Wearable devices

Abstract

A wearable system is for mounting against the skin of a subject. It comprises a flexible circuit board sandwiched (e.g. laminated) between a top layer and a base layer. The flexible circuit board has a meandering section between end pads. The base layer and the top layer are bonded together by a bonding layer having a meandering opening around the meandering section. This means that the stretchability of the meandering section is not inhibited by the lamination process.

Description

Technical Field

[0001] The present invention relates to wearable devices, such as actuators or sensors. For example, the present invention is interested in sensors for measuring one or more physiological parameters of a subject, wherein the sensor can be worn by the subject. For example, the present invention relates to wearable patches, which can implement photoelectric pulse wave (PPG) sensors, electrocardiogram (EGC) sensors, electroencephalogram sensors (EEG), wearable ultrasound sensors (US), wearable heart rate sensors, wearable galvanic skin response sensors (GSR) or motion sensors. Background Art

[0002] There is an increasing interest in the monitoring of physiological parameters to allow better diagnosis and patient monitoring. For example it is known to provide wearable monitoring devices, such as patches, that subjects can wear in low-acuteness settings (such as general wards) and at home. Better monitoring in general wards is needed to reduce mortality. Moreover, trusted medicine drives the need to discharge patients to their homes and continue monitoring levels at home for a period of time, typically up to 30 days.

[0003] WEI PINGHUNG et al.: “A stretchable and flexible system for skin-mounted measurement of motion tracking and physiological signals” (201436TH ANNUALINTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGYSOCIETY, IEEE, August 26, 2014 (2014-08-26), pp. 5772-5775, XP032674410, DOI: 10.1109 / EMBC.2014.6944939) discloses a stretchable wearable system that can i) measure multiple physiological parameters and ii) send data to a smartphone via radio frequency.

[0004] RAJ M et al.: “Soft bio-integrated systems for continuous health monitoring” (VISUAL COMMUNICATIONS AND IMAGE PROCESSING; 20-1-2004; SAN JOSE, Volume 9083, June 4, 2014 (2014-06-04), Pages 90831M-90831M, XP060037124, DOI: 10.1117 / 12.2051272 ISBN: 978-1-62841-730-2) discloses new mechanical and electrical design strategies for wearable devices with mechanical properties close to those of biological tissue.

[0005] In general, patch comfort is very important, especially in the context of home monitoring where it will affect patient compliance. In addition to comfort, reliability of the wearable sensor is important in order to reach the desired period of home monitoring (e.g., 30 days).

[0006] Wearable devices are convenient to use because they provide users with increased freedom of movement while monitoring physiological parameters. In this way, physiological parameters can be measured in various environments, such as at different levels of physical exertion of the subject.

[0007] Physiological parameter sensors may be mounted differently to the user in different applications. The location of the mounted physiological parameter sensor relative to the subject depends on the type of physiological parameter sensor and / or the environment in which the physiological sensing occurs. Typically, the physiological parameter sensor should be in contact with the skin, but there are other situations where the physiological parameter sensor should be separated from the subject's body.

[0008] For example, in PPG monitoring, a stable distance between the optical sensor and the skin is desirable for optimal stability of the sensor signal. For ultrasound transducer patches, good contact with the skin is critical for high-quality images. Similarly, the electrodes of an ECG monitoring device or a GSR sensor should be in contact with the skin.

[0009] Many sensor designs utilize multiple sensing locations of the skin, for example so that conductivity can be measured between those points, or so that different signal timings at different locations can be determined.Sensor systems that employ multiple different sensing modalities may also have multiple sensing locations.

[0010] The present invention relates in particular to wearable systems utilizing contact locations for sensing or actuation. The multiple locations may, for example, be related to the monitoring of a single physiological parameter or multiple parameters. It is desirable to enable these multiple sensor or actuation locations to be movable relative to each other so that the body to which they are attached can move, for example due to breathing, heart beats, or just general body movement of the subject wearing the sensor system.

[0011] Typically, these different locations need to be able to communicate electrically with each other, for example so that a single processing point can collect sensing data from multiple areas. This requires connecting conductive tracks between the contact locations. It is known to provide these connecting conductive tracks as tortuous paths to provide a degree of stretchability. Flexibility and stretchability are critical for comfort and for good skin contact.

