JP6357752B2 - Manufacturing method of visual reproduction assist device - Google Patents

Description

The present invention relates to a method of manufacturing a visual reproduction assisting device having a device implanted in a patient's body.

  In recent years, research on a visual reproduction assisting device that performs a part of the lost visual function has been made. For example, an apparatus that has an electronic circuit that is embedded in a patient's body, such as the eye, together with a large number of electrodes, and outputs a current from the electronic circuit through the electrodes to stimulate cells related to the patient's vision is known. . In some devices of this type, the electronic circuit is protected from the patient's body fluid by sealing the electronic circuit in a case. For example, Patent Document 1 describes an electronic circuit that is sealed between an installation table and a lid by joining the installation table and the lid.

JP 2008-055000 A

  By the way, when an electronic circuit is exposed to high temperatures, it may be destroyed by heat. For this reason, the sealing process applied to the case is desired to be a process that can be performed at a low temperature that does not cause trouble in the electronic circuit and that provides good airtightness.

The present invention has been made in view of the above circumstances, in a case embedded in the body of a patient, and an object to provide a way to better seal the electronic circuit.

According to another aspect of the present invention, there is provided a method for manufacturing a visual reproduction assisting device comprising: an attachment step in which an electronic circuit is attached to a body part having biocompatibility; A lid part to be formed, and a joining step of sealing the electronic circuit in the housing space in an insulating case composed of the main body part and the lid part. An average of 1 μm or less on at least one of the bonding surface of the main body portion with the lid portion and the bonding surface of the lid portion with the main body portion. The method further includes an application step of applying a metal powder of a predetermined metal having a particle diameter, wherein the metal powder is interposed between the bonding surfaces in the bonding step. The, while pressing at a pressure greater than or equal to 100 Mpa, 80 ° C or higher, by heating in the range of 300 ° or less, the metal powder and the main body portion via a bonding layer formed by being bulked by sintering The lid portion is joined to each other.

  According to the present invention, there is an effect that an electronic circuit embedded in a patient's body is easily sealed well in a case.

It is the figure which showed the outline of the visual reproduction assistance apparatus in this embodiment. It is the figure which showed the structure of the intracorporeal device. It is sectional drawing of a stimulus control apparatus. It is the schematic diagram which showed the mounting | wearing aspect of the internal apparatus with respect to a patient's eye.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. First, the schematic configuration of the visual reproduction assisting device 1 will be described with reference to FIG.

  The visual reproduction assisting apparatus 1 of the present embodiment prompts the reproduction of the patient's vision by electrically stimulating the cells related to the patient's vision. As shown in FIG. 1, in this embodiment, the visual reproduction assistance device 1 includes an extracorporeal device 10 and an in-vivo device 20. The extracorporeal device 10 acquires information on the outside world. The extracorporeal device 10 processes the acquired information and transmits a signal to the intracorporeal device 20. On the other hand, the in-vivo device 20 of the present embodiment provides electrical stimulation to the cells constituting the retina based on the signal sent from the extracorporeal device 10.

  In the present embodiment, the extracorporeal device 10 includes a visor 11, a photographing device 12, an external device 13, and a transmission unit 14. The visor 11 has a glasses shape, and is mounted in front of the patient's eyes as shown in FIG. The imaging device 12 is attached to the front surface of the visor 11 and images a subject in front of the patient. For the imaging device 12, for example, a CCD camera can be used.

  The external device 13 includes a data modulation unit 13a and a battery 13b. The battery 13b supplies power for the visual reproduction assisting device 1 (the extracorporeal device 10 and the in-vivo device 20). The data modulation unit 13a has an arithmetic control device such as a CPU, and performs image processing on a subject image photographed by the photographing device 12 to generate a control signal for visual reproduction. The data modulator 13a superimposes the control signal on the power transmission signal by amplitude modulation or the like. As a result, the control signal and the power transmission signal are transmitted as electromagnetic waves from the primary coil of the transmission unit 14 to the in-vivo device 20 side (in this embodiment, wireless transmission). In addition, a magnet 15 for fixing a position with respect to a receiving unit 30 described later is attached to the center of the transmission unit 14.

