Medical instrument volume type micro flow measurement standard device

Abstract

The invention discloses a medical instrument volume type micro flow measurement standard device which comprises a non-deformation balloon, an elastic membrane is fixedly connected to the middle of the interior of the non-deformation balloon, and the interior of the non-deformation balloon is divided into a left cavity and a right cavity which are independent from each other through the elastic membrane; a magnetic sheet is arranged in the middle of the elastic diaphragm, reed pipes are respectively arranged on the wall of the non-deformable balloon on the two sides of the magnetic sheet, the time required for filling the balloon every time is a timing period, the total volume of output liquid in each timing period is about V, and then the flow velocity is calculated. According to the invention, metering is more accurate and rapid, and high-accuracy and high-repeatability traceability can be obtained under different temperatures, humidity and airflows.

Description

Technical Field

[0001] This invention relates to the field of flow metering device technology, and specifically to a volumetric micro-flow metering standard device for medical instruments. Background Technology

[0002] In the medical field, micro-flow rates typically refer to those below 10 mL / min. Precise measurement of these rates remains a highly challenging technological frontier. Compared to conventional large-flow rate measurement, micro-fluids are more significantly affected by changes in Reynolds number, surface tension, tube wall roughness, and fluid physical properties. Currently, mainstream micro-flow rate measurement methods include thermal measurement, Coriolis force measurement, and displacement / volume measurement. Thermal measurement, based on Thomas's law, heats the fluid using a heating element on the probe and measures the temperature difference using upstream and downstream temperature sensors. This method suffers from poor universality, extreme dependence on fluid properties, and inability to provide accurate and rapid results. Coriolis force measurement utilizes the Coriolis force generated when the fluid flows in a vibrating tube, causing the measuring tube to twist. The amount of twist is proportional to the mass flow rate. While relatively accurate, it is susceptible to vibration and exhibits significant zero-point drift. Volumetric measurement uses mechanical cavities (such as elliptical gears or miniature pistons) to divide the fluid into small units of known volume. Currently, there are no national calibration procedures for fluid control components such as micro-valves, micro-pumps, and micro-flowmeters, making it difficult to guarantee the accuracy of these measuring components' structures, and consequently, the accuracy of their test data. Therefore, there is an urgent need to research a metrological standard device capable of measuring the minute flow rates (1-50 ml / h) of medical infusion pumps and syringe pumps.

[0003] Traceability methods for volumetric measurements include traceability of time and volume. Traceability of time is mainly accomplished through timers, which is highly accurate. Therefore, the traceability accuracy of standard devices for volumetric measurements depends on the traceability results of volume. There are currently two main methods for volumetric traceability: the dimensional method and the weighing method. The weighing method involves filling the chamber of the metering standard device with liquid, weighing the mass of liquid discharged at a set standard volume, and calculating the standard volume to obtain the traceability result of the standard device's volume in one step. This method is more suitable for standard devices with large weighing masses. However, for metering standard devices with small flow rates, the weighing mass is small and time is long, the amount of liquid evaporation cannot be ignored, the traceability repeatability is poor under different temperatures, humidity, and airflow conditions, and the stress at the pipe outlet will cause an indefinite amount of liquid to adhere, resulting in a large deviation in traceability results at the mL level. The dimensional method mainly measures the dimensional accuracy of the plunger or piston cylinder and the longitudinal displacement accuracy of the drive components such as motors. By tracing the cross-sectional area and movement distance separately, the volumetric traceability result of the standard device is obtained. This method is also time-consuming. For injections with small flow rates, a certain volume of liquid is required to obtain the measurement result, and therefore, the current flow rate cannot be displayed in real time. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, the present invention aims to provide a volumetric micro-flow metering standard device for medical instruments. This standard device can avoid the effects of liquid evaporation and uneven liquid adhesion at the pipe outlet before and after tracing caused by long-term tracing, and achieve high accuracy, high repeatability, and reproducibility of tracing under different temperatures, humidity, and airflow conditions.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A volumetric micro-flow metering standard device for medical instruments is characterized by comprising a non-deformable balloon, with an elastic diaphragm fixedly connected in the middle inside the non-deformable balloon, dividing the inner cavity of the non-deformable balloon into two independent cavities, left and right. A magnetic sheet is provided in the middle of the elastic diaphragm, and a reed switch is respectively installed on the non-deformable balloon wall on both sides of the magnetic sheet. The two reed switches are connected in a circuit as trigger switches to control the solenoid valves in the entire circuit. The trigger signal of the reed switch is sent to the SR register, and the output signal of the SR register controls the operation of transistors Q1 / Q2 respectively, and is also sent to the signal acquisition unit, and then transmitted to the microcontroller to calculate the flow rate data. The left and right cavities of the non-deformable balloon are each connected to and communicate with an inlet pipe and an outlet pipe, wherein the inlet pipe of the left cavity and the outlet pipe of the right cavity are connected to the same normally open solenoid valve, and the outlet pipe of the left cavity and the inlet pipe of the right cavity are connected to the same normally closed solenoid valve.

