CN100411596C - Two-way digital wireless pressure monitoring system for biological implant joints - Google Patents

Abstract

Bidirectional digital wireless pressure monitoring system for biological implant joints, involving low power consumption circuit design, piezoelectric ceramic intermittent power supply circuit design and data wireless transmission circuit design, belongs to the technical field of medical implant joint pressure monitoring system, the system includes internal parts: pressure Electric ceramic device, energy storage device, analog-digital hybrid chip, antenna; external part: external transceiver wireless data transmission device, computer control and processing device; the system has three working modes: piezoelectric ceramic device, energy storage device and analog-digital hybrid chip Combined working mode, combined working mode of analog-digital hybrid chip, antenna, external transceiver wireless data transmission device and computer control and processing device, and system sleep mode. The present invention is for the early detection of the working condition of the implanted joint of the living body, and the power consumption is low. For the first time, the communication between the joint of the living body implanted and the outside of the body is realized, so that the computer outside the body can obtain the pressure data through the wireless method to make reasonable adjustments to the implanted joint. diagnosis.

Description

Two-way digital wireless pressure monitoring system for biological implant joints

technical field

The invention relates to a bidirectional digital wireless pressure monitoring system for biological implant joints, in particular to low power consumption circuit design, piezoelectric ceramic intermittent power supply circuit design and data wireless transmission circuit design, and belongs to the technical field of medical implant joint pressure monitoring system.

Background technique

Physical disability is one of the important diseases that affect the quality of life of the disabled. Artificial joints and prosthetics are an important means of re-establishing motor function for people with joint damage. After the artificial joint is implanted in the human body, it is in a long-term working state. Integrated circuit technology is used to establish a physical channel for signal transmission between the human implanted joint and the outside world, and early monitoring of the working conditions, pressure, and dislocation of the implanted joint. Testing is an effective means of reducing the suffering of patients.

At present, domestic research on human joints mainly focuses on robot joint control systems, simulation and modeling of articulated virtual human arms, control of pick-and-place and obstacle avoidance actions of manipulators, and joint judgment motion algorithms in manipulators and robots. Applying microelectronics technology to the human body implant system, the Institute of Microelectronics of Tsinghua University has independently developed and developed cochlear implants to solve the hearing of the deaf, chips such as gastric endoscopes for detecting gastrointestinal problems, and related nerve electrode technology Research. In foreign countries, there are many types of research on implanted systems in vivo. These systems mainly include: various implanted measurement systems, implanted stimulators, implanted drug therapy (control) devices, implanted artificial organs and auxiliary devices. device. The Department of Mechanics of Nebraska-Lincoln University in the United States is studying the application of piezoelectric ceramics to generate low-frequency electric energy. It is mentioned that installing piezoelectric ceramic devices in human implanted joints can power circuits and provides a simple model. However, this model is only limited to the experimental stage, without considering the actual application environment, and many parameters are not set according to the actual situation, and there are the following three problems: 1. It is only a functional application of the experimental environment, and does not consider the low power consumption that can be applied in practice 1. Circuit design with low voltage and low noise; 2. No consideration of the design of the external circuit, that is, how to wirelessly transmit the data in the joint to the external body; 3. The design of the power circuit is lacking. These issues will be resolved in this project.

At present, there is no research on the detection of implanted joints using microelectronics technology. The present invention can be applied to implanted joints that can give pressure to implanted piezoelectric ceramic devices in daily life, such as human knee joints, hip joints, etc.

Contents of the invention

The object of the present invention is to provide a two-way digital wireless pressure monitoring system with two-way wireless communication, controllable and real-time processing and storage of artificial joint pressure data in a living body and its realization method.

