CN110571877A - A bendable wireless charging device - Google Patents

Abstract

A bendable wireless charging device having an operational bend radius of approximately 90 degrees includes a flexible substrate, a receiving coil, a battery, a flexible EMI shielding layer, and a control module. The receiving coil is arranged on one surface of the substrate and is electrically connected to the control module. The battery, which may be a flexible battery, is disposed below the other surface of the substrate. An EMI shielding layer is disposed between the receiver coil and the battery.

Description

A bendable wireless charging device

technical field

The present invention relates to an electronic charging device, in particular to a wireless charging device with an operable bending radius of about 90 degrees in use.

Background technique

Recently, with the development of non-contact (ie, wireless) charging technology, portable electronic devices have adopted inductive wireless charging devices for wireless charging. Wireless power transfer can be defined as resonant wireless power transfer through magnetic induction between a coil located in a power transmitting unit (PTU) and a coil located in a power receiving unit (PRU); the PRU then transmits the received power to batteries of various types of portable electronic devices.

Wearable electronics in particular require thin and light batteries to keep the wearer comfortable and secure. As wearable electronics take on more complex shapes, there is a need for batteries that can bend or flex with the wearer's body. Although some flexible batteries have been disclosed, these often have various rigid or brittle components, such as ceramic separators, that limit the extent to which the battery can be bent. The integration of the PRU itself with the aforementioned flexible battery was also considered another challenge; since the receiving coil is usually formed from thick metal wires that are not easily bendable.

Therefore, integrating PRUs and flexible batteries into flexible charging devices has become a challenge for battery manufacturers. There is an urgent need for a bendable wireless charging device and a flexible battery; such a device and battery can be used in bendable electronic devices, such as portable wearable electronic devices.

Contents of the invention

It is an object of the present invention to provide a wireless charging device that addresses the above and other needs. According to one aspect of the present invention, there is provided a bendable wireless charging device integrating a battery, especially a flexible battery.

According to one embodiment of the present invention, a bendable wireless charging device includes a flexible substrate, a flexible receiving coil, a battery, a flexible EMI shielding layer and a control module. The base plate has an operable bend radius of approximately 90 degrees. The receiving coil is arranged on a surface of the substrate. The battery is located under the other surface of the substrate. The EMI shielding layer is disposed between the receiving coil and the battery on the substrate. The control module is arranged or formed on the side of the substrate adjacent to the receiving coil, and is electrically connected to the receiving coil and the battery respectively.

According to another aspect of the present invention, the bendable wireless charging device further includes an additional output connection group connected to an external load, enabling the flexible battery to simultaneously perform a wireless charging process and a discharging process on the external load. The control module controls the charging process of the flexible battery and/or the discharging process of the load.

Description of drawings

The drawings of the invention show the invention by way of illustration and not limitation. In the drawings, identical or similar reference numerals denote identical or similar elements, wherein:

Fig. 1 schematically shows a bendable wireless charging device according to an embodiment of the present invention;

Fig. 2 shows an example of a bendable wireless charging device according to an embodiment of the present invention;

Figure 3 shows an example of a cross-sectional view of a bendable wireless charging device without a battery;

Fig. 4 shows an example of practical implementation of a bendable wireless charging device according to an embodiment of the present invention;

Fig. 5 schematically shows a control module according to an embodiment of the present invention;

Fig. 6 schematically shows a bendable wireless charging device according to another embodiment of the present invention;

Fig. 7 shows an example of a bendable wireless charging device according to the embodiment shown in Fig. 6;

Fig. 8 schematically shows a bendable wireless charging device according to the embodiment shown in Fig. 6;

FIG. 9 depicts a flexible battery structure that can be used in the bendable wireless charging device shown in FIG. 1;

Figure 10 depicts a Jellyroll battery structure that can be used in the bendable wireless charging device shown in Figure 1; and

FIG. 11A and FIG. 11B respectively depict the structures of the sponge membranes of the present invention and the corresponding prior art.

Detailed ways

In the following description, various flexible batteries and flexible wireless charging devices are exemplified. It will be apparent to those skilled in the art that modifications, including additions and/or substitutions, can be made without departing from the scope and spirit of the present invention. Descriptions of specific details may be omitted in order not to obscure the invention; however, this specification has been written to enable one skilled in the art to practice the teachings herein without undue experimentation.

