RU2631643C2 - Cardioqvark cardiac monitor scheme - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: device for obtaining a cardiogram contains capacitive sensors of the electric field installed on the housing. A potentiometre and the first stage of a differential amplifier with a common-mode filter are connected to the capacitive sensors, receiving a signal from the capacitive sensors of the electric field and the bias voltage from the potentiometre. The first stage is connected to the second stage of the differential amplifier with the common-mode filter, which is connected to an analog-to-digital converter (ADC) driver, which transmits signals to the first and second inputs of a two-channel ADC with the common-mode filter in parallel. The device contains a trigger for data reception control from the ADC to a controller which receives signals from the power monitor connected to the logical switching unit of the USB port and is connected to the ADC, to the potentiometer and to the DC power supply with interference-suppression filters, a crypto processor, a USB port switching logic unit and a USB port hub connected to the DC power supply, the logical switching unit of the USB port and an overvoltage protection unit of the USB port, and receiving signals from the power monitor connected to the logical switching unit of the USB port.

EFFECT: increased accuracy and reliability of measurements, reliability of received information on cardiac activity and simplified design.

6 cl, 1 dwg

Description

The invention relates to medicine, in particular to a device for obtaining a cardiogram according to standard cardiological lead I, and is intended for taking a cardiogram using devices having a USB interface.

As the closest analogue (prototype) of the claimed invention, you can take a wrist cardiomonitor-watch to amplify the electrocardiogram, in which a non-differential amplifier is used, and only two electrodes are used to pick up the electrocardiogram and supply it to the amplifier input: one, the nearest one, is installed on the watch case, and another, a remote electrode, is designed to be installed on the surface of the chest, which are connected to the inputs of the electrocardiogram amplifier with a cable made as a twisted pair wire in isolated, wherein one of the twisted pair wires is connected at one end to the first input of the amplifier and a second end remote from the electrode; the second wire of the twisted pair is connected at one end to the near electrode, and the second end is left free. To visualize the results of the analysis of the electrocardiogram, a matrix liquid crystal indicator is used, which allows displaying not only digital data, but also text messages. For transmission of an electrocardiogram for analysis to a medical institution via computer media or via the Internet, the cardiomonitor contains an infrared port operating according to the standard IrDA protocol (RU 2308883, 10.27.2007).

The disadvantages of the aforementioned device are the non-differential electrocardio signal amplification circuit, which does not allow to effectively suppress common mode interference; the presence of a wiring harness - a patient cable with a remote electrode, leveling the advantages of a compact main unit; the inability to quickly install the electrodes and start recording the electrocardiogram when the need for express analysis; the need to ensure reliable electrical contact of the electrode with the patient’s skin, which, on the one hand, requires galvanic isolation on the side of the main device, and on the other, requires special measures to ensure the stability of the skin-electrode transition resistance over the entire measurement period, for example, contact gels and the use of hypoallergenic materials or electrode coatings.

The problem to which the invention is directed is to create a device for obtaining a cardiogram, which would eliminate the above disadvantages.

The technical result achieved by the implementation of this invention is to increase the accuracy and reliability of measurements, the reliability of the received information about cardiac activity and simplification of the design through the use of capacitive sensors installed directly on the product’s body with integrated electrodes, which are connected by a differential circuit, do not require an electric contact with the patient’s skin and provide galvanic isolation on the side of the main device without additional circuitry elements.

The specified technical result is achieved in a device for obtaining a cardiogram containing capacitive electric field sensors mounted on the housing, a potentiometer connected to them, a first stage of a differential amplifier with a common mode filter, receiving a signal from capacitive electric field sensors and connected with a second stage of a differential amplifier with a common mode filter interference driver analog-to-digital Converter, transmitting in parallel signals to the first and second inputs of a two-channel analog a digital converter (ADC) with an in-phase noise filter, a trigger for controlling the reception of data from the ADC to a controller connected to a DC power source with noise suppression filters, a crypto processor, a USB port switching logic unit and a USB port splitter connected to a DC power source and a protection unit from overvoltage of the USB port, and receiving signals from the power monitor connected to the USB port switching logic block.

The potentiometer is made by digital two-channel.

As an ADC, a stereo audio codec-decoder is used, containing a microphone input and digital interface buses.

A cardiogram is obtained according to standard cardiological lead I.

Capacitive sensors of the electric field are capacitive receivers of an alternating electric field with built-in compact electrodes that exclude galvanic communication between the user and the device.

The DC power supply is made program-controlled, with the function of stabilization and conversion of a unipolar supply voltage to a bipolar one, with the possibility of partial disconnection of consumers in a low-power mode.