The two-way digital wireless implanted joint pressure monitoring system of the present invention is a two-way wireless communication, controllable and real-time processing and storage of biological implanted joint pressure data two-way digital wireless pressure monitoring system, which The characteristic is that the system consists of two parts including in vivo and in vitro:

(1) Parts of the body:

(1) Piezoelectric ceramic device, including 3 piezoelectric ceramic elements, which are not only sensors to transmit pressure data but also generate energy under pressure; the three output terminals of the piezoelectric ceramic device are respectively connected to the input terminals of the following analog-digital hybrid chip and The input terminals of the energy storage device are connected;

(2) The energy storage device includes a rectifier circuit and an energy storage circuit. The current output by the three output terminals of the piezoelectric ceramic device passes through the rectifier circuit and then supplies the energy storage circuit. The energy storage device supplies power to the analog-digital hybrid chip, and its power supply mode is Intermittent; the output of the energy storage device is connected to the power input of the analog-digital hybrid chip;

(3) Analog-digital hybrid chip, its function is to process and store the pressure data in the non-volatile storage unit, and transmit the data in the non-volatile storage unit out of the body through the radio frequency module, and it is also responsible for detecting Whether the piezoelectric ceramic element is worn out and manage the power circuit; the chip adopts the software of Synopsys and Cadence to design, synthesize, simulate, and make the layout of the digital part and the analog part respectively, and finally tape it out. The design of the chip power supply circuit overcomes the shortcoming that the model mentioned in the background technology section lacks this design.

(4) In-body antenna, which is connected together with the wireless transceiver device in the analog-digital hybrid chip;

(2) External parts The external parts are mainly signal receiving and processing devices, including:

(1) An external antenna, which is connected to an external wireless data transmission device for sending and receiving;

(2) External transceiver wireless data transmission device, which is connected in series by radio frequency circuit and large-capacity storage unit, and the radio frequency circuit is designed by the software of Cadence Company; this device is used to transmit radio frequency signal and receive and transmit data in the body; it is controlled and processed by computer connected to the device;

(3) The computer control and processing device is composed of a monitor, a host computer and a wireless data transceiver card connected to the host computer. This part is used to process data from the body for analysis and diagnosis by doctors.

The working mode of the two-way digital wireless implanted joint pressure monitoring system according to the present invention is characterized in that: it works according to any one of the following three working modes:

1) Joint working mode of piezoelectric ceramic device, energy storage device and analog-digital hybrid chip. This mode of operation occurs in the patient's daily life. When the patient moves and the piezoelectric ceramic is compressed, the piezoelectric ceramic can generate energy, which is stored in the energy storage circuit and powers the analog-digital hybrid chip, the analog-digital hybrid chip. The internal voltage regulator converts these energies into the voltage and current required by the chip and supplies energy. The hybrid analog-to-digital chip processes the pressure data from the sensor and stores it in a non-volatile memory unit. This way of working does not affect the patient's daily life.

2) Combined working mode of analog-digital hybrid chip, antenna, external transceiver wireless data transmission device, and computer control and processing device. This method occurs when a doctor is inquiring for a patient. The doctor uses the external transceiver wireless data transmission device to send the radio frequency signal to the analog-digital hybrid chip in the body. The analog-digital hybrid chip starts to work by obtaining energy from the radio frequency signal, and stores The data in the permanent storage unit is sent to the wireless data transmission device inside and outside the body, and then transmitted to the computer through the wireless data transceiver card.

3) System sleep mode. This working mode occurs in situations other than the two working situations described above, that is, there is no pressure on the piezoelectric ceramic device, and it is not the time of consultation. At this time, the system has no energy generation and is in a power-off state.

Invention effect:

1) The system can perform early detection of the working conditions of the implanted joints in the body, including the working ability of the implanted joints in the body (such as walking), abnormal asymmetric pressure, abnormal high pressure, looseness and angle errors, etc. The system provides doctors with The real-time monitoring data of the implanted joint pressure can relieve the patient's pain as soon as possible. The system has three different working modes. The first is the joint working mode of piezoelectric ceramic device, energy storage device and analog-digital hybrid chip. This method means that in the patient's daily life, the implanted joints will generate pressure during normal movement, and the system can collect pressure data and process and store it under the power supply of piezoelectric ceramics. This way of working does not affect the patient's daily life. The second is the combined working mode of an analog-digital hybrid chip, an antenna, an external receiving and receiving wireless data transmission device, and a computer control and processing device. This working mode occurs when the doctor is inquiring about the patient, and the internal and external radio frequency devices are used to supply power to the internal circuit and at the same time obtain the data in the non-volatile storage unit in the internal body. And through the wireless data transceiver card connected with the computer, the data can be transmitted to the computer for the doctor to diagnose. The third is the system sleep mode. This working mode means that when the patient’s implanted joints do not move in daily life, the piezoelectric ceramics are not under pressure and will not generate energy. All circuits are in a power-off state, and the system sleeps.