[0006] Furthermore, the non-deformable spherical capsule is ellipsoidal.

[0007] Furthermore, the above-mentioned volumetric micro-flow metering standard device for medical instruments is used as follows: Step 1): Set the volume of the non-deformable balloon cavity to a fixed value V; first, pump liquid into the left cavity of the non-deformable balloon through the liquid inlet of the normally open solenoid valve and the corresponding liquid inlet pipe. The liquid pushes the elastic diaphragm to the right to undergo elastic deformation until the non-deformable balloon cavity is filled. The SR register outputs a high level, driving transistors Q1 and Q2 to work. The solenoid valve drive circuit is turned on. At this time, the microcontroller timer is t1. Step 2): Open the normally closed solenoid valve and close the normally open solenoid valve. Pump liquid into the right cavity of the non-deformable balloon through the inlet of the normally closed solenoid valve and the corresponding inlet pipe. The liquid pushes the elastic diaphragm to the left to undergo elastic deformation. The liquid in the left cavity flows out through the normally closed solenoid valve. The liquid continues to push the elastic diaphragm to the left to undergo elastic deformation until the inner cavity of the non-deformable balloon is filled with liquid. The reed switch on the left closes under the attraction of the magnetic plate. The SR register outputs a low level. Transistors Q1 and Q2 do not work. The solenoid valve drive circuit does not conduct. Both the normally closed and normally open solenoid valves return to their initial state. The microcontroller detects the corresponding signal and times once. Step 3): Repeat steps 1) and 2) multiple times. The time from the start of step 1) to the start of step 2) is one timing cycle. The next timing cycle is from the start of step 2) to the start of the next timing cycle of step 1), and so on. The volume in the time period corresponding to each timing cycle is V, and the time period of each cycle is Δt. The flow rate = V / Δt is obtained by the microcontroller and displayed on the display.

[0008] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes the liquid output from a syringe pump or infusion pump to drive an elastic diaphragm inside a balloon. Because the non-deformable balloon has a small and fixed volume, the volume of liquid exiting the balloon within a cycle is constant. The time required for the balloon to fully fill each time constitutes one timing cycle. The total volume of liquid output within each timing cycle is approximately V, from which the flow rate is calculated. Using this invention, measurement is more accurate and faster, and traceability with high accuracy and repeatability can be achieved under different temperatures and humidity conditions. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the non-deformable balloon structure described in this invention. Detailed Implementation

[0010] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. Any parts not detailed below are based on existing techniques in the art.

[0011] like Figure 1-2As shown, a volumetric micro-flow metering standard device for medical instruments according to the present invention includes a non-deformable balloon 1, an elastic diaphragm 2, a left cavity 1.1, a right cavity 1.2, a first Y-type interface 3, a second Y-type interface 4, a first inlet pipe 5, a first outlet pipe 6, a second inlet pipe 7, a second outlet pipe 8, a normally open solenoid valve 9, a normally closed solenoid valve 10, a magnetic sheet 11, a first reed switch K1, a second reed switch K2, an SR register 12, a signal acquisition unit 13, a microcontroller 14, and a display 15.

