on the skin of the user, extend through the stratum corneum of the skin for extracting interstitial fluid of the user.
In Example 13, the subject matter of any one of Examples 1 to 12 can optionally include that the first plurality of hollow needles and/or the second plurality of hollow needles are made of a biocompatible and/or biodegradable material.
In Example 14, the subject matter of any one of Examples 1 to 13 can optionally include that the hollow needles of the first plurality of hollow needles and/or the hollow needles of the second plurality of hollow needles have a length such that, when the wearable device is attached on the skin of the user, they protrude into the skin of the user in a range from about 300 pm to about 500 pm.
In Example 15, the subject matter of any one of Examples 1 to 14 can optionally include that each needle of the first plurality of hollow needles and/or the second plurality of hollow needles respectively includes pyramidal tip, a cuboid body, an opening within the pyramidal tip, and a channel within the cuboid body connecting the opening fluidly with the first electrochemical sensor and/or the second electrochemical sensor, respectively. Optionally the first plurality of hollow needles and/or the second plurality of hollow needles may include a base on which the hollow needles are arranged. In some aspects, the base may be made of a same material as the hollow needles.
In Example 16, the wearable device of any one of Examples 1 to 15 can optionally further include: a first reservoir fluidly connected with each of the first plurality of hollow needles and with the first electrochemical sensor, the first reservoir being arranged between the first plurality of hollow needles and the first electrochemical sensor in flow direction, thereby providing a reservoir for extracted interstitial fluid; and/or a second reservoir fluidly connected with each of the second plurality of hollow needles and with the second electrochemical sensor, the second reservoir being arranged between the second plurality of hollow needles and the second electrochemical sensor in flow direction, thereby providing a reservoir for extracted interstitial fluid.
In Example 17, the wearable device of any one of Examples 1 to 16 can optionally further include: one or more batteries configured to provide energy to the first electrochemical sensor, the second electrochemical sensor and, provided that in combination with Example 6, the processor.
In Example 18, the wearable device of Examples 9 and 17 can optionally further include: a first module including the substrate, the first plurality of hollow needles, the second plurality of hollow needles, the first electrochemical sensor, the second electrochemical sensor, and a first holding structure; and a second module including the processor, the wireless communication interlace, the one or more batteries, and a second holding structure; wherein the first holding structure and the second holding structure are configured to be releasably attachable to each other (e.g., by sliding the first holding structure into the second holding structure) such that the first plurality of hollow needles and the second plurality of hollow needles are exposable, thereby allowing to releasably attach the first module to the second module.
In Example 19, the wearable device of Example 18 can optionally further include: a (e.g., flexible) fixing device coupled to the second module and allowing to attach the wearable device on the skin of the user such that the first plurality of hollow needles and the second plurality of hollow needles extend through the stratum corneum of the skin for extracting interstitial fluid of the user.
In Example 20, the subject matter of Example 19 can optionally include that the fixing device includes at least one of a hook and loop fastener (e.g., a Velcro® fastener), a bracelet (e.g., for the wrist), and/or a patch configured to be wrappable around an (e.g., lower or upper) arm and/or a leg and/or a torso of the user.
In Example 21, the subject matter of any one of Examples 18 to 20 can optionally include that the first module further includes a cover element being releasably attachable to the first module and configured to cover the first plurality of hollow needles and the second plurality of hollow needles.
Example 22 is a wearable device including: a substrate; a plurality of hollow needles extending from a first side of the substrate to a second side of the substrate opposite to the first side and protruding from the second side for extracting interstitial fluid of a user when the wearable device is attached on skin of the user; and an electrochemical sensor including a working electrode arranged on the first side of the substrate and fluidly connected with the plurality of hollow needles, wherein the electrochemical sensor is configured to detect a physiological parameter in interstitial fluid; wherein the plurality of hollow needles is configured to, when the wearable device is attached on skin of the user, extract the interstitial fluid of the user and transport the interstitial fluid to the working electrode by capillary effect.
In Example 23, the subject matter of Example 22 can optionally include that the hollow needles of the plurality of hollow needles are internally coated with a hydrophilic material, optionally a hyaluronic acid.
In Example 24, the subject matter of Example 22 or 23 can optionally include that the physiological parameter is one of the following physiological parameters in interstitial fluid: an alcohol level within the interstitial fluid, a drug level within the interstitial fluid, a glucose level within the interstitial fluid, or an oxygen level within the interstitial fluid.
In Example 25, the wearable device of any one of Examples 22 to 24 can optionally further include: a processor configured to receive a signal from the electrochemical sensor, wherein the signal represents a concentration of the physiological parameter.
In Example 26, the subject matter of Example 25 can optionally include that the processor is configured to determine the concentration of the physiological parameter based on the signal.
In Example 27, the wearable device of Example 26 can optionally further include: a wireless communication interface coupled to the processor, wherein the processor is configured to transmit, via the wireless communication interface, a communication signal representing the determined concentration of the physiological parameter. In Example 28, the wearable device of any one of Examples 25 to 27 can optionally further include: a current detection unit, wherein the electrochemical sensor is configured to provide a reaction current representing the concentration of the physiological parameter to the current detection unit, and wherein the current detection unit is configured to provide a digital signal in accordance with the reaction current as the signal to the processor.