2) The design of the in vitro part of the present invention overcomes the shortcoming that the model mentioned in the background section does not consider the design of in vitro circuits. In addition, the entire system is designed with the purpose of low power consumption, low voltage and low noise, the system operating voltage is controlled at about 1 volt, and the analog-to-digital voltage is isolated, thereby reducing system power consumption, reducing system noise, and making up for the background noise. The model mentioned in the technical section is lacking.

3) For the first time, the communication between the body implanted in the joint and the body outside the body is realized, so that the computer outside the body can obtain pressure data wirelessly to make a reasonable diagnosis of the implanted joint.

4) It can collect all-round data on the pressure of the implanted joints in the living body. Through these pressure data, it can effectively detect the working ability (such as walking) of the implanted joints in the living body, abnormal asymmetric pressure, abnormal high pressure, looseness and angle errors etc.

5) The system has two power supply modes. In the above-mentioned first working mode, the system is intermittently powered by piezoelectric ceramic equipment. In the above-mentioned second working mode, the system is powered by radio frequency signals.

6) The implanted joint pressure data is simplified into simple characteristic data through a certain algorithm, which reduces the size of the non-volatile storage unit.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the body part of the present invention.

Fig. 2 is a schematic diagram of the structure of the in vitro part of the present invention.

Fig. 3 is a schematic diagram of a piezoelectric ceramic element used in the present invention.

FIG. 4 is a schematic diagram of the circuit principle of the radio frequency module of the wireless data receiving and transmitting device in the body of the present invention.

Fig. 5 is a structural schematic diagram of the piezoelectric ceramic signal processing process of the present invention.

FIG. 6 is a schematic diagram of the circuit principle of the analog-digital hybrid chip of the present invention.

Fig. 7 is a schematic diagram of the working state of the system of the present invention.

Detailed ways

The invention proposes a fully digital living body implanted joint pressure monitoring system which is controllable by two-way wireless communication and can save pressure data in real time. The system adopts the design scheme of analog-digital hybrid, which is composed of six parts: piezoelectric ceramic device, energy storage device, analog-digital hybrid chip, antenna, in vitro wireless data transmission device, and computer control and processing device. Piezoelectric ceramic devices, both sensors that transmit pressure signals and that generate energy under pressure to power other circuits, are placed in implanted joints. These pressure signals enter the analog-to-digital conversion circuit through the amplifier, filter and multiplexer in the analog-to-digital hybrid chip, and then the characteristic data are processed by the algorithm of the control unit and stored in the non-volatile storage unit. The chip is also placed in the implanted joint, and its encapsulation housing is made of a polymer compatible material. The control unit in the chip also performs power management and logic control of the entire circuit. One end of the chip is connected to the piezoelectric ceramic device, and the other end is connected to the antenna. The antenna outside the chip can realize data communication inside and outside the chip around the chip. The radio frequency circuit part in the body, the antenna, and the wireless transceiver module outside the body jointly complete the data transmission function.

There are two power supply methods in the body: one is piezoelectric ceramic power supply; the other is radio frequency signal power supply. Among them, the piezoelectric ceramic power supply mode is intermittent. The energy generated by piezoelectric ceramics under pressure enters the energy storage capacitor after being rectified by the full-wave bridge. According to the characteristics of the capacitor, when the energy generated by piezoelectric ceramics is not enough for the load to work, the energy will charge the storage capacitor. When the storage capacitor When the energy is sufficient for the load to work, the storage capacitor is in a discharged state. The current from the capacitor passes through the energy rectifier to obtain a stable current. RF signal power supply means that in the case of consultation, the external circuit sends a radio frequency signal, and the internal circuit obtains energy from the radio frequency signal to work. The external wireless receiving and transmitting data transmission device includes an antenna receiving array to receive the pressure data transmitted from the body and send it to the computer control and processing device. In the computer control and processing device, the wireless data transceiver card and the transceiver antenna connected to the computer host realize two-way data communication with the wireless transceiver device in the body, and at the same time, the pressure data of the patient's implanted joints can be observed on the monitor in real time. The host computer can process data to assist doctors in diagnosis. When performing the implanted joint inspection, the patient sits on a chair, and the doctor aligns the external transceiver device at the implanted joint of the patient at a distance of about 20 cm. After about 1 minute of irradiation, the data in the body can be transmitted to the computer. The whole operation is simple, and the patient has no discomfort and pain.

