TW202011892A - Biological information sensing circuit and operating method thereof - Google Patents

Abstract

A biological information sensing circuit and an operating method thereof are disclosed. The biological information sensing circuit is coupled to a micro-controller and a plurality of electrodes respectively. The biological information sensing circuit includes a power supply module and an electrode state detecting module. The power supply module is coupled to the micro-controller and receives a wake-up signal from the micro-controller. The electrode state detecting module is coupled to the electrodes and the power supply module respectively. The electrode state detecting module includes a switching unit. The switching unit is coupled to an electrode of the switching unit, a reference voltage and a ground voltage respectively and switches the electrode to conduct to the reference voltage or the ground voltage according to the wake-up signal.

Description

Biological information sensing circuit and its operating method

The invention relates to the sensing of biological information, in particular to a biological information sensing circuit and its operating method.

Please refer to FIG. 1, which illustrates a schematic diagram of a conventional electrode state detector applied to a dual-channel electrocardiography (ECG) sensing system ECG.

As shown in Figure 1, the electrocardiogram signals generated by multiple electrodes LA, RA, and LL contacting the human body are filtered by high-pass filters HPF1~HPF2, and then amplified by low noise amplifiers LNA1~LNA2, and then transmitted to the analog- The digital converters ADC1~ADC2 are converted into digital signals and output. The electrode state detector LOD detects whether the human body actually touches the electrode to ensure that a good ECG signal can be obtained.

In the prior art, in order to maintain the electrode state detection function, it is necessary to continuously supply a fixed current to the electrode state detector LOD to maintain its real-time, resulting in a substantial increase in system power consumption, such as up to 100uA, for wearable batteries that use batteries Or portable electronic devices are particularly disadvantageous, and need to be improved in the power saving part.

In view of this, the present invention provides a biological information sensing circuit and an operation method thereof to solve the problems mentioned in the prior art.

A preferred embodiment of the present invention is a biological information sensing circuit. In this embodiment, the biological information sensing circuit is respectively coupled to the microcontroller and the multiple electrodes. The biological information sensing circuit includes a power supply module and an electrode state detection module. The power supply module is coupled to the microcontroller and receives the wake-up signal from the microcontroller. The electrode state detection module is respectively coupled to the electrodes and the power supply module. The electrode state detection module includes a switching unit. The switching unit is respectively coupled to the electrode, the reference voltage and the ground voltage of the electrodes, and switches the electrode to the reference voltage or the ground voltage according to the wake-up signal.

In an embodiment of the invention, the electrode state detection module further includes a logic circuit. The logic circuit is coupled to the electrode, the operating voltage and the switching unit through the node. When the voltage on the node is lower than the operating voltage, the logic circuit provides a start signal to the microcontroller. The microcontroller generates a wake-up signal based on the start signal.

In an embodiment of the invention, the power supply module includes a temporary register. The register is coupled to the operating voltage and used to store control information. When the biological information sensing circuit enters the sleep mode, the register receives the power supply of the operating voltage and supplies power to the electrode state detection module according to the control information.

In one embodiment of the present invention, when the biological information sensing circuit operates in the working mode, the microcontroller transmits control information to the register.

In one embodiment of the present invention, when the bio-information sensing circuit operates in the sleep mode, the switching unit switches the electrode to conduct to the ground voltage; when the bio-information sensing circuit operates in the operating mode, the switching unit switches the electrode to conduct to the reference voltage .

In an embodiment of the invention, the electrode state detection module further includes a resistor, coupled between the switching unit and the electrode.

Another preferred embodiment of the present invention is an operation method of a biological information sensing circuit. In this embodiment, the biological information sensing circuit includes a power supply module and an electrode state detection module. The power supply module is coupled to the microcontroller. The electrode state detection module is respectively coupled to the electrodes and the power supply module. The operation method of the biological information sensing circuit includes the following steps: (a) the power supply module receives the wake-up signal from the microcontroller; and (b) the electrode state detection module switches the electrodes of the electrodes to the reference voltage according to the wake-up signal Or ground voltage.

