WO2010004408A1

WO2010004408A1 - System for transferring information by light modulation through skin

Info

Publication number: WO2010004408A1
Application number: PCT/IB2009/006185
Authority: WO
Inventors: Mathias Buttet
Original assignee: Bnb Concept (Holding) Sa
Priority date: 2008-07-11
Filing date: 2009-07-08
Publication date: 2010-01-14
Also published as: CH699108A2

Abstract

The present invention relates to a system, implantable in the body and enabling a piece of information to be transferred by light modulation through the skin and made visible on the surface. For example, the system is placed under the skin (1) of the wrist, between the forearm (2) and the hand (3), and the system has an electroluminescent diode network (6) emitting a light, the essential portion of the spectral distribution of the emitted power of which is 620 to 660 nm (red) and the brightness of which is at least equal to 100 mcd for a skin thickness of less than 5 mm, so as to make a piece of information, consisting of the points of light, appear on the surface of the skin.

Description

SYSTEM FOR TRANSFERRING INFORMATION BY LIGHT MODULATION THROUGH THE SKIN

The present invention relates to an implantable system in the body, for transferring information by modulating light through the skin and making it visible on the surface of the skin.

Absorption and diffusion of light through biological tissues varies substantially depending on the nature of said tissue and the wavelength of the applied light. The skin is a complex combination of heterogeneous tissues that can be represented by a superposition of 3 layers of variable thickness (epidermis, dermis, hypodermis). In addition to the specifically heterogeneous nature of the constituent tissues of the skin, the transfer of light is disturbed by numerous discontinuities created by the presence of hairs, blood vessels, nerves, folds and other wrinkles. The light passing through the skin is consequently subjected to absorption, diffusion, refraction and reflection phenomena, greatly reducing the resolution of the information that can be displayed on the surface.

In the visible range (wavelengths of about 400 to 700 nm), it is known that the main causes of light absorption through the skin are melanin (responsible for the pigmentation of the skin) and the Hemoglobin, a component of blood that irrigates the various layers of the skin. The absorption coefficient due to melanin varies considerably from one individual to another, depending on the degree of radiation, sun exposure and the location of the body. Roughly, it can be estimated that, in the visible spectrum, the melanin absorption coefficient decreases by a factor of 5 to 10 from violet (400 nm) to red (700 nm). The absorption coefficient due to the hemoglobin is also very variable, according to the place considered, with strong fluctuations in the case of proximity of a blood vessel. Here, too, the absorption decreases overall from purple to red, by a factor of more than 500. The addition of these two absorption factors leads to the existence of a privileged "window" for the transmission of light visible through the skin in the spectrum from yellow to red. The phenomenon of diffusion is a limitation as important as that of absorption. A ray of light focused on one side of the skin will be strongly scattered and perceived on the other side in the form of a halo whose intensity decreases away from the center of the spot of light. Depending on the thickness of the tissues traversed, the focusing optics, the directivity of the emitted beam and the ambient light, the size of the visible spot after passing through the skin may be substantially greater than the diameter of the light source. upstream.

Medical knowledge shows that subcutaneous implants should be placed in such a way as to ensure good vascularization of the tissues. The larger the surface of the implant, the more it will be necessary to ensure that the skin thickness above is sufficient to provide proper irrigation. If this is not the case, the tissues may be damaged or become necrotic. It is also established that a tissue capsule tends to form around the implants. It is one of the mechanisms that human and animal bodies use to defend themselves from foreign bodies. The thickness and nature of this tissue layer are likely to vary greatly from one individual to another and increase over time. For the two reasons mentioned above, any transcutaneous display system will be covered with at least 2 to 3 mm of biological tissue. In addition to physical absorption and diffusion constraints, as well as other body and environmental variables, these limitations greatly reduce the ability to display information through the skin. Concrete achievements will be limited to the display of a modest number of points, mainly red or orange. It is unfair to consider the skin as transparent to visible light. Reality shows that a significant incident light intensity must be applied to perceive a deformed, enlarged, diffuse spot with a fairly weak intensity. The use of high resolution displays (for example LCD type), without active light emission, for a transcutaneous transfer of visible and readable information, is not possible and does not take account for natural limitations to the passage of light through the skin.