  As shown in FIGS. 2A and 2B, the in-vivo device 20 includes a receiving unit 30, a stimulation unit 40, and the like. The receiving unit 30 receives an electromagnetic wave transmitted from the extracorporeal device 10. The reception unit 30 includes a reception unit 31 and a control unit (first in-vivo signal output device) 32. In the present embodiment, the receiving unit 31 includes a secondary coil that receives electromagnetic waves from the extracorporeal device 10. The control unit 32 extracts a control signal and electric power from the electromagnetic wave received by the reception unit 31. The electric power extracted by the control unit 32 is supplied to each unit of the in-vivo device 20. The receiving unit 30 is also provided with a magnet (not shown) for fixing the position of the transmission unit 14.

  As shown in FIG. 2A, a feedback electrode 34 is attached to the receiving unit 30. Although details will be described later, the return electrode 34 is attached so as to sandwich the stimulation unit 40 and the patient's eye. A voltage for guiding the current output from the stimulation unit 40 is applied to the return electrode 34.

  As shown in FIG. 2A, the receiving unit 30 and the stimulation unit 40 are connected by a lead wire 35. The control unit 32 supplies power to the stimulation unit 40 via the lead wire 35 and outputs a control signal.

  In the present embodiment, the stimulation unit 40 electrically stimulates cells constituting the retina. The stimulation unit 40 includes an electrode unit 50 and a stimulation control unit (second in-vivo signal output device) 60. In the present embodiment, the stimulation unit 40 is installed on the eyeball. In particular, in this embodiment, a part of the stimulation unit 40 is installed between layers (or within layers) of layered eye tissue. For example, it is installed between the sclera and the choroid.

  The electrode unit 50 is a multi-electrode array in which a plurality of electrodes 51 are formed on a substrate 52. The electrodes 51 are arranged at regular intervals in a grid pattern or alternately at regular intervals. The number of the electrodes 51 should just be determined according to the resolution at the time of visual reproduction. In the present embodiment, 54 electrodes 51 are described as being formed on the substrate 52. However, more or less electrodes 51 may be provided on the substrate 52. The electrode 51 is formed of a highly biocompatible conductor. For example, the electrode 51 can be formed of a noble metal such as gold and platinum.

  The board | substrate 52 is formed in the plate shape with the insulator. The substrate 52 is preferably formed of a material having high biocompatibility. Moreover, it is preferable that the board | substrate 52 follows the shape of an eyeball. For example, the substrate 52 may be formed to be bendable with a required thickness. Inside the substrate 52, a plurality of lead wires 52a are provided. Each electrode 51 is electrically connected to the stimulus control unit 60 via the lead wire 52a.

  As shown in FIG. 2, the stimulus control unit 60 of the present embodiment has an electronic circuit 61. In this embodiment, the electronic circuit 61 mounts a plurality of electronic components such as a custom IC, a capacitor, and a diode on a ceramic substrate. In the present embodiment, the electronic circuit 61 is a demultiplexer, and a current (in this embodiment, a bipolar pulse) is supplied to each electrode 51 based on a control signal received from the control unit 32 via a lead 35 described later. Distribute.

  The stimulation control unit 60 has a case 62 that seals the electronic circuit 61. Here, the detailed configuration of the stimulus control unit 60 will be described with reference to FIG. As illustrated in FIG. 3, the stimulus control unit 60 includes a bonding layer 65 and a plurality of connection terminals 66 in addition to the electronic circuit 61 and the case 62.

  In the present embodiment, the case 62 includes an installation base (main body part) 63 and a lid part 64. The storage space C of the electronic circuit 61 is formed by joining the joint surface 63a of the installation base 63 and the joint surface 64a of the lid portion 64. Both the installation base 63 and the lid portion 64 have biocompatibility.

  In the present embodiment, an electronic circuit 61 is attached on the installation base 63. In the present embodiment, a ceramic flat plate is used for the installation base 63. The material of the installation base 63 is not limited to ceramic, and various insulators having biocompatibility can be used. In addition, in order to install the stimulation control unit 60 in the body for a long period of time, it is preferable to use a material with little deterioration over time in the body for the installation base 63. For example, glass, sapphire, etc. satisfy the above conditions.

  In order to reduce unevenness generated on the ceramic surface, in this embodiment, the joint surface 63a of the installation table 63 is polished. The joining surface 63a of this embodiment is polished by a polishing process after being polished by a lapping process. When the polishing process is performed, the joint surface 63a is more preferably smoothed. The polishing process may not be performed in relation to the accuracy required for sealing the electronic circuit 61.

