WO2024105277A1

WO2024105277A1 - Layered photonic textile sensor

Info

Publication number: WO2024105277A1
Application number: PCT/EP2023/082432
Authority: WO
Inventors: Ursula Wolf; Oliver DA SILVA-KRESS; Tarcisi CANTIENI; Elodie MORLEC
Original assignee: Universität Bern; Empa Eidgenössische Materialprüfungs- Und Forschungsanstalt
Priority date: 2022-11-20
Filing date: 2023-11-20
Publication date: 2024-05-23

Abstract

The present invention relates to a photonic sensor device (1), the sensor device comprising a flexible base layer (40), a plurality of first optical fibers (2) and a plurality of second optical fibers (3), each first optical fiber (2) being connected to the flexible base layer (40) and comprising a loop (20) for emitting light (L) and each second optical fiber (3) connected to the flexible base layer (40) and comprising a loop (30) for collecting light (L), wherein the loops (20, 30) of the first and second optical fibers protrude from a top side (40a) of the flexible base layer (40), and a flexible mask layer (10) arranged on top of the top side (40a) of the flexible base layer (40), the flexible mask layer (10) comprising a plurality of through-holes (100), wherein each loop (20, 30) protrudes into one of the through-holes (100).

Description

Layered Photonic Textile Sensor

Specification

The present invention relates to a photonic sensor device, particularly for determining an oxygen saturation in a tissue of a human or animal subject.

It is a basic principle of fiber optics, which rely on the principle of total internal reflection (TIR) to guide light along the longitudinal axis of the fiber without losing energy by radiation, that any optical fiber has a given critical bending radius under which light can no longer be totally internally reflected but instead does radiate energy tangential to the point of critical curvature. It has also been shown that by taking advantage of this effect, that fiber optics should theoretically be able to be embroidered into a textile such that the optical fiber is locally curved in order to emit light from a desired localized point from the textile’s surface.

Although technically feasible, there are drawbacks to such an implementation of fiber optics when worn against the skin such as in cases of using the light emitting points as a means to transmit light into the skin and into underlying tissue, for instance when conducting nearinfrared spectroscopy. The loops formed by the fiber optics are limited in their minimum radii by plastic deformation and subsequent breakage, meaning the loops cannot be made small enough to not irritate the skin by means of friction. Furthermore, the directionality of the emitted light is poorly controlled, meaning that if fiber optic loops are also used to collected reflected light from tissue, as would be the case in near-infrared spectroscopy, the light from emission point will reach detection points without first going through the skin and tissue in an effect called light piping. This effect, even if small, can severely deteriorate the measurement data. This effect may be negated if the photonic textile has weight beared upon it so that skin is adequately pressed between emission and detection points, but the quality of the contact between photonic textile and skin cannot be adequately quantified.

Finally, such an embroidery process would mean that the holding yarns responsible for maintaining the counter-tension required for the optical fibers to form loops upon retraction of the stitching needle would be located on the side that the loops are formed. As this is the side to be in contact with the skin, these loose fibers add another element of discomfort and, if not fixated properly, allow the fiber optic loops to be pulled back through the textile to the side not facing the skin thus eliminating the light emission or detection properties in the scope of introducing or collecting light from the surface of the skin.

Therefore, based on the above, the problem to be solved by the present invention is to provide a photonic sensor device that is improved with respect to the above-described disadvantage of light piping and of irritating the skin of a person to which the sensor is applied. This problem is solved by a photonic sensor device having the features of claim 1

Preferred embodiments of this aspect of the present invention are stated in the corresponding dependent claims and are also described below.

According to claim 1 , a photonic sensor device, particularly for determining an oxygen saturation in a tissue of e.g. a human or an animal subject, is disclosed, comprising:

- a flexible base layer,

- a plurality of first optical fibers and a plurality of second optical fibers, each first optical fiber being connected to the flexible base layer and comprising a loop for emitting light and each second optical fiber connected to the flexible base layer and comprising a loop for collecting light, wherein the loops of the first and second fibers protrude from a top side of the flexible base layer, and

- a flexible mask layer arranged on top of the top side of the flexible base layer, the mask layer comprising a plurality of through-holes wherein each loop protrudes into one of the through-holes.

