Biotic stimulation device

Abstract

To enhance strength of biotic stimulation through application of multiphasic pulses.SOLUTION: A retinal stimulation device comprises an electrode controller that outputs to an electrode (51B) a pulse current in which a positive phase and a negative phase alternately switch. In synchronization with a timing at which the positive phase and the negative phase of the pulse current alternate, the retinal stimulation device switches an electrode to which the pulse current flowing from the electrode (51B) returns, from a return electrode (43) to electrodes (51A, 51C).SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to biostimulators. [Background technology]

[0002] Biostimulation devices that stimulate living organisms using pulsed currents are known. As an example of a biostimulation device, Patent Document 1 describes a visual regeneration assistance device that stimulates the retina of the eye. The visual regeneration assistance device stimulates the retina using a biphasic pulsed current (biphasic pulse). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-212233 Summary of the Invention [Problem to be solved by the invention]

[0004] However, biostimulation devices that use monophasic pulse currents (monophasic pulses) can cause irreversible changes such as dissolution of electrode materials. Therefore, implant-type biostimulation devices such as the visual regeneration assist device of Patent Document 1 use biphasic pulses, which are less likely to cause irreversible changes.

[0005] However, it is known that biphasic pulses are less effective at stimulating the living body than monophasic pulses.

[0006] One aspect of the present disclosure is directed to increasing the intensity of biostimulation using multiphasic pulses. [Means for solving the problem]

[0007] In order to solve the above problems, a biostimulation device according to one embodiment of the present disclosure is a biostimulation device that stimulates a living organism by passing a pulse current, the biostimulation device comprising: a stimulation electrode; a first return electrode to which the pulse current flowing from the stimulation electrode returns; a second return electrode to which the pulse current flowing from the stimulation electrode returns and which is located spatially separated from the first return electrode; and an output unit that outputs a pulse current whose positive and negative phases alternate to the stimulation electrode, and is configured to switch the electrode to which the pulse current flowing from the stimulation electrode returns from the first return electrode to the second return electrode in synchronization with the timing at which the positive and negative phases of the pulse current alternate.

[0008] In the biostimulation device according to the second aspect of the present disclosure, the first return electrode may be provided sufficiently far from the stimulation electrode, and the second return electrode may be provided in the vicinity of the stimulation electrode.

[0009] In a biostimulation device according to aspect 3 of the present disclosure, the stimulation electrodes may include a first stimulation electrode and a second stimulation electrode, and the output unit may cause the second stimulation electrode to output the negative phase of the pulse current while causing the first stimulation electrode to output the positive phase of the pulse current.

[0010] The biostimulation device according to the fourth aspect of the present disclosure may be a device that stimulates the retina of a human eye to reproduce vision. [Effects of the Invention]

[0011] According to one aspect of the present disclosure, the intensity of biostimulation can be increased using multiphasic pulses. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing an outline of a retinal stimulation device according to a first embodiment of the present disclosure. [Figure 2] FIG. 1 is a diagram showing the configuration of an intracorporeal device. [Figure 3] FIG. 2 is a schematic diagram showing how a stimulation unit is attached to a patient's eye. [Figure 4] 4A to 4C are diagrams illustrating control of a stimulation unit in the first embodiment. [Figure 5] 4A to 4C are diagrams illustrating control of a stimulation unit in the first embodiment. [Figure 6] 10 is a graph showing a simulation result. [Figure 7] 10A and 10B are diagrams illustrating control of a stimulation unit in a modified example of the first embodiment. [Figure 8] 10A and 10B are diagrams illustrating control of a stimulation unit in a modified example of the first embodiment. [Figure 9] 10 is a graph for explaining stimulation of a living organism as a stimulation target in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Embodiment 1] (Retinal stimulation device 1 overview) An embodiment of the present disclosure will be described in detail below. In the following description, a retinal stimulation device 1, which is an example of a biostimulation device, will be described. First, a schematic configuration of the retinal stimulation device 1 will be described with reference to Fig. 1. Fig. 1 is a diagram showing an outline of the retinal stimulation device 1.