The system has three different working modes. The first is the joint working mode of piezoelectric ceramic device, energy storage device and analog-digital hybrid chip. In this way, the patient's daily life, the implanted joints will generate pressure during normal movement, and the system can collect pressure data and process and store it under the power supply of piezoelectric ceramics. This way of working does not affect the patient's daily life. The second is the joint working mode of analog-digital hybrid chip, antenna, external transceiver wireless data transmission device, and computer control and processing device. This working mode occurs when a doctor consults a patient. While supplying power, the data in the non-volatile storage unit in the body is obtained. Because the system includes a wireless data transmitter connected with the computer, and an external wireless transceiver capable of real-time communication with the computer. So in vivo data can be transmitted to a computer for doctors to diagnose. The third is the system sleep mode, which means that when the patient is implanted in the joints in daily life and does not move, the piezoelectric ceramics are not under pressure and will not generate energy, all circuits are in a power-off state, and the system sleeps.

Fig. 1 is a schematic diagram of the overall structure of the body part of the present invention. Among them, 1 is a piezoelectric ceramic device, 2 is an energy storage device, 3 is an analog-digital hybrid chip, and 4 is an antenna. Piezoelectric ceramic devices, both sensors that transmit pressure signals and that generate energy under pressure to power other circuits, are placed in implanted joints. The analog-digital hybrid chip processes and stores the pressure data in the non-volatile storage unit, and can transmit the data in the non-volatile storage unit out of the body through the radio frequency module, and it is also responsible for detecting whether the piezoelectric ceramic element is worn or not. wear. The analog-digital hybrid chip is placed in the implanted joint as well as the piezoceramic element. The chip packaging shell is made of compatible polymer materials. One end of the chip is connected to the piezoelectric ceramic device, and the other end is connected to the antenna. The antenna outside the chip can be placed around the chip.

Fig. 2 is a schematic structural diagram of the in vitro part of the present invention, wherein 5 is a wireless transceiver device, and 6 is a computer control and processing device. During consultation, the external part starts to work, and the wireless transceiver device sends radio frequency signals to the radio frequency module in the body, and receives data in the body to the computer control and processing device.

3 is a schematic diagram of the piezoelectric ceramic element used in the present invention, wherein 7 is a pressure dispersing metal plate, 8 is a bearing, and 9 is a piezoelectric ceramic element. This figure includes 3 piezoelectric ceramic elements.

Fig. 4 is a block diagram of the circuit principle of the radio frequency module of the present invention. 401 is a modulation device, 402 is an RF (Radio Frequency) limiter, 403 is a detector, 404 is a regulator, 405 is an oscillator, 406 is a demodulator, 407 is a clock generator, 408 is a current bias circuit, 409 is a modulator, 410 is a reset signal generation circuit; P1 and P2 are interfaces connected to the antenna; S1 is a clock signal, S2 is a data signal, and S3 is a reset signal. S1, S2 and S3 are output signals. The output of the modulation device (401) is connected to the input of the RF limiter (402) and the input of the regulator (404), and the output of the RF limiter (402) is connected to the input of the detector (403) and the demodulator (405) , the outputs of the detector (403) and the demodulator (405) are respectively connected to the input of the regulator (404) and the clock generator (407), and the output of the regulator (404) is connected to the oscillator (405), current Input to the bias circuit (408) and reset signal generation circuit (410).

Fig. 5 is a schematic structural diagram of the sensor signal processing process of the present invention. S4-S6 are signals from three piezoelectric ceramic sensors, 502 is a switch for time-division multiplexing of three signals, 503 is a power amplifier, and 504 is a low-pass filter. S7 is the analog pressure signal after multiplexing and filtering. The pressure signal obtained by the piezoelectric ceramic sensor is multiplexed into the amplifier and filter, and then enters the analog-to-digital conversion circuit to obtain the digital signal of pressure.

