WO2013046119A1

WO2013046119A1 - Flexible substrate with spacing member

Info

Publication number: WO2013046119A1
Application number: PCT/IB2012/055098
Authority: WO
Inventors: Jacobus Petrus Johannes VAN OS; Guofu Zhuo; Leon Wilhelmus Godefridus Stofmeel
Original assignee: Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 2011-09-26
Filing date: 2012-09-25
Publication date: 2013-04-04
Anticipated expiration: 2014-03-26

Abstract

A light emitting device for application near mammal tissue is disclosed. The device comprises a substrate having a front surface accommodating at least one light source and an elastomeric layer arranged on the front surface of the substrate. The elastomeric layer covers the at least one light source and a substantial part of the front surface. The elastomeric layer further comprises at least one protrusion aligned with the at least one light source and extending perpendicular to elastomeric layer. The protrusion comprises a top surface for contacting mammal tissue.

Description

Flexible substrate with spacing member

FIELD OF THE INVENTION

The present invention relates to flexible substrates comprising sensors and/or actuators and a spacing member for maintaining a distance between these sensor and/or actuators and the environment. More specifically, the present invention relates to a light emitting device comprising an electronic textile, also referred to as functional textile, with integrated light emitting devices and a spacing member for maintaining a distance between the light emitting devices and an external surface.

BACKGROUND OF THE INVENTION

Light emitting devices for use in light therapy are well known. Some of these devices are design to be wearable and applied near the skin or in contact with the skin.

WO 2008/152558 Al discloses a light emitting device comprising a first layer accommodating a plurality of light sources that are distributed in a two-dimensional pattern and attached to a sheet of textile-like material, and a second layer comprising a plurality of flexible ribbons having a refracting structure, where at least a subset of the ribbons are arranged parallel to each other and arranged in relation in relation to the sheet of textile-like material such that light emitted from the light sources is refracted by the ribbons. The lighting device maintains the inherent flexibility of a photonic textile- like material while at the same time improving the homogeneity of the distribution of light emitted from the device.

SUMMARY OF THE INVENTION

It would be advantageous to have a flexible wearable light emitting device which can be safely applied close to or in contact with the skin. It would further be desirable to maintain a fixed distance between the light source(s) of the light emitting device and the skin, such that the light distribution applied to the skin can be accurately controlled.

To better address one or more of these concerns, in a first aspect of the invention a light emitting device is presented for application near mammal tissue, comprising a substrate having a front surface for accommodating at least one light source thereon and an elastomeric layer arranged on the front surface and covering the at least one light source and a substantial part of the front surface. The elastomeric layer comprises at least one protrusion aligned with the at least one light source and extending perpendicular to the layer, wherein the protrusion comprises a top surface for contacting the mammal tissue.

The protrusion according to the invention established a fixed distance between the light source(s) arranged on the substrate and the mammal tissue when the light emitting device is applied close to or in contact with the tissue, irrespective of any pressure applied to the light emitting device for bringing the light emitting device in contact with the tissue and conforming to the contours of the tissue.

The protrusion may have a height in a direction perpendicular to the elastomeric layer between about 1 mm and about 10 mm. The lower value assures a minimum distance between the light source(s) and the tissue to avoid direct physical contact which may damage the light source(s) and/or direct thermal contact which may induce burns on the tissue. The maximum height of the protrusion is selected to preserve the intrinsic flexibility of the substrate, which of course decreases with increasing thickness of the elastomeric layer and the protrusion thereon.

The protrusion preferably comprises a transparent or translucent material, preferably PDMS, for transmitting light received from the at least one light source to the top surface of the protrusion and emitting the light through the top surface to the mammal tissue. In a preferred embodiment, the protrusion has a geometric shape having certain optical properties for controlling the light distribution of the light received from the at least one light source towards the top surface and the mammal tissue and/or in a lateral direction across said top surface. In addition to safeguarding a certain distance between the light source and the mammal tissue when the light emitting device is applied to the mammal tissue, the protrusion can also control the light distribution applied to the mammal tissue.

On the one hand, the protrusion is arranged to increase the robustness of the light emitting device and safeguard a certain distance between the light source and the mammal tissue and should therefore show a minimum stiffness. On the other hand, the protrusion may be arranged for contacting mammal tissue and should therefore be soft touching. In one embodiment, the protrusion may therefore comprise a stiff elastomer with a shoreA > 50 near the at least one light source, for providing robustness and encapsulation of said at least one light source, and a soft elastomer with a shoreA < 50 near said top layer, for providing comfort and a soft contact with the mammal tissue.