[0014] The retinal stimulation device 1 stimulates the cells that make up the retina by applying electrical stimulation to the retina. By stimulating the cells that make up the retina, the retinal stimulation device 1 promotes the restoration of vision that has been lost in a patient. The retinal stimulation device 1 of this embodiment is a device that employs the STS method (Suprachoroidal transretinal stimulation). The retinal stimulation device 1 includes an extracorporeal device 10 and an intracorporeal device 20.

[0015] (Extracorporeal device 10) As shown in Fig. 1, the extracorporeal device 10 is worn outside the patient's body. The extracorporeal device 10 acquires external world information and transmits information relating to the acquired external world information to the intracorporeal device 20. The extracorporeal device 10 includes a wearable device 11, an imaging device 12, an extracorporeal control device 13, and a transmission unit 14.

[0016] The wearing device 11 has a spectacle shape and is worn in front of the patient's eyes as shown in Fig. 1. In this embodiment, the photographing device 12 is attached to the front of the wearing device 11. The photographing device 12 may also be attached to the temple portion of the wearing device 11.

[0017] The image capturing device 12 captures an image of the external world in front of the patient (for example, an image of a subject). The image captured by the image capturing device 12 is provided to the extracorporeal control device 13. The image capturing device 12 may be, for example, a CCD camera.

[0018] The extracorporeal control device 13 controls each part of the extracorporeal device 10. The extracorporeal control device 13 has a control unit 13a and a battery 13b. The control unit 13a is a computer including a processor that executes calculation processing, such as a CPU (Central Processing Unit), and memories, such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The control unit 13a executes various programs stored in the memory to perform various controls and calculations.

[0019] Specifically, the control unit 13a acquires an external image from the photographing device 12. The control unit 13a performs image processing on the acquired external image and generates a control signal to be transmitted to the intracorporeal device 20 as image information from the photographing device 12. The control unit 13a wirelessly transmits the generated control signal to the intracorporeal device 20 via the transmission unit 14.

[0020] The battery 13b supplies power to each unit (extracorporeal device 10 and intracorporeal device 20) included in the retinal stimulation device 1. The control unit 13a converts DC power from the battery 13b into AC power. The control unit 13a wirelessly transmits the converted AC power to the intracorporeal device 20 via the transmission unit 14. Note that power may also be supplied from the battery 13b to the intracorporeal device 20 via a wired connection.

[0021] The transmitter 14 communicates wirelessly with the intracorporeal device 20. Specifically, the transmitter 14 communicates signals by electromagnetic waves with the receiver 30 of the intracorporeal device 20. The transmitter 14 transmits a control signal generated by the controller 13a to the intracorporeal device 20. The transmitter 14 also transmits power supplied from the battery 13b to the intracorporeal device 20.

[0022] (Internal apparatus 20) The intracorporeal device 20 will be described with reference to FIG. 2. FIG. 2 is a diagram showing the configuration of the intracorporeal device 20. The intracorporeal device 20 is implanted in the patient's body. The intracorporeal device 20 stimulates cells constituting the retina by outputting a pulse current based on a signal transmitted from the extracorporeal device 10. As shown in FIG. 2, the intracorporeal device 20 includes a receiving unit 30 and a stimulation unit 40. The receiving unit 30 receives electromagnetic waves transmitted from the transmitting unit 14 of the extracorporeal device 10. The receiving unit 30 provides the signal received from the transmitting unit 14 to an intracorporeal control device 41 of the stimulation unit 40.

[0023] The stimulation unit 40 is a unit for electrically stimulating the retina and includes an internal control device 41, a return electrode 43, an electrode unit 50, and an electrode control unit 60.

[0024] The internal control device 41 controls each part of the internal device 20. The internal control device 41 is a computer equipped with a processor that executes arithmetic processing, such as a CPU (Central Processing Unit), and memories, such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The internal control device 41 performs various controls and calculations by executing various programs stored in the memory.