Referring to FIG. 1 and FIG. 2, FIG. 1 is a schematic diagram of a bendable wireless charging device according to an embodiment of the present invention; FIG. 2 is an example diagram showing a bendable wireless charging device according to an embodiment of the present invention. In this embodiment, the bendable wireless charging device 10 includes a flexible substrate 100 , a substantially planar receiving coil 20 , a flexible battery 40 , a flexible EMI shielding (electromagnetic interference shielding) layer 102 , and a control module 30 . The substrate 100 has an operable bend radius of at least 90 degrees. The term "operable bend radius" means that the charging device can be bent to at least 90 degrees and still be electrically and mechanically functional. Furthermore, it may also be able to bend up to 120 degrees or 180 degrees (with the halves superimposed on each other) and still function. The receiving coil 20 is disposed on the surface of the substrate 100 and used for receiving electric energy from the external transmitting inductive coil 11 . This external transmitting inductor is typically connected to a power source, such as a conventional wall outlet, or to a computer power source through a USB port. It should be noted that the battery 40 can be a flexible battery, and the relevant details will be described later. Alternatively, it can be a very small battery, such as a button battery or a thin-film battery, and the small volume allows the charging device to be turned on and bent without being disturbed. The flexible battery 40 is located under the vicinity of another surface of the substrate 100 which may also be provided with the receiving coil 20 . The EMI shielding layer 102 is disposed between the receiving coil 20 and the flexible battery 40 . The control module 30 is disposed or formed on a side of the substrate 100 adjacent to the receiving coil 20, and is electrically connected to the receiving coil 20 and the flexible battery 40, respectively.

The control module 30 may also include a first set of output connections 300 formed with two electrodes 302 , 304 (eg conductive pads) representing the positive and negative terminals of the respective flexible battery 40 .

In addition, refer to FIG. 3 , which is an exemplary diagram illustrating a cross-sectional view of a bendable wireless charging device without a flexible battery. The receiving coil 20 consists of a metal layer 202 fabricated on the flexible substrate 100 using an additive or subtractive coating method and at least one cover layer 204 attached to the metal layer 202 . The material of the metal layer 202 may be copper, silver, copper alloy, silver composite material or a combination thereof. At least one cover layer 204 protects the metal layer 202 from mechanical damage or oxidation, and it may also include an optional adhesive layer (not shown) over the metal layer 202, the cover layer 204 being positioned over the optional adhesive layer. The material of the substrate 100 and the cover layer 204 may be polyimide (PI) sheet, polyether ether ketone (PEEK), transparent conductive polyester film, elastomer film, polyethylene terephthalate (PET) or its combination.

The thickness of the metal layer 202 is in the range of 5-100 μm, and the thickness of the substrate 100 or the cover layer 204 is in the range of 2-100 μm.

The EMI shielding layer 102 may be formed of an electromagnetic wave absorbing material or an electromagnetic wave reflecting material such as thermoplastic or elastomeric material or a combination thereof and a conductive metal film or powder or fibrous filler such as metal/carbon powder or fiber. Exemplary EMI shielding materials include copper and nickel coated polyurethane sheets, silicone rubber with embedded magnetic ferrite particles.

Referring to Fig. 4, Fig. 4 shows an example diagram of an implementation of a wireless charging device according to an embodiment of the present invention. In this embodiment, the wireless charging device is mounted on the outer surface of a helmet. As shown in FIG. 4 , the wireless charging device 10 is bent into an arc along the contour of the helmet 50 .

The receiving coil of the bendable wireless device according to the present invention can withstand at least 2000 repeated bendings (with a bending radius of 20-40 mm and a bending angle of at least 120 degrees) without loss of charging performance.

Refer to Figure 1, Figure 2 and Figure 5. FIG. 5 is a schematic diagram of a control module according to an embodiment of the invention. In this embodiment, the control module 30 includes a wireless charging circuit 300 , a battery charging circuit 320 and a protection circuit 340 connected in series.

The wireless charging circuit 300 is electrically connected to the receiving coil 20 . The battery charging circuit 320 regulates the voltage and current from the wireless charging circuit 300 , and outputs the regulated voltage and current to the protection circuit 340 .

The protection circuit is connected to the flexible battery through the first output connection group, and further includes a switch module 360 connected between the protection circuit and the flexible battery. A protection circuit is used to sense and control the switch module. When the current or voltage input from the battery charging circuit exceeds or falls below a predetermined value, the switch module turns OFF, which can avoid wrong charging of the flexible battery. Predetermined values can be defined as thresholds for corresponding scenarios including short circuit, overcharge and undercharge. Those skilled in the art will recognize that the predetermined value may vary based on the desired use or type of flexible battery. For example, the overvoltage range measured between the first set of output connections may be chosen to be 3.5 volts to 5 volts, and the undervoltage range may be chosen to be 2 volts to 3 volts.