In addition to controlling light transmission and light distribution from the light source to the mammal tissue, the protrusion may comprise or be manufactured from a heat conducting material for transfering heat generated by the light source to top surface of the protrusion and to said mammal tissue. Nearly all light sources produce next the light an amount of heat as a residual energy. This heat may advantageously be used in applications where both light and heat are beneficially to mammal tissue, for example in applications of pain relief where example red/IR light together with heat are used or other applications heat can assist or enhances the photonic biological processes in mammal tissue. The heat conducting property of the protrusion may therefore assist in transferring at least part of the residual heat generated by the light source to the mammal tissue.

In a preferred embodiment of the invention the substrate accommodates a plurality of light sources on said front surface and the elastomeric layer comprises a plurality of protrusions aligned with the plurality of light sources, the protrusions extending perpendicular to said substrate and elastomeric layer and the protrusions providing a plurality of top surfaces for contacting mammal tissue. It is evident that the advantages described above in relation to one protrusion aligned with the one light source, such as robustness and the soft touch, may be applied to the plurality of protrusions aligned with a plurality of light sources. The effects will be visible (in terms of optical light distribution) and experienced (in terms of thermal conductivity) across a larger area of the mammal tissue.

One of the advantages of the protrusions is to safeguard a certain distance between the substrate accommodating the light sources and the mammal tissue. In other words, the protrusions support the substrate in a well-defined relation to the mammal tissue. This support functionality does not necessarily require the presence of a light source. That is, supporting protrusions may also be present at locations where there are no light sources. Therefore in a further embodiment, the elastomeric layer comprises at least one supporting protrusion extending perpendicular to the layer but not aligned with any of the light sources and having a top surface for contacting mammal tissue. In addition to providing support to the substrate, these supporting protrusions may further assist in conducting residual heat or transmitting light from neighbouring sources.

In a further embodiment, the substrate comprises a back surface, opposing the front surface. The device further comprises an elastomeric backing layer arranged on the back surface of the substrate and covering a substantial part of that back surface. In this embodiment the elastomeric layer at the front surface and the elastomeric backing layer encapsulate the substrate and thus improve robustness of the device. The encapsulation also improves cleaning of the device, which may be important when the light emitting device is used in medical applications. The substrate may be one of an electronic textile, a flexible PCB, an RF4 flexible foil and a stretchable plastic.

Preferred light sources include light emitting dioded (LED).

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, as well as additional objects, features and advantages of the present invention, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, when taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a schematic view of a cross section of a light emitting device according to an embodiment of the invention.

Fig. 2 shows an embodiment having at least one supporting protrusion.

Fig. 3 shows an embodiment wherein the protrusion comprises two elastomeric materials with different shoreA properties.

Fig. 4 shows an embodiment wherein the elastomeric layer comprises white particle for maximum reflection of light towards the skin.

Fig. 5 shows an embodiment wherein the elastomeric layer, preferably the backing layer, comprises black particles for avoiding light losses to the back of the device.

Fig. 6 shows a picture of an elastomeric layer with protrusions according to an embodiment of the invention.

Fig. 7 shows a picture of a substrate (in casu electronic textile) with LED surface mounted on the substrate and covered by an elastomeric layer having protrusions according to an embodiment of the invention.

Fig. 8 shows examples of dimensional properties of protrusion according to embodiments of the invention.

DETAILED DESCRIPTION

A light emitting device according to the invention is schematically depicted in Fig. l which illustrates the following features: a protrusion 1 in the form of a silicone dome, LEDs 2 or other components such as for example sensors, an optional interposer to mount the LEDs on a substrate, a substrate 4 which may comprise an electronic textile, a fabric or a flexible PCB, and optionally a silicone encapsulant at the back of the substrate.

Fig. 2 shows an embodiment comprising protrusion not aligned with a light source. These protrusion may be referred to as 'heat transfer domes'. These dummy domes only act as heat contact pads to the human body. Heat generated by the LEDs will flow to the dummy domes and go via them to the human body.

Fig. 3 shows an embodiment having protrusions with a mix of soft and stiff silicone material to improve comfort. The domes are made of different silicone types, for example a relatively stiff silicone which serves the robustness around the LED and on top a relatively soft silicone which makes body contact more comfortable.

Fig. 4 shows an embodiment wherein the elastomeric layer comprises a white silicone, for example by mixing white particles in the silicone mass. The white silicone improve the optical performance of the device by directing all the light to the body.