[0025] The internal control device 41 supplies the power acquired from the receiving unit 30 to each component of the internal device 20. The internal control device 41 generates a control signal to be transmitted to the stimulation unit 40 based on the control signal acquired from the receiving unit 30. The internal control device 41 includes a current source 41a that generates a pulse current based on the power acquired from the receiving unit 30. The current source 41a generates a biphasic pulse current (hereinafter referred to as a biphasic pulse) in which a positive phase and a negative phase alternate. The internal control device 41 also includes a switching element that switches the electrical connection between the return electrode 43 and each electrode 51 of the electrode unit 50.

[0026] The return electrode 43 is electrically connected to the electrode control unit 60 via the conductor 42. The return electrode 43 is an example of a first return electrode. The return electrode 43 is provided sufficiently far from the electrode 51 of the electrode unit 50. The return electrode 43 is placed, for example, so as to sandwich the retina between the electrode 51 and the return electrode 43. The return electrode 43 may be placed inside the eyeball E or outside the eyeball E. The return electrode 43 only needs to be placed so as to be located sufficiently far from the electrode 51. A voltage is applied to the return electrode 43 to guide the pulse current output from the electrode 51.

[0027] The electrode unit 50 is electrically connected to the internal control device 41 via a cable 45. The electrode unit 50 includes a plurality of electrodes 51 and a substrate 52. The electrode unit 50 is a multi-electrode array in which a plurality of electrodes 51 are formed on the substrate 52. The electrodes 51 are an example of a stimulation electrode. The plurality of electrodes 51 are arranged at equal intervals in a grid pattern on the substrate 52, but this configuration is not limited to this. The number of electrodes 51 may be determined depending on the resolution required to reproduce vision. A plurality of lead wires 52a are provided inside the substrate 52. Each electrode 51 is electrically connected to the electrode control unit 60 via the lead wires 52a. At least a portion of the electrode unit 50 is placed between (or within) layers of layered ocular tissue.

[0028] The electrode control unit 60 performs various controls on the electrode unit 50 during retinal stimulation based on a control signal transmitted from the internal control device 41. Specifically, based on a control signal from the internal control device 41, the electrode control unit 60 causes a specific electrode 51 of the multiple electrodes 51 to function as a stimulation electrode that applies stimulation to the retina to be stimulated. That is, during retinal stimulation, the electrode control unit 60 performs control to switch the electrical connection relationship so that a biphasic pulse flows through the specific electrode 51. The electrode control unit 60 may be provided with a switching element (not shown) that selects a specific electrode 51 from the multiple electrodes 51.

[0029] The electrode control unit 60 also causes the biphasic pulse generated by the current source 41a to be output to a specific electrode 51. The electrode control unit 60 is an example of an output unit. More specifically, the electrode control unit 60 causes a specific electrode 51 of the multiple electrodes 51 to output a biphasic pulse based on image information from the extracorporeal device 10.

[0030] The electrode control unit 60 includes, for example, an electronic circuit 61. The electronic circuit 61 is a circuit having a demultiplexer function. The electronic circuit 61 selects one of the electrodes 51 based on a control signal received from the internal control device 41. The electronic circuit 61 operates using power supplied from the internal control device 41.

[0031] (Attachment of the stimulation unit 40 to the patient's eye) An example of how the stimulation unit 40 is attached to a patient's eye will be described with reference to FIG. 3. FIG. 3 is a schematic diagram showing how the stimulation unit 40 is attached to a patient's eye E. As shown in FIG. 3, the stimulation unit 40 is placed in the patient's eye E. In the example shown in FIG. 3, the return electrode 43 is placed inside (vitreous body of) the patient's eye E. The electrode unit 50 is placed between the sclera E3 and the choroid E2 by inserting the electrode unit 50 into an opening formed by incising a part of the sclera E3 of the patient's eye E. That is, the substrate 52 of the electrode unit 50 is placed along the retina E1. The retina E1 is located between the return electrode 43 and each electrode 51. The cells constituting the retina E1 are stimulated by biphasic pulses output from the stimulation unit 40.