Compared with the prior art, the biological information sensing circuit and the operating method of the present invention can achieve the following advantages and effects:

(1) Automatic switching operation mode: When the bio-information sensing circuit of the present invention senses that the electrode has fallen off, it will generate a Lead-off signal to make the sensing device automatically enter the sleep mode, once all the electrodes are in contact with the human body The biological information sensing circuit of the present invention will automatically send a lead-on signal to make the circuit enter the working mode from the sleep mode.

(2) Save unnecessary power consumption: Since the bioinformation sensing circuit of the present invention does not need to provide a fixed current to the electrode state detection module at any time, the power consumption can be changed from the prior art in the normal temperature sleep mode 100uA is greatly reduced to less than 1uA.

(3) Wide range of applications: The bioinformation sensing circuit of the present invention can be applied to any bioinformation sensing device that requires multiple electrodes, especially wearable or portable bioinformation that needs to effectively save power consumption to extend the use time Sensing device.

The advantages and spirit of the present invention can be further understood through the following detailed description of the invention and the accompanying drawings.

Reference will now be made in detail to exemplary embodiments of the present invention, and examples of the exemplary embodiments will be described in the accompanying drawings. Elements/components with the same or similar reference numerals used in the drawings and embodiments are used to represent the same or similar parts.

A preferred embodiment according to the present invention is a biological information sensing circuit. In this embodiment, the biological information sensing circuit can be applied to any biological information sensing device, such as an electrocardiogram (ECG) measurement device, a photoplethysmography (PPG) device, a human body impedance measurement device, etc. Especially suitable for wearable or portable bio-information sensing devices that need to effectively save power consumption, but not limited to this.

Please refer to FIG. 2, which is a schematic diagram of the biological information sensing circuit in this embodiment. As shown in FIG. 2, the biological information sensing circuit 1 is coupled to the microcontroller 2 and the plurality of electrodes RA/LA, respectively. The biological information sensing circuit 1 includes a power supply module 10, an electrode state detection module 12, and a processing module 14. The power supply module 10 is respectively coupled to the microcontroller 2, the electrode state detection module 12 and the processing module 14. The electrode state detection module 12 is respectively coupled to the microcontroller 2, the power supply module 10 and the electrodes RA/LA. The processing module 14 is respectively coupled to the electrodes RA/LA and the power supply module 10.

The power supply module 10 can be coupled to the microcontroller 2 through an Inter-Integrated Circuit bus interface I2C or a serial peripheral interface (Serial Peripheral Interface) SPI, but it is not limited thereto. The processing module 14 may be an analog front end (AFE) circuit, which is used to amplify and convert the sensing signal SEN from the electrode RA or LA into digital sensing information, and then pass the I2C or The serial peripheral interface SPI is transferred to the microcontroller 2.

When the electrodes RA and LA are in contact with the human body, the processing module 14 receives the sensing signals SEN from the electrodes RA and LA and digitizes them, and transmits them to the micro-controller through the bus interface I2C or serial peripheral interface SPI between integrated circuits器2. At the same time, the electrode state detection module 12 also receives the sensing signals SEN of the electrodes RA and LA and determines whether the electrodes RA or LA maintain contact with the human body according to the sensing signals SEN.

When the electrode state detection module 12 senses that the electrode RA or LA has not maintained contact with the human body, it means that the electrode RA or LA in contact with the human body has fallen off. The electrode state detection module 12 transmits an interrupt signal LOFF To the power supply module 10, the power supply module 10 enters the sleep state according to the interrupt signal LOFF and stops power supply; once the electrode state detection module 12 senses that the electrode RA or LA returns to contact with the human body again, it means that the fallen electrode has been restarted In contact with the human body, the electrode state detection module 12 transmits a start signal LON to the microcontroller 2, and then the microcontroller 2 changes from the sleep state to the working state according to the start signal LON and sends a wake-up signal WK to the power supply module 10. When the power supply module 10 receives the wake-up signal WK from the microcontroller 2, the power supply module 10 resumes normal power supply PW to the electrode state detection module 12 and the processing module 14.

