System and method for remote powering at least one sensor or actuator from a RF power source

Abstract

A system for remote powering at least one sensor or actuator from a RF power source including a flexible waveguide having a flexible dielectric layer and at least one flexible conductive layer connected to the flexible dielectric layer. The at least one sensor or actuator is arranged to be coupled to the flexible waveguide and the RF power source is arranged to be wirelessly coupled to the flexible waveguide and to generate RF power. The flexible waveguide guides the propagation of the RF power from the RF power source to the sensor or actuator in order to wirelessly power the sensor or actuator.

Claims

1. A system for remote powering at least one sensor or actuator from a RF power source, comprising a flexible waveguide comprising a flexible dielectric layer and at least one flexible conductive layer connected to said flexible dielectric layer, said at least one sensor or actuator, arranged to be coupled to said flexible waveguide, said RF power source, arranged to be wirelessly coupled to said flexible waveguide and to generate RF power, the flexible waveguide guiding the propagation of said RF power from said RF power source to said at least one sensor or actuator in order to wirelessly power said at least one sensor or actuator, wherein said RF power source is placed in the flexible dielectric layer, such that it is inside the flexible waveguide.

2. The system of claim 1, said flexible waveguide forming a flexible sheet device being configured to be placed on a target.

3. The system of claim 1, said at least one sensor or actuator being in the flexible dielectric layer.

4. The system of claim 1, said at least one sensor or actuator being outside the waveguide, the waveguide comprising an antenna for transmitting the RF power from said RF power source to said sensor or actuator.

5. The system of claim 1, the flexible waveguide comprising an antenna being a slot antenna formed in the conductive layer.

6. The system of claim 1, comprising two conductive layers, the dielectric layer being between the first conductive layer and the second conductive layer.

7. The system of claim 1, the sensor or actuator comprising a RF/DC power converter and a DC power supply module connected to said converter.

8. The system of claim 1, the sensor or actuator being arranged to be powered with RF power of some tens of mW or less.

9. The system of claim 1, the thickness of the flexible waveguide being less than 5 mm, e.g. 1 mm.

10. The system of claim 1, the dielectric layer and/or the metallic layer(s) being stretchable and/or elastic.

11. The system of claim 1, wherein said flexible waveguide forms a bi-dimensional flexible sheet device comprising a plurality of sensors or actuators distributed along the two directions of the bi-dimensional flexible sheet device; the flexible sheet device being configured such that each sensor or actuator of the plurality of sensors or actuators is powered by the power generated by the RF power source and guided along the two directions of the bi-dimensional flexible sheet device.

12. A method for remote powering at least one sensor or actuator from a RF power source using a system according to claim 1, wherein the method comprises the steps of: generating a RF power from said RF power source, said RF power source being wirelessly coupled to a flexible waveguide, said flexible waveguide comprising a flexible dielectric layer and at least one flexible conductive layer guiding the propagation of said RF power from said RF power source to said at least one sensor or actuator, said at least one sensor or actuator being coupled to said flexible waveguide receiving said RF power by said at least one sensor or actuator and powering said at least one sensor or actuator by using said RF power, e.g. by converting said RF power to DC power.

13. The system of claim 1, wherein the flexible sheet comprises an artificial skin suitable for prosthetics exoskeletons, tactile service and industrial robots.

14. The system of claim 2, being standalone and self-standing.

15. The system of claim 2, wherein said flexible sheet device is configured to be placed on a receiving device.

16. The system of claim 2, wherein the flexible sheet device comprises a connecting means allowing to perform a mechanical connection between the flexible sheet device and the receiving device.

17. The system of claim 2, wherein the flexible sheet comprises an artificial skin suitable for prosthetics exoskeletons, tactile service and industrial robots.

18. The system of claim 2, wherein the flexible sheet device comprises a connecting means allowing to perform a mechanical connection on the target.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood with the aid of the description of an embodiment given by way of example and illustrated by the Figures, in which:

(2) FIG. 1 shows a top view of a first embodiment of the system comprising a flexible waveguide comprising nodes, according to an embodiment;

(3) FIG. 2 shows a section view of the system according to an embodiment;

(4) FIG. 3 shows a section view of the system according to another embodiment;

(5) FIG. 4 illustrates an arrangement of the nodes on the flexible waveguide, according to an embodiment; and

(6) FIG. 5 illustrates an arrangement of the nodes on the flexible waveguide, according to another embodiment

DETAILED DESCRIPTION OF POSSIBLE EMBODIMENTS

(7) FIG. 1 shows a top view of a first embodiment of the system 100 according to the invention. The system 100 comprises a flexible waveguide, better visible on FIGS. 2 and 3. In the embodiments of FIGS. 2 and 3 it comprises a first flexible conductive layer 1, a second flexible conductive layer 2 and a flexible dielectric layer 3 in between the first and second conductive layers 1, 2.