[0012] A flexible printed circuit board (PCB) comprising meandering interconnections may for example be provided. Specific meandering shapes may be used to minimize the forces required to stretch in 3D while minimizing stresses at critical points, thus minimizing the chance of cracking or breaking.

[0013] The PCB may, for example, be packaged in a housing together with the sensor circuit to form a sensor patch.

[0014] For example it is known to have a PCB encapsulated. A preferred manufacturing process is a lamination process. A laminated sensor patch is for example built up of layers that are primarily manufactured by a reel-to-reel process. Summary of the invention

[0015] The present invention is based on the recognition that the reliability of the interconnections provided by a meandering PCB is reduced as the meandering becomes more lamination-constrained. In particular, the stretching capability provided by the meandering sections is limited. Therefore, there is a need for an improved design for a wearable device, such as for use as a wearable sensor patch.

[0016] The invention is defined by the independent claim. The dependent claims define advantageous embodiments.

[0017] According to an example of an aspect of the invention, there is provided a wearable system for mounting against the skin of a subject, comprising:

[0018] Grassroots;

[0019] A flexible circuit board, comprising:

[0020] a first terminal pad having a first contact area facing the base layer;

[0021] a second terminal pad having a second contact area facing the base layer; and

[0022] a flexible tortuous section between the first end pad and the second end pad; and

[0023] a top layer, wherein the flexible circuit board is sandwiched between the base layer and the top layer,

[0024] The base layer and the top layer are bonded together by a bonding layer having a tortuous opening surrounding the flexible tortuous section.

[0025] The system has two (or more) pads for contacting the skin of a subject or for positioning very close to the skin of the subject, for example for obtaining readings of one or more physiological parameters, which in particular require (either alone or together) two or more contact points. It can instead be used to provide signals to the skin. The two pads are connected by a tortuous section that gives stretchability to the system so that it can adapt to the shape of the subject, and it can also evolve as the subject moves. The tortuous section is in a non-bonded area so that out-of-plane bending of the tortuous section is not inhibited by coupling to the top layer and / or the base layer. The deformation is therefore not forced and / or constrained by the top layer and / or the base layer.

[0026] This arrangement gives an increased freedom of deformation of the meandering section, and this significantly increases the reliability of the interconnection. A completely separate interconnection gives usability problems, for example the interconnection may be damaged by snagging behind something (e.g. clothing). Therefore, the present invention provides encapsulation between the top layer and the base layer (e.g. by lamination), but without adhesion in the area of ​​the meandering section.

[0027] The base layer may include a first base layer opening and a second base layer opening below the first contact area and the second contact area. These enable direct access to the pad contact area. This is of interest if direct galvanic contact with the skin is desired. This depends on the type of sensor or actuator. For example, indirect contact may be sufficient for a capacitive sensor or a motion sensor, while direct contact may be desired for a skin resistance sensor or an ECG sensor.

[0028] The system may then comprise: a first skin contact electrode and a second skin contact electrode in the first opening and the second opening, connected to the first contact area and the second contact area. These may protrude out of the plane of the base layer to provide protruding contact electrodes. The first skin contact electrode and the second skin contact electrode for example comprise gel electrodes.

[0029] The bonding layer may also include a first bonding layer opening and a second bonding layer opening corresponding to the first base layer opening and the second base layer opening. When the bonding layer is below the flexible circuit board (i.e., between the circuit board and the base layer), these openings allow direct contact with the contact area of ​​the terminal pad again. However, the bonding layer may be above the circuit board (i.e., between the circuit board and the top layer) instead, in which case the opening is not required.

[0030] The bonding layer may include contact anchor points within the tortuous openings. These may, for example, be connected in tortuous spaces such that they add to the overall structural unity of the system but do not constrain the movement of tortuous segments.

[0031] The first terminal pad may have a first circuit region on opposite sides of the first contact region, and the second terminal pad may have a second circuit region on opposite sides of the second contact region.