  In the present embodiment, the joining surface 63a of the installation base 63 is subjected to sintering (sintering) after polishing. The sintering process here is a heat treatment for moving the glass of the installation table 63 to the surface side of the bonding surface 63a by heating the installation table 63. By performing the sintering process on the installation table 63, fine cavities (voids) on the installation surface 63, which cannot be removed only by polishing, are filled with glass. As a result, the joint surface 63a is further smoothed. In the sintering process, the installation base 63 is heated to about 1000 ° C., for example. For this reason, in this embodiment, the grinding | polishing and sintering process of the joint surface 63a are performed before the electronic circuit 61 is attached to the installation base 63. FIG.

  Further, a metal thin film (metal layer, in this embodiment, a thin film of gold (Au)) is formed on the joint surface 63a of the installation base 63 by metallization. As will be described later, since the bonding layer 65 of this embodiment is formed of metal, the bonding strength between the non-metal mounting base 63 and the metal bonding layer 65 is ensured by interposing a metal thin film. The airtightness at the interface between the two can be improved. In the present embodiment, the metal thin film is formed by a well-known metallization process such as a vacuum deposition method, a sputtering method, or an active metal method on the setting table 63 after the sintering process.

  Further, as shown in FIG. 3, the installation base 63 is provided with a plurality of connection terminals 66 penetrating from the mounting surface of the electronic circuit 61 to the opposite surface. Some of the connection terminals 66 are independently connected to the electrode 51 via lead wires 52 a in the substrate 52. The remaining connection terminals 66 are connected to the control unit 32 via the lead wires 35. With such connection terminals 66, the electronic circuit 61 is connected to an external device in a state of being enclosed in the case 62.

  In the present embodiment, the connection terminal 66 is made of platinum (Pt). The connection terminal 66 may be formed of a biocompatible conductor other than platinum (for example, a noble metal such as gold), but platinum that is not easily electrolyzed in vivo is particularly preferable. The connection terminal 66 has a conductive via portion 66b that penetrates the installation base 63 and a terminal portion 66a that is exposed to the outside of the case 62. Of these, only the terminal portion 66a that can touch the living body is platinum. May be formed.

  In the present embodiment, the lid portion 64 is formed with a recess 64 b for accommodating the electronic circuit 61. The lid portion 64 is joined to the installation base 63 so as to cover the electronic circuit 61. The lid portion 64 is preferably formed of a material having biocompatibility such as glass, sapphire, or a predetermined ceramic and having little aging deterioration in the body. Glass is used for the lid portion 64 of the present embodiment.

  A metal thin film similar to the bonding surface 63a of the installation base 63 is also formed on the bonding surface 64a of the lid portion 64 in order to ensure bonding strength with the metal bonding layer 65 and airtightness.

  Next, the bonding layer 65 will be described. The bonding layer 65 is formed by a bonding process between the installation base 63 and the lid portion 64. In this bonding process, a metal powder of a predetermined metal having an average particle diameter of 1 μm or less (a sintered body of metal powder) is interposed between the bonding surface 63a of the installation table 63 and the bonding surface 64a of the lid portion 64, This is done by heating the metal powder.

  The metal powder is applied in advance to at least one of the joint surface 63a of the installation base 63 and the joint surface 64a of the lid portion 64. Application | coating of metal powder may be performed by apply | coating the mixture (metal paste) of metal powder, an organic solvent, etc. to joining surface 63a, 64a. A metal having biocompatibility can be used as the metal powder applied to the joining surfaces 63a and 64a. In the present embodiment, gold (Au) metal powder is used. The metal powder applied to the joining surfaces 63a and 64a can be one having an average particle size of 1 μm or less. In the present embodiment, a gold metal powder having an average particle diameter of 0.3 μm or more and 0.5 μm or less is used. In addition, the average particle diameter in this embodiment can be obtained based on the particle size distribution of the metal particles obtained by the light transmission centrifugal sedimentation method. As the average particle size, for example, the particle size at 50 percent of the integrated value of the particle size distribution may be used.

  The predetermined metal used as the material of the metal powder is not necessarily limited to gold. The predetermined metal has biocompatibility and is heated at a temperature not higher than the melting point of the metal bulk body (for example, 300 ° C. or lower) when a sintered body is formed from a powder having an average particle diameter of 1 μm or less. Any metal may be used as long as it is pressed and densified (bulked) by sintering. For example, noble metals such as gold, silver, platinum, and palladium may be used by appropriately adjusting the particle size of the metal powder. The metal powder may be a mixed powder of two or more kinds of metals that meet the above conditions.