Fig. 6 is a schematic block diagram of the circuit of the analog-digital hybrid chip of the present invention. Among them, 601 is a sensor switch detection circuit, which is used to detect whether the piezoelectric ceramic element is worn out; 602 is a low-power control unit, which is responsible for processing pressure data and storing the data in a non-volatile storage unit; 603 is a non-volatile 604 is a data modulation and error detection module; 605 is a sensor interface; 606 is a sensor signal processing module, including a multiplexing circuit, a power amplifier circuit and a filter circuit; 607 is an analog-to-digital converter; 608 is a wireless transceiver device; 609 610 is a power management circuit; 611 is a radio frequency energy regulator; 612 is a radio frequency signal processing circuit. The input end of the sensor switch detection circuit (601) is respectively connected with the output end of the piezoelectric ceramic device (1) and the output end of the control unit (602). The output terminal of the control unit (602) is also connected to the input terminal of the non-volatile storage unit (603), and the non-volatile storage unit (603) is bidirectionally connected with the data modulation and error detection module (604). The detection module (604) is bidirectionally connected with the wireless transceiver (608). The input end of the sensor interface (5) is connected to the output end of the piezoelectric ceramic device (1), the output end of the sensor interface (5) is connected to the input end of the sensor signal processing module (606), and the sensor signal processing module (606) The output terminal is connected to the input terminal of the analog-to-digital converter (607). The output of the analog-to-digital converter (607) is connected to the input of the control unit (602). The input terminal of the voltage regulator (609) is connected to the output terminal of the energy storage device (2), and its output terminal is connected to the input terminal of the power management circuit (610). The output end of the radio frequency energy regulator (611) is also connected to the input end of the power management circuit (610), and its input end is connected to the output end of the radio frequency signal processing circuit (612). Both the wireless transceiver (608) and the radio frequency signal processing circuit (612) are bidirectionally connected to the antenna (4).

Fig. 7 is a schematic diagram of the working state machine of the system of the present invention. Among them, State0 is the system sleep mode, State1 is the consultation state, and State2 is the patient's daily life state. co1: The power supply voltage of the radio frequency circuit and the voltage generated by the piezoelectric ceramic equipment are both lower than the system operating voltage; co2: The power supply voltage of the radio frequency circuit is equal to the system operating voltage and the voltage generated by the piezoelectric ceramic equipment is less than the system operating voltage; co3: The power supply voltage of the radio frequency circuit is less than The system operating voltage and the voltage generated by piezoelectric ceramic equipment and other system operating voltages

The piezoelectric ceramic device (1) includes three piezoelectric ceramic elements (9), a pressure dispersing metal plate (7) and a bearing (8). The piezoelectric ceramic element (9) is not only a sensor for transmitting pressure data but also generating energy under pressure . In the daily life of the patient, the implanted joints will generate pressure during normal movement, and the pressure will be converted into electrical energy through the piezoelectric ceramic device (1) and output to the energy storage device (2). The energy storage device (2) is an analog-digital hybrid chip ( 3) Power supply to make it work, the analog-digital hybrid chip (3) collects pressure data and processes and stores it when the piezoelectric ceramic device (1) is powered. The signals (S4-S6) from the three piezoelectric ceramic sensors enter the sensor signal processing module (606) (including the switch (502) through the sensor interface (605) to realize time-division multiplexing of the three-way signals, and the power amplifier (503) amplifies weak signal and low-pass filter (504)) to obtain the multiplexed and filtered analog pressure signal (S7), and the analog pressure signal (S7) enters the analog-to-digital converter (607) to obtain the digital signal of pressure. The low power consumption control unit (602) processes the pressure data according to a certain algorithm and saves the data to the non-volatile storage unit (603). At the same time, the sensor switch detection circuit (601) detects whether the piezoelectric ceramic element is worn out.