Refer to FIGS. 6 to 8 . Fig. 6 is a schematic diagram of a bendable wireless charging device according to another embodiment of the present invention; Fig. 7 is an example diagram showing a bendable wireless charging device according to the embodiment shown in Fig. 6; Fig. 8 is a diagram according to the embodiment shown in Fig. 6 Schematic diagram of the control module. This embodiment is similar to the embodiment shown in FIG. 1 . The difference is that the control module of the embodiment shown in FIG. 6 further includes: a second output connection group 310 and a switch module 361, wherein the second output connection group 310 is electrically connected to an external load, system or electronic device (hereinafter Referred to as "load 60"), the switch module 361 is composed of a charge switch and a discharge switch cascaded in series.

In this embodiment, as shown in FIGS. 6 and 7 , the control module 30 is located on the side of the substrate 100 adjacent to the receiving coil 20 , and is electrically connected to the receiving coil 20 , the flexible battery 40 and the load 60 for controlling the flexible battery 40 and the load 60 . The process of charging the battery 40 and/or the process of discharging the load 60 . The flexible battery 40 is located below the EMI shielding layer 102 . The load 60 is not shown in Figure 7, but it can be considered any type of battery powered electronic device, such as a cordless electric toothbrush, a watch or eyeglasses. Those skilled in the art will recognize that the implementation and configuration of wireless charging for these devices may be different, because the bendable wireless charging device of the present invention will generally be provided in corresponding devices by taking advantage of its flexible capabilities.

As shown in FIG. 8 , the switch module 361 includes a charge switch 362 and a discharge switch 363 . In this embodiment, each of the charge switch 362 and the discharge switch 363 may be an N-type MOSFET (Metal Oxide-Semiconductor Field Effect Transistor). Each MOSFET has a gate, a drain and a source. Gates of the charge switch 362 and the discharge switch 363 are connected to the protection circuit 340, respectively. Drains of the charge switch 362 and the discharge switch 363 are connected to each other. The source of charge switch 362 is connected to the negative terminal of load 60 . The source of the discharge switch 363 is connected to the negative terminal of the flexible battery 40 . The positive terminals of the flexible battery 40 and the load 60 are connected to a common node.

The battery charging circuit 320 regulates the voltage and current from the wireless charging circuit 300 , and outputs the regulated voltage and current to the protection circuit 340 through VBAT shown in FIG. 8 . The protection circuit 340 will continuously monitor the flexible battery 40 and the load 60 by detecting the voltage and/or current status of the flexible battery 40 and the load 60 .

As described in the above paragraphs, the protection circuit 340 includes a plurality of predetermined values for determining whether the bendable wireless charging device of the present invention is working normally. When the voltage detected during charging or discharging is higher or lower than a certain predetermined value, the protection circuit 340 will selectively reduce the voltage on the gate of the charging switch 362 during the charging process or selectively reduce the voltage on the gate of the charging switch 362 during the discharging process. The voltage on the gate of discharge switch 363 is lowered. Since the gate voltage is low, the charge switch 362 and the discharge switch 363 will be switched OFF, so the protection circuit 340 will be open due to the high resistance of the OFF MOSET type switch.

In contrast, for a conventional wireless charging device without an additional (ie, second) output connection set, a corresponding external load or electronic device can still be connected to and draw power from the battery. The advantage of having the second output connection group connected to the protection circuit of the control module is that the wireless charging device of the present invention can not only prevent the battery from being damaged by overcharging or over-discharging during charging and discharging, but also wirelessly charge the battery , and discharge to the load at the same time; thus, the practicability and convenience of the present invention are enhanced.

FIG. 9 schematically shows a cross-section of a portion of a flexible and foldable lithium-ion battery according to an aspect of the present disclosure, which can be used as the battery 40 in the bendable wireless charging device of the present invention. The battery 40 has an operational bend radius of 180 degrees. As used herein, the term "operating bend radius" refers to the degree to which a battery can be bent to still generate power without interruption of operation. The 180-degree operating bend radius means the battery can completely fold on itself while still producing electricity.

