A micro-injection device integrated with precise control function of medicine liquid

Abstract

The application provides a micro-injection device integrated with precise liquid medicine metering control function, and relates to the technical field of medical devices, comprising a syringe, a closed-loop control system, a driving motor electrically connected with the closed-loop control system and a pressure sensing component connected with the driving motor, an output shaft of the driving motor connected with a lead screw through a coupling, an anti-backlash nut pair arranged on the lead screw, the pressure sensing component connected between the anti-backlash nut pair and a syringe push rod for collecting axial reaction force data generated by the syringe push rod in the process of pushing liquid medicine in real time, and the closed-loop control system dynamically adjusting the step pulse frequency output to the driving motor according to the axial reaction force data and comparing with a preset characteristic curve. The application solves the problem of displacement response lag caused by mechanical fitting gap in the prior art micro-injection device.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a micro-injection device that integrates precise drug dosage control. Background Technology

[0002] Micro-injection devices are key equipment used in clinical medicine and high-precision scientific research experiments to accurately control the titration rate of drug solutions. However, in situations involving ultra-micro-volume drug administration or high-frequency micro-adjustment, existing micro-injection devices generally have physical gaps in the mechanical cooperation between the motor, lead screw, and push rod. During the device startup phase or when making micro-step frequency switching, displacement response lag is prone to occur, resulting in a deviation between the actual dispensing volume and the theoretical calculation value. Summary of the Invention

[0003] The purpose of this invention is to provide a micro-injection device that integrates precise drug metering and control functions, which solves the problem of displacement response lag caused by mechanical fit gaps in existing micro-injection devices.

[0004] The technical solution of this invention:

[0005] This invention provides a micro-injection device integrating precise drug metering control, comprising a syringe, a closed-loop control system, a drive motor and a pressure sensing component electrically connected to the closed-loop control system, wherein the pressure sensing component is connected to the drive motor, and the output shaft of the drive motor is connected to a lead screw via a coupling, and a backlash-free nut is fitted on the lead screw; the pressure sensing component is connected between the backlash-free nut and the syringe plunger, for real-time acquisition of axial reaction force data generated by the syringe plunger during the drug delivery process; the closed-loop control system dynamically adjusts the stepping pulse frequency output to the drive motor based on the axial reaction force data and by comparing it with a preset characteristic curve.

[0006] Furthermore, the surface of the lead screw has a trapezoidal thread, and its lead deviation is controlled within ±0.005mm.

[0007] Furthermore, the coupling is a flexible diaphragm coupling, and the output shaft of the drive motor is coaxial with and fixedly connected to the lead screw.

[0008] Furthermore, the backlash-eliminating nut assembly is connected to the tail of the syringe plunger via a slider mechanism, and the displacement hysteresis time during the start-up phase is less than 10ms.

[0009] Furthermore, the backlash-free nut assembly includes a main nut and a secondary nut that cooperate with each other, and a preload spring is connected between the main nut and the secondary nut, and the preload spring is always in a compressed state.

[0010] Furthermore, the axial backlash-eliminating torque generated by the backlash-eliminating nut assembly satisfies the formula:

[0011]

[0012] in, For preload, The mean diameter of the leadscrew. For thread helix angle, It is the equivalent friction angle.

[0013] Furthermore, the pressure sensing component includes a force sensor, which employs a full-bridge strain gauge structure, with its sensing surface perpendicular to the axis of the syringe plunger.

[0014] Furthermore, the closed-loop control system includes a control unit that acquires real-time pressure data at a sampling