[0032] (Regarding control of stimulation unit 40 during retinal stimulation) Next, control of the stimulation unit 40 during retinal stimulation will be described with reference to Fig. 4 and Fig. 5. Fig. 4 and Fig. 5 are diagrams for explaining control of the stimulation unit 40. In the following description, it is assumed that a current flowing due to the output of a positive-phase biphasic pulse (hereinafter referred to as a positive-phase current) is a current discharged from the electrode 51B, and a current flowing due to the output of a negative-phase biphasic pulse (hereinafter referred to as a negative-phase current) is a current absorbed by the electrode 51B. Furthermore, it is assumed that the electrode 51B functions as a stimulation electrode and outputs a so-called anodic-first (positive-phase current flows first) biphasic pulse.

[0033] First, the control when a positive-phase current flows will be described. As shown in Fig. 4, when a positive-phase current flows, the internal control device 41 controls the return electrode 43 and each electrode 51 so that the positive-phase current flowing from electrode 51B returns to the return electrode 43. The electrode control unit 60 controls the switching element of the electrode control unit 60 based on a control signal from the internal control device 41 so that a positive-phase current flows to electrode 51B. The internal control device 41 controls the switching element of the internal control device 41 so that a positive-phase current flows between the return electrode 43 and electrode 51B. At this time, the electrode control unit 60 controls the switching element of the electrode control unit 60 so that a positive-phase current does not flow to electrodes 51A and 51C.

[0034] The electrode control unit 60 applies the current generated by the internal control device 41 between the electrode 51B and the return electrode 43. The internal control device 41 generates a voltage to be applied to the electrode 51B and the return electrode 43 so that the positive-phase current flowing between the electrode 51B and the return electrode 43 is constant. A potential difference generated between the electrode 51B and the return electrode 43 causes a positive-phase current to flow between the electrode 51B and the return electrode 43.

[0035] Next, control when a negative-phase current flows will be described. As shown in FIG. 5, when a negative-phase current flows, the internal control device 41 controls the return electrode 43 and each electrode 51 so that the negative-phase current flowing from electrode 51B returns to electrode 51A and electrode 51C. That is, the internal control device 41 switches the electrode to which the negative-phase current flowing from electrode 51B returns from the return electrode 43 to each electrode 51A, 51C in synchronization with the timing when the biphasic pulse switches from a positive phase to a negative phase. Electrodes 51A and 51C are electrodes 51 provided near electrode 51B, and function as return electrodes when a negative-phase current flows through electrode 51B. Electrodes 51A and 51C are examples of second return electrodes. The timing when the positive and negative phases of the biphasic pulse switch may be zero phase, when the phases of the positive and negative phases are zero.

[0036] Based on a control signal from the internal control device 41, the electrode control unit 60 controls the switching element of the electrode control unit 60 so that the negative phase current flowing from the electrode 51B returns to the electrodes 51A and 51C. The internal control device 41 controls the switching element of the internal control device 41 so that the negative phase current does not flow between the return electrode 43 and each of the electrodes 51A, 51B, and 51C. In other words, the internal control device 41 switches so that the return electrode 43 and each of the electrodes 51A, 51B, and 51C are not electrically connected to each other.

[0037] The electrode control unit 60 applies the voltage generated by the internal control device 41 to each of the electrodes 51A, 51B, and 51C. The internal control device 41 generates the voltage to be applied to each of the electrodes 51A, 51B, and 51C so that the sum of the negative-phase currents flowing between the electrodes 51B and 51A and between the electrodes 51B and 51C is constant. A potential difference between the electrodes 51B and 51A causes a negative-phase current to flow between the electrodes 51B and 51A, and a potential difference between the electrodes 51B and 51C causes a negative-phase current to flow between the electrodes 51B and 51C. When negative-phase currents are caused to flow between the electrodes 51B and 51A and between the electrodes 51B and 51C, the electrodes 51A and 51C may be electrically connected and short-circuited to maintain a constant sum of the negative-phase currents flowing through the electrodes. The amount of charge of the negative-phase current flowing through electrode 51B is the same as the amount of charge of the positive-phase current flowing through electrode 51B described above.