Due to the flexible mask layer and loops protruding into the respective through-hole, the loops protrude less from the sensor device, wherein ideally, the distal end of the respective loop can be arranged flush with a contact surface of the device for contacting the skin of the subject (which contact surface can be formed by a top side of the mask layer).

The invention therefore allows to bring the loops in close contact with the tissue of the subject without the need for providing considerably weight of or on the photonic sensor device which drastically reduces the risk of creating uncomfortable and dangerous pressure points (such as those which may lead to pressure injuries) the light-emitting mechanism via the loops is sufficiently thin and flexible and allows a high degree of integration into the base layer and mask layer, particularly without negatively affecting the properties of the flexible base and mask layer such as breathability or comfort against the skin.

According to a preferred embodiment of the present invention, each loop of the first optical fibers is formed by or comprise a bent section of the respective first optical fiber which bent section is bent by at least 180°. Furthermore, according to a preferred embodiment, each loop of the second optical fibers is formed by or comprise a bent section of the respective second optical fiber which bent section is bent by at least 180°. Particularly, a suitable bending radius can be in the range from 0.5mm to 1 mm according to an embodiment. Such a radius would be enough to transmit and collect about 90% of the light. Possible radii depend on plastic deformation limits and breakage which depends on fiber diameter and mechanical properties. According to a preferred embodiment of the present invention, the photonic sensor device comprises a contact surface for contacting the skin of the subject, wherein - according to a preferred embodiment - the contact surface is formed by a top side of the flexible mask layer, said top side facing away from the top side of the flexible base layer, or by a further layer being arranged on the top side of the flexible mask layer. Preferably the respective loop does not protrude past the contact surface. Particularly, a distal end of the respective loop can be flush with the contact surface.

According to a preferred embodiment of the present invention, the flexible base layer is formed out of or comprises a textile. Preferably, according to an embodiment, the textile is preferably relatively stiff in the extension plane of the textile yet flexible to bending and conformity. Preferably, the textile is thin and breathable, which is optimal for the embroidery of the optical fibers. Particularly, the textile can be a wool felt. Other non-woven matted types of textiles may fit these requirements as well.

Particularly, in the framework of the present invention, a textile is understood to be a flexible material made out of elongated flexible elements, which elements can e.g. be of one of fibers, yarns, threads (yarns and threads may be produced by spinning raw fibers from either natural or synthetic sources into long and twisted lengths), wherein the textile is preferably formed by one of weaving, knitting, crocheting, knotting, tatting, felting, bonding, or braiding these elongated elements together. According to a preferred embodiment, the textile is a woven textile.

According to a preferred embodiment of the present invention, the flexible mask layer is formed out of or comprises a foam. In an embodiment, the foam can be a double-sided adhesive foam layer that does not require an additional adhesive layer on either side. According to a further embodiment, the flexible mask layer can be formed out of or comprise a textile, particularly a wool felt. Furthermore, according to an embodiment, the mask layer can also be formed out of or comprise any other textile that achieves the requirements of being thick enough, comfortable enough against the skin, and preferably breathable. This may be soft shell materials used in athletic clothing, cotton, cotton blends. Because it is adhered to the base layer in particular, it does not require any specific mechanical properties. It just needs to serve the purpose described by the mask layer, i.e. act as a spacer.

Further, according to a preferred embodiment of the present invention, the loops are fixed to the flexible base layer by means of holding sutures (e.g. threads) which can extend through the loops and can be stitched to the flexible base layer. According to a preferred embodiment, these holding sutures can be fixed in place by sandwiching them between the flexible mask layer and the flexible base layer. Further, according to a preferred embodiment of the present invention, the photonic sensor device comprises a flexible light-proof backing layer arranged on a bottom side of the flexible base layer, the bottom side facing away from the top side of the flexible base layer.