[0012] The non-deformable balloon 1 has a vertically arranged circular elastic diaphragm 2 fixedly connected to its interior center. The elastic diaphragm 2 divides the internal cavity of the non-deformable balloon 1 into two independent and non-communicating cavities: a left cavity 1.1 and a right cavity 1.2. A first Y-shaped interface 3 is formed on the side wall of the non-deformable balloon 1 corresponding to the left cavity 1.1, with its other two ports connected to a first inlet pipe 5 and a first outlet pipe 6, respectively. A second Y-shaped interface 4 is formed on the side wall of the non-deformable balloon 1 corresponding to the right cavity 1.2, with its other two ports connected to a second inlet pipe 7 and a second outlet pipe 8, respectively. The first inlet pipe 5 is connected to the inlet passage of the normally open solenoid valve 9, and the second outlet pipe 8 is connected to the outlet passage of the normally open solenoid valve 9; the second inlet pipe 7 is connected to the inlet passage of the normally closed solenoid valve 10, and the first outlet pipe 6 is connected to the outlet passage of the normally closed solenoid valve 10; the inlet passages of the normally open solenoid valve 9 and the normally closed solenoid valve 10 are ultimately connected to the same inlet manifold (inlet port).

[0013] The internal volume V of the non-deformable balloon 1 is set to a fixed value, such as 0.1ml or 0.5ml. The elastic diaphragm 2 is made of elastic rubber. A magnetic sheet 11 is fixedly connected to the middle of the elastic diaphragm 2. A first reed switch K1 and a second reed switch K2 are fixedly connected to the outer walls of the non-deformable balloon on the left and right sides of the magnetic sheet 11, respectively. The positive terminal of the second reed switch K2 is connected to the positive terminal Vi of the power supply. The negative terminal of the first reed switch K1 is connected to the negative terminal of the power supply via R1 and R2. The negative terminal of the first reed switch K2 is connected to the negative terminal of the power supply via R3 and R4. The R input port of the SR register 12 is connected between R1 and R2 for sampling, and the S input port of the SR register is connected between R3 and R4 for sampling. The Q output port of the SR register is connected to the base b of transistors Q1 and Q2 respectively. The collector c of transistors Q1 and Q2 is connected to the positive terminal Vi of the power supply respectively. The emitter e of transistor Q1 is connected to the coil of normally closed solenoid valve 10 to control its operation. The emitter e of transistor Q2 is connected to the coil of normally open solenoid valve 9 to control its operation. The input terminal of the signal acquisition unit 13 is connected to the output Q port of the SR register 12. The output terminal of the signal acquisition unit 13 is connected to the input terminal of the microcontroller 14. The output terminal of the microcontroller 14 is connected to the input terminal of the microcontroller 15 (to display the calculated flow rate). The microcontroller used in this application can be a 51 microcontroller, utilizing its timing and calculation functions.

[0014] There are two processes involved in the work: Process 1: Liquid enters the left cavity 1.1 through the normally open solenoid valve 9, and liquid in the right cavity 1.2 is discharged through the normally open solenoid valve 9 until the cavity is full. The magnetic plate 11 approaches the second reed K2, at which time K2 closes. The input signals S and R of the SR register 12 are 1 and 0 respectively, and the SR register outputs a high level 1. The high level drives Q1 and Q2 to work, the normally open solenoid valve 9 and the normally closed solenoid valve 10 work, K2 closes, the microcontroller detects the rising edge of the square wave and starts timing once, which is recorded as t1. Process 2: Liquid flows into the right cavity 1.2 through the normally closed solenoid valve 10. Diaphragm 2 moves to the left, and magnet 11 moves away from the second reed switch K2, causing K2 to open. At this time, the input state of SR register 12 becomes 00, while the output remains 1. The high level drives Q1 and Q2 to work continuously, and the two solenoid valves 9 and 10 continue to work. Liquid in the left cavity 1.1 is discharged through the normally closed solenoid valve 10, and the liquid continues to flow into the right cavity 1.2 until it is full. Magnet 11 approaches the first reed switch K1, at which time K1 closes. The input signals S and R of SR register 12 are 0 and 1 respectively, and SR register 12 outputs a low level of 0. Q1 and Q2 stop working, and the two solenoid valves 9 and 10 return to their initial states (normally open and normally closed). At this time, the microcontroller 14 times once, which is recorded as t2. Afterward, the liquid re-enters the left half-chamber through the normally open solenoid valve. When the diaphragm moves to the right, K1 disconnects, and the SR register input state becomes 00, maintaining a low output level of 0. Q1 and Q2 remain disconnected, and the liquid continues to enter the left half-chamber through the normally open solenoid valve, repeating process one and process two. The time from the start of process one to the start of process two constitutes one cycle. The next cycle begins from the start of process two to the start of the next process one, and so on. The volume within each cycle is V, and the time period of each cycle is Δt. The time Δt obtained by the timer is Δt = t2-t1 / t3-t2 / t4-t3 / t5-t4, etc. Within one timing cycle, the liquid fills the cavity once, and the liquid volume is V. The flow rate is calculated by the microcontroller as V / Δt. This method of filling the cavity once allows for faster flow rate measurement.