[0038] The simulation results when the stimulation unit 40 is controlled as described above will be described with reference to Fig. 6. Fig. 6 is a graph showing the simulation results. In the graph of Fig. 6, the solid line indicates the vertical component of the electric field, and the dashed line indicates the horizontal component of the electric field. Here, the vertical direction of the electric field means the direction perpendicular to the substrate 52, and the horizontal direction of the electric field means the direction parallel to the substrate 52.

[0039] As shown in Figure 6, the simulation results show that there is a significant asymmetry in the current waveforms inside the target organism when a positive-phase current is passed and when a negative-phase current is passed. Specifically, the amplitude of the vertical component of waveform S1 when a positive-phase current is passed is larger than the amplitude of the vertical component of waveform S2 when a negative-phase current is passed. These simulation results show that it is possible to apply stimulation to the organism that is similar to biostimulation using monophasic pulses, which have good stimulation efficiency, while using biphasic pulses, which are less likely to cause irreversible changes to electrodes, etc.

[0040] According to the retinal stimulation device 1 described above, a biphasic pulse including at least one pair of currents of opposite polarities is output to electrode 51B. That is, while using the biphasic pulse, the electrode to which the pulse current flowing from electrode 51B returns can be switched from return electrode 43 to electrodes 51A and 51C, which function as return electrodes, in synchronization with the timing at which the positive and negative phases of the biphasic pulse are switched. This allows the current distribution in the living body after switching to electrodes 51A and 51C to be more localized than before the switching. Therefore, the amplitude of the current flowing between electrode 51B and return electrode 43 is relatively increased, and the intensity of retinal stimulation can be improved using the biphasic pulse.

[0041] Each of the electrodes 51A and 51C, functioning as a second return electrode, is located near the stimulation electrode 51B. For example, when a positive-phase current flows through the return electrode 43, switching from the return electrode 43 to each of the electrodes 51A and 51C allows a negative-phase current to be drawn from each of the electrodes 51A and 51C located near the electrode 51B. Therefore, when a current flows between the electrode 51B and the return electrode 43, the current is distributed isotropically within the living body. However, when a current flows between the electrode 51B and each of the electrodes 51A and 51C, the range of the current distribution within the living body can be localized. This increases the amplitude of the pulse current flowing between the electrode 51B and the return electrode 43, improving the intensity of retinal stimulation.

[0042] From the viewpoint of efficient retinal stimulation, it is preferable that an anodic-first biphasic pulse is output from the specific electrode 51, but this is not limitative. A so-called cathodic-first (negative phase current flows first) biphasic pulse may also be output from the specific electrode 51.

[0043] 4 and 5, electrodes 51A and 51C functioning as second return electrodes are arranged adjacent to electrode 51B, but this is not the only possible configuration. Another electrode 51 may be arranged between electrode 51B and each of electrodes 51A and 51C. A second return electrode may also be provided separately in electrode unit 50.

[0044] Furthermore, after the biphasic pulse is output from the electrode 51B, the internal control device 41 may electrically connect and short-circuit the return electrode 43 and each of the electrodes 51A, 51C that functioned as the return electrode. This adjusts the charge balance between the return electrode 43 and each of the electrodes 51A, 51B, 51C. That is, the total current flowing in and out of all the electrodes becomes zero.

[0045] (Variation) A modified example of the first embodiment of the present disclosure will be described below with reference to FIGS. 7 and 8. FIGS. 7 and 8 are diagrams illustrating the control of the stimulation unit 40 in this modified example. Note that in this modified example, the control of the stimulation unit 40 during retinal stimulation differs from that in the first embodiment. In this modified example, the electrode 51B outputs an anodically-first biphasic pulse, and the electrode 51D outputs a cathodic-first biphasic pulse. That is, while the electrode 51B outputs a positive-phase biphasic pulse, the electrode 51D outputs a negative-phase biphasic pulse. The electrode 51B is an example of a first stimulating electrode, and the electrode 51D is an example of a second stimulating electrode.