Thus, improving the accuracy and reliability of measurements, the reliability of the received information about cardiac activity and simplifying the design is achieved in a device for receiving a cardiogram according to a standard cardiological lead I, which contains capacitive sensors with integrated electrodes, a differential amplifier, a digital potentiometer, a controller, a cryptoprocessor, a controlled power source , ADC, USB interface with surge protection unit.

The sensors are capacitive receivers of an alternating electric field with built-in compact electrodes, which exclude galvanic communication between the user and the device and increase the safety of using the device.

The potentiometer for controlling the displacements in the differential amplifier is selected as a two-channel, programmable, with a digital standard bus.

The differential amplifier is made according to a multistage circuit, contains common-mode noise filters and an ADC driver for matching the signal level.

As an ADC, a stereo audio encoder-decoder containing a microphone input and digital interface buses was selected.

The crypto processor ensures the correct operation of the device with Apple products.

The DC power supply is made program-controlled, with the function of stabilization and conversion of a unipolar supply voltage to a bipolar one, with the possibility of partial disconnection of consumers in a low-power mode.

The USB port has a splitter with an automatic switch to one of two external devices. The USB port also serves to supply external voltage to the cardiogram device.

The controller executes the embedded program algorithm, issues control signals to the functional units of the device, coordinates their work, sets the operating modes, manages the power, receives data from the sensors from the ADC and processes them, exchanges data with external devices via the USB port, and performs self-diagnostics.

The invention is illustrated by the drawing, which shows a block diagram of a device for obtaining a cardiogram (cardiomonitor).

The device for receiving a cardiogram contains capacitive sensors 1 and 3 of the electric field, a two-channel digital potentiometer 2, the first stage 4 of the differential amplifier with an in-phase noise filter, the second stage 6 of the differential amplifier with an in-phase noise filter and an ADC driver, a two-channel ADC 5 with an in-phase noise filter, a trigger 7 control the reception of data from the ADC to the controller, software-controlled power supply 8 with noise suppressing filters, controller 9 with control and data buses, cryptoprocessor 10, logical b approx 11 USB port switching, the monitor 12 power protection unit 13 against overvoltage USB port splitter 14 USB ports.

Structurally, the device for receiving a cardiogram is a plastic case worn on the back of an external device - a mobile phone. Inside the plastic case is a printed circuit board with electronic components and capacitive sensors. Access to the sensors for the fingers of two hands is provided by cutouts on the outside of the case. There are power and data connectors on the inside and outside of the case.

The external device is a mobile phone with pre-installed software that serves to transmit commands to the device controller 9 for receiving cardiograms, displaying diagnostic information, measurement results in text and graphic form and exchanging data with remote databases via wireless communication channels. An external device can also be a tablet, personal computer connected via a cable via a USB port.

A device for receiving a cardiogram works as follows.

Initial activation of the device occurs sequentially in several stages.

When connecting an external device to the first (USB1) or second (USB2) output of the splitter 14 of the USB port, the voltage of the external device +5 V from the third output of the splitter 14 is supplied to the logic unit 11 and activates the built-in trigger, which, in turn, gives a command to the input its composition is a two-channel analog USB port switch for connecting an external device to the data bus of the device. At the same time, from the third output of the splitter 14, a +5 V supply voltage from an external device is supplied to the second input of a program-controlled power supply 8, which forms a stabilized voltage of +3.3 V on the corresponding power output bus, supplying the digital part of the device.

After that, an initialization signal is generated at the output of the power monitor 12, which is fed to the third signal input of the controller 9 and sets its software and ports to the initial configuration, the same signal is fed to the input of the logic unit 11 and fixes the selected configuration of the USB port.

Following the power supply of +3.3 V, the cryptoprocessor 10 is also activated, from the output of which the data necessary for data exchange via the USB bus with the Apple device is transmitted to the first input of the controller 9 via the bus.

At the end of the initial activation procedure, the controller 9, following the algorithm embedded in its non-volatile memory and using the data of the cryptoprocessor 10, establishes information exchange with an external device and is waiting for external commands.

In the absence of external commands, the controller 9 after a specified period of time switches to low power mode and remains there until the activation signal arrives from an external device, or until the power is turned off via the USB port from the external device, or until the external device is physically disconnected from the USB port connector of the cardiac monitor .

If there is a request from an external device for registering a cardiogram, controller 9 activates the corresponding firmware block and starts a sequence of commands that allow you to register a cardiological signal, process, convert, decode it and transfer it via an USB port to an external device for storage, display, analysis and further manipulations.