(8) The dielectric layer is in this context a layer made by a dielectric, i.e. an electrical insulator that can be polarized by an applied electric field.

(9) The conductive layers 2 and 3 are in the illustrated embodiments two identical metallic layers. However, they can be made by different materials. Moreover the present invention is not limited to metallic layers, but covers also conductive layers comprising a mesh or a bunch of parallel conductors.

(10) Although the flexible waveguide of FIGS. 2, 3 is made of a sandwich of a first flexible conductive layer 1, a flexible dielectric layer 3 and a second conductive layer 2, it must be understood that the present invention is not limited to the presence of two flexible conductive layers 1, 2, and that it can work with only one flexible conductive layer 1 or 2.

(11) In a variant, the flexible waveguide can comprise only the flexible dielectric layer 3; in other words, the dielectric waveguide is used without a metallic surface.

(12) However, the two flexible conductive layers 1, 2 allow a more efficient guided propagation in the flexible dielectric layer 3 of the RF power signal generated by the RF power source.

(13) In one preferred embodiment, the flexible waveguide is realised on a PCB (Printed Circuit Board), in particular on a flexible PCB.

(14) The system according to the invention comprises a RF power source 10. In the embodiments of FIGS. 1 to 3, the RF power source 10 is placed in the flexible dielectric layer 3, so it is inside the flexible waveguide (for this reason it has been represented with dotted lines on FIG. 1).

(15) The RF power source 10 is a source generating a power having a frequency belonging to the range from 1 MHz to several hundred GHz (sub-THz), in particular to the range from 1 MHz to 100 GHz, in particular to the range from 1 GHz to 10 GHz, for example 2.4 GHz. It is a wireless power source. In one preferred embodiment, the RF power source is a Bluetooth power source, generating e.g. a power of about 100 mW with a frequency of 2.4 GHz.

(16) The flexible waveguide is designed so that it can guide the propagation of the power or guide the power generated by the RF power source 10 in the flexible dielectric layer 3. For example, the thickness of the conductive layers 1, 2 is higher than the skin depth, which mainly depends on the frequency of the power signal and on the material of the conductive layers 1, 2. For example, the thickness e1 and e2 of metallic conductive layers 1 respectively 2 is in the range of 2 m to 100 m for a frequency of the RF power of 2.4 GHz. If the thickness e1 and e2 of metallic conductive layers 1 respectively 2 are sensibly lower than 2 m, e.g. 0.02 m, the corresponding layers will have low conductive properties and their use in the system according to the invention will be not efficient. Layers of such low thickness, fabricated e.g. by using vacuum metallization techniques, can be used mainly for corrosion protection.

(17) The thickness e3 of the flexible dielectric layer 3 is in one embodiment in the range of 1 mm to 3 mm. However, its thickness could vary with potential applications and frequency of operation. We note that, as the dielectric layer 3 is flexible, the bigger the thickness e3, the lower the flexibility of the layer 3.

(18) The three layers 1 to 3 are then superposed, and have substantially the same size and shape. In the embodiment of FIG. 1, they have a rectangular shape and form a flexible sheet device. In particular, the sizes along the x and y axes of the flexible waveguide of FIG. 1 are at least one order the magnitude bigger than the size along the z axis, i.e. than the total thickness e1+e3+e2 of the flexible waveguide. For example, for a total thickness e1+e3+e2 of the flexible waveguide of less than 5 mm, the sizes along the x and y axes of the flexible waveguide of FIG. 1 can be of the order of magnitude of about 5 cm to 10 cm for a medical application, e.g. for being placed on a hand of a patient.

(19) Therefore, the flexible waveguide according to the invention is substantially bi-dimensional, i.e. the power can propagate with two independent propagation directions.

(20) Of course, the flexible sheet device is not limited to a rectangular shape and can have other type of shapes, regular or irregular.

(21) The flexible sheet device according to the invention can be coupled with at least one node 20, 20. The term node designates in particular a sensor or an actuator. In a preferred embodiment, the flexible sheet device according to the invention comprises a plurality of nodes 20, 20, for example at least 10 nodes or more. Those nodes need to be powered.

(22) According to the invention, the nodes 20, 20 are advantageously powered with the power from the RF power source 10 in a wireless way via the flexible waveguide. In other words, the flexible waveguide distributes power via guided propagation, by remotely or wirelessly powering the nodes 20, 20. Therefore, the flexible waveguide acts as power distribution and delivery system.