  In the present embodiment, metal powder is applied to the joint surface 64 a of the lid portion 64. Thereafter, the lid 64 is heated at a predetermined temperature using an electric furnace or the like for a predetermined time. Thereby, metal powders fuse | melt at a mutual contact part, are couple | bonded moderately, and the sintered compact of metal powder is formed. In addition, it is preferable that the heating temperature at the time of sintering shall be 80 to 300 degreeC. If it is less than 80 ° C., point contact of metal particles hardly occurs, and an appropriate sintered body cannot be obtained. On the other hand, when heated at a temperature exceeding 300 ° C., the metal particles are excessively bonded to each other, and the lid 64 is difficult to be joined to the installation base 63 side in the subsequent processing. In addition, when apply | coating a metal paste to the cover part 64, after forming a sintered compact, the process of drying the cover part 64 and removing the remaining organic solvent is good.

Next, after the installation base 63 to which the electronic circuit 61 is attached is overlapped with the lid portion 64, the sintered body is pressurized while being heated. The metal powder constituting the sintered body is bonded while being plastically deformed, and a joining layer 65 for joining the installation base 63 and the lid portion 64 is formed. As a result, the electronic circuit 61 is sealed in the storage space C of the case 62. At this time, when the sintered body is heated at a temperature of about 80 ° C. to 300 ° C., a good bonding layer 65 is easily obtained. If the temperature is lower than 80 ° C., bonding is difficult to obtain, and if it is 300 ° C. or higher, the bonding layer 65 is easily affected by thermal strain during cooling. Moreover, in this embodiment, densification of a sintered compact can be favorably advanced by applying a pressure of 100 Mpa or more during heating. The higher the pressure applied to the sintered body, the better the bonding layer 65 can be obtained. However, at a pressure higher than about 200 Mpa, the effect of pressurization becomes constant. The bonding layer 65 obtained by heating and pressing the sintered body is a bulk body of high-purity metal. Therefore, unless the bonding layer 65 is heated at a high temperature (to the vicinity of the melting point of the metal), it does not remelt. Therefore, when the installation base 63 and the lid part 64 are joined by the above method, the airtightness in the case 62 is easily maintained. Thus, the electronic circuit 61 is accommodated in the case 62 with high airtightness. In the helium leak test conducted by the present inventor, a sample having the same configuration as the case 62 of the present embodiment exhibits a high airtight performance of 1.0 × 10 ⁻¹³ Pa · m ³ / S or less. There was also.

  By the way, it is preferable that the heating temperature at the time of bonding is set sufficiently lower than the heat resistance temperature of the electronic circuit 61. This is because the lower the heating temperature at the time of bonding, the lower the possibility that the electronic circuit 61 will be destroyed due to the influence of heat at the time of bonding.

  With reference to FIG. 4, the attachment aspect to the patient's eye of the intraocular apparatus 20 is illustrated. As shown in FIG. 4, the intraocular device 20 can stimulate the cells constituting the retina E1 by installing the electrode 51 on the choroid E2. In this case, the stimulation unit 40 is placed on the patient's eye by inserting the distal end portion of the substrate 52 on which the electrode 51 is formed into a pocket created by cutting a part of the sclera E3. The return electrode 34 is placed at a position closer to the anterior segment. Therefore, the retina E1 is located between the electrode 51 and the return electrode 34. While applying a voltage to the feedback electrode 34, the current from the stimulation control unit 60 is output via the electrode 51, so that the stimulation current efficiently penetrates the retina, and electrical stimulation is suitably applied to the retina. Can be given.

  As described above, according to the visual reproduction assistance device 1 of the present embodiment, the electronic circuit 61 is sealed in the storage space C of the case 62 formed by joining the installation base 63 and the lid portion 64. Here, the installation base 63 and the lid portion 64 are metal powders of a predetermined metal having an average particle diameter of 1 μm or less interposed between the joint surfaces 63a and 64a (in this embodiment, gold powder). Are bonded together by a bonding layer 65 formed by sintering. As described above, the bonding layer 65 can be formed at a temperature sufficiently lower than the melting point temperature of the metal bulk body. For this reason, for example, the electronic circuit 61 is prevented from being destroyed by heat during sealing. The size of the case 62 enclosing the electronic circuit 61 is considered to require a larger margin as the amount of heat transferred from the case 62 to the electronic circuit 61 when the case 62 is joined. As described above, in the visual reproduction assistance device 1 of the present embodiment, the case 62 may be joined at a low temperature. For this reason, for example, even in the small case 62, the electronic circuit 61 is easily sealed well.