[0032] A battery may be provided on the first circuit area, and a signal processing circuit may be provided on the second circuit area. One of the first circuit area and / or the second circuit area may, for example, include wireless communication circuitry. Thus, required circuit components may be shared between available areas. Electrical functions include, for example, local battery power, local memory storage, wireless signal transmission (and optionally also signal reception, such as for receiving commands to perform sensing or download stored sensor data), and optionally sensor signal processing. One of the first circuit area and the second circuit area may also include a display device that enables sensor information to be read out directly rather than or as well as being stored and / or transmitted to an external device.

[0033] The meandering section preferably carries only interconnecting tracks.In particular, the flexible meandering section preferably comprises an electrical connection between the first end pad and the second end pad.

[0034] The bonding layer may comprise a hot melt layer, a pressure sensitive adhesive, a UV curing adhesive or a double sided adhesive tape, which is used, for example, to connect the top layer and the bottom layer as part of a thermal lamination process.

[0035] The device preferably comprises a wearable sensor patch.There may be three or more end pads interconnected by two or more flexible meandering sections.

[0036] The sensor comprises, for example, one (or more) from the following list:

[0037] ECG sensor;

[0038] PPG sensor;

[0039] EEG sensor;

[0040] GSR sensor;

[0041] Thermistor temperature sensor;

[0042] Accelerometer.

[0043] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] For a better understanding of the invention and to more clearly show how it may be implemented, reference will now be made, by way of example only, to the accompanying drawings in which:

[0045] Figure 1 A known sensor patch is shown;

[0046] Figure 2 The design of a bonding layer for a sensor patch according to one example of the present invention is shown in simplified form;

[0047] Figure 3 An example of a sensor system is shown in an exploded view;

[0048] Figure 4 Variations in the design of the bonding layer are shown; and

[0049] Figure 5 Shows the Figure 4 Modification of the design of the bonding layer. DETAILED DESCRIPTION

[0050] The present invention will be described with reference to the accompanying drawings.

[0051] It should be understood that the detailed description and specific examples, when indicating exemplary embodiments of the apparatus, system and method, are intended for illustrative purposes only and are not intended to limit the scope of the invention. These and other features, aspects and advantages of the apparatus, system and method of the present invention will become better understood from the following description, claims and accompanying drawings. It should be understood that the drawings are only schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to indicate the same or similar parts.

[0052] The present invention provides a wearable system, such as a sensor system for mounting against the skin of a subject. It comprises a flexible circuit board sandwiched (e.g. laminated) between a top layer and a base layer. The flexible circuit board has a meandering section between end pads. The base layer and the top layer are bonded together by a bonding layer having a meandering opening around the meandering section. This means that the stretchability of the meandering section is not inhibited by the lamination process.

[0053] Figure 1 A known sensor patch 10 is shown, comprising a base layer 12, a flexible circuit board 20 and a top layer 30. The flexible circuit board 20 has two terminal pads 22, 24 which are connected to each other via a meandering section 26.

[0054] The three layers shown are laminated together to form a sealing patch.

[0055] Figure 2 The design of a bonding layer used in a lamination process for a sensor system according to an example of the present invention is shown in simplified form. In this example, a bonding layer 40 will be provided on a flexible circuit board. The bonding layer 40 has openings 42 on the meandering section 26 so that the meandering section is not constrained by the lamination process. For clarity, Figure 2 The tortuous section 26 beneath the bonding layer is shown viewed through the opening 42 .

[0056] Figure 3 An example of a wearable system is shown in an exploded view.

[0057] The wearable system includes a base layer 12, a flexible circuit board 20, a top layer 30, and a bonding layer 40 having a meandering opening 42. In this example, the bonding layer 40 is below the flexible circuit board 20, i.e., between the flexible circuit board 20 and the base layer 12. Bonding may additionally or alternatively be provided between the top layer 30 and the flexible circuit board 20, again excluding the meandering section 26. Thus, bonding may be provided above and / or below the flexible circuit board.

[0058] The flexible circuit board 20 includes a first terminal pad 22 having a first contact area facing the substrate (and thus Figure 4 In one example, the opposite side of the first contact area may include a first circuit area that provides a connection to the battery 23, for example.

[0059] The second terminal pad 24 has a second contact area facing the substrate (again at Figure 3 In one example, the opposite side of the second contact area may include a second circuit area that provides connections to, for example, sensor processing circuitry and wireless transmission circuitry 25.