(23) The RF power source 10 feeds the flexible waveguide without the need of mechanical contacts or wires between the nodes 20, 20 and the RF power source 10, e.g. via the conductive layer(s) 1, 2.

(24) In the embodiment illustrated in FIG. 1, the flexible waveguide forms a bi-dimensional flexible sheet device. In other words, the flexible sheet device 100 extends in the x and y directions, wherein the dimension along the x and y directions are at least one order the magnitude larger than the dimension along the z direction (see FIG. 2 or 3). The flexible sheet device 100 comprises a plurality of nodes 20, 20 that are distributed along the x and y directions (i.e., substantially in the plane of the flexible sheet device within and/or outside the flexible waveguide, see below). The bi-dimensional flexible sheet device 100 is designed so that it can guide the propagation of the power or guide the power generated by the RF power source 10 in the flexible dielectric layer 3, in the x and y directions. Thus the power propagates in two independent propagation the x and y directions such that each node 20, 20 of the plurality of nodes 20, 20 can be powered with the power from the RF power source 10 in a wireless way via the power generated by the RF power source 10 propagating of the flexible dielectric layer 3 in the x and y directions.

(25) In an embodiment shown in FIG. 4, the plurality of nodes 20, 20 are arranged on the bi-dimensional flexible sheet device 100 in a starlike network where the nodes 20, 20 are distributed around the RF power source 10.

(26) FIG. 5 illustrates another arrangement wherein the plurality of nodes 20, 20 are arranged in a mesh pattern on the bi-dimensional flexible sheet device 100.

(27) The system 100 of the invention allows for increased flexibility in placing the nodes 20, 20 along the x and y directions on the flexible sheet device 100. For instance, the system 100 allows for modifying the placement of the nodes 20, 20, adding and/or removing the nodes 20, 20 on the flexible sheet device 100 and thus, changing the arrangement (or topology) of the nodes 20, 20. The nodes 20, 20 can be powered by the power generated by the RF power source 10 propagating of the flexible dielectric layer 3 in the x and y directions, independently of their position on the bi-dimensional flexible sheet device 100.

(28) The system according to the invention is then battery-less. It is also robust as mechanical contacts or wires, which can be difficult to implement and could be a source of failure, are absent.

(29) Moreover, the system according to the invention is easy and cheap to manufacture, in particular when a plurality of nodes 20, 20 are present. Finally, the positions of nodes 20, 20 are not constrained by the presence of wires or connections, for powering or communication.

(30) In one preferred embodiment, the nodes 20, 20 comprise a RF/DC power converter (not illustrated) arranged to convert the received RF power from the RF power source 10 to a DC power, which is sent to a DC power supply module (not illustrated) connected to the converter.

(31) In another embodiment, the node 20, 20 is suitable to be powered with RF power of some tens of mW or less.

(32) The layers 1 to 3 of the waveguide are flexible, i.e. they can be bent without breaking. For example, the dielectric layer 3 can be made by flexible plastic substrates, such as polyimide, PET or silicone. The conductive layer can be made e.g. by a flexible copper foil or by a flexible foil comprising a copper alloy or any other flexible metal or alloy. In another embodiment, the conductive layer comprises or it is made of Indium tin oxide (ITO), zinc oxide (ZnO). In another embodiment it comprises or it is made of a coating (i.e. performed by the Aerosol Jet technology) comprising a conductive alloy or any other flexible metal or alloy, or any other non-metallic flexible material having electrical conductivity. In one embodiment, the conductive layer comprises or is made of liquid metal.

(33) In a preferred embodiment, the layers 1 to 3 of the waveguide are also stretchable, i.e. they are made or be capable of being made longer or wider without tearing or breaking. For example the dielectric layer can be made by stretchable materials such as silicones or polyurethanes, and the conductive layer by carbon-based materials.

(34) In another embodiment, they are also elastic, i.e. they can easily return to their original size or shape after being stretched or otherwise deformed.

(35) The flexible sheet device according to the invention can then be easily placed on a target and can conform to the surface of the target thanks to its flexibility. It can take different shapes and various contours depending on the application. It can be rolled on a pipe or tube. Moreover, it can also be stretchable.

(36) In one preferred embodiment, the flexible sheet device is an artificial skin that can be used for prosthetics exoskeletons, tactile service and industrial robots able to work around people, as e.g. cyber skin.

(37) In one preferred embodiment, the flexible sheet device comprises connecting means allowing to perform a mechanical connection, preferably a removable connection, with the target on which it is placed. Examples of such connecting means comprises glue, adhesive, Velcro, belt, strip, etc.

