KR101687108B1 - Charge balancing technique for neural micro stimulator using charge detectors - Google Patents

Abstract

For the safety of the biomedical stimulator, a charge balance circuit and a maintenance method using charge amount detection are suggested. In order to secure the safety of the bio-stimulator proposed in the present invention, the charge balance circuit using the charge amount detection is a charge detector that receives only the Cascodic waveform and operates fluidly according to the inputted Cascodic waveform and performs the charge detection operation and the charge balance operation. And a biomedical stimulator for simultaneously performing the charge balancing operation and the charge discharging using the charge detecting operation and the charge balancing operation of the charge detector.

Description

[0002] Charge balancing techniques using neural micro stimulator using charge detectors for the safety of a biomedical stimulator [

The present invention relates to a biomedical stimulator implementation technique that ensures balance of charge without minimizing the stimulation waveform and minimizes the function of the controller.

The biomedical stimulator transmits visual information to the optic nerve according to the purpose of the biological stimulator through current or voltage stimulation of the vital nerve or stabilizes the vestibulopathy and motor nerve by brain stimulation for a patient with Parkinson's disease. Recently, researches have been conducted to transmit electricity by radio and transmit data required for stimulation wirelessly and to use it semi-permanently in vivo. It is desirable to design the biomedical stimulator using a safer current stimulator. It must be small in size because it is inserted in the living body, and most importantly, it should be designed so that charges do not damage the cells due to stimulation in the living body.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram of an overall system of a biomedical stimulator according to the prior art.

1, a biomedical stimulator according to the related art may include a power amplifier, a data modulator, an external controller, a data demodulator, a voltage rectifier, a power recovery circuit, an MCU or a controller, and a stimulator. Like a whole system of a biomedical stimulator, a wireless biomedical stimulator wirelessly transmits power and data by using a mutual inductance of the inductor, converts the AC voltage into a DC voltage by using a power recovery circuit, and supplies power to the stimulator and the controller. The overall system of the biomedical stimulator shown in Fig. 1 and the general waveform required for stimulation are shown in Fig.

FIG. 2 shows the general stimulation waveforms required for the stimulation of the whole system of the biomedical instrument according to the prior art.

Referring to FIG. 2, waveforms used for stimulation can be divided into a cathodic waveform and an anodic waveform. The cathodic waveform serves to stimulate the nerve and the anodic waveform serves to discharge the charge accumulated in the cell due to the cathodic waveform. At this time, the cells in the living body are not damaged when the charge due to the cathodic waveform and the charge due to the anodic waveform are the same. Therefore, a charge balancing technique is required to compensate the charge when the charge of the cathodic waveform and the anodic waveform are not the same. As shown in Fig. 2, the charge balance of a general magnetic pole waveform is achieved by continuously providing a small pulse train. In FIG. 2, negative current and positive current can be seen from the current stimulation waveform. Negative currents define minus and plus in the direction of current between two channels in multiple channels of the stimulator. The general structure of the current stimulator is shown in Fig.

FIG. 3 shows the structure of a conventional current stimulator according to the prior art.

FIG. 3 (a) shows a cathodic current direction of a conventional current stimulator according to the prior art, and FIG. 3 (b) shows an anodic current direction of a conventional current stimulator according to the prior art.

The conventional current stimulator according to the related art controls the direction of the current by turning on / off the switch according to the signal of the controller and controls the magnitude of the current according to the input to the DAC.

 In recent papers, MCU is used for control of most stimulators, so it can be designed using complex and various functions, but MCU has a disadvantage that it takes up a lot of volume. The proposed stimulation process is to input the size and time of the cathodic waveform and calculate the size and time of the anodic waveform through the MCU and the size of the cathodic waveform, The size and time of the anodic waveform are input to control the stimulator. Then, after one stimulation and emission, make sure that no charge is accumulated through the charge balance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a bio-stimulator system in which an anodic and a charge balance are simultaneously performed to minimize a function for integrating a controller on a chip, ) Circuit and method for accurately discharging the charge so that even if a waveform enters, it does not damage the living body.

According to an aspect of the present invention, there is provided a charge balance circuit using the charge amount detection for the safety of a bio-stimulator proposed in the present invention. The charge balance circuit receives only a cascode waveform and operates fluidly according to the input cascode waveform, And a biomedical stimulator for simultaneously performing the charge balancing operation and the charge discharging using the charge detecting operation and the charge balancing operation of the charge detector.

