JP2020081720A - Visual sensation regeneration aid apparatus - Google Patents

Abstract

To provide a visual sensation regeneration aid apparatus capable of outputting stimulation currents from multiple electrodes at a sufficient frame rate.SOLUTION: A visual sensation regeneration aid apparatus to regenerate the visual sensation of a patient includes: a stimulation unit comprising a plurality of electrodes for outputting stimulation pulse signals; an electrode unit comprising a plurality of stimulation units; a buffer unit for supplying power to the electrode unit; wiring electrically connecting the electrode unit and the buffer unit for transmission of power supply signals; a power supply unit for supplying power to the buffer unit; and a cable electrically connecting the buffer unit and the power supply unit for transmission of power supply signals. The power supply unit supplies low frequency power to the buffer unit, and the buffer unit supplies high frequency power to the electrode unit.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a visual reproduction assisting device that reproduces a patient's vision.

Conventionally, as one of the techniques for treating blindness, an intraocular implanting device (internal device) having electrodes and the like is installed in the eye, and electrical stimulation pulse signals (charges) are output from the electrodes to remove cells that make up the retina. A visual regeneration assisting device that attempts visual regeneration by electrically stimulating is known. This kind of visual regeneration assisting device, for example, converts an image captured outside the body into an optical signal or an electromagnetic signal, and then transmits the signal to an in-vivo device installed in the eye, and a plurality of electrodes provided in the in-vivo device. Emits an electrical stimulation pulse signal (stimulation current) from the cells to stimulate cells constituting the retina, thereby promoting visual regeneration (see Patent Document 1).

In this visual regeneration assisting device, tens of electrodes provided in the electrode unit output stimulating current, but the pulse width of the stimulating pulse signal required to stimulate one electrode is about 1 ms. Even if the electrodes are sequentially stimulated one by one, a sufficient frame rate (for example, about 20 Hz) for stimulating all the electrodes is secured. Since only one electrode outputs the stimulus at the same time, only the multiplexer is installed in the electrode unit, the stimulating current source is installed in the power supply unit, and the power supply to the electrode unit is performed intermittently during the period in which the stimulation operation is not performed. It is being appreciated.

JP, 2016-193068, A

Here, in order to increase the resolution of the external image that can be recognized by the patient, it is necessary to arrange more electrodes (for example, 100 or more electrodes) on the retina and to stimulate the retina from the many electrodes. However, when a stimulation current is output from more than one hundred electrodes, a sufficient frame rate could not be secured if the stimulation operation was sequentially performed one electrode at a time. Therefore, if several hundred electrodes are provided in the electrode unit, there is a possibility that it will not be possible to perform a stimulation operation on those many electrodes at a sufficient frame rate.

Therefore, in order to solve the above-described problems, it is an object of the present disclosure to provide a visual regeneration assisting device that can output a stimulating current from a large number of electrodes at a sufficient frame rate.

One form of the present disclosure made to solve the above problems is
In the visual regeneration assisting device that regenerates the patient's vision,
A stimulation unit comprising a plurality of electrodes for outputting stimulation pulse signals;
An electrode unit including a plurality of the stimulation units,
A buffer unit for supplying power to the electrode unit,
A wiring that electrically connects the electrode unit and the buffer unit and transmits a power supply signal,
A power supply unit for supplying power to the buffer unit,
A cable that electrically connects the buffer unit and the power feeding unit and transmits a power feeding signal,
The power feeding unit performs low frequency power feeding to the buffer unit,
The buffer unit supplies high frequency power to the electrode unit.

According to the visual regeneration assisting device of the present disclosure, the stimulation current can be output from a hundred or more electrodes at a sufficient frame rate.

It is a figure which shows the extracorporeal device in the visual reproduction assistance device of this embodiment. It is a figure showing an in-vivo device in a visual regeneration auxiliary device of this embodiment. It is a figure which shows a stimulation unit, (a) is the front view seen from the bottom side, (b) is sectional drawing seen from the side. It is a figure which shows the installation position of the electrode unit with respect to an eyeball. It is a figure which shows the circuit structure of an internal device.