According to a further preferred embodiment of the present invention, the respective first optical fiber comprises two connecting sections connected by the loop (particularly by the bent section) of the respective first optical fiber, said connecting sections of the respective first optical fiber being configured to connect the respective first optical fiber to a light generating unit. In this way light generated by the light generating unit can be coupled into a connecting section of a first optical fiber to travel into the loop to be emitted from the loop into adjacent tissue. Furthermore, according to a preferred embodiment, the respective second optical fiber comprises two connecting sections connected by the loop (particularly the bent section) of the respective second optical fiber, said connecting sections of the respective second optical fiber being configured to connect the respective second optical fiber to a light detecting unit, so that light having interacted with tissue can be received by the loop of the respective second optical fiber and travel to the light detecting unit.

Further, according to yet another preferred embodiment of the present invention, the connecting sections extend between the flexible light-proof backing layer and the flexible base layer. This allows to protect the optical fibers from abrasive/mechanical impacts and minimizes the risk of having adjacent structures becoming entangled with the optical fibers.

According to a preferred embodiment of the present invention, the photonic sensor device forms or comprises a flexible patch configured to be adhered to the skin of a person or to be connected (particularly adhered) to a garment to be worn by a subject, the flexible patch comprising at least the flexible base layer, the flexible mask layer and preferably also the flexible backing layer as well as the first and second optical fibers connected to the flexible base layer.

Furthermore, according to a preferred embodiment of the present invention, the photonic sensor device, particularly the flexible patch, comprises an adhesive layer for adhering the flexible patch to the skin of the person or for adhering the flexible patch to the garment.

According to a preferred embodiment of the present invention, the adhesive layer is arranged on the backing layer for adhering the flexible patch to the garment. In this case, the top side of the flexible mask layer can provide a contact surface for contacting the skin of the person, which contact surface does however not need to be connected to the skin, since the flexible patch will be held by e.g. a garment to which the flexible patch is connected via the adhesive layer. According to a preferred alternative embodiment, the adhesive layer is arranged on the mask layer for adhering the flexible patch to the skin of the subject. Here, the adhesive layer preferably also forms a contact surface of the flexible patch for contacting the skin of the subject. Thus, the flexible patch of the photonic sensor device is adhered to the skin of the subject via the mask layer, i.e., the photonic sensor device does not need a garment as a carrier. Particularly, in case the adhesive layer is arranged on the mask layer a further adhesive layer can be provided on the other side of the mask layer so that the mask layer particularly forms a double-sided adhesive foam so that in particular no additional adhesive layers are needed. Particularly the further components can connect to the further adhesive layer.

Particularly, in a preferred embodiment, when the adhesive layer is provided on the flexible mask layer, the adhesive layer comprises through-holes aligned with the through-holes of the mask layer. Further, the adhesive layer comprises a top side facing away from the top side of the flexible base layer, wherein the respective loop does not protrude past the top side of the adhesive layer/contact surface. Particularly, a distal end of the respective loop can be flush with the top side of the adhesive layer, which top side of the adhesive layer forms the contact surface.

Furthermore, according to a preferred embodiment of the present invention, the photonic sensor device further comprises a light generating unit operatively connected to the first optical fibers so as to couple light, particularly near infrared light, into the respective first optical fiber and to emit light via the loop of the respective first optical fiber.

Further, according to a preferred embodiment of the present invention, the photonic sensor device further comprises a light detecting unit operatively connected to the second optical fibers so as to detect light received by the loop of the respective second optical fiber.

According to a preferred embodiment of the present invention, the photonic sensor device further comprises a processing unit configured to determine an oxygen saturation value of a tissue of the subject using measured intensities of near infrared light, particularly near infrared light, that has been emitted by the loops of the first optical fibers, travelled through said tissue and has been collected by the loops of the second optical fibers and has been detected by the light detecting unit.

Particularly, in an embodiment, the processing unit is configured to determine an oxygen saturation distribution of the tissue using said measured intensities of light detected by the light detecting unit, the oxygen saturation distribution assigning to each of a plurality of points in said tissue an oxygen saturation value of the tissue. According to a preferred embodiment of the present invention, the processing unit is configured to be arranged remote from the flexible patch. According to a further preferred embodiment, the processing unit is configured to receive data indicative of said measured intensities of light detected by the light detecting unit via wireless communication (e.g. via radio communication using known protocols).