In particular, various futuristic publications by Robert A. Freitas, including works on nano-medicine, as well as the concepts presented by the futurist artist Giana Miller, evoke very high resolution displays (several million pixels) across the world. skin. WO 96/39977 (Singer and White) also describes the use of a high resolution passive display (LCD) for transmitting visible information. These various documents, however, evoke concepts that do not take into account the natural limitations of light transmission through biological tissues and that ignore the real constraints associated with active implants.

The use of red or infrared light transmission through biological tissues to measure, for example, heart rate, blood flow, oxygen level in the blood or blood glucose, is well known and is subject to many publications. These systems expose the tissues to a light source and analyze, using a photoreceptor, the variations of the transmitted light. The nature of the information lies in the modulation of a light source by a variable parameter. In the invention presented here, the transmitted information is created by the activation of a number of light sources distributed over a given surface, where, on the contrary, it seeks to overcome the variable parameters of the transmission. .

Since the advent of implanted cardiac pacemakers, many communication systems have been developed to allow remote interrogation, by means of an external device, the memory of the pacemaker, or to proceed to its programming. These systems mainly use low frequency radio waves, whose absorption by the tissues is negligible. The present invention describes a light display system which, incidentally, also uses such an electromagnetic communication system, based on the coupling of two coils, one being part of the implant, the other outside the body, located near the first, for the Bidirectional data transmission with the implant and for battery charging.

The object of the present invention is to allow the display on the surface of the skin of visual information, readable by the wearer of the implant or by a third party. Unlike the transmission of information by the electromagnetic path, which aims to transmit a large number of data over a short period of time, the invention makes it possible to display, by means of a set of light points, information the content of which is simple, but whose graphic representation brings a new dimension for the user. Transcutaneously transmitted information is immediately available, visible on the surface of the skin and requires no external system for display.

The present invention provides a concrete solution to the difficulties of transferring information by modulating light through the skin and making them visible and readable by the human eye. The presented solution is industrially feasible and the performance of prototypes of the system have been evaluated. The features of the invention have been adapted to the specific limitations introduced by the complex nature of the skin. More specifically, the invention relates to an information transfer system by light modulation through the skin, comprising at least one module, biocompatible and waterproof, implantable in the body, characterized in that said module contains means of emission, at one or more points of its surface, of light visible by the human eye, whose dominant wavelength is between 400 and 700 nm and of sufficient light intensity, so as to show the surface of the skin an information constituted by said light. For example, for an emission in which most of the spectral distribution of the transmitted power is between 620 and 660 nm (red color) and for a skin thickness of less than 5 mm, the luminous intensity must be at least equal to 100 mcd. The invention will be better understood on reading the description which follows, given with reference to the appended drawing, in which:

- Figures 1 and 2 illustrate various configurations of the light emitting means; especially for displaying the time.

- Figures 3 to 6 show several embodiments of the system.

The implantable system in the body - or implant - of the present invention allows the display through the skin, graphically, analogically or alphanumerically, of various types of simple information. An example of a graphical representation of the "bar chart" type is presented in FIG. In this example, the display device comprises 24 diodes 6 distributed in 3 lines. Figure la illustrates information where respectively 7, 3 and 4 diodes are lit, appearing 3 "bars" of different light lengths, visible on the skin.