Hereinafter, typical embodiments of the present disclosure will be described in detail with reference to the drawings. The visual regeneration assisting device of the present embodiment regenerates or replaces a patient's lost visual function. More specifically, based on an external image captured outside the body, electrical stimulation is performed on the optic nerve system that has lost function, thereby causing the patient to see an image by pseudo-light sensation (phosphene). In the present embodiment, a case where the present disclosure is applied to a retina stimulation type visual reproduction assisting device will be described as an example.

The visual reproduction auxiliary device in the present embodiment is an external imaging type device in which an imaging unit for obtaining an external image is provided outside the body. Such a visual reproduction assist device is roughly classified into an external device 20 (see FIG. 1) and an internal device 10 (see FIG. 2). The visual regeneration assisting device shown in the drawing is a device adapted to suprachoroidal transretinal stimulation (STS). In this case, the electrode 105 (stimulation unit 100) is inserted from an incision (flap) formed by making an incision in the eye sclera, and the electrode 105 is positioned on the choroid. As a result, electrical stimulation can be performed without directly contacting the electrode 105 with the retina.
<Schematic configuration of extracorporeal device>

As shown in FIG. 1, the extracorporeal device 20 is a glasses-type wearable device, and is worn on the face in the present embodiment. Further, the extracorporeal device 20 of the present embodiment includes a camera 204, a processing device 202, and a transmission unit 206.

The camera 204 (mainly a video camera) is used to acquire an external image of the front of the patient. For example, a CCD camera or the like may be used. The camera 204 is preferably attached to the patient's head so that an external image corresponding to the orientation of the patient's head is captured, for example.

The processing device 202 has a processor that performs arithmetic processing/control processing. The processing device 202 processes the external image (image) acquired by the camera 204 to generate a control signal to be transmitted to the in-body device 10. The generated control signal is output to the transmission unit 206. The control signal includes at least control information for controlling the operation of the internal device 10. This control information is used to control the stimulation current output by the in-vivo device 10 in the present embodiment.

The transmission unit 206 is used to transmit the signal generated by the processing device 202 to the internal device 10 (more specifically, the power feeding unit 150: see FIG. 2 ). The transmission unit 206 transmits information included in the signal to the in-vivo device 10 as an electromagnetic wave. For example, an electromagnetic wave in which at least one of wavelength, period, amplitude, phase, etc. is modulated according to a signal is transmitted to the in-body device 10 in a non-contact manner (for example, a coil link). The transmitter 206 is fixed near the position of the receiver 151 (in the present embodiment, the power feeding unit 150: see FIG. 2) implanted in the body.

In the present embodiment, the battery 203 is provided in the extracorporeal device 20 as a power source of the visual reproduction assisting device. Electric power to each unit is supplied from the battery 203. Electric power is transmitted from the transmission unit 206 to the in-vivo device 10 in a contactless manner. For example, power is transmitted to the in-body device 10 with the control signal superimposed. Further, it may be transmitted to the in-vivo device 10 as a power signal different from the control signal in a non-contact manner. In the present embodiment, power transmission from the extracorporeal device 20 to the intracorporeal device 10 is continuously executed.
<Schematic configuration of internal device>

As shown in FIG. 2, the in-vivo device 10 includes at least the electrode unit 50, the buffer unit 60, the power feeding unit 150, and the cable 160. The electrode unit 50 includes a plurality of stimulation units 100. The intracorporeal device 10 further includes a return electrode (not shown), which is electrically connected to the stimulation unit 100.

Each stimulation unit 100 that constitutes the electrode unit 50 includes a plurality of electrodes 105 that are implanted in the eye tissue. In the present embodiment, the stimulation unit 100 is installed (implanted) in the vicinity of the retina (an example of the visual nervous system), and outputs a stimulation current from each electrode 105 to the retina (in other words, electrical stimulation is performed). Do). The stimulation current is conducted to the return electrode. Therefore, the stimulation unit 100 and the return electrode are installed so as to sandwich the site (tissue) to be stimulated.