Please refer to FIG. 3. In another embodiment, the power supply module 10 includes a first register 101, a second register 102 and a low dropout voltage regulator LDO. The low-dropout voltage regulator LDO is respectively coupled to the microcontroller 2, the operating voltage VDD, the first register 101 and the processing module 14. The first register 101 is respectively coupled to the microcontroller 2, the low-dropout voltage regulator LDO, the second register 102 and the electrode state detection module 12. The second register 102 is respectively coupled to the operating voltage VDD, the first register 101 and the electrode state detection module 12.

When the biological information sensing circuit 1 operates in the working mode, the microcontroller 2 will continue to send the control information of the electrode state detection module 12 to the first register through the bus interface I2C between the integrated circuits or the serial peripheral interface SPI 101 and stored in the first register 101, and the second register 102 also receives the control information of the electrode state detection module 12 from the first register 101 and stores it. When the content of the real-time control information stored in the first register 101 changes, the real-time control information stored in the second register 102 is also updated synchronously.

Once the bio-information sensing circuit 1 enters the sleep mode from the operating mode, both the low-dropout voltage regulator LDO and the first register 101 stop operating, and the second register 102 receiving the power supply of the operating voltage VDD operates normally and can be used according to its The stored control information of the electrode state detection module 12 continuously supplies power to the electrode state detection module 12 to maintain the normal operation of the electrode state detection module 12.

Next, please refer to FIG. 4, which illustrates an embodiment of the electrode state detection module 12. For example, it is used in ECG sensing system, but not limited to this.

As shown in FIG. 4, the electrode state detection module 12 includes a switching unit 120, a logic circuit 122, current sources I1-I2 and a resistor R. The logic circuit 122 is respectively coupled to the power supply module 10, the microcontroller 2, the electrodes LA and RA. One end of the current source I1 is coupled to the operating voltage VDD and the other end is coupled between the logic circuit 122 and the electrode LA. One end of the current source I2 is coupled to the operating voltage VDD and the other end is coupled between the logic circuit 122 and the electrode RA. The switching unit 120 is coupled to the junction ND between the logic circuit 122 and the electrode RA through the resistor R. The switching unit 120 includes switches S2 and S2B, respectively coupled to the reference voltages VREF and VGND.

In this embodiment, the switching unit 120 is coupled to the electrode RA or LA, the reference voltage VREF, and the ground voltage VGND, respectively. The switching unit 120 switches the electrode switching unit 120 to the reference voltage VREF or the ground voltage VGND according to the wake-up signal WK.

When the electrode RA or LA is not in contact with the human body, the biological information sensing circuit 1 operates in the sleep mode, and the switching unit 120 switches the electrode RA or LA to the ground voltage VGND to reduce unnecessary power consumption; when the electrode RA or LA When the LA has recovered contact with the human body, the biological information sensing circuit 1 operates in the operating mode, and the switching unit 120 switches the electrode RA or LA to the reference voltage VREF to restore the normal sensing of the electrode RA or LA.

Although this embodiment takes the switching unit 120 coupled to the contact ND between the logic circuit 122 and the electrode RA as an example, in fact, the switching unit 120 may also be coupled to the contact between the logic circuit 122 and the electrode LA, but the switching The unit 120 can only be coupled to one other, and cannot be coupled to both at the same time.

Please refer to FIG. 3 and FIG. 4 at the same time, assuming that an external electrode RL that constantly provides a reference voltage exists, and the external electrode RL is coupled to the electrodes LA and RA through the bulk resistance RB, respectively. When the system is turned on, the microcontroller 2 sends a wake-up signal WK to the low-dropout voltage regulator LDO, so that the low-dropout voltage regulator LDO operates normally and provides a voltage of 1.8 volts to the first register 101, at which time the bioinformation sensing The circuit 1 is in the working mode and all circuits are operating normally. Therefore, it can be judged whether a path is connected from the external electrode RL to the electrode RA by detecting the voltage of the contact ND between the logic circuit 122 and the electrode RA.