An important category of information displayable by the present invention are physiological parameters of the wearer, collected by the implant or other implant, such as body temperature, heart rate, blood glucose level and other representative data of the present invention. the state of health or metabolism of the wearer. The system also advantageously makes it possible to display a particular pattern or code in the event of an alarm related to the health of the wearer, for example in the event of cardiac arrhythmia, low glucose levels in diabetics and other measures to be rapidly transmitted to the bearer. Note that this information from the wearer's body is displayed immediately on the skin, without external intervention, and without recourse to any external communication system. ^•

Another important category of displayable information according to the present invention is data stored in the memory of the implant. For example, it can act data related to the identity of the wearer or his state of health, or other information such as a code W

access or a particular symbol. The vast majority of active implants marketed; such pacemakers or cochlear implants, include a memory capable of storing such information, which can be communicated to the outside by means of the electromagnetic communication interface. Similarly, T. Knapp's patents, such as WO / 9733513 and US / 599431, describe the use of so-called "transponder" RFID systems for the remote identification of medical implants. The present invention differs fundamentally from these applications, mainly by the mode of transmission and display of the information. The display application through the skin of information stored in the implant is not limited to humans. The present invention also applies to the identification of animals.

In a particularly advantageous and original way, the present invention allows the display of the time, according to Figures Ib and Ic. The system is implanted at the wrist, between the forearm 2 and the hand 3, under the skin 1. In a synthetic, graphic and simple manner, the system can respect the conventional approach of displaying the time and minutes on a 12-hour dial, similar to an analog mechanical or electronic watch. The transcutaneous representation of the needles is done by the successive illumination of luminous points 6 and 7 arranged in concentric circles, as illustrated in FIG. 2b or by a set of elongate light points 10, arranged along a radius, as represented on FIG. Figure 2c. In this latter configuration, the illumination of all the diodes of a ray represents the minute hand 9 and the illumination of a reduced portion of the ray represents the hour hand 8. In order to facilitate the reading of the hour, it is possible to complete the display by a bright spot 4 in the center, preferably of different size or color from other light points, and a light point 5 indicating the "noon" position where "12 o'clock" of the dial. The examples shown in Figures Ib and Ic display "8 h and 5 min". Another configuration consists in arranging the light points according to an XY matrix allowing an alphanumeric display of the time. According to the above description, the main practical and practical feature of the present invention is to emit sufficient energy at an appropriate wavelength in a sufficient number of points to ensure that the information in the form of residual light after passing through the skin is visible and readable. This energy is preferably produced by light-emitting diodes 4, 5, 6 and 7 or laser diodes whose dominant wavelength is between 400 and 700 nm. Advantageously, this light source has a spectral distribution of the emitted power essentially between 620 and 660 nm (red color) and a light intensity of at least 100 mcd in the case of a skin thickness less than 5 mm.

According to the directivity of the light emitted and the size of the light source, a focusing optic 11 is disposed above the diode or a focusing or reflection mirror is placed at the rear of the diode. To reduce the spot size transmitted towards the skin and the opening angle of the beam, is added over the diode network, provided with holes 12 for closing plate ¹ the periphery of the radius of light and let only light in the center of the beam. This same plate 12, with holes of particular shape, allows the display of light spots of various shapes, for example elongate or oblong, as illustrated in Figure 2c.

The present invention also includes means for adapting the emitted light energy level to account for variations in tissue absorption over time, ambient light, and readability objectives of the displayed information. This adaptation of the level of light emitted can be achieved by one or the other of the following means:

- Adjustment of the energy emitted by means of the communication and programming system by electromagnetic coupling, and storage of the adjusted value in the internal memory of the implanted system. - Measurement of the intensity of light at the surface, after passing through the skin and adjustment of the energy emitted according to above.

- Measurement of the intensity of ambient light at the skin and adjustment of the energy emitted according to above. - Measurement of the intensity of ambient light transmitted from the outside to the implant, through the skin. In this configuration, the implanted system includes a photoreceptor. The energy emitted is automatically adapted to the intensity of the ambient light. - Application on the surface of the skin of a light source of known intensity, measuring the intensity transmitted to the implant by the photoreceptor described above and automatic adjustment of the emitted energy. By this means, it is possible to automatically compensate for the variations in the absorption of light by the skin, due to the increase in skin thickness, the evolution and the growth of the tissues of the capsule surrounding the implant. , and pigmentation or vascularization changes.