Particularly, according to a preferred embodiment of the present invention, the processing unit can be configured to determine at each point a concentration of oxy-hemoglobin and a concentration of deoxy-hemoglobin in the tissue using measured intensities of light detected by the light detecting unit and to determine said oxygen saturation distribution in the tissue (StO₂) at each point via StO₂ = [HbO₂]/([HbO₂] + [HHb] , where [HbO₂] denotes the concentration of oxy-hemoglobin at the respective point and [HHb] denotes the concentration of deoxy-hemoglobin at the respective point.

Particularly, in an embodiment, the light generating unit can be configured to generate and couple at least light of a first wavelength and light of a second wavelength into the first optical fibers wherein the first and second wavelengths differ from one another. Particularly, the respective light can comprise other wavelengths as well. Particularly, the respective light can have a spectrum comprising a maximal intensity at the respective wavelength. Particularly, using more than two different wavelengths of near infrared light allows to increase precision of the measurement. Furthermore, particularly, regarding all embodiments of the present invention, the light generating unit can be configured to generate near infrared light of a first and of (a different) second wavelength (or of even more different wavelengths, see above) and to couple near infrared light of the first and of the second wavelength into the first optical fibers.

Preferably, the respective light in the above-stated examples preferably is in the range from 650 nm to 1500 nm, particularly 650 nm to 1000 nm, and can be near infrared light (NIR).

Particularly, in an embodiment, the first wavelength is in the range from 660 nm to 800 nm and/or the second wavelength is in the range from 800 nm to 1000 nm, the second wavelength being different from the first wavelength.

Furthermore, in an embodiment, the light generating unit can comprise a plurality of light sources (e.g. LEDs) for generating light of the first and second wavelength.

Furthermore, the light detecting unit can comprise a plurality of photodetectors, wherein the respective photodetector can be a photodiode. In the following, embodiments of the present invention as well further features and advantages and other aspects of the present invention shall be described with reference to the Figures, wherein

Fig. 1 shows a schematic exploded view of an embodiment of a photonic sensor device according to the present invention,

Fig. 2 shows a schematic cross-sectional view of the embodiment shown in Fig. 1 ,

Fig. 3 shows perspective view of a flexible patch of an embodiment of a photonic sensor device according to the present invention,

Fig. 4 shows an embodiment of a photonic sensor device, wherein the flexible patch(es) can be adhered to a garment,

Fig. 5 shows a schematic exploded view of a flexible patch of an embodiment of a photonic sensor device according to the present invention that is configured to be adhered to a garment (as e.g. shown in Fig. 4),

Fig. 6 shows an embodiment of a photonic sensor device, wherein the flexible patch(es) can be adhered to the skin of a subject/person,

Fig. 7 shows a schematic exploded view of a flexible patch of an embodiment of a photonic sensor device according to the present invention that is configured to be adhered to the skin of a subject (as e.g. shown in Fig. 6),

Fig. 8 shows a schematic exploded view of a flexible patch of a further embodiment of a photonic sensor device according to the present invention that is configured to be adhered to the skin of a subject (as e.g. shown in Fig. 6), and

Fig. 9 shows a schematic view of an embodiment of the present invention, wherein the control unit may comprise a housing accommodating the light generating and detecting units and particularly the communication module.

The present invention relates to a photonic sensor device 1 as e.g. shown in Figs. 1 and 2 that can comprise a multi-layered structure which incorporates a flexible base layer 40 that can be a textile to which layer 40 first and second optical fibers 2, 3 comprising loops 20, 30, respectively, can be connected (the loops 20, 30 can be embroidered in the base layer 40) for the purpose of emitting and collecting light from the surface of the skin of a human or animal subject. This layer 40 can also be referred to as the active layer, and the side from which the light emitting and collecting loops 20, 30 project, can be referred to as the active side of the active layer. A second flexible layer 10, which can also be a textile or a foam, forms a flexible mask layer 10 for the loops 20, 30 that is arranged on the base layer 40 in a way which solves the current problems facing the direct implementation of such a photonic textile.