The power consumed by the stimulation unit 100 is supplied by the power supply signal from the power supply unit 150. The power supply signal is transmitted via the cable 160 that electrically connects the buffer unit 60 and the power supply unit 150, and the wiring 170 that electrically connects the stimulation unit 100 and the buffer unit 60. The cable 160 and the wiring 170 are covered with an insulating and biocompatible sheath.

In the present embodiment, as shown in FIG. 2, one electrode unit 50, that is, a plurality of stimulation units 100 are provided for one power supply unit 150. In the example shown in FIG. 2, in order to suppress the number of wirings that connect the stimulation unit 100 and the buffer unit 60 according to the number of the stimulation units 100, wiring is provided between at least a part of the plurality of stimulation units 100. Is shared.

Power is supplied to each stimulation unit 100 included in the electrode unit 50 from the power supply unit 150 via the cable 160, the buffer unit 60, and the wiring 170. In addition, in the present embodiment, as shown in FIG. 3A, a plurality of electrodes 105 are installed on one surface of each stimulation unit 100. A circuit (for example, a demultiplexer) that may become a bottleneck in increasing the number of electrodes is provided in each stimulation unit 100, and as a result, the electrode arrangement density can be increased and the resolution of the image viewed by the patient can be increased. It will be easier.

The electrode unit 50 is provided with a plurality of stimulation units 100, and further, in the device configuration in which the plurality of electrodes 105 are arranged in each stimulation unit 100, a rectification circuit and a demultiplexer are provided in each stimulation unit 100. It is necessary to implement a stimulus circuit with etc. Therefore, as shown in FIG. 3B, a one-chip IC (IC chip 101) having a size similar to that of the stimulation unit 100 is provided in each stimulation unit 100. A rectifying circuit, a stimulating circuit, and the like are mounted on the IC chip 101 (details will be described later). In the stimulation unit 100, the IC chip 101 is installed on the surface opposite to the installation surface of the electrode 105. The IC chip 101 is hermetically sealed by the case 107.

Here, since the wiring 170 for supplying power to the stimulation unit 100 is arranged on the flexible substrate 51, it is conceivable that the insulation performance is deteriorated. In that case, an improper current may flow between the location where the insulation performance is degraded and the stimulation electrode of the stimulation unit. Therefore, a capacitor that blocks direct current should be installed at the power supply input terminal to the stimulation unit 100. Will be needed. Further, in the electrode unit 50, for example, when the total number of electrodes is 100 or more, it is desirable that the diameter of each stimulation unit 100 is suppressed to about 1 mm or less and the diameter of the electrode unit 50 is suppressed to about 20 mm or less. Be done. Therefore, in the stimulation unit 100, it may be impossible to secure a space for mounting a component (for example, a crystal oscillator for generating a reference clock, a capacitor having a relatively large capacity, or the like). If the diameter of the stimulation unit 100 is to be suppressed to about 1 mm or less, it is difficult to mount components other than the IC chip. Therefore, the capacitors usable in the stimulation unit 100 can be mounted in the IC chip in total. A small-capacity capacitor such as 100 pF order is a realistic option. Along with this, the capacitance value of the above-mentioned capacitor that blocks direct current is limited, so that it becomes necessary to employ a higher alternating frequency in the power supply signal.

<Installation position of internal device>
The installation position of the internal device 10 will be described with reference to FIG. The electrode unit 50 is arranged near the fovea centralis as shown in FIG. Specifically, the flexible substrate 51 is inserted from an incision (flap) formed by making a cut in the eye sclera, and the electrode 105 is placed on the choroid. As a result, electrical stimulation can be performed without directly contacting the electrodes with the retina.

On the other hand, the power supply unit 150 is installed at a predetermined position in the living body that can receive signals (data and electric power for electrical stimulation pulse) from the transmission unit 206 provided in the extracorporeal device 20. For example, the receiving unit 151 is embedded under the skin of the patient's temporal region, and the transmitting unit 206 is installed at a position facing the receiving unit 151 through the skin. Since a magnet is attached to the receiving unit 151 like the transmitting unit 206, by positioning the transmitting unit 206 on the implanted receiving unit 151, the transmitting unit 206 and the receiving unit 151 are attracted to each other by magnetic force. The transmitting unit 206 is held on the side of the head.