[0060] The flexible circuit board may comprise a conventional polyimide flex PCB, but it may also comprise a screen-printed or inkjet-printed circuit on a bendable polymer substrate, such as polyethylene naphthalate (PEN) or polyethylene terephthalate (PET).

[0061] The meander section 26 is between the first terminal pad and the second terminal pad and provides electrical connection between the circuits carried by the terminal pads, as well as providing connection to the contact areas of the terminal pads. The meander section preferably only carries interconnection tracks. In particular, the meander section preferably includes an electrical connection between the first terminal pad and the second terminal pad.

[0062] The flexible circuit board is, for example, a double-sided board in which the contact areas facing the base layer serve as sensor input pads or actuator output pads, and the electrical tracks facing the top layer serve as connection lines and contact pads for circuit components.

[0063] exist Figure 3 In the example shown in , the contact area below the terminal pad is used to make direct galvanic contact with the skin. The base layer 12 has an opening 14 aligned with the contact area, and the bonding layer 40 also has a corresponding opening 44.

[0064] To provide an interface between the skin and the contact area, glue contact electrodes 50 may be provided. These fit into the openings 14 and 44 so that the skin contact pads extend beyond the plane of the base layer 12.

[0065] Most basic designs have two pads for contacting the subject's skin, but there may be three or more pads interconnected to each other by meandering segments. The meandering segments 26 are in non-bonded areas so that stretching of the meandering segments is not inhibited by coupling to the top or base layers. In this way, there is an increased degree of freedom for deformation of the meandering segments.

[0066] The tortuous section 26 is preferably planar and defines an undulating track in that plane, such as a sequence of alternating U-shaped tubes as shown. However, other tortuous paths may be formed, such as ones that generally follow a straight path or a curved path.

[0067] The bonding layer 40 may simply surround the outer edge of the overall wearable system housing so that the openings 42, 44 are formed as a single opening.

[0068] However, the bonding layer 40 preferably surrounds or covers the terminal pads 22, 24 (from above or below) so that each terminal pad is formed into its own housing. Figure 3 In the example of , there is an area of ​​bonding layer 40 that completely surrounds each opening 44, and Figure 2 In the example of FIG. 4 , the bonding layer 40 completely covers each terminal pad. This provides a better seal for the circuit components.

[0069] The meandering opening 42 may be rectangular corresponding to the outer envelope shape of the meandering section 26. However, other shapes may be used. The meandering opening 42 may completely surround the meandering section 26, but there may be portions of the meandering section 26, such as ends, that are covered by the bonding layer.

[0070] Figure 4 A variation of the design of the bonding layer 40 is shown. The terminal pads are each formed as a double circle to achieve an increased contact area. The circuit may for example be all on the downward facing side of the flexible circuit board. The central area 60 provides a connection to the non-flexible printed circuit board.

[0071] The tortuous opening 42 is formed into two sections 42 a , 42 b , one on each side of the central region 60 .

[0072] Figure 5 Shows the Figure 4 The bonding layer 40 has contact anchor points 70 within the meandering openings 42a, 42b. These make connections between the top layer and the base layer in the spaces between the meandering paths of the circuit board. The overall structural unity of the system is improved without constraining the movement of the meandering sections 26.

[0073] The bonding layer 40 may be a hot melt layer for heat curing during lamination, such as a polyurethane film, or another adhesive using, for example, a silicone adhesive, a polyurethane adhesive, or an acrylic adhesive. Adhesive foam may also be used.

[0074] The top layer 30 is, for example, a foam structure, such as a thermoformed foam structure, having a shape that provides a housing area for circuit components.

[0075] The flexible circuit board 20 is, for example, a polyimide flexible foil (for example, having a thickness of several tens of micrometers) having a copper conductor layer (for example, also having a thickness of several or several tens of micrometers).

[0076] The base layer 12 comprises a backing of silicone or thermoplastic polyurethane.

[0077] The contact electrodes 50 for example comprise screen printed silver chloride provided at the contact areas (at the bottom of the flexible circuit board).The contact electrodes may alternatively be provided using a conductive adhesive.

[0078] The wearable system for example comprises one (or more) sensor types from the following list:

[0079] ECG sensor;

[0080] PPG sensor;

[0081] EEG sensor;

[0082] GSR sensor;

[0083] Thermistor temperature sensor;

[0084] Accelerometer.