Wherein the charge detector comprises a plurality of hysteresis comparators having subdivided accumulated charge amounts according to a predetermined criterion and having windows of different sizes according to the subdivided predefined criterion wherein the plurality of hysteretic comparators have a positive charge quantity and a negative charge quantity The output is initialized to '0' or '1'.

Wherein the charge detector adjusts the charge release time of the biomedical stimulator according to the output of the plurality of hysteresis comparators having the windows of different sizes and performs charge detection again after the charge release time to accumulate the amount of charge to a predetermined criterion Only when applicable, the next cascaded waveform is input.

According to another aspect of the present invention, there is provided a method for maintaining a charge balance using detection of a charge amount for safety of a biomedical stimulator proposed in the present invention, wherein only a Cathodic waveform is received through a charge detector, Performing a charge detection operation and a charge balancing operation, concurrently performing the charge balancing operation and the charge discharging through the biostimulator using the charge detecting operation and the charge balancing operation of the charge detector.

Wherein the step of performing the charge detection operation and the charge balance operation while receiving only the Cathodic waveform and operating fluidly according to the input Cathodic wave form comprises subdividing the accumulated charge amount according to a predetermined criterion, Initializing the output of the plurality of hysteresis comparators having windows of different sizes to '0' or '1' to detect positive and negative charge amounts, using a plurality of hysteretic comparators having windows of different sizes Generating an output for controlling the charge discharging time of the biomedical stimulator, adjusting the charge discharging time of the biomedical stimulator according to the output of the plurality of hysteresis comparators having windows of different sizes, , After the charge release time, And a step of receiving the next cascoded waveform only when the accumulated amount of electric charge corresponds to a predetermined criterion.

According to the embodiments of the present invention, in order to minimize the function of integrating the controller into the chip without using the MCU in the existing bio-stimulator system, anodic and charge balancing are simultaneously performed to form a cathodic ) Even if a waveform comes in, the charge can be released accurately so as not to damage the living body.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram of an overall system of a biomedical stimulator according to the prior art.
FIG. 2 shows the general stimulation waveforms required for the stimulation of the whole system of the biomedical instrument according to the prior art.
FIG. 3 shows the structure of a conventional current stimulator according to the prior art.
Figure 4 is a diagram illustrating the operation of a conventional charge detector.
5 is a diagram illustrating the operation of a charge detector in accordance with an embodiment of the present invention.
6 is a diagram illustrating a charge detector circuit in accordance with an embodiment of the present invention.
FIG. 7 is a flowchart illustrating a charge balance maintaining method using charge amount detection according to an embodiment of the present invention. Referring to FIG.
FIG. 8 is a diagram illustrating a simulation result of an operation of a stimulator according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 4 is a diagram illustrating the operation of a conventional charge detector.

The charge detector according to the prior art can only know if the positive or negative charge exceeds the reference in accordance with the designer's criteria. The criterion specifies the amount of accumulated charge that the designer does not damage the cell, typically 50mV.

Assuming that the designer's criterion is 50 mV as shown in FIG. 4, the existing charge detector detects whether the accumulated charge is more than 50 mV. Charge detection is performed after the input of cathodic and anodic waveforms. Accordingly, if the absolute value is more than 50 mV, a small pulse flows as a current to the channel of the stimulator (Small pulse insertion). Repeat the detection and small pulse input until you enter the safe zone. This process is called charge balancing.

In addition, the proposed charge detection and charge balance are based on the assumption that cathodic waveforms are not input, or cathodic and anodic waveforms when anodic waveforms are not input correctly. If the charge difference is large, charge detection takes a long time. If a cathodic waveform is not input, an unnecessary anodic waveform is input even though the charge is not accumulated, and the charge balancing operation is performed again. There is a risk that these unnecessary movements can damage cells.

5 is a diagram illustrating the operation of a charge detector in accordance with an embodiment of the present invention.

The charge balance circuit using the proposed charge amount detection circuit includes a charge detector that receives only a Cascodic waveform and performs a charge detection operation and a charge balance operation while being fluidically operated according to the input Cascodic waveform, And a biomedical stimulator for simultaneously performing the charge balancing operation and the charge discharging using the charge balancing operation.