The cable 160 extends from the receiver 151 embedded in the temporal region under the skin toward the patient's eye along the temporal region, and is inserted into the orbit through the inside of the upper eyelid of the patient. A cable 160 placed in the orbit passes outside the sclera and is connected to the buffer unit 60.
<Details of internal device>

In the present embodiment, the power feeding unit 150 superimposes control information on electric power to generate a power feeding signal, and outputs the power feeding signal to the electrode unit 50 via the buffer unit 60. Thereby, each stimulation unit 100 of the electrode unit 50 is supplied with power based on the power supply signal from the buffer unit 60.
<Structure of power supply unit>

As shown in FIGS. 2 and 5, the power feeding unit 150 according to the present embodiment includes at least the receiving unit 151 and the low frequency drive circuit 152. In the present embodiment, the wiring is shared by the plurality of stimulation units 100, and power is constantly supplied to each unit. That is, the control information acquired based on the power supply is always input to each stimulation unit 100. In this case, for example, each stimulation unit 100 is set so as to process only the command associated with the predetermined identification code for each stimulation unit 100, whereby each stimulation unit 100 is independently controlled. May be done.

The reception unit 151 acquires the power and control information transmitted from the extracorporeal device 20 via the coil link. The power supply unit 150 may have a rectifier circuit (not shown), and the electric power received by the internal device 10 is once converted into DC power.

The low frequency drive circuit 152 generates a low frequency power supply signal of several MHz. This low-frequency power supply signal is a differential signal whose positive and negative waveforms are symmetrical. The low frequency drive circuit 152 of the present embodiment generates a power supply signal of 5 MHz, for example. This low frequency power supply signal is transmitted via the cable 160 and input to the buffer unit 60. The power supply signal generated by the low frequency drive circuit 152 is a modulated wave in which a control signal such as an electrode designation signal for controlling the stimulation operation of the electrode 105 in each stimulation unit 100 is superimposed on the AC voltage. A well-known modulation method (AM modulation, FM modulation, phase modulation, etc.) is used for the modulation for superimposing the control signal on the AC voltage.

Here, in the cable 160, a plurality of conducting wires (wires) made of a biocompatible precious metal, such as platinum, platinum iridium, stainless steel, titanium, etc., is made of an insulating resin having good biocompatibility, such as silicone or parylene. It is formed by bundling together by the tube formed in. In addition, as the conducting wire, a conducting wire for transmitting electric power of the electrical stimulation pulse signal, a conducting wire pair for transmitting an AC voltage, and the like are prepared. The conductors themselves are also coated with a resin having good biocompatibility and insulation such as parylene. Since the power supply signal transmitted to the cable 160 is an AC voltage instead of a DC voltage, electrolysis of body fluid or the like is less likely to occur even when the insulation performance of the cable is reduced.

Further, since the cable 160 is a flexible cable, the parasitic capacitance thereof is as large as several hundred pF (in this embodiment, for example, about 100 pF). As described above, in the stimulation unit 100, it is necessary to adopt a higher AC frequency in the power supply signal, but if a high frequency power supply signal (tens of MHz) is transmitted from the power supply unit 150 via the cable 160, power consumption increases. As a result, power efficiency becomes poor. Therefore, in order to avoid deterioration of power efficiency, the power feeding unit 150 of the present embodiment performs low frequency power feeding (several MHz) up to the buffer unit 60.
<Configuration of buffer unit>

As shown in FIG. 5, the buffer unit 60 of this embodiment has at least a rectifier circuit 61, a comparator 62, a PLL circuit 63, and a high frequency drive circuit 64. Further, the buffer unit 60 is provided with power supply lines 65 and 66 connected to the cable 160 and coupling capacitors 67 and 68. The buffer unit 60 converts a low frequency power supply signal of several MHz into a high frequency power supply signal of several tens of MHz.

The rectifier circuit 61 converts the low frequency power supply signal transmitted via the cable 160 into a DC signal. In the present embodiment, the rectifier circuit 61 is a full-wave rectifier circuit, and converts the power supply signal to DC except for the timing when the low frequency power supply signal switches between the positive phase and the negative phase. The DC power converted by the rectifier circuit 61 is supplied to each circuit included in the buffer unit 60.