The present invention provides for storing, in one or more batteries 15, the electrical energy necessary for the operation of the implant and the activation of the light-emitting diodes. An advantageous configuration consists of a rechargeable battery, recharged by means of the electromagnetic coupling system also used for programming. The state of charge of the battery is measured by the electronic circuit of the implant. When recharging is necessary, the information can be transmitted to the carrier by means of the luminous display, either by a particular code or pattern, or by flashing one or more diodes.

The system described in the present invention includes an antenna, an integral part of the implant, consisting of a coil with coaxial turns. This winding makes it possible to carry out an electromagnetic coupling with an external antenna placed nearby. This coupling allows: - charging the battery,

- bidirectional communication between an external programming system and the implant.

These two modes of operation can be simultaneous or sequential.

In order to minimize the electrical consumption of the implant, the present invention provides for the activation of the light-emitting diodes only when the wearer wishes to display information. Activation of the display is advantageously triggered by a particular movement of the implant, detected by an accelerometer 29 integrated in the implanted electronic circuit. In the case of the application of displaying the time, a predetermined movement of the wrist or the arm activates the light-emitting diodes, for a short time. The display turns off automatically after sufficient display time to ensure correct reading of the information.

Any active implant placed in the body for a long time should be:

- Biocompatible: all materials in contact with surrounding tissues or body fluids must be biologically compatible with them.

- Hermetic: no fluid or gas must be able to penetrate the housing and no fluid or gas must be able to come out of it. If, for example, moisture could seep up to the level of the electronic circuit, some elements could corrode. The chemical components resulting from this corrosion could then escape, by the same path taken by the moisture to infiltrate, and cause intoxication of the wearer of the implant. All non-biocompatible materials must imperatively be encapsulated in order to avoid contact, direct or indirect, with the tissues. - Clean at the time of implantation: the surface of the implant must be free of foreign bodies, likely to become detached, non-biocompatible or cause rejection reactions or inflammations. - Sterile at the time of implantation: the surface of the implant must be free of living organisms, such as viruses, bacteria, or spores, which may initiate an infection.

The present invention can be concretely realized by various encapsulation configurations satisfying the above four criteria. Figures 3 to 6 illustrate 4 embodiments of the information modulation system by light modulation through the skin described above.

Figure 3 illustrates an implanted system encapsulated in a biocompatible plastics material. One of the preferred embodiments is to over-mold all the components, pre-assembled and electrically connected, so that they are embedded in a mass of plastic material 18. In this way, the components are protected mechanically and against the penetration of moisture. The light-emitting diodes 4, 6 and 7 are protected by their focusing optics 11. These optical elements are preassembled, for example by gluing, on the light-emitting diodes, before overmolding the assembly. The overmolding mold is designed to save the outer face of the optical elements. A shutter plate 12 is placed above the set of light-emitting diodes and their optics. This plate is provided with round holes or of particular shape corresponding to the desired shape of the light spots visible on the surface of the skin. The holes are placed in the axis of the beams of light emitted by the diodes. Sealing is ensured by the adhesion of the overmoulding plastic to the periphery surface of the optical elements. The light-emitting diodes are attached, for example in CMS-SMD (Surface Mounted Components) technique on the front face of a rigid or flexible PCB-type support 13 (Printed Circuit Board). Others electronic components 14 are arranged on the other side of the printed circuit 13. The communication and charging antenna is formed by a winding 16 placed in the periphery of the housing, so as to have a sufficient surface for the electromagnetic coupling with the outdoor antenna. The battery 15, preferably rechargeable, for example of the Li-Ion type, connected to the electronic circuit before the overmolding operation, is also included in a mass of plastic, in order to protect it to the best of the humidity and to prevent chemical compounds do not escape if the battery leaks. The mold is designed to create, in the overmoulded mass, one or more holes for the passage of a suture. This suture is used to secure the implant in the body, if necessary. This mode of execution by overmolding also allows to maintain a slight flexibility to all, by the choice of a plastic material 18 little stiff, for example a type of polyurethane commonly used by manufacturers of pacemakers. This ability to deform slightly allows the implant to better adapt to body movements and reduces implant erosion of surrounding tissue.