[0046] In the following description, the control of the stimulation unit 40 when the electrode 51B outputs an anodic-first biphasic pulse is the same as the control of the stimulation unit 40 in the above-described embodiment 1. Therefore, in this modification, only the points different from the control in embodiment 1 will be described.

[0047] First, as shown in Fig. 7, the internal control device 41 controls the return electrode 43 and each electrode 51 so that a positive-phase current flows through electrode 51B and a negative-phase current flows through electrode 51D. The internal control device 41 controls the return electrode 43 and each electrode 51 so that the negative-phase current flowing from electrode 51D returns to electrodes 51C and 51E. Electrodes 51C and 51E are electrodes 51 provided near electrode 51D, and function as return electrodes when a negative-phase current flows through electrode 51D. Electrodes 51C and 51E are examples of second return electrodes.

[0048] The electrode control unit 60 controls the switching elements of the electrode control unit 60 so that a negative-phase current flows through each of the electrodes 51C, 51D, and 51E based on a control signal from the internal control device 41. The internal control device 41 controls the switching elements of the internal control device 41 so that no current flows between the return electrode 43 and each of the electrodes 51A, 51C, 51D, and 51E. In other words, the internal control device 41 switches so that the return electrode 43 and each of the electrodes 51A, 51C, 51D, and 51E are not electrically connected to each other.

[0049] The electrode control unit 60 applies the voltage generated by the internal control device 41 to each of the electrodes 51C, 51D, and 51E. The internal control device 41 generates the voltage to be applied to each of the electrodes 51C, 51D, and 51E so that the sum of the negative-phase currents flowing between the electrodes 51D and 51C and between the electrodes 51D and 51E is constant. The amount of charge of the negative-phase current flowing through the electrode 51D is the same as the amount of charge of the positive-phase current flowing through the electrode 51B.

[0050] 8, the internal control device 41 controls the return electrode 43 and each electrode 51 so that a negative-phase current flows through the electrode 51B and a positive-phase current flows through the electrode 51D. The internal control device 41 controls the return electrode 43 and each electrode 51 so that the positive-phase current flowing from the electrode 51D returns to the return electrode 43. That is, the internal control device 41 switches the electrode to which the positive-phase current flowing from the electrode 51D returns from each of the electrodes 51C and 51D to the return electrode 43 in synchronization with the timing when the biphasic pulse switches from a negative phase to a positive phase.

[0051] Based on a control signal from the internal control device 41, the electrode control unit 60 controls the switching element of the electrode control unit 60 so that a positive-phase current flows through electrode 51D. The internal control device 41 controls the switching element of the internal control device 41 so that a positive-phase current flows between the return electrode 43 and electrode 51D. That is, the internal control device 41 switches the return electrode 43 and electrode 51D to a state in which they are electrically connected. At this time, the electrode control unit 60 controls the switching element of the electrode control unit 60 so that a positive-phase current does not flow through electrodes 51C and 51E.

[0052] The electrode control unit 60 applies the voltage generated by the internal control device 41 to each of the electrode 51D and the return electrode 43. The internal control device 41 generates the voltage to be applied to the electrode 51D and the return electrode 43 so that the positive-phase current flowing between the electrode 51D and the return electrode 43 is constant. The charge amount of the positive-phase current flowing through the electrode 51D is the same as the charge amount of the negative-phase current flowing through the electrode 51B.

[0053] Stimulation of a living organism as a stimulation target according to this modification will be described with reference to Fig. 9. Fig. 9 is a graph for explaining stimulation of a living organism as a stimulation target according to this modification. In the graph of Fig. 9, the solid line indicates the vertical component of the electric field, and the dashed line indicates the horizontal component of the electric field.