In FIG. 9 , element 5 represents a single cell of a battery including a first current collector 521 , a second current collector 531 , and a separator 51 . The first current collector 521 may be selected from metals such as aluminum. Aluminum may be a sheet having a thickness of about 5 microns to about 100 microns. Active material 522 may be coated on one or both sides of the aluminum sheet to form a cathode. The active material can be selected, for example, from LiCoO2, LiMn2O4, Li2MnO3, LiNiMnCoO2, LiNiCoAlO2, LiFePO4 or LiNi0.5Mn1.5O4, but other active materials and mixtures thereof can also be used.

The second current collector may be selected from metals such as copper. Copper may be a sheet having a thickness of about 5 microns to about 100 microns. Active material 532 may be coated on one or both sides of the copper sheet to form an anode. Active materials for the anode include carbon-based active materials such as graphite, carbon nanotubes, graphene, silicon, silicon/carbon composites, germanium, tin, metal oxides, metal hydrides, and mixtures thereof.

The separator 51 is located between the current collectors and prevents the current collectors from contacting each other. The separator 51 is a highly porous high-elastic polymer fiber felt sponge, and the resilience of the sponge is sufficient to maintain the separation of the current collectors 521 and 531 no matter the battery is bent, folded, cut or penetrated by foreign objects. As used herein, the term "sponge" refers to a porous, absorbent, and elastic structure that retains liquid while maintaining resiliency. The sponge returns to its original shape after being deformed. That is, as long as the external force is maintained, the sponge can be squeezed into a smaller area; once the external force is removed, the sponge returns to its original shape and volume. The separator acts as a sponge to hold the liquid electrolyte firmly, but also maintains sufficient absorbency to keep the liquid electrolyte in a leak-free state when the battery case is punctured or cut, thereby preventing the escape of harmful electrolyte. In addition, the resilience of the sponge septum enables the electrodes to return to their proper separated positions after mechanical damage such as cutting and puncturing, thereby endowing the overall structure with self-healing properties. As used herein, the term "self-restoring" refers to a battery structure that can return to its original configuration after mechanical damage such that power continues to be generated after a power interruption caused by the mechanical damage. The sponge separator can return to its original shape and volume due to its sponge properties, thus enabling the self-healing of the entire battery structure.

Electrolytes used in batteries may include one or more organic solvents, such as one or more of ethylene carbonate, dimethyl carbonate, and diethyl carbonate. Dissolved in the solvent is one or more lithium salts such as LiPF6, LiBF4 or LiClO4. The composition of the electrolyte is typically adjusted based on the active materials selected for the cathode and anode.

Although FIG. 9 shows the cells of a battery based on a stack of components, layers of components can be formed and rolled into a so-called "core roll" configuration, as shown in FIG. 10 . In Figure 10, a separator layer 51 is placed not only between the cathode and anode of each "cell" layer, but also between adjacent cell layers to prevent short circuits between electrodes, resulting in a self-recoverable overall flexible And has a resilient structure.

Sponge membranes can be formed from a mat of submicron fibers. In one aspect, the fibers can have a diameter between about 100 nm and 300 nm. The porosity may be from about 60% to about 90%, with an average pore size of less than about 1 micron. Specifically, submicron fibers can be made of polymers such as polyvinylidene fluoride (PVDF), polyimide (PI), polyamide (PA), polyacrylonitrile (PAN), polyethylene terephthalate (PET), poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), (vinylidene fluoride-chlorotrifluoroethylene) copolymer (PVDF-co-CTFE) or a mixture thereof.

In another embodiment, the sponge membrane may be a nonwoven polymer fiber mat, wherein the polymer fibers are a composite of a first polymer material and a second polymer material. The first polymer material may include poly(vinylidene fluoride) (PVDF), polyimide (PI), polyamide (PA) or polyacrylonitrile (PAN). The second polymer material may include polyethylene glycol (PEG), polyacrylonitrile (PAN), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-hexa Fluoropropylene) (PVDF-HFP) or (vinylidene fluoride-chlorotrifluoroethylene) copolymer (PVDF-co-CTFE), wherein the second polymer material is different from the first polymer material. The weight ratio of the first and second polymeric materials may range from about 3:1 to about 1:1, more specifically from about 3:1 to about 2:1, more specifically from about 3:1 to about 3:2 within, and more specifically about 3:1.

PVDF is widely used in the manufacture of ultrafiltration and microfiltration membranes due to its excellent chemical resistance and good thermal stability. Pure PVDF polymer has a high melting point and crystallinity, and has good mechanical properties. However, it is only soluble in a limited class of solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF ), dimethyl sulfoxide (DMSO), and exhibit low swelling capacity when soaked in common electrolytes.