When the electrode RA falls off and does not come into contact with the human body, there is an open circuit from the external electrode RL to the electrode RA, and the voltage of the contact ND will be pulled to the operating voltage VDD. At this time, the logic circuit 122 provides an interrupt signal LOFF to the power supply module The first register 101 of 10 is then transmitted to the microcontroller 2 through the bus interface I2C between the integrated circuits or the serial peripheral interface SPI, so that the microcontroller 2 knows that the electrode RA is in a state of falling off and not contacting the human body, according to A visual or audible warning message is issued to inform the operator to reattach the electrode RA to the human body.

When the electrode RA is reattached to the human body and comes into contact with the human body, the path from the external electrode RL to the electrode RA is a path. The voltage at the junction ND between the logic circuit 122 and the electrode RA will be lower than the operating voltage VDD. At this time, the logic circuit 122 provides a start signal LON to the microcontroller 2, and the microcontroller 2 generates a wake-up signal WK to the low dropout voltage regulator LDO according to the start signal LON.

Assuming that there is no external electrode RL that provides a fixed reference voltage, when the system is turned on, the switching unit 120 is controlled by the wake-up signal WK from the microcontroller 2 to turn on the switch S2, so that the electrode RA can be coupled through the resistor R and the turned-on switch S2 To the reference voltage VREF. When the electrodes RA and LA are both connected to the human body, the loop between the electrodes RA and LA is turned on, and the logic circuit 122 sends a start signal LON to the microcontroller 2 to determine that the biological information sensing circuit 1 is in the operating mode.

Once the electrode RA comes off, the voltage at the junction ND between the logic circuit 122 and the electrode RA is pulled to the operating voltage VDD. At this time, the logic circuit 122 provides the interrupt signal LOFF to the first register 101 of the power supply module 10, and then transmits it to the microcontroller 2 via the inter-integrated circuit bus interface I2C or the serial peripheral interface SPI, so that the microcontroller 2 Knowing that the electrode RA is in a state of falling off without contacting the human body, it can issue a visual or audible warning message to inform the operator to reattach the electrode RA to the human body.

When the electrode RA is reattached to the human body and comes into contact with the human body, the path from the external electrode RL to the electrode RA is a path. The voltage at the junction ND between the logic circuit 122 and the electrode RA will be lower than the operating voltage VDD. At this time, the logic circuit 122 provides a start signal LON to the microcontroller 2, and the microcontroller 2 generates a wake-up signal WK to the low dropout voltage regulator LDO according to the start signal LON.

The bioinformation sensing circuit of the present invention can also be applied to the measurement of bioimpedance, such as body fat measurement. For example, as shown in FIG. 5, in a commonly used bio-impedance measurement model, four electrodes E1~E4 are respectively contacted with the human body BD, and an alternating current Iac is input from the electrode E1 to the electrode E4, and through the AC voltmeter V Measure the voltage signal between electrodes E2 and E3.

Please also refer to FIG. 6. In the measurement of the human body impedance mode, the AC currents +Iac and -Iac generated by the electrodes E1 and E4 pass through the external capacitor C to isolate the DC voltage. The DC reference voltage of the human body BD can be provided through the aforementioned electrode state detection module 12. Please refer to FIGS. 4 and 6 at the same time. The electrodes RA and LA in FIG. 4 may correspond to the electrodes E2 and E3 in FIG. 6, respectively. Once the four electrodes E1~E4 are in contact with the human body BD, the AC currents +Iac and -Iac generated by the electrodes E1 and E4 flow through the human body BD, so that an AC voltage signal is generated between the electrodes E2 and E3, and then through the sensing circuit SC The impedance of the human body BD can be calculated by measuring the AC voltage signal.

In the sleep state, the current switches ISW[0]~ISW[1] and the voltage switches VSW[0]~VSW[1] are not conducting, so that there is no alternating current between the electrodes E1 and E4 and the electrodes E2 and E3 are also not conducting To the electrode state detection module 12 and the sensing circuit SC. Once the body impedance is detected, the electrode state detection module 12 will output a start signal LON to the microcontroller 2 to make the system enter the working mode.