  In particular, the visual reproduction assisting device 1 has a high airtightness of the electronic circuit 61, and water (water vapor) hardly enters the case, so that the electronic circuit 61 is hardly deteriorated by moisture. Therefore, the electronic circuit 61 tends to operate stably for a long period of time with the electronic circuit 61 (stimulation unit 50) embedded in the body.

  Moreover, according to the visual reproduction auxiliary device 1 of the present embodiment, the sintering process is performed on the joint surface 63a of the ceramic material installation base 63. Since the surface of the joining surface 63a is smoothed by the sintering process, a gap is hardly generated between the joining layer 65 and the joining surface 63a in the joining process using the metal powder (sintered metal powder). Therefore, in the visual reproduction assistance device 1, the electronic circuit 61 is easily sealed well.

  Furthermore, in the present embodiment, the sintering process is performed on the joint surface 63a that has been previously polished. As a result, since the bonding layer 65 is bonded to the extremely smooth bonding surface 63a, the electronic circuit 61 is sealed even better in the visual reproduction assistance device 1.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above-described embodiment, and various modifications can be made.

  For example, in the above-described embodiment, the case where the installation base 63 and the lid portion 64 of the case 62 are formed of different materials has been described. However, the installation base 63 and the lid part 64 may be formed of the same material. The installation table 63 and the lid part 64 are thermally expanded by heating during the bonding process. At this time, the larger the difference in the thermal expansion coefficient between the installation base 63 and the lid 64 in the range from room temperature to the temperature during the bonding process, the more easily the bonding layer 65 is distorted during cooling, and the electronic circuit 61 is sealed better. It becomes difficult to be done. On the other hand, when the installation base 63 and the lid portion 64 are formed of the same material, the same degree of expansion occurs in both, so that the bonding layer 65 is hardly distorted and the electronic circuit 61 is easily sealed well. . Further, even when the installation base 63 and the lid portion 64 are formed of different materials, if the thermal expansion coefficients in the range from room temperature to the temperature during the bonding process are close to each material, the heat during the bonding Strain due to expansion hardly occurs in the bonding layer 65, and the electronic circuit 61 can be sealed well.

  In the above embodiment, the electrode 51 is placed on the eyeball and the cells constituting the retina are stimulated. However, the present invention is not limited to this. Any structure may be used as long as it stimulates the cells or tissues related to the patient's vision to promote the reproduction of the patient's vision. For example, electrodes may be placed on the optic nerve, cerebral cortex, and the like.

  Note that all or part of the configuration of the receiving unit 30 may be included in the stimulation control unit 60 of the stimulation unit 40. At this time, the stimulus control unit 60 may be arranged at a position away from the patient's eye (that is, from the electrode unit 50).

  In the above embodiment, the case where the same material (gold in the above embodiment) as the bonding layer 65 is used for the metal thin film formed on the mounting base 63 by the metallization process has been described. It may be formed.

DESCRIPTION OF SYMBOLS 1 Visual reproduction auxiliary | assistance apparatus 51 Electrode 61 Electronic circuit 62 Case 63 Installation stand 64 Cover part 65 Joining layer 66 Connection terminal C Storage space

Claims (3)

An attachment step in which an electronic circuit is attached to the main body having biocompatibility;
The main body part and a lid part that forms a housing space for the electronic circuit by being joined to the main body part are joined, and the electronic circuit is mounted on an insulating case composed of the main body part and the lid part. A joining step for sealing in the accommodation space;
A method of manufacturing a visual reproduction assisting device including:
It is an application step performed before the joining step, and an average particle diameter of 1 μm or less is provided on at least one of a joint surface of the main body portion with the lid portion and a joint surface of the lid portion with the main body portion. A coating step of applying a metal powder of a predetermined metal having
In the joining step, the metal powder is heated in a range of 80 ° C. or more and 300 ° or less while pressurizing the main body part and the lid part interposed between the joining surfaces at a pressure of 100 Mpa or more. By doing so, the said main-body part and the said cover part are mutually joined through the joining layer formed by the said metal powder being bulked by sintering, The manufacturing method of the visual reproduction assistance apparatus characterized by the above-mentioned. In the application step, the metal powder is applied to the joint surface of the lid,
The visual reproduction according to claim 1, further comprising a pre-heating step of heating the lid portion to which the metal powder is applied to form a sintered body by the metal powder before the joining step. A manufacturing method of an auxiliary device.   The method for manufacturing a visual regeneration assisting device according to claim 1, wherein polishing and sintering for the joint surface of the main body are performed before the attaching step.