The PVDF-HFP copolymer can improve electrolyte solubility, making the polymer soluble in common organic solvents such as acetone and tetrahydrofuran (THF), which can further enhance the processability. In addition, it has a very high swelling capacity, which can enhance the electrolyte absorption of the separator layer.

The inventors of the present application have found that the composite of PVDF and PVDF-HFP provides many advantages over other polymers in the manufacture of separators, such as: electrochemical stability from 0 V to 5 V with respect to Li+/Li; Pure PVDF has better solubility, which enhances processability; faster electrolyte wettability than PVDF; better control of electrolyte leakage; durable adhesion to electrodes; and good flexibility.

The composite material can be formed into a nonwoven fibrous mat by electrospinning, described in further detail below. Electrospinning can be performed from a polymer formulation onto aluminum foil to obtain a free-standing separator. The polymeric formulation may comprise the first and second polymeric materials in a total amount of about 15-25%, preferably about 15-20%, more preferably about 16.5% by weight of the formulation. The polymer formulation for electrospinning to obtain a sponge membrane may further comprise about 1-5% by weight, preferably about 2-5% by weight, more preferably about 3-5% by weight, most preferably about 5% by weight of at least one additive . The additive may be Lithium Chloride (LiCl) to facilitate ion transfer across the membrane and to facilitate the electrospinning process by increasing the conductivity of the polymer solution. In a preferred embodiment, the polymer formulation may comprise about 0.1-0.6 μg, preferably about 0.1-0.5 μg, more preferably about 0.2-0.4 μg, most preferably about 0.3-0.4 μg of LiCl.

In another embodiment, in combination with any of the above and following embodiments, the polymer formulation used for electrospinning to obtain the nonwoven nanofibrous membrane of the present application may include at least one solvent selected from the group consisting of: N-methyl- 2-Pyrrolidone (NMP), N,N-Dimethylacetamide (DMAC), N,N-Dimethylformamide (DMF), Dimethylsulfoxide (DMSO), Acetone, and Tetrahydrofuran (THF). In a preferred embodiment, the polymer formulation may include DMF and acetone. In another preferred embodiment, the polymer formulation may comprise a weight ratio of about 3:1 to about 1:1, preferably about 2:1 to about 1:1, more preferably about 1.5:1 to 1:1, most preferably About 1.25:1 DMF and acetone is preferred.

In another embodiment, in combination with any of the above and following embodiments, the nonwoven nanofibrous membrane of the present application can be electrospun by adding the first and second polymeric materials to at least one solvent, either Optionally added together with LiCl; the resulting mixture was heated and stirred at about 80-100°C for about 2-5 hours; optionally at least one additive was added, followed by heating at about 80-100°C for about 2-5 hours; the polymer The formulation solution was cooled to room temperature; and the polymer formulation solution was loaded into the carriage for electrospinning.

The electrospinning of the sponge separator of the present application can be carried out under the following parameters: temperature: about 20-30°C; voltage: about 20-50kV; relative humidity (RH): about 25-60%; spinner height: 100- 150mm; feed rate: 5.5-8.5ml/h.

On the other hand, additives such as tetramethylorthosilicate (TMOS) or tetraethylorthosilicate (TEOS) can be used with polymer formulations. These additives can be hydrolyzed into ceramic components, thereby improving the surface texture of the sponge separator and increasing dimensional stability.

The microstructure of an exemplary sponge membrane is shown in FIG. 11A ; as shown in FIG. 11A , individual fibers were easily distinguished and formed many pores with a porosity of about 80%. In comparison, the microstructure of a prior art commercially available separator (Celgard 2400 polypropylene separator) with about 40% porosity is shown in FIG. 11B . In this lower porosity structure, individual fibers are not easily distinguishable. The individually interconnected fibers in the sponge of FIG. 11A create a flexible and resilient sponge membrane that contributes to the self-healing properties of batteries of various embodiments.

While the application has been described in terms of several embodiments and implementations thereof, the application is not so limited but covers various obvious modifications and equivalent arrangements, which fall within the scope of the appended claims. Although features of the present application are presented in certain combinations between the claims, it is contemplated that these features can be arranged in any combination and order.