FIG. 4 illustrates an implanted system composed of several interconnected modules, so as to maintain a certain flexibility, adapted to the movements of the body. One of the preferred embodiments comprises 3 modules, a display module 23, an electronic module 21 and an antenna module 19.

The display module 23 comprises the light-emitting diodes 4, 5, 6 and 7, and preferably their focusing optics and a shutter plate.

The encapsulation of this module can be carried out in a manner similar to that described in FIG. 3. The display module is electrically connected to the module 21 by a plurality of insulated and flexible conducting wires 22. The constituent materials of the conductive wires are biocompatible, for example platinum wire and insulating silicone or polyurethane. - The electronic module 21 comprises the electronic circuit and the battery. The encapsulation of this module can be carried out in a manner similar to that described in FIG. 3. Alternatively, this module can be encapsulated in a titanium case, similarly to that described in FIG. 6. The electronic module is electrically connected. to the display module 23 and the antenna module 19, by a plurality of conducting wires 22 and 20, as described above.

- The antenna module 19 comprises a coil 16 concentric or in. spiral. The wire used for winding is biocompatible, preferably flexible. The preferred embodiment of this module is to insert the coil in a flexible patch, made for example by two flexible silicone disks placed under and on the winding. The antenna module is electrically connected to the electronic module 21 by two conducting wires 20, as described above.

FIG. 5 illustrates an implanted system encapsulated in a biocompatible plastics material, in a manner similar to that described in FIG. 3, but with two additional elements intended to improve the mechanical strength of the assembly and the hermeticity:

- On the front side, the light emitting diodes 4, 6 and 7, and their focusing optics 11 are covered with a biocompatible transparent glass 24, preferably sapphire. This glass ensures a very good seal at the interface between the focusing optics and the molding plastic mass. On the inner surface of the glass, it is possible to produce a mask, for example by screen printing, so as to close the light beams, equivalent to the hole plate 12 described in FIG.

On the rear face of the implant, a titanium plate improves the rigidity and the mechanical strength of the implant, while protecting the battery. This titanium plate also prevents the exfiltration of possible chemical compounds in case of leakage of the battery.

The system according to Figure 5 is rigid. The mechanical strength provided by the glass and the titanium plate reduces the thickness of the device. This embodiment is particularly suited to the application of the system for displaying the time through the wrist skin. The principle of overmolding is preserved, so as to protect the components and ensure tightness. The overmolding plastic adheres to the glass over a large part of its internal surface. This improves the sealing and ensures that in case of rupture of the glass, for example following an impact, the pieces remain firmly attached to the overmoulding mass. Components 24 and 25 are intrinsically hermetic. As they cover more than 90% of the external surface of the implant, the possible diffusion of moisture through the overmolding plastic is reduced accordingly.

Figure 6 illustrates an implanted system encapsulated in a titanium housing 26, covered with a glass 24. The seal of the assembly is improved by the addition of a seal 27 between the glass and the housing. Compared with the embodiment described in Figure 5, the present system further improves the hermeticity and mechanical rigidity. On top of the glass, a plate 28, provided with holes, fulfills a triple function:

- Protection of the glass against impacts

- In case of breakage of the glass, the protection plate prevents pieces of glass from coming off the implant

- Obturation and shaping of the light beams, similar to the hole plate 12 described in Figure 3.