[0054] 9, when the stimulation unit 40 is controlled as in this modification, it is considered that the electrode 51B stimulates the living organism as a stimulation target with a waveform as shown in graph 100, and the electrode 51D stimulates the living organism as a stimulation target with a waveform as shown in graph 101. That is, it is considered that the vertical component of waveform S3 when a negative-phase current is passed through electrode 51D is offset by the vertical component of waveform S1 when a positive-phase current is passed through electrode 51B. It is also considered that the vertical component of waveform S2 when a negative-phase current is passed through electrode 51B is offset by the vertical component of waveform S4 when a positive-phase current is passed through electrode 51D. As a result, it is possible to apply stimulation to the living organism that is similar to biostimulation by monophasic pulses, which have good stimulation efficiency, while using biphasic pulses that are less likely to cause irreversible changes to electrodes, etc.

[0055] The biphasic pulse from electrode 51B has an anodic-first waveform, while the biphasic pulse from electrode 51D has a cathodic-first waveform, allowing for biphasic pulses to be delivered. This increases the current amplitude of the pulse current flowing between electrode 51B and return electrode 43 and the pulse current flowing between electrode 51D and return electrode 43. The current actually flowing within the body is the sum of the currents flowing from electrodes 51B and 51D. That is, a positive-phase current of waveform S1+waveform S3 flows in the first phase, and a positive-phase current of waveform S2+waveform S4 flows in the second phase, resulting in a current similar to that of a monophasic pulse flowing within the body as a whole. This further improves the intensity of biostimulation. Therefore, the intensity of retinal stimulation can be further improved.

[0056] Other Embodiments In the above-described embodiment, the retinal stimulation device 1 has been described as an example of a biostimulation device, but the biostimulation device is not limited to this. The biostimulation device of the present disclosure can be applied to implant-type biostimulation devices that are embedded in a living body, such as cardiac pacemakers, cochlear implants, and stimulation devices that stimulate the vagus nerve. Such a biostimulation device includes a stimulation electrode, a first return electrode provided sufficiently far from the stimulation electrode, and a second return electrode provided spatially separated from the first return electrode and near the stimulation electrode.

[0057] In the above-described embodiment, the biostimulation device uses biphasic pulses, but the invention is not limited to this configuration. The biostimulation device may use, for example, a three-phase pulse current, known as a triphasic pulse, or a multiphasic pulse, known as a multiphasic pulse.

[0058] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. [Explanation of symbols]

[0059] 1 Retinal stimulator 10 Extracorporeal devices 20 Internal apparatus 40 stimulation units 41 Internal Control Device 43 Return electrode 50 electrode units 51 electrode 60 Electrode control unit E1 retina

Claims

1. A biostimulation device that stimulates a living organism by passing a pulse current, the biostimulation device, A stimulation electrode; a first return electrode to which the pulse current flowing from the stimulation electrode returns; a second return electrode to which the pulse current flowing from the stimulation electrode is returned, the second return electrode being provided at a position spatially separated from the first return electrode; an output unit that outputs a pulse current whose positive and negative phases alternate to the stimulation electrode; Equipped with In synchronization with the timing at which the positive phase and the negative phase of the pulse current are switched, an electrode to which the pulse current flowing from the stimulation electrode returns is switched from the first return electrode to the second return electrode. A biostimulation device characterized by:

2. The first return electrode is provided sufficiently far from the stimulation electrode, and the second return electrode is provided in the vicinity of the stimulation electrode. The biostimulation device according to claim 1 .

3. the stimulation electrodes include a first stimulation electrode and a second stimulation electrode; The output unit While the positive phase pulse current is being output to the first stimulation electrode, the negative phase pulse current is being output to the second stimulation electrode. The biostimulation device according to claim 1 .

4. The biostimulation device is a device that stimulates the retina of a human eye to restore vision.

4. The biostimulation device according to claim 1, wherein the first and second electrodes are electrically connected to the first and second electrodes.

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