The comparator 62 binarizes the difference between the signals from the two power supply lines 65 and 66, generates a positive phase signal and a negative phase signal, and outputs the positive phase signal and the negative phase signal to the PLL circuit 63. The PLL circuit 63 multiplies the frequency of the input signal by n times (n is an integer) and outputs it to the high frequency drive circuit 64.

The high frequency drive circuit 64 generates a high frequency power supply signal of several tens of MHz. The high frequency drive circuit 64 of the present embodiment generates a power supply signal of 50 MHz, for example. This high frequency power supply signal is transmitted via the power supply lines 171, 172 and input to the stimulation unit 100.

In this way, the buffer unit 60 converts the input low frequency power supply signal into a high frequency power supply signal that is an integral multiple. Then, the converted high frequency power supply signal is output to each stimulation unit 100 of the electrode unit 50. The buffer unit 60 of this embodiment converts, for example, a low-frequency power supply signal of 5 MHz into a high-frequency power supply signal of 50 MHz (10 times). The buffer unit 60 can convert the input low-frequency power supply signal into a high-frequency power supply signal obtained by multiplying an integer by a fraction expressed by a ratio of integers and output the high-frequency power supply signal. Therefore, the conversion is not limited to 50/5 times (=10 times) as in the present embodiment, and conversion can be performed at a magnification of 19/2 times, for example.

By providing such a buffer unit 60 between the cable 160 and the electrode unit 50, low-frequency power supply is performed from the power supply unit 150 to the cable 160, and high-frequency power supply is performed from the buffer unit 60 to the electrode unit 50. be able to. Therefore, in the visual reproduction auxiliary device that supplies power via the cable 160, highly efficient power supply can be performed without deteriorating the power efficiency, and a sufficient frame rate can be obtained from the hundred or more electrodes 105 provided in the electrode unit 50. (In this embodiment, for example, 20 Hz) can output the stimulation current.
<Configuration of electrode unit (stimulation unit)>

As shown in FIG. 5, the electrode unit 50 of the present embodiment is composed of a plurality of stimulation units 100 and has 100 or more electrodes 105. In this electrode unit 50, a plurality of stimulating units 100 are arranged at regular intervals on a sheet-shaped flexible substrate 51 made of a material having good biocompatibility such as silicone or parelin. The flexible substrate 51 of the present embodiment has a disk shape having a thickness of about 0.1 mm and a diameter of about φ20 mm. And each stimulation unit 100 in the electrode unit 50 is electrically connected. In addition, in this embodiment, the arrangement interval between the stimulation units 100 in the electrode unit 50 is set to be constant, but the arrangement interval is not limited to this. In the electrode unit 50, the stimulating units 100 may be closely spaced at a certain portion and may be sparse at another portion, and the stimulating units 100 may be disposed at a predetermined distance depending on a location on the eyeball or the like.

An IC chip 101 is installed in each stimulation unit 100 that constitutes the electrode unit 50, and various circuits are mounted on the IC chip 101. As shown in FIG. 5, at least a rectifying circuit 110 and a stimulating circuit 120 are mounted on the IC chip 101. Furthermore, the coupling capacitors 141 and 142 may be mounted on the IC chip 101. The IC chip 101 may be, for example, a CMOS chip.

The two power supply lines 171 and 172 shown in FIG. 5 are connected to the buffer unit 60, and a high frequency power supply signal is transmitted from the buffer unit 60. The high frequency power supply signal is input to the rectifier circuit 110 via the coupling capacitors 141 and 142.

In this way, the stimulation unit 100 and the two power supply lines 171, 172 are connected via the coupling capacitors 141, 142. Even if body fluid infiltrates the wiring 170 or the like and the power supply signal leaks to the living body, the coupling capacitors 141 and 142 can disconnect the circuit in the stimulation unit 100 in terms of direct current, and thus can be separated from the stimulation electrode or the like. It is possible to prevent improper current flow.