Particularly, the flexible mask layer 10 comprising a plurality of through-holes 100, wherein each loop 20, 30 of the first and second optical fibers 2, 3 protrudes into one of the through- holes 100. In this way, the flexible mask layer 10 acts as a buffer between the optical fibers 2, 3 and the skin of the subject and prevents light piping and irritation of the skin of the subject due to protruding loops 20, 30. Particularly, a thickness of the mask layer 10 can be chosen such that distal ends 200, 300 of the loops 20, 30 are flush with a contact surface 10a that can be formed by the mask layer 10 and rests against the skin of the subject.

Particularly, according to a preferred embodiment, the loops 20, 30 can be fixed to the base layer 40 by means of holding sutures (e.g. threads) which can extend through the loops 20, 30 and can be sutured to the base layer 40. These holding sutures can be fixed in place by sandwiching them between the flexible mask layer 10 and the flexible base layer 40.

As indicated in Figs. 1 and 2, each loop 20, 30 of the first and second optical fibers 2, 3 can be formed by or comprises a bent section 20, 30 of the respective optical fiber 2, 3 which bent section 20, 30 is bent by at least 180°. Due to the curvature of the respective loop 20, 30 light can be emitted from loops 20 of the first optical fibers 2 and received by loops 30 of the second optical fibers 3. The loops 20, 30 can be distributed such over the flexible base layer 40 that a plurality of different paths of light travelling through the tissue can be measured which allows to measure a distribution of the desired quantity (e.g. oxygen saturation) based on measured intensities of light emitted by loops 20 of the first optical fibers 2 and received by opposing loops 30 of the second optical fibers 3.

Furthermore, as shown in Figs. 1 and 2, the photonic sensor device 1 preferably comprises a flexible light-proof backing layer 50 arranged on a bottom side 40b of the flexible base layer 40, the bottom side 40b facing away from the top side 40a of the flexible base layer 40.

Preferably, the photonic sensor device 1 forms a flexible patch 4 (cf. e.g. Fig. 3) configured to be adhered to the skin 8 of a person as shown in Fig. 6 or to be connected, particularly adhered, to a garment 7 to be worn by a subject., as shown in Fig. 4. Particularly, the flexible patch 4 preferably comprises the flexible base layer 40, the flexible mask layer 10 and the flexible backing layer 50 as well as the first and second optical fibers 2, 3 connected to the flexible base layer 40. Particularly, the flexible patch 4 forms a stand-alone functional unit that can contain, without integration into a wearable garment, all functions needed to measure physiological parameters associated with a spectroscopy method such as near infrared spectroscopy (NIRS). Particularly, the patch 4 can be connected to the necessary light generating and detecting units 61 , 62 as well as to a suitable processing unit 64 as shown in Figs. 4 and 6 to perform such tasks.

Particularly, as indicated in Figs. 4 and 6 the light generating unit 61 of the photonic sensor device 1 is operatively connected to the first optical fibers 2 so as to couple light into the respective first optical fiber 2 and to emit light via the loop 20 of the respective first optical fiber 2. Furthermore, the light detecting unit 62 is operatively connected to the second optical fibers 3 so as to detect light received by the loop 30 of the respective second optical fiber 3. Further, the photonic sensor device 1 comprises a processing unit 64 configured to determine e.g. an oxygen saturation value of the tissue of the subject that is contacted by the patch(es) 4 using intensities of light, particularly near infrared light, detected by the light detecting unit 62 as described herein.

Preferably, the processing unit 64 is configured to be arranged remote from the flexible patch(es) 4 and is preferably configured to receive data indicative of said intensities of light detected by the light detecting unit 62 via wireless communication 65. For this, the photonic sensor device 1 can comprise a communication module 63 that may form part of a control unit 600

Preferably as indicated in Fig. 9, the control unit 600 may comprise a housing 6 accommodating the light generating and detecting units 61 , 62 and particularly the communication module 63. The housing 6 is preferably configured to be worn by the subject and may comprise a fastening means to fasten the housing 6 to the subject. Particularly, as an example, the housing 6 may be configured to be mounted to a wheel chair or to a bed and the sensor is then connected to it via the optical fibers. Alternatively, the housing 6 may also be worn on the body. Particularly, it can be placed/mounted to a clothing article by a mechanical fastener such as a clip, or inserted into a small pocket of the garment, particularly in a location that does not cause discomfort or restrict movement.