The charge detector includes a plurality of hysteretic comparators having subdivided accumulated charge amounts according to predetermined criteria and windows of different sizes according to the subdivided predetermined criteria. The plurality of hysteresis comparators are initialized to '0' or '1' in order to detect the amount of positive charge and the amount of negative charge.

The charge detector also adjusts the charge release time of the biomedical stimulator according to the output of the plurality of hysteresis comparators having the different sized windows. Then, the charge detection is performed again after the charge release time, and the next Cathodic waveform is received only when the accumulated amount of charge corresponds to a predetermined criterion.

The proposed biomedical stimulator inputs both cathodic waveforms and anodic waveforms and inputs only cathodic waveforms, discharges the charges using charge detection and charge balancing, Balance. This means that the controller does not need data about the anodic waveform or need to be calculated in the controller according to the cathodic waveform. In order to efficiently perform the above operation, the operation of the proposed charge detector that can operate in a fluid manner according to the situation is shown in FIG. The detection operation of the charge detector is further subdivided to adjust the time of the current that can discharge the charge in accordance with the charge accumulated in the charge balancing operation.

For example, when an electric charge of 50 mV or less is accumulated as shown in FIG. 5, the following stimulation waveform is applied as a safe zone. When a charge of 50 ~ 100 mV is accumulated, a small pulse is inserted. When a charge of 100 ~ 200 mV is accumulated, a large pulse is inserted. When a charge of 200 ~ 400 mV is accumulated, Very wide pulse insertion allows efficient charge discharge operation depending on the situation. Negative charge is detected more than 50mV or less than 50mV.

Thus, a positive charge is accumulated due to the cathodic waveform, and charge balancing is achieved by the charge discharging operation. Since the charge discharging operation is designed so as not to be large even when the negative charge amount is accumulated at the time of charge discharge, the negative charge amount detects only 50 mV or more.

6 is a diagram illustrating a charge detector circuit in accordance with an embodiment of the present invention.

For example, five hysteresis comparators are required for operation as shown in FIG. The window size of the hysteresis comparator is designed to have four sizes for operation in FIG.

To detect the positive charge, initialize the output node of the comparator to '0' before detection. Therefore, the output becomes 1 day only when the amount of accumulated charge exceeds the window size. For example, when a charge amount of 250 mV is accumulated, the outputs of Hcharge [0], Hcharge [1], and Hcharge [2] become HIGH and the output of Hcharge [3] is LOW in FIG. To detect the negative charge, initialize the output node of the comparator to '1' before detection. Accordingly, the output of Lcharge [0] becomes LOW only when the accumulated amount of charge is larger than -50 mV. It detects the amount of electric charge accumulated by the above operation and allows the discharge of electric charge of the stimulator in a fluid manner.

 The overall operation of the proposed biomedical stimulator detects the amount of charge when a cathodic waveform is applied and discharges the charge in accordance with the accumulated amount of charge. Then, when the charge is detected again after the discharge of the charge, and the accumulated charge enters the safe zone, the next excitation waveform is input.

Because of the above operation, when no cathodic waveform is inputted, the biomedical stimulator does not input unnecessary anodic waveform like a conventional stimulator because there is no accumulated electric charge. This can minimize unexpected cell damage.

FIG. 7 is a flowchart illustrating a charge balance maintaining method using charge amount detection according to an embodiment of the present invention. Referring to FIG.

A method for maintaining charge balance using detection of a charge amount includes a step 710 of receiving only a cascode waveform through a charge detector and performing a charge detection operation and a charge balance operation in a floating manner according to the input cascode waveform, (720) simultaneously performing the charge balancing operation and the charge discharge through the biomedical stimulator using the charge detection and charge balancing operations of the charge detector.