The rectifier circuit 110 converts the high frequency power supply signal output from the buffer unit 60 into a DC signal. In the present embodiment, the rectifier circuit 110 is a full-wave rectifier circuit, and converts the power supply signal into DC except at the timing when the high frequency power supply signal switches between the positive phase and the negative phase. In the present embodiment, the rectifier circuit 110 is configured to include a transistor (for example, CMOS transistor) built in the IC chip 101.

Further, the rectifier circuit 110 supplies the converted DC signal to the stimulation circuit 120 as DC power.

The stimulation circuit 120 generates a stimulation current based on the control signal, for example. For example, a bipolar pulse signal may be generated as the stimulation current. The stimulation circuit 120 selects the electrode 105 that outputs the stimulation current based on the control signal. Such a function can be realized by a circuit including a demultiplexer, for example.

In such an electrode unit 50, in each stimulation unit 100, a stimulation current is sequentially output from each electrode 105 provided in the stimulation unit 100 based on a control signal. At this time, since the control signal is transmitted in parallel to each stimulation unit 100, the stimulation current may be output at the same timing in the electrodes 105 provided in different stimulation units 100. By such power supply control, the frame rate can be increased, and the stimulation current can be output from a large number of hundreds or more electrodes 105 of the electrode unit 50 at a sufficient frame rate.

As described above, in the visual regeneration assisting device of this embodiment, since the buffer unit 60 is provided between the cable 160 and the electrode unit 50, low-frequency power feeding from the power feeding unit 150 to the cable 160 is performed. Then, the buffer unit 60 can supply high frequency power to the electrode unit 50. As a result, according to the visual reproduction auxiliary device of the present embodiment, even if the power is supplied via the cable 160, the power efficiency is not deteriorated, and the electrode unit 50 can be supplied with high efficiency. Therefore, the stimulation current can be output at a sufficient frame rate from the hundreds or more of the electrodes 105 provided in the electrode unit 50.

The above-described embodiment is merely an example and does not limit the present disclosure in any way, and it is needless to say that various improvements and modifications can be made without departing from the gist thereof. For example, in the above embodiment, the retinal stimulation type visual reproduction assisting device was illustrated, but the present disclosure can be applied to a retinal stimulation type visual stimulation assisting device such as a brain stimulation type or an optic nerve stimulation type. ..

10 Internal Device 20 External Device 50 Electrode Unit 60 Buffer Unit 63 PLL Circuit 100 Stimulation Unit 105 Electrode 141 Coupling Capacitor 142 Coupling Capacitor 150 Power Supply Unit 160 Cable 170 Wiring

Claims (5)

In the visual regeneration assisting device that regenerates the patient's vision,
A stimulation unit comprising a plurality of electrodes for outputting stimulation pulse signals;
An electrode unit including a plurality of the stimulation units,
A buffer unit for supplying power to the electrode unit,
A wiring that electrically connects the electrode unit and the buffer unit and transmits a power supply signal,
A power supply unit for supplying power to the buffer unit,
A cable that electrically connects the buffer unit and the power feeding unit and transmits a power feeding signal,
The power feeding unit performs low frequency power feeding to the buffer unit,
The visual reproduction assisting device, wherein the buffer unit supplies high frequency power to the electrode unit. The visual reproduction auxiliary device according to claim 1,
The electrode unit includes 100 or more electrodes,
The power supply unit supplies low frequency power of several MHz,
The visual reproduction auxiliary device, wherein the buffer unit supplies high frequency power of several tens of MHz. The visual reproduction auxiliary device according to claim 1 or 2,
The visual regeneration assisting device, wherein the stimulating unit includes a coupling capacitor in an input section. The visual reproduction auxiliary device according to any one of claims 1 to 3,
The visual reproduction auxiliary device, wherein the buffer unit converts the input low-frequency power supply signal into a high-frequency power supply signal that is a fractional multiple expressed by a ratio of integers and outputs the converted high-frequency power supply signal. The visual reproduction auxiliary device according to claim 4,
The visual reproduction assisting device, wherein the buffer unit has a PLL circuit that converts the low frequency power supply signal into the high frequency power supply signal.

Images