The control unit 600 further comprises a driver 610 configured to drive the light generating unit 61 , and a light detector controller 620 for controlling the light detecting unit 62. Both the driver 610 and the controller 620 are preferably housed in housing 6, too. The control unit 600 further preferably comprises an analogue to digital converter 66 and amplifiers 67 as well as a power supply (e.g. battery) 68. The communication module 63 can be configured for radio communication, e.g. based on a bluetooth standard. Furthermore, the first and second optical fibers 1 , 2 connect the control unit 600 to the patch 4 via connectors 601 , 602 provided on the housing 6 so that generated light can be passed via connector 601 and the first optical fibers 1 to the patch 4 and light received by the patch 4 can be passed via the second optical fibers

2 and connector 602 to the light detecting unit 62.

The control unit 600 according to Fig. 9 may be used in conjunction with all embodiments described herein.

Particularly, as indicated in Figs. 4 and 6, the photonic sensor device 1 can comprise a plurality of flexible patches 4 (here e.g. two such patches 4) that can contact the skin of the subject.

Particularly, in order to provide light from a light generating unit 61 to the respective loop 20 of the first optical fibers 2 or to send light collected by the loops 30 of the second optical fibers 3 to a light detecting unit 62, the respective optical fiber 2, 3 can comprise two connecting sections 21 , 31 (cf. e.g. Figs. 1 and 2) connected by the loop 20, 30 of the respective first/second optical fiber 2, 3. Particularly, these connecting sections 21 , 31 extend between the flexible light-proof backing layer 50 and the flexible base layer 40 to an edge region of a flexible patch 4 of the photonic sensor device 1 as shown in Fig. 3, from where the respective connecting sections 21 , 31 can run towards the light generating unit 61 in case of the first optical fibers 2 and towards a light detecting unit 62 in case of the second optical fibers 62.

As shown in Fig. 4, the flexible patch(es) 4 of the photonic sensor device 1 can be configured to be connected to a garment 7 which then carries the patch(es) 4 while the latter contact(s) the skin of the subject when wearing the garment 7. An embodiment of such a flexible patch 4 is shown in Fig. 5. According thereto, the flexible patch 4 comprises the flexible base layer 40 with the optical fibers 2, 3 connected thereto, and the flexible mask layer 10 arranged on top of the top side 40a of the flexible base layer 40. Here, particularly, the flexible mask layer 10 is connected to the flexible base layer 40 via a breathable double-sided adhesive layer 70 comprising an adhesive on a top side 70a to connect to a bottom 10b of the flexible mask layer 10 and an adhesive on a bottom side 70b to connect to the top side 40a of the flexible base layer 40 thereby also fixing the holding sutures 41 that keep the loops 20, 30 in place between the flexible base layer 40 and the layer 70 / mask 40. Here, the top side 10a of the mask layer 10 forms a contact surface of the flexible patch 4 that is configured to contact the skin of the subject. Furthermore, the flexible patch 4 according to Fig. 5 particularly comprises a lightproof backing layer 50 that is formed as a double-sided adhesive layer and comprises an adhesive on a top side 50a to connect to the bottom side 40b of the base layer 40 and an adhesive on a bottom side 50b of the backing layer 50 that allows to adhere the flexible patch 4 to the inside of a garment 7 as shown in Fig. 4. The clothing itself may also act as the or a light-proof backing layer, but that depends on the clothing and where it is worn. To protect the adhesive on the bottom side 50b of the backing layer 50 before applying the flexible patch 4 to the garment 7, a peelable liner (not shown) can be arranged on the bottom side/adhesive 50b.

Furthermore, as shown in Fig. 5, the layer 70 as well as the mask layer 10 comprise a plurality of through-holes 100, 700 that are aligned with one another (e.g. in a congruent fashion), wherein the loops 20, 30 protrude into the aligned through-holes 700, 100 so that their distal ends 200, 300 (cf. Figs. 1 and 2) do not protrude past the contact surface (top side) 10a of the mask layer 10.