Another preferred embodiment of the present invention is an operation method of a biological information sensing circuit. In this embodiment, the biological information sensing circuit includes a power supply module and an electrode state detection module. The power supply module is coupled to the microcontroller. The electrode state detection module is respectively coupled to the electrodes and the power supply module.

Please refer to FIG. 7, which is a flowchart of the operation method of the biological information sensing circuit in this embodiment.

As shown in FIG. 7, the operation method of the biological information sensing circuit may include the following steps:

Step S10: The power supply module receives the wake-up signal from the microcontroller; and

Step S12: The electrode state detection module switches one of the electrodes to the reference voltage or the ground voltage according to the wake-up signal.

In one embodiment, the wake-up signal in step S10 is generated by the microcontroller according to the start signal provided by the electrode state detection module. In detail, the electrode state detection module can be coupled to the electrode and the working voltage through a node. When the voltage on the node is lower than the working voltage, the electrode state detection module provides a start signal to the microcontroller, so that the microcontroller generates a wake-up signal to the power supply module according to the start signal.

In step S12, when the biological information sensing circuit operates in the sleep mode, the electrode state detection module will switch the electrode to the ground voltage; when the biological information sensing circuit operates in the working mode, the electrode state detection module Will switch the electrode to the reference voltage.

In practical applications, the power supply module may include a temporary register. The register is coupled to the operating voltage and used to store control information. When the biological information sensing circuit operates in the working mode, the microcontroller transmits control information to the register to store the control information in the register; when the biological information sensing circuit enters the sleep mode, the register receives the operating voltage According to the control information, the electrode state detection module is powered.

Compared with the prior art, the biological information sensing circuit and the operating method of the present invention can achieve the following advantages and effects:

(1) Automatic switching operation mode: When the bio-information sensing circuit of the present invention senses that the electrode is off (Lead-off), it will generate an interrupt (Lead-off) signal to make the sensing device automatically enter the sleep mode, once all the electrodes When the human body contacts the electrodes, the bio-information sensing circuit of the present invention automatically sends a lead-on signal to make the circuit enter the working mode from the sleep mode.

(2) Save unnecessary power consumption: Since the bioinformation sensing circuit of the present invention does not need to provide a fixed current to the electrode state detection module at any time, the power consumption can be changed from the prior art in the normal temperature sleep mode 100uA is greatly reduced to less than 1uA.

(3) Wide range of applications: The bioinformation sensing circuit of the present invention can be applied to any bioinformation sensing device that requires multiple electrodes, especially wearable or portable bioinformation that needs to effectively save power consumption to extend the use time Sensing device.

With the above detailed description of the preferred embodiments, it is hoped that the features and spirit of the present invention can be described more clearly, rather than limiting the scope of the present invention with the preferred embodiments disclosed above. On the contrary, the purpose is to cover various changes and equivalent arrangements within the scope of the patent application of the present invention.

LOD: electrode state detector ECG: electrocardiogram system HPF1~HPF2: High-pass filter LNA1~LNA2: low noise amplifier ADC1~ADC2: analog-to-digital converter 1: Bioinformatics sensing circuit 2: microcontroller 10: Power supply module 12: Electrode state detection module 14: Processing module 101: first register 102: second register 120: Switching unit 122: logic circuit RA, LA, LL: electrode WK: wake up signal I2C/SPI: bus interface between integrated circuits/serial peripheral interface LON: start signal LOFF: interrupt signal VREF: reference voltage VGND: ground voltage SEN: Sensing signal PW: power supply VDD: working voltage LDO: Low dropout voltage regulator RL: external electrode RB: body resistance LG: logic control unit R: resistance ND: contact I: current source E1~E4: electrode Iac: AC current V: AC voltmeter BD: Human body C: capacitance SC: sensing circuit ISW[0]~ISW[1]: current switch VSW[0]~VSW[1]: voltage switch S10~S12: Step

The drawings of the present invention are described as follows: FIG. 1 illustrates a schematic diagram of a conventional electrode state detector applied to a dual-channel ECG sensing system. FIG. 2 is a schematic diagram of a biological information sensing circuit according to a preferred embodiment of the present invention. FIG. 3 shows a schematic diagram of the power supply module including a plurality of temporary registers. FIG. 4 illustrates an embodiment of the electrode state detection module. FIG. 5 illustrates an embodiment of a biological impedance measurement model. FIG. 6 shows an embodiment of measuring the impedance of the human body. FIG. 7 is a flow chart of the operation method of the biological information sensing circuit according to another preferred embodiment of the present invention.