In Example 29, the subject matter of any one of Examples 22 to 28 can optionally include that the hollow needles of the plurality of hollow needles are arranged in an array of hollow needles.
In Example 30, the subject matter of any one of Examples 22 to 29 can optionally include that the hollow needles of the plurality of hollow needles are configured to, when the wearable device is attached on the skin of the user, extend through the stratum corneum of the skin for extracting interstitial fluid of the user.
In Example 31, the subject matter of any one of Examples 22 to 30 can optionally include that the hollow needles of the plurality of hollow needles are made of a biocompatible and/or biodegradable material.
In Example 32, the subject matter of any one of Examples 22 to 31 can optionally include that the hollow needles of the plurality of hollow needles have a length such that, when the wearable device is attached on the skin of the user, they protrude into the skin of the user in a range from about 300 pm to about 500 pm.
In Example 33, the subject matter of any one of Examples 22 to 32 can optionally include that each needle of the plurality of hollow needles respectively includes pyramidal tip, a cuboid body, an opening within the pyramidal tip, and a channel within the cuboid body connecting the opening fluidly with the electrochemical sensor.
In Example 34, the wearable device of any one of Examples 22 to 33 can optionally further include: a reservoir fluidly connected with each of the plurality of hollow needles and with the electrochemical sensor, the reservoir being arranged between the plurality of hollow needles and the electrochemical sensor in flow direction, thereby providing a reservoir for extracted interstitial fluid.
In Example 35, the wearable device according to any one of Examples 22 to 34 can optionally further include: one or more batteries configured to provide energy to the electrochemical sensor and, provided that in combination with Example 25, the processor.
In Example 36, the wearable device of Examples 27 and 35 can optionally further include: a first module including the substrate, the plurality of hollow needles, the electrochemical sensor, and a first holding structure; and a second module including the processor, the wireless communication interface, the one or more batteries, and a second holding structure; wherein the first holding structure and the second holding structure are configured to be releasably attachable to each other such that the plurality of hollow needles are exposable, thereby allowing to releasably attach the first module to the second module.
In Example 37, the wearable device of Example 36 can optionally further include: a fixing device coupled to the second module and allowing to attach the wearable device on the skin of the user such that the plurality of hollow needles extend through the stratum corneum of the skin for extracting interstitial fluid of the user. In Example 38, the subject matter of Example 37 can optionally include that the fixing device includes at least one of a hook and loop fastener, a bracelet, and/or a patch configured to be wrappable around an arm and/or a leg and/or a torso of the user.
In Example 39, the subject matter of any one of Examples 36 to 38 can optionally include that the first module further includes a cover element being releasably attachable to the first module and configured to cover the plurality of hollow needles. In Example 40, the subject matter of any one of Examples 22 to 39 can optionally include that the plurality of hollow needles is a first plurality of hollow needles, that the electrochemical sensor is a first electrochemical sensor, that the working electrode is a first working electrode, and that the physiological parameter is a first physiological parameter; wherein the wearable device further includes: a second plurality of hollow needles extending from the first side of the substrate to the second side of the substrate and protruding from the second side for extracting interstitial fluid of the user when the wearable device is attached on skin of the user; a second electrochemical sensor including a second working electrode arranged on the first side of the substrate and fluidly connected with the second plurality of hollow needles, wherein the second electrochemical sensor is configured to detect a second physiological parameter different from the first physiological parameter in the interstitial fluid.
The wearable device of Example 40 may be, where applicable, configured to in accordance with one or more of the Examples 1 to 21.
In the context of the various embodiments, the articles "a", "an", and "the" as used with regard to a feature or element include a reference to one or more of the features or elements.
As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
While terms such as "first", "second" etc., may be used to describe various devices, such cameras, are not limited by the above terms. The above terms are used only to distinguish one device from another, and do not define an order and/or significance of the devices.
The term "processor" as used herein may be understood as any kind of technological entity that allows handling of data. The data may be handled according to one or more specific functions that the processor may execute. Further, a processor as used herein may be understood as any kind of circuit, e.g., any kind of analog or digital circuit. A processor may thus be or include an analog circuit, digital circuit, mixed-signal circuit, logic circuit (e.g., a hard-wired logic circuit or a programmable logic circuit), microprocessor (for example a Complex Instruction Set Computer (CISC) processor or a Reduced Instruction Set Computer (RISC) processor), Central Processing Unit (CPU), Graphics Processing Unit (GPU), Digital Signal Processor (DSP), Field Programmable Gate Array (FPGA), integrated circuit, Application Specific Integrated Circuit (ASIC), etc., or any combination thereof. A "processor" may also be a logic-implementing entity executing software, for example any kind of computer program, for example a computer program using a virtual machine code such as for example Java. A "processor" as used herein may also include any kind of cloud-based processing system that allows handling of data in a distributed manner, e.g. with a plurality of logic-implementing entities communicatively coupled with one another (e.g. over the internet) and each assigned to handling the data or part of the data. By way of illustration, an application running on a server and the server can also be a "processor". Any other kind of implementation of the respective functions, which will be described below in further detail, may also be understood as a processor. It is understood that any two (or more) of the processors detailed herein may be realized as a single entity with equivalent functionality or the like, and conversely that any single processor detailed herein may be realized as two (or more) separate entities with equivalent functionality or the like.