[0085] Thus, the wearable system can be used to determine one or more of various parameters such as: heart rate, breathing rate, heart rate variability, skin temperature, body posture, fall detection, and activity level (such as step count).

[0086] As mentioned above, the wearable system is preferably battery operated, and the battery is provided on one of the circuit areas. Signal conditioning or processing circuitry and wireless communication circuitry are also provided on the circuit area. There may also be memory storage, display devices.

[0087] The invention is applicable to wearable sensors or actuators, and it may take the form of a patch or fabric.

[0088] The invention is not limited to physiological sensory body systems. The invention can also be used, for example, for body motion sensing. In this case, the wearable sensor will not measure physiological body parameters, but will be in the form of a gyroscope or accelerometer to determine the movement of the body. Another option is non-sensory electronics in the shirt, such as lights, stretchable displays, solar cells, heating devices, or even certain therapeutic options. The zigzag design can be used in all these stretchable electronics cases.

[0089] By studying the drawings, the specification and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the word "one" or "an" does not exclude multiple. A single processor or other unit can implement the functions of several items recorded in the claims. The mere fact that specific measures are recorded in mutually different dependent claims does not indicate that the combination of these measures cannot be used advantageously. The computer program can be stored / distributed on a suitable medium (such as an optical storage medium or solid-state medium supplied together with other hardware or as part thereof), and can be distributed in other forms (such as via the Internet or other wired or wireless telecommunications systems). Any figure mark in the claims should not be interpreted as limiting the scope.

Claims

1. A wearable system (10) for mounting against the skin of a subject, the wearable system comprising: Base (12); A top layer (30), and a flexible circuit board (20) sandwiched between the base layer (12) and the top layer (30), the flexible circuit board (20) comprising: a first end pad (22) having a first contact area facing the base layer (12); a second end pad (24) having a second contact area facing the base layer (12); and a flexible zigzag section (26) between the first end pad (22) and the second end pad (24); wherein the base layer (12) and the top layer (30) are bonded together by a bonding layer (40) having a zigzag opening (42) surrounding the flexible zigzag section (26), wherein the flexible zigzag section (26) is in a non-bonding area and is not subject to the bonding constraint.

2. The system according to claim 1, wherein: The base layer (12) comprises a first base layer opening and a second base layer opening (14) below the first contact area and the second contact area.

3. The system according to claim 2, further comprising: The first and second skin contact electrodes (50) in the first and second base layer openings (14) are connected to the first and second contact areas.

4. The system according to claim 3, wherein: The first skin contact electrode and the second skin contact electrode (50) comprise gel electrodes.

5. The system according to any one of claims 1 to 4, wherein: The bonding layer (40) comprises a first bonding layer opening and a second bonding layer opening (44) corresponding to the first base layer opening and the second base layer opening (14).

6. The system according to any one of claims 1 to 4, wherein: The bonding layer (40) includes a contact anchor point (70) within the meandering opening (42).

7. The system according to any one of claims 1 to 4, wherein: The first terminal pad (22) has a first circuit region on an opposite side of the first contact region and the second terminal pad (24) has a second circuit region on an opposite side of the second contact region.

8. The system of claim 7, comprising a battery (23) on the first circuit area.

9. The system of claim 7, comprising a signal processing circuit (25) on the second circuit area.

10. The system according to claim 7, wherein: One of the first circuit area and the second circuit area includes a wireless communication circuit and / or a display device.

11. The system according to any one of claims 1 to 4, wherein: The bonding layer (40) comprises a hot melt layer, a pressure sensitive adhesive, a UV curing adhesive or a double-sided adhesive tape.

12. The system according to any one of claims 1 to 4, wherein: The flexible meandering section (26) includes an electrical connection between the first end pad (22) and the second end pad (24).

13. A system according to any one of claims 1 to 4, comprising a wearable sensor patch.

14. The system of any one of claims 1 to 4, comprising a set of three or more end pads interconnected by two or more flexible tortuous sections.

15. The system according to any one of claims 1 to 4, comprising one or more from the following list: ECG sensor; PPG sensor; EEG sensor; GSR sensor; thermistor temperature sensor; accelerometer.

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