Claims (20)

1. a bendable wireless charging device, comprising:

A flexible substrate having an operable bend radius of at least 90 degrees;

A substantially planar receiving coil for receiving electrical energy from an external transmitting inductor and disposed on a surface of the flexible substrate;

A flexible battery having a bend radius of at least 90 degrees operable;

A flexible EMI shield layer positioned between the receiver coil and the flexible battery for blocking electromagnetic interference from the receiver coil;

And the control module is positioned or formed at one side of the flexible substrate, is adjacent to the receiving coil and is electrically communicated with the receiving coil and the battery, wherein the control module is used for controlling the charging process of the flexible battery and the discharging process of the load.

2. The apparatus of claim 1, wherein the control module further comprises a first set of output connections and a second set of output connections, wherein the control module is connected to the flexible battery through the first set of output connections and to the load through the second set of output connections.

3. The apparatus of claim 1, wherein the control module further comprises a wireless charging circuit, a battery charging circuit, and a protection circuit connected in series, wherein the wireless charging circuit is connected to the receiving coil, and a switch module is connected between the protection circuit and the flexible battery.

4. The apparatus of claim 3, the switch module comprising a charge switch and a discharge switch connected in series.

5. The apparatus of claim 4, wherein the protection circuit selectively turns on and off a charge switch during charging or selectively turns on and off a discharge switch during discharging by comparing a predetermined value with a voltage and/or current of the flexible battery or the load.

6. the apparatus of claim 4, wherein the charge switch and the discharge switch are MOSFET devices having a gate, a drain, and a source,

The grid electrode of the charging switch and the grid electrode of the discharging switch are respectively connected to the protection circuit;

The drain electrode of the charging switch and the drain electrode of the discharging switch are connected with each other;

a source of the charge switch is connected to a negative terminal of the load;

the source of the discharge switch is connected to the negative terminal of the flexible battery, and the positive terminal of the flexible battery and the positive terminal of the load are connected to a common node.

7. The device of claim 1, wherein the flexible battery is a lithium ion battery.

8. The device of claim 7, wherein the lithium ion battery comprises an electrospun polymer fiber sponge separator.

9. The apparatus of claim 8, wherein the lithium ion battery is a self-healing lithium ion battery.

10. A bendable wireless charging device, comprising:

a flexible substrate having an operable bend radius of at least 90 degrees;

A substantially planar receiving coil for receiving electrical energy from an external transmitting inductor and disposed on a surface of the flexible substrate;

A battery;

A flexible EMI shield layer positioned between the receiver coil and the battery for blocking electromagnetic interference from the receiver coil;

a control module located or formed on one side of the flexible substrate adjacent to the receiving coil and in electrical communication with the receiving coil, the battery and an external load, wherein the control module is configured to control a charging process of the battery.

11. The apparatus of claim 10, wherein the control module further comprises a first output connection set having two electrodes on the flexible substrate, wherein the two electrodes are electrically connected to two ends of the battery, respectively.

12. The apparatus of claim 11, wherein the control module further comprises a wireless charging circuit, a battery charging circuit, and a protection circuit connected in series, wherein the wireless charging circuit is connected to the receiving coil, and a switching module is connected between the protection circuit and the battery.

13. The apparatus of claim 12, wherein the protection circuit selectively turns the switching module on and off during charging by comparing a predetermined value with a voltage and/or current of the flexible battery.

14. The apparatus of claim 10, wherein the receive coil is comprised of a metal layer and at least one cover layer attached to the metal layer, wherein the metal layer is fabricated on the flexible substrate by additive or subtractive coating.

15. The apparatus of claim 14, wherein the metal layer is selected from the group consisting of copper, silver, copper alloys, silver composites.

16. The apparatus of claim 14, wherein the at least one capping layer protects the metal layer from mechanical damage or oxidation.

17. The apparatus of claim 14, wherein said receiver coil further comprises an adhesive layer over said metal layer, said cover layer being over said adhesive layer.

18. The apparatus of claim 14, wherein the material of the flexible substrate and the cover layer comprises a Polyimide (PI) sheet, Polyetheretherketone (PEEK), transparent conductive polyester film, elastomeric film, polyethylene terephthalate (PET), or a combination thereof.

19. the apparatus of claim 14, wherein the metal layer has a thickness in a range of about 5-100 μ ι η, and the flexible substrate and the cover layer have a thickness in a range of about 2-100 μ ι η.

20. The apparatus of claim 10, wherein the flexible EMI shielding layer is selected from the group consisting of metal-coated polymers or polymers with embedded conductive particles or fibers, polyurethane sheets, silicone rubber with embedded magnetic ferrite particles, polyesters, elastomers, and combinations thereof.