The term "memory" as used herein may be understood as a computer-readable medium (e.g., a non-transitory computer-readable medium), in which data or information can be stored for retrieval. References to "memory" included herein may thus be understood as referring to volatile or non-volatile memory, including random access memory (RAM), read-only memory (ROM), flash memory, solid-state storage, magnetic tape, hard disk drive, optical drive, among others, or any combination thereof. Furthermore, it is appreciated that registers, shift registers, processor registers, data buffers, among others, are also embraced herein by the term memory. It is also appreciated that a single component referred to as "memory" or "a memory" may be composed of more than one different type of memory, and thus may refer to a collective component including one or more types of memory. It is readily understood that any single memory component may be separated into multiple collectively equivalent memory components, and vice versa. Furthermore, while memory may be depicted as separate from one or more other components (such as in the drawings), it is understood that memory may be integrated within another component, such as on a common integrated chip.
The word "over", used herein to describe forming a feature, e.g. a layer "over" a side or surface, may be used to mean that the feature, e.g. the layer, may be formed "directly on", e.g. in direct contact with, the implied side or surface. The word "over', used herein to describe forming a feature, e.g. a layer "over" a side or surface, may be used to mean that the feature, e.g. the layer, may be formed "indirectly on" the implied side or surface with one or more additional layers being arranged between the implied side or surface and the formed layer, and may mean that an element, e.g., a sensor, may be in some aspect directly over a side or surface and in other aspects one or more additional elements may be associated with.
A wireless communication connection may be or may include a long-range network connection (e.g., a cellular network (in some aspects referred to as mobile phone network) connection, such as 2G (GSM), 3G (UMTS), 4G (LTE), and/or 5G) and/or a medium-range and/or a short-range network connection (e.g., according to any suitable short-range communication standard, such as a Bluetooth communication standard, a wireless local area network (WLAN) communication standard (e.g., according to any IEEE 802.11 standard), a near-field communication, NFC, standard, an ultra-wideband, UWB, communication standard, etc.).
An electrochemical sensor may be or may include a three-electrode electrochemical sensor. The three-electrode electrochemical sensor may include a working electrode (also referred to as sensing electrode), a counter electrode, and a reference electrode. The working electrode may be the electrode where a chemical reaction takes place. The counter electrode may be configured to balance the reaction of the working electrode. The reference electrode may be configured to anchor the potential of the working electrode to ensure its conditions. An electric current flowing through the working electrode and the counter electrode may represent a value (e.g., a concentration) of the parameter to be measured. Interstitial fluid is the body fluid in spaces around body cells. It is derived from substances that leak out of blood capillaries (the smallest type of blood vessel). It helps bring oxygen and nutrients to cells and to remove waste products from them.
Interstitial fluid consists of a water solvent containing physiological parameters/biomarkers/biochemicals such as sugars, salts, fatty acids, amino acids, coenzymes, hormones, neurotransmitters, white blood cells and cell waste-products. Studies have shown that the concentrations of physiological parameters/biomarkers/biochemicals in interstitial fluid correlates closely to that of physiological parameters/biomarkers/biochemicals in blood. Accordingly, interstitial fluid represents a good source for monitoring the physiological status of the user. A physiological parameter of a user may, in general, any parameter indicating or representing a condition of a body of the user, such as blood pressure, body temperature, breathing rate, heart rate, blood oxygen saturation, and various electrophysiological signals. A physiological parameter that can be obtained from interstitial fluid of the user may, for example, be an alcohol level within the interstitial fluid, a drug (e.g., opioid) level within the interstitial fluid, a glucose level within the interstitial fluid, or an oxygen level within the interstitial fluid. For example, the alcohol level and the drug level may be obtained from the interstitial fluid since the interstitial fluid includes waste-products (such as alcohol and/or drugs) from the body cells of the user.
REFERENCE SIGNS
1: opening 2: channel 5 3: gap 4: electrochemical sensor 5: base 6: pyramidal tip 7: cuboid body 10: wearable device 20: one or more user devices 100: detection device 102: substrate 104: electrochemical sensor 106: plurality of hollow needles 108: top view 110: bottom view 112: reservoir 114: counter electrode 116: reference electrode 118: counter plurality of hollow needles 120: reference plurality of hollow needles 122: working electrode contact 124: counter electrode contact 126: reference electrode contact 200: detection module 202: needle element 204: sensor element 206: first frame layer 208: second frame layer 210: cover element 300: read-out module 302: suitable interface 304: processor 306: current amplifier 308: potentiostat 310: wireless communication interface 312: one or more batteries 314: battery cover 400: fixing device