In order to guarantee optimum protection of the electronic components, the system described in FIG. 6 retains the principle of filling all the free space inside the casing with a mass of plastic molded or injected into the casing. The concept of a titanium housing 26, machined in a single block of material, ensures a very good rigidity, despite a very slim caseback. The seal 27, between the glass and the housing, can also fulfill a function of mechanical connection between these two components, further improving the mechanical strength of the assembly. For example, a hot-melt adhesive seal, a cold-cut washer, placed between the glass and the housing, and then melting by heating, provides excellent sealing while intimately bonding the glass to the housing. The shell thus formed has optimum mechanical strength.

FIG. 6 also illustrates the presence of an accelerometer or motion detector 29, mounted on the electronic circuit 13. Its function is to detect a particular movement of the wrist, predefined. This movement corresponds to the activation signal of the display. It is also possible to use the accelerometer 29 as a shock detector. In the event of a major shock, the impact recorded by the accelerometer will be processed by the microprocessor and an alarm will eventually be transmitted.

FIG. 6 also shows the possible presence of a humidity detector 30 mounted on the electronic circuit 13. This detector has two functions:

- Detection of an abnormally high rate of humidity resulting from a loss of sealing of the encapsulation of the system.

- Detection of the presence of fluids from a battery leak.

In both cases, the humidity detector triggers an alarm, transmitted for example by the transdermal light display system. Depending on where in the body the implant is placed, the thickness of the device may be a critical parameter. The limiting component with respect to the thickness is the battery. An alternative to the embodiments described in Figures 3, 5 and 6 is to place the battery next to the printed circuit supporting the light emitting diodes, to minimize the overall height of the encapsulation. It should be noted that in a general manner the biocompatible glass 24 covering the front face of the diodes and their optics can be any transparent material and in particular sapphire.

On the other hand, the humidity sensor integrated in at least one of said module makes it possible to detect, on the one hand, that the module is no longer watertight, for example in the event that moisture penetrates from the outside into the module, and secondly a leak for example of the battery in said module.

The intensity of the diodes or of the light source is greater than 80 mili candela (mcd) and preferably between 180 and 250 mcd.

Claims

An information transfer device disposed in at least one biocompatible and sealed module, implantable in a living body, characterized in that it comprises a source of rechargeable electric current; an electronic circuit powered by this current source and controlling transmission means in at least one point of the surface of the module, of light visible by the human eye whose dominant wavelength is between 400 and 700 nanometers (nm) and light intensity of at least 80 mili candela (mcd), to reveal on the surface of the skin, information formed by said light.

2. Device according to claim 1, characterized in that said light has a spectral distribution of the transmitted power substantially between 620 and 660 nm (red color) and an intensity of between 180 mcd and 250 mcd.

3. Device according to one of claims 1 and 2, characterized in that the light-emitting means comprise at least one light-emitting diode or at least one laser diode or a set of light-emitting diodes or laser diodes.

4. Device according to one of claims 1 to 3, characterized in that said information consists of a set of light spots.

5. Device according to claim 4, characterized in that said light points are of substantially oval or elongated shape so as to present a detectable orientation by the human eye.

6. Device according to one of claims 4 or 5, characterized in that the electronic circuit controls the intensity of the light emitted by the transmitting means.

7. Device according to claim 6, characterized in that said luminous intensity is variable as a function of the extra corporeal ambient light measured, through the skin, by a photodiode or a phototransistor integrated in said electronic circuit.

8. Device according to one of claims 4 to 7, characterized in that said information consists of a set of light points displaying the time.

9. Device according to claim 8, characterized in that it comprises an additional luminescent diode indicating a particular point of the time display, center of the dial or "noon" position.

10. Device according to claim 9, characterized in that the additional light diode differs from other light points by a different color, shape, light intensity or blinking.

11. Device according to one of claims 4 to 7, characterized in that said information consists of a set of light points for displaying alphanumeric information.