(38) In one embodiment, if the flexible sheet device according to the invention is not placed on a target, it is substantially flat. In other words, each flexible layer 1 to 3 can be substantially planar when not used on a target.

(39) Examples of sensors 20, 20 of the system according to the invention are temperature sensors, pressure sensors, humidity sensors, position sensors, acceleration sensors, orientation sensors, vibration sensors, stress sensors, etc. They can also use different technologies and be e.g. inductive sensors, capacitive sensors, Hall sensors, magnetoresitive sensors, etc.

(40) Examples of actuators according to the invention are micro-motors, piezoelectric actuators, electroactive polymers, biomorph, camera's actuators, etc.

(41) In the illustrated embodiments, the RF power source 10 is in the flexible dielectric layer 3. However the present invention is not limited to such configuration, and the RF power source 10 can also be placed outside the waveguide. In such a case, the RF power source will be placed in proximity to the flexible waveguide, so that the wireless transmission of the power from RF power source 10 to the flexible waveguide can be efficiently achieved.

(42) In the embodiment of FIG. 2, the node 20 is in the flexible dielectric layer 3, so in the flexible waveguide: in such a case, the node is powered by the power wirelessly conveyed by the flexible waveguide, in particular by its dielectric layer 3.

(43) In the embodiment of FIG. 3, the node 20 is outside the waveguide, e.g. placed on the external surface of the first flexible conductive layer 1. In such a case, the waveguide comprises an antenna 4, distinct from the RF power source 10, for transmitting the RF power from the RF power source 10 to the node 20. In such a case, the node 20 would be placed at a distance from the antenna 4 allowing the reception by the node 20 of at least the minimum power necessary to the node for working

(44) In the embodiment of FIG. 3, the antenna 4 is a slot antenna formed in the conductive layer 1 of the waveguide. In this case, the slot antenna consists of a conductive surface, e.g. the surface of the conductive layer 1 or 2, comprising a hole or slot 5 cut out. As knows, the shape and size of the hole or slot 5, as well as the driving frequency, determine the radiation distribution pattern of the antenna 4.

(45) Although in FIG. 3 the antenna 4 is formed only on the first conductive layer 1, the present invention is not limited to such embodiment and one or more antenna can be present on the second conductive layer 2 only or on both conductive layers 1, 2.

(46) As the conductive layers 1, 2 are flexible, the antenna 4 will be flexible as well. If the conductive layers 1, 2 are also stretchable and/or elastic, the antenna 4 will be stretchable and/or elastic as well.

(47) In one preferred embodiment, the conductive layers 1 or 2 according to the invention comprise more than one antenna 4.

(48) The system according to the invention can comprise both nodes 20 inside the flexible dielectric layer 3, and nodes 20 outside the flexible dielectric layer 3, as illustrated in FIG. 1.

(49) The system according to the invention is easy to use: in a preferred embodiment, it comprises sensors and/or actuators and their power source, it does not need any other device for work, it can be easily placed on a target and conform to its surface. Sensors can then collect data for the specific application.

(50) The present invention concerns also a method for remote powering at least one sensor or actuator 20 from a RF power source 10, comprising generating a RF power from the RF power source 10 wirelessly coupled to a flexible waveguide, the flexible waveguide comprising a flexible dielectric layer 3 and at least one flexible conductive layer 1 or 2, guiding the propagation of the RF power or guiding the RF power from the RF power source 10 to the at least one sensor or actuator 20, the at least one sensor or actuator being coupled to the flexible waveguide, receiving the RF power by at least one sensor or actuator 20, and powering at least one sensor or actuator 20 by using the RF power, e.g. by converting the RF power to DC power.

(51) The present invention concerns also the use of a flexible waveguide comprising a flexible dielectric layer 3 and at least one flexible conductive layer 1, 2, for guiding the propagation of a RF power or guiding the RF power from a RF power source 10 arranged to be wirelessly coupled to the flexible waveguide, to at least one sensor or actuator 20 arranged to be coupled to the flexible waveguide, in order to wirelessly power this sensor or actuator 20.

REFERENCE NUMBERS AND SIGNS USED IN THE FIGURES

(52) 1 First flexible conductive layer 2 Second flexible conductive layer 3 Flexible dielectric layer 4 Antenna 5 Hole or slot 10 RF power source 20 Node inside the waveguide 20 Node outside the waveguide 100 System e1 Thickness of the first flexible conductive layer e2 Thickness of the second flexible conductive layer e3 Thickness of the dielectric layer