In operation 710, the charge detection operation and the charge balance operation are performed while the cascode waveform is inputted through the charge detector and the cascode waveform is inputted, the cumulative amount of charge is subdivided according to a predetermined criterion, (711) initializing the output of a plurality of hysteresis comparators having windows of different sizes according to a subdivided predetermined reference to '0' or '1' to detect positive and negative charge amounts, Generating (712) an output for adjusting the charge release time of the biomedical stimulator using a plurality of hysteretic comparators having a window, generating (712) an output for adjusting the charge release time of the biomedical stimulator based on outputs of the plurality of hysteresis comparators Adjusting the charge release time to perform charge release 713, After charge-discharge time again performing the detection by the charge comprises the following: receiving cathodic waveform only when the accumulated charge amount corresponding to the predetermined reference phase (909).

The proposed biomedical stimulator inputs both cathodic waveforms and anodic waveforms and inputs only cathodic waveforms, discharges the charges using charge detection and charge balancing, Balance. This means that the controller does not need data about the anodic waveform or need to be calculated in the controller according to the cathodic waveform. In order to efficiently perform the above operation, the operation of the proposed charge detector that can operate in a fluid manner according to the situation is shown in FIG. The detection operation of the charge detector is further subdivided to adjust the time of the current that can discharge the charge in accordance with the charge accumulated in the charge balancing operation.

For example, when an electric charge of 50 mV or less is accumulated as shown in FIG. 5, the following stimulation waveform is applied as a safe zone. When a charge of 50 ~ 100 mV is accumulated, a small pulse is inserted. When a charge of 100 ~ 200 mV is accumulated, a large pulse is inserted. When a charge of 200 ~ 400 mV is accumulated, Very wide pulse insertion allows efficient charge discharge operation depending on the situation. Negative charge is detected more than 50mV or less than 50mV.

Thus, a positive charge is accumulated due to the cathodic waveform, and charge balancing is achieved by the charge discharging operation. Since the charge discharging operation is designed so as not to be large even when the negative charge amount is accumulated at the time of charge discharge, the negative charge amount detects only 50 mV or more.

FIG. 8 is a diagram illustrating a simulation result of an operation of a stimulator according to an embodiment of the present invention.

It can be seen that the voltage difference between ch1 and ch2, that is, the amount of charge accumulated, is always less than 50 mV after one stimulation is completed. The charge detector also detects the amount of charge accurately by outputting 5-bit data.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (6)

In a charge balance circuit using detection of charge quantity,
A charge detector for receiving only a cascode waveform and performing a charge detection operation and a charge balance operation while being fluidically operated according to the inputted cascode waveform; And
A biomedical stimulator for simultaneously performing the charge balancing operation and the charge discharging using the charge detecting operation and the charge balancing operation of the charge detector
Lt; / RTI >
The charge detector comprises:
A plurality of hysteresis comparators each having a window of a different size according to the subdivided predetermined criterion,
Lt; / RTI >
The plurality of hysteresis comparators may be configured such that an output is initialized to '0' or '1' to detect the amount of positive charge and the amount of negative charge
Charge amount balance circuit. delete The method according to claim 1,
The charge detector comprises:
Wherein the control unit controls the charge discharging time of the biomedical stimulator according to the output of the plurality of hysteresis comparators having the windows of different sizes and performs charge detection again after the charge discharging time and only when the accumulated charge amount corresponds to a predetermined reference Input of the next cascaded waveform
Charge amount balance circuit. A method for maintaining charge balance using detection of charge quantity,
Performing a charge detection operation and a charge balance operation while receiving only a Cathodic waveform through a charge detector and operating fluidly according to the inputted Cathodic waveform; And
Simultaneously performing the charge balancing operation and the charge discharging through the biomedical stimulator using the charge detecting operation and the charge balancing operation of the charge detector
Lt; / RTI >
Wherein the step of performing the charge detection operation and the charge balance operation while receiving only the Cathodic waveform and operating in accordance with the inputted Cathodic waveform,
0 " or " 1 " in order to detect positive and negative charge amounts of outputs of a plurality of hysteresis comparators having windows of different sizes according to the subdivided predetermined reference, ; And
Generating an output for adjusting the charge release time of the biomedical stimulator using a plurality of hysteretic comparators having windows of different sizes
The method comprising the steps of: delete 5. The method of claim 4,
Controlling a charge discharging time of the biomedical device according to an output of the plurality of hysteresis comparators having windows of different sizes to perform charge discharging; And
Receiving the next cascaded waveform only when charge detection is performed after the charge release time and the accumulated amount of charge corresponds to a predetermined criterion
The method comprising the steps of:

Images