12. Device according to one of claims 4 to 7, characterized in that said information consists of a set of light points for displaying information in graphical form.

13. Device according to claim 1 and claim 8, characterized in that said electronic circuit incorporates an electronic clock.

14. Device according to claim 1, characterized in that said electronic circuit integrates an electronic memory containing alphanumeric information displayed using said transmitting means.

15. Device according to claim 1, characterized in that said electronic circuit incorporates at least one sensor for measuring a physiological parameter of the carrier to be displayed by the transmitting means.

16. Device according to claim 1, characterized in that said electronic circuit includes communication means for receiving information from another implant located in the wearer's body to display them using the means of program.

17. Device according to claim 1, characterized in that said electronic circuit integrates at least one induction antenna for performing an inductive electromagnetic coupling with an external antenna placed in its vicinity.

18. Device according to claim 17, characterized in that the electromagnetic coupling is used to transfer electrical energy from the antenna external to the electronic circuit for recharging said current source.

19. Device according to claim 17, characterized in that said electromagnetic coupling is used to transfer information from the external antenna to the implanted antenna, from the antenna implanted to the external antenna, or in both directions.

20. Device according to claim 1, characterized in that said electronic circuit incorporates at least one microprocessor or programmable electronics.

21. Device according to claim 1, characterized in that said or one of said modules integrates at least one accelerometer or a motion detector.

22. Device according to claim 21, characterized in that the light display is activated by a particular movement detected by the accelerometer.

23. Device according to claim 1, characterized in that said or one of said modules incorporates at least one humidity sensor for activating an alarm, when its encapsulation is no longer sealed or when fluids escape of the battery, using the transmission means.

24. Device according to claim 4, characterized in that said transmitting means are used to signal to the carrier that the current source is discharged.

25. Device according to one of the preceding claims, characterized in that said module or said modules is encapsulated in a rigid or substantially flexible biocompatible plastic material, allowing its slight deformation according to the displacement of the surrounding tissues.

26. Device according to one of claims 1 to 25, characterized in that it comprises three implanted modules interconnected in a flexible manner, ie: - a display module comprising light-emitting diodes,

an electronic module comprising components of the electronic circuit and a source of electrical energy.

- An antenna module.

27. Device according to claims 1 to 25, consisting of a single module and characterized in that said module is encapsulated in a rigid plastic material and protected on the rear face by a titanium plate and on the front face by a plate transparent material covering the light emitting means.

28. Device according to claims 1 to 25, consisting of a single implanted module, characterized in that said module is encapsulated in a housing comprising at least the following elements:

a box of biocompatible metal, such as titanium, with a surface slightly greater than that of the display, of low height, open on the front face,

a plate of biocompatible transparent material, such as sapphire, covering precisely the opening of the metal box, a seal placed between the canister and the transparent material plate, in order to seal and secure the glass to the housing.

Device according to claim 28, characterized in that the free volume inside the housing, not occupied by components, is filled with a plastic material which protects the components from moisture and corrosion and from strengthen the mechanical rigidity of the housing.

30. Device according to claim 3 and one of claims 25 to 29, characterized in that the opening angle or the shape of the light beam emitted by each light-emitting diode is reduced by a blanking plate provided with small holes arranged in the axis of the diodes.

31. Device according to claim 30, characterized in that said closure plate is formed by an opaque deposit on the inner or outer surface of the plate of transparent material, with openings of size and shape adapted to the angle. of opening and the desired shape of the beams of light.

32. Device according to claim 3 and one of claims 25 to 29, characterized in that the light beam emitted by each light-emitting diode is focused by an optical focusing lens placed in front of each diode.

33. Device according to one of claims 27 to 29, characterized in that a grid protects the plate of transparent material against impacts outside and avoids, in case of rupture of this plate, that debris are detached.

34. Device according to one of claims 25 to 29, characterized in that at least one of said modules is provided with holes for the passage of a suture for securing and maintaining it in the body.