Fig. 5 shows an embodiment to reduce the light emission through the back of the device. A silicone backing layer comprising for example black particles is used at the back of the substrate.

Fig. 8 shows an example of dimensional properties of protrusion according to an embodiment of the invention. On the left side of Fig. 8 an exemplary protrusions is depicted with a cylindrical shape having a height between 3 mm and 12 mm, a diameter between 6 mm and 15 mm and an outer radius of curvature between 0 mm (cylindrical protrusion with flat top surface) and 7 mm (cylindrical protrusion with rounded rim at the top surface). The cylindrical protrusion completely covers the light source and/or the substrate.

On the right side of Fig. 8 a dome shaped protrusion is depicted with an inner radius of curvature between 0 mm (flat bottom surface) and 6.5 mm (open space wihtin the dome covering the ligth sources). The dome may be designed to cover the the light source - e.g. a surface mounted LED - without contacting the light source and thus creating an air gap between the light source and the dome. Both exemplary protrusion therefore have different optical properties.

Benefits of embodiments of the invention may include:

The domes are robust and cannot be compressed.

• The domes will face the body. There will be enough spacing to let air go through which will maintain the breathability function. The domes will be built on the flexible textile fabric (or flex PCB). The total device will be as flexible / stretchable as the base textile substrate (comfort testing is done).

• The domes will contact the human body and will transfer the heat generated by the LEDs directly to the body. This heat will be beneficial in the medical treatment

(Temperature measurements are done). • The optical dome structure makes control over the light pattern feasible. The silicones are well known for their optical performance. The LED light will be directed to the human body in a high efficient way.

The integrated dome structure will improve the robustness of the device significantly because it encapsulates it to the outside environmental influences and improves the mechanical stability. Cleaning is no problem.

• The dome structure is optimized for maximizing the diffusion in lateral direction and enough peak vs. average optical power.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A light emitting device for application near mammal tissue, comprising:

- a substrate having a front surface, said substrate accommodating at least one light source on said front surface;

- an elastomeric layer arranged on said front surface of said substrate, said elastomeric layer covering said at least one light source and a substantial part of said front surface;

wherein said elastomeric layer comprises at least one protrusion aligned with said at least one light source and extending perpendicular to said layer, and

wherein said protrusion comprises a top surface for contacting said mammal tissue.

2. The light emitting device according to claim 1 wherein said protrusion has a height in a direction perpendicular to said elastomeric layer between about 1 mm and about 10 mm.

3. The light emitting device according to claim 1 wherein said protrusion comprises a transparent or translucent material, preferably PDMS, for transmitting light received from said at least one light source to said top surface (and emitting through said top surface to said mammal tissue).

4. The light emitting device according to claim 1 wherein said protrusion comprises a stiff elastomer with a shoreA > 50 near said at least one light source for providing robustness and encapsulation of said at least one light source, and comprising a soft elastomer with a shoreA < 50 near said top layer for providing comfort and a soft touch with said mammal tissue.

5. The light emitting device according to claim 1 wherein said protrusion comprises at least one optical structure, preferably a geometric shape of said protrusion, for controlling a light distribution of said light received from said at least one light source in perpendicular direction towards said top surface (and towards said mammal tissue) and in a lateral direction across said top surface.

6. The light emitting device according to claim 1 wherein said protrusion comprises a heat conducting material for transfering heat generated by said at least one light source to said top surface (and to said mammal tissue).

7. The light emitting device according to claim 1 wherein said substrate accommodates a plurality of light sources accommodated on said front surface and wherein said elastomeric layer comprises a plurality of protrusions aligned with said plurality of light sources and extending perpendicular to said elastomeric layer, said plurality of protrusions providing a plurality of top surfaces for contacting said mammal tissue.

8. The light emitting device according to claim 1 wherein said elastomeric layer further comprises at least one supporting protrusion extending perpendicular to said layer but not aligned with any of said at least one light source and having a top surface for contacting said mammal tissue.

9. The light emitting device according to claim 1 wherein said substrate further comprises a back surface, opposing said front surface and wherein said device further comprises a elastomeric backing layer arranged on said back surface and covering a substantial part of said back surface, said elastomeric layer and said elastomeric backing layer encapsulating said substrate.

10. The light emitting device according to claim 1 wherein said substrate is one of an electronic textile, a flexible PCB, and RF4 flexible foil and a stretchable plastic and wherein said at least one light source is a LED.