Further, as indicated in Fig. 5, the flexible mask layer 10 extends past a circumferential edge 40c of the flexible base layer 40 to make said edge 40c more comfortable for the subject.

In contrast to Figs. 4 and 5, Fig. 6 shows an embodiment of a photonic sensor device 1 according to the present invention, wherein here the flexible patch(es) 4 can be adhered directly to the skin 8 of the subject, so that the loops 20, 30 can emit light and collect light coming from the tissue.

Particularly, according to a first embodiment, shown in Fig. 7, the flexible patch 4 of the photonic sensor device 1 comprises the flexible base layer 40 with the optical fibers 2, 3 connected thereto, and the flexible mask layer 10 arranged on top of the top side 40a of the flexible base layer 40, wherein, as described above, the flexible mask layer 10 is connected to the flexible base layer 40 via a breathable double-sided adhesive layer 70 comprising an adhesive on a top side 70a to connect to a bottom 10b of the flexible mask layer 10 and an adhesive on a bottom side 70b to connect to the top side 40a of the flexible base layer 40 thereby also fixing the holding sutures 41 that keep the loops 20, 30 in place between the flexible base layer 40 and the tape 70 / mask 40. Further, the flexible patch 4 preferably comprises a double-sided adhesive layer 80 comprising an adhesive on a top side 80a of the layer 80 which forms a contact surface of the flexible patch 4 that is configured to contact the skin of the subject and to thereby adhere to the skin 8. Furthermore, the layer 80 comprises an adhesive on the bottom side 80b of the layer 80 to connect to the top side 10a of the flexible mask layer 40. Particularly, a peelable liner (not shown) can be provided on the contact surface (adhesive) 80a to protect the adhesive before applying it to the skin 8 of the subject.

Furthermore, the flexible patch 4 preferably comprises a light-proof backing layer 50 which is now formed as a single-sided adhesive layer and comprises an adhesive on a top side 50a to connect to the bottom side 40b of the base layer 40 while the bottom side 50b of the backing layer 50 is a non-adhesive surface.

Further, as shown in Fig. 7, the layer 80, the mask layer 10 as well as the layer 70 of the flexible patch 4 comprise a plurality of through-holes 800, 100, 700 that are aligned with one another (e.g. in a congruent fashion), wherein the loops 20, 30 protrude into the aligned through-holes 800, 100, 700 so that their distal ends 200, 300 (cf. Figs. 1 and 2) do not protrude past the contact surface (top side) 80a of the layer 80.

Again, the flexible mask layer 10 extends past a circumferential edge 40c of the flexible base layer 40 to make said edge 40c more comfortable for the subject.

Furthermore, Fig. 8 shows a modification of the embodiment shown in Fig. 7, wherein here the layer 80 is omitted. Instead, an adhesive is provided on the top side 10a of the flexible mask layer 10. Other than that, the remaining features of the photonic sensor device 1 of Fig. 8 can be designed as described in conjunction with Fig. 7. However, in a further modification, the breathable double-sided adhesive layer 70 can be omitted and the mask layer 10 is then configured to be a double-sided adhesive mask layer (particularly foam layer) which connects to the flexible base layer 40.

Claims

Patent claims

1. A photonic sensor device (1), comprising: a flexible base layer (40), a plurality of first optical fibers (2) and a plurality of second optical fibers (3), each first optical fiber (2) being connected to the flexible base layer (40) and comprising a loop (20) for emitting light (L) and each second optical fiber (3) connected to the flexible base layer (40) and comprising a loop (30) for collecting light (L), wherein the loops (20, 30) protrude from a top side (40a) of the flexible base layer (40), and a flexible mask layer (10) arranged on top of the top side (40a) of the flexible base layer (40), the flexible mask layer (10) comprising a plurality of through-holes (100), wherein each loop (20, 30) protrudes into one of the through-holes (100).

2. The photonic sensor device according to claim 1 , wherein the loops (20, 30) are fixed to the flexible base layer (40) by means of holding sutures (41) fixed in place by sandwiching them between the flexible mask layer (10) and the flexible base layer (40).