When the doctor consults a patient, the radio frequency device in the body, namely the radio frequency signal processing circuit (612), the radio frequency device (5) in the body and the antenna (4) inside and outside the body, supplies power for the analog-digital hybrid chip (3) and simultaneously obtains the nonvolatile memory in the body. The data in permanent storage unit (603). And through the wireless data transceiver card connected with the computer (6), the pressure data can be transmitted to the computer for the doctor to diagnose. In this case, the data modulation and error detection module (604) performs modulation and error detection on the communicated data. The wireless transceiver (608) is an internal antenna. The voltage regulator (609) adjusts the voltage generated by the radio frequency signal to meet the operating voltage of the analog-digital hybrid chip (3), and the radio-frequency energy regulator (611) adjusts the energy of the radio frequency signal to make it sufficient to produce a voltage consistent with the analog-digital hybrid chip (3). Operating Voltage. The power management circuit (610) manages the power generated by the piezoelectric ceramic device (1) and the power generated by the radio frequency signal, so that they can provide power for the analog-digital hybrid chip (3) without conflict, and at the same time determine their size to determine the analog-digital hybrid chip (3) Working status. The analog-digital hybrid chip (3) has three working states: sleep state (State0), consultation state (State1) and patient’s daily life state (State2). When the power supply voltage of the RF circuit and the voltage generated by the piezoelectric ceramic device are lower than the voltage (co1), the analog-digital hybrid chip (3) enters the dormant state (State0); when the power supply voltage of the radio frequency circuit is equal to the system operating voltage and the voltage generated by the piezoelectric ceramic device is lower than the system operating voltage (co2), the analog-digital hybrid chip (3) Enter the consultation state (State1); when the power supply voltage of the radio frequency circuit is lower than the system operating voltage and the system operating voltage (co3) such as the voltage generated by the piezoelectric ceramic device, the analog-digital hybrid chip (3) enters the patient's daily life state ( State2).

The radio frequency signal processing circuit (612) includes the following parts: the signal enters the modulation device (401) from the interface (P1 and P2) connected to the antenna (4) to receive modulation, and the signal from the interface (P1) simultaneously enters the RF limit The detector (402) is adjusted to make the energy meet the system requirements, and the adjusted signals respectively enter the detector (403) and the demodulator (406) to become a lower pulse square wave and enter the regulator (404) to receive waveform adjustment. The clock generator (407) extracts a clock from the demodulated signal for the operation of the digital circuit and outputs a clock signal (S1). The current bias circuit (408) provides a current bias for the radio frequency signal processing circuit (612). An oscillator (405) generates a high frequency clock for the memory cells to operate. The modulator (409) modulates the signal from the modulation device (401) and outputs a data signal (S2). A reset signal generation circuit (410) generates a reset signal S3.

Thus, the system realizes the purpose of the invention.

Claims (1)

1. Two-way digital wireless implanted joint pressure monitoring system, characterized in that the system consists of two parts: inside and outside the body: (1) Parts of the body include: (1) Piezoelectric ceramic device, including 3 piezoelectric ceramic elements, which are not only the sensor to transmit pressure data but also generate electrical energy output under pressure; the three output terminals of the piezoelectric ceramic device are respectively connected to the input terminals of the analog-digital hybrid chip below and the input end of the energy storage device; (2) An energy storage device, including a rectifier circuit and an energy storage circuit; the current output from the three output terminals of the piezoelectric ceramic device passes through the rectification circuit and then supplies the energy storage circuit, and the energy storage device supplies power to the analog-digital hybrid chip; the energy storage device The output end is connected to the power input end of the analog-digital hybrid chip; (3) Analog-digital hybrid chip, including non-volatile storage unit, radio frequency module and wireless transceiver device, its function is to process and store the pressure data generated by the implanted joints during the patient's daily movement in the non-volatile storage unit , and can transmit the data in the non-volatile storage unit out of the body through the radio frequency module, and it is also responsible for detecting whether the piezoelectric ceramic element is worn out and managing the power circuit; (4) In-body antenna, which is connected together with the wireless transceiver device in the analog-digital hybrid chip; (2) In vitro parts include: (1) An external antenna, which is connected to an external wireless data transmission device for sending and receiving; (2) The wireless data transmission device for sending and receiving outside the body, which is composed of a radio frequency circuit and a large-capacity storage unit in series, and is used to transmit radio frequency signals and receive and transmit data in the body; it is connected with the computer control and processing device; (3) The computer control and processing device is connected with the wireless data transmission device outside the body, and this part is used to process the data from the part inside the body for analysis and diagnosis by doctors.

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