1: Bioinformatics sensing circuit

2: microcontroller

10: Power supply module

12: Electrode state detection module

14: Processing module

120: Switching unit

RA/LA: multiple electrodes

WK: wake up signal

I2C/SPI: bus interface between integrated circuits/serial peripheral interface

LON: start signal

LOFF: interrupt signal

VREF: reference voltage

VGND: ground voltage

SEN: Sensing signal

PW: power supply

Claims (10)

A bio-information sensing circuit is respectively coupled to a microcontroller and a plurality of electrodes. The bio-information sensing circuit includes: A power supply module coupled to the microcontroller and receiving a wake-up signal from the microcontroller; and An electrode state detection module, respectively coupled to the electrodes and the power supply module, Among them, the electrode state detection module includes: A switching unit is respectively coupled to one of the electrodes, a reference voltage, and a ground voltage, and switches the electrode to the reference voltage or the ground voltage according to the wake-up signal. The biological information sensing circuit as described in item 1 of the patent application scope, wherein the electrode state detection module further includes: A logic circuit is coupled to the electrode, an operating voltage and the switching unit through a node, and when a voltage on the node is lower than the operating voltage, the logic circuit provides a start signal to the microcontroller, the microcontroller The generator generates the wake-up signal according to the start signal. The bio-information sensing circuit as described in item 1 of the patent application scope, wherein the power supply module includes a register, the register is coupled to an operating voltage and used to store a control information, when the bio-information sensing circuit When entering a sleep mode, the register receives the power supply of the working voltage and supplies power to the electrode state detection module according to the control information. The biological information sensing circuit as described in item 3 of the patent application scope, wherein when the biological information sensing circuit operates in a working mode, the microcontroller transmits the control information to the register. The bio-information sensing circuit as described in item 1 of the patent scope, wherein when the bio-information sensing circuit operates in a sleep mode, the switching unit switches the electrode to the ground voltage; when the bio-information sensing circuit When operating in a working mode, the switching unit switches the electrode to the reference voltage. The biological information sensing circuit as described in item 1 of the patent application scope, wherein the electrode state detection module further includes a resistor coupled between the switching unit and the electrode. A method for operating a biological information sensing circuit. The biological information sensing circuit is respectively coupled to a microcontroller and a plurality of electrodes. The biological information sensing circuit includes a power supply module and an electrode state detection module. The power supply module is coupled to the microcontroller, and the electrode state detection module is respectively coupled to the electrodes and the power supply module. The method includes the following steps: (a) The power supply module receives a wake-up signal from the microcontroller; and (b) The electrode state detection module switches one of the electrodes to a reference voltage or a ground voltage according to the wake-up signal. The method as described in item 7 of the patent application scope, wherein the electrode state detection module is coupled to the electrode and an operating voltage through a node, and when a voltage on the node is lower than the operating voltage, the electrode state detection module The test module provides a start signal to the microcontroller, and the microcontroller generates the wake-up signal according to the start signal. The method as described in item 7 of the patent application scope, wherein the power supply module includes a register, the register is coupled to an operating voltage and used to store a control information, when the biological information sensing circuit enters a sleep mode At this time, the register receives the power supply of the working voltage and supplies power to the electrode state detection module according to the control information. The method as described in item 7 of the patent application scope, wherein when the bio-information sensing circuit operates in a sleep mode, the electrode state detection module switches the electrode to the ground voltage; when the bio-information sensing circuit When operating in a working mode, the electrode state detection module switches the electrode to the reference voltage.

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