3. The photonic sensor device according to claim 1 or 2, wherein each loop (20) of the first optical fibers (2) is formed by or comprise a bent section (20) of the respective first optical fiber (2) which bent section (20) is bent by at least 180°, and/or wherein each loop (30) of the second optical fibers (3) is formed by or comprise a bent section (30) of the respective second optical fiber (3) which second section (30) is bent by at least 180°.

4. The photonic sensor device according to one of the preceding claims, wherein the flexible mask layer (10) comprises a contact surface (10a, 80a) for contacting the skin of the subject, wherein the contact surface is formed by a top side (10a) of the flexible mask layer (10), said top side (10a) facing away from the top side (40a) of the flexible base layer (40), or by a further layer (80) being arranged on the flexible mask layer (40), and wherein the respective loop (20, 30) does not protrude past the contact surface (10a, 80a).

5. The photonic sensor according to one of the preceding claims, wherein the flexible base layer (40) is formed out of or comprises a textile.

6. The photonic sensor according to one of the preceding claims, wherein the flexible mask layer (10) is formed out of or comprises a foam or a textile.

7. The photonic sensor device according to one of the preceding claims, wherein the photonic sensor device (1) comprises a flexible light-proof backing layer (50) arranged on a bottom side (40b) of the flexible base layer (40), the bottom side (40b) facing away from the top side (40a) of the flexible base layer (40).

8. The photonic sensor device according to one of the preceding claims, wherein the respective first optical fiber (2) comprises two connecting sections (21) connected by the loop (20) of the respective first optical fiber (2), said connecting sections (21) of the respective first optical fiber (2) being configured to connect the respective first optical fiber (2) to a light generating unit (61), and/or wherein the respective second optical fiber (2) comprises two connecting sections (31) connected by the loop (30) of the respective second optical fiber (3), said connecting sections (31) of the respective second optical fiber (3) being configured to connect the respective second optical fiber (3) to a light detecting unit (62).

9. The photonic sensor device according to claims 7 or 8, wherein the connecting sections (21 , 31) extend between the flexible light-proof backing layer (50) and the flexible base layer (40).

10. The photonic sensor device according to one of the preceding claims, wherein the photonic sensor device (1) comprises a flexible patch (4) configured to be adhered to the skin (8) of a subject or to be connected to a garment (7) to be worn by a subject, the flexible patch (4) comprising the flexible base layer (40), the flexible mask layer (10) and the flexible backing layer (50) as well as the first and second optical fibers (2, 3) connected to the flexible base layer (40).

11. The photonic sensor device according to claim 10, wherein the flexible patch (4) comprises an adhesive layer (80a, 10a, 50b) for adhering the flexible patch (4) to the skin (8) of the subject or to the garment (7).

12. The photonic sensor device according to claim 11 , wherein the adhesive layer (50a) is arranged on the backing layer (50) for adhering the flexible patch (4) to the garment (7), or wherein the adhesive layer (10a, 80a) is arranged on the mask layer (10) for adhering the flexible patch (4) to the skin (8) of the subject.

13. The photonic sensor device according to one of the preceding claims, wherein the photonic sensor device (1) further comprises a light generating unit (61) operatively connected to the first optical fibers (2) so as to couple light into the respective first optical fiber (2) and to emit light via the loop (20) of the respective first optical fiber (2).

14. The photonic sensor device according to one of the preceding claims, wherein the photonic sensor device (1) further comprises light detecting unit (62) operatively connected to the second optical fibers (3) so as to detect light received by the loop (30) of the respective second optical fiber (3). The photonic sensor device according to one of the preceding claims, wherein the photonic sensor device (1) further comprises a processing unit (64) configured to determine an oxygen saturation value of a tissue using intensities of light, particularly near infrared light, detected by the light detecting unit (62). The photonic sensor device according to claims 10 and 15, wherein the processing unit (64) is configured to be arranged remote from the flexible patch (4) and/or to receive data indicative of intensities of light detected by the light detecting unit (62) via wireless communication (65).