Before the registration of the cardiogram, the controller 9 gives the command to turn on the analog part of the device, which is designed so that it requires bipolar power +3.3 V / -3.3 V. The block of program-controlled power supply 8, which generates a voltage of negative polarity in addition to during the initial activation, the voltage generation block +3.3 V is started by the signal supplied to the first input of the power source 8 from the fourth signal output of the controller 9. As a result, on the corresponding output bus Single supply 8 appears stabilized voltage 3.3 V is turned on and the analog portion of the device, namely: the sensors of the differential amplifier and the ADC.

When the analog part is turned on, the biological potentials of the selected cardiac lead are recorded by capacitive sensors 1 and 3, after which the amplified signals are transmitted respectively to the first and second inputs of the first stage 4 of a low-noise precision differential amplifier with an in-phase noise filter, and bias voltages from potentiometer 2 are separately fed to these inputs digital dual channel programmed at factory calibration. The purpose of the calibration is to equalize the gain of the sensors to increase the reliability of the results obtained; the potentiometer is controlled by the controller 9 via a digital bus, for which the third controller output (bus) is connected to the potentiometer input.

The signal from the first output of the first stage 4 of the differential amplifier is fed to the first input, and the signal of the second output of the first stage 4 of the differential amplifier is synchronously fed to the second input of the second stage 6 of a two-channel precision differential amplifier with an in-phase noise filter and an ADC driver, where the signals are normalized by level, and then, in parallel, respectively, are fed to the first and second inputs of the two-channel ADC 5 with an in-phase interference filter. Due to the similarity of the parameters of speech and cardiac signals, a stereo audio codec with standard digital buses for data exchange with controller 9 is used as an ADC, while the outputs of one of the available microphone inputs are used as the first and second inputs. Digitized and pre-processed data are transmitted from the ADC via the command and data bus connecting the first output of the ADC 5 and the second input of the controller 9, while the data transfer permission signal is generated by the data reception control trigger 7 connected between the first signal output of the controller 9 and the third ADC input 5. The logic of the trigger 7 involves the prohibition of data transmission from the ADC in the absence of a command to turn on the analog part of the device.

The data received by the controller 9 from the ADC 5 is processed in accordance with the embedded algorithm and transmitted from the second controller output via the USB bus to the first input of the splitter 14, and from the first or second output of the splitter are redirected to the USB input of the connected external device. Control signals are transmitted on the same channel.

Depending on the program settings, the controller can transmit both processed data and raw data, accompanied by time stamps.

The length of time for recording a cardiogram is set programmatically and controlled by controller 9. Upon receipt of sufficient data for analysis or after a specified period of time, controller 9 stops receiving data from the ADC 5, removes synchronization signals from the corresponding bus, and if there is a command from an external device, at the end of the session, the controller 9 programmatically disables the analog part, removing the corresponding enable signal from the power source 8, and then goes into standby mode previous commands as after the initial initialization.

To protect the elements of the cardiomonitor circuit from static electricity discharges and other types of impulse noise of various power and duration, distributed components of the protection unit 13, which are combinations of semiconductor surge arresters, are installed on the input circuits of the splitter 14.

Claims (6)

1. A device for obtaining a cardiogram, characterized in that it contains capacitive electric field sensors mounted on the housing, a potentiometer connected to them, a first stage of a differential amplifier with a common mode filter, receiving a signal from capacitive electric field sensors, bias voltage from the potentiometer and connected to the second a differential amplifier cascade with a common-mode interference filter and an analog-to-digital converter driver that transmits in parallel signals to the first and second inputs of a two-channel an analog-to-digital converter (ADC) with an in-phase noise filter, a trigger for controlling the reception of data from the ADC to the controller connected to the ADC, with a potentiometer and with a DC power supply with noise suppression filters, a crypto processor, a USB logic switch unit and a USB port splitter, connected to a DC power supply, a USB port switching logic unit and a USB port surge protector, and receiving signals from a power monitor connected to a US port logic block B. 2. A device for obtaining a cardiogram according to claim 1, characterized in that the potentiometer is made digital two-channel. 3. A device for obtaining a cardiogram according to claim 1, characterized in that a stereo audio encoder-decoder containing a microphone input and digital interface buses is used as an ADC. 4. A device for obtaining a cardiogram according to claim 1, characterized in that a cardiogram is obtained according to a standard cardiological lead I. 5. A device for obtaining a cardiogram according to claim 1, characterized in that the capacitive sensors of the electric field are capacitive receivers of an alternating electric field with built-in compact electrodes that exclude galvanic communication between the user and the device. 6. The device for obtaining a cardiogram according to claim 1, characterized in that the DC power supply is made programmatically controlled, with the function of stabilizing and converting a unipolar supply voltage to a bipolar one with the possibility of partial disconnection of consumers in low power mode.

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