[0015] Table 1: Truth Table of SR Register .

Claims

1. A volumetric micro-flow metering standard device for medical instruments, characterized in that, The device includes a non-deformable balloon, inside which an elastic diaphragm is fixedly connected in the middle. The elastic diaphragm divides the inner cavity of the non-deformable balloon into two independent cavities, left and right. A magnetic sheet is located in the middle of the elastic diaphragm, and a reed switch is installed on the non-deformable balloon wall on both sides of the magnetic sheet. The two reed switches are connected in a circuit, serving as trigger switches to control the solenoid valves in the entire circuit. The trigger signal of the reed switch is sent to the SR register, and the output signal of the SR register controls the operation of transistors Q1 and Q2 respectively. At the same time, the signal is sent to the signal acquisition unit, and then transmitted to the microcontroller to calculate the flow rate data. The left and right cavities of the non-deformable balloon are each connected to an inlet pipe and an outlet pipe. The inlet pipe of the left cavity and the outlet pipe of the right cavity are connected to the same normally open solenoid valve, and the outlet pipe of the left cavity and the inlet pipe of the right cavity are connected to the same normally closed solenoid valve.

2. The volumetric micro-flow metering standard device for medical instruments according to claim 1, characterized in that, The non-deformable balloon is ellipsoidal.

3. A volumetric micro-flow metering standard device for medical instruments according to claim 1 or 2, characterized in that, Its usage method is as follows: Step 1): Set the volume of the non-deformable balloon cavity to a fixed value V; first, pump liquid into the left cavity of the non-deformable balloon through the liquid inlet of the normally open solenoid valve and the corresponding liquid inlet pipe. The liquid pushes the elastic diaphragm to the right to undergo elastic deformation until the non-deformable balloon cavity is filled. The SR register outputs a high level, driving transistors Q1 and Q2 to work. The solenoid valve drive circuit is turned on. At this time, the microcontroller timer is t1. Step 2): Open the normally closed solenoid valve and close the normally open solenoid valve. Pump liquid into the right cavity of the non-deformable balloon through the inlet of the normally closed solenoid valve and the corresponding inlet pipe. The liquid pushes the elastic diaphragm to the left to undergo elastic deformation. The liquid in the left cavity flows out through the normally closed solenoid valve. The liquid continues to push the elastic diaphragm to the left to undergo elastic deformation until the inner cavity of the non-deformable balloon is filled with liquid. The reed switch on the left closes under the attraction of the magnetic plate. The SR register outputs a low level. Transistors Q1 and Q2 do not work. The solenoid valve drive circuit does not conduct. Both the normally closed and normally open solenoid valves return to their initial state. The microcontroller detects the corresponding signal and times once. Step 3): Repeat steps 1) and 2) multiple times. The time from the start of step 1) to the start of step 2) is one timing cycle. The next timing cycle is from the start of step 2) to the start of the next timing cycle of step 1), and so on. The volume in the time period corresponding to each timing cycle is V, and the time period of each cycle is Δt. The flow rate = V / Δt is obtained by the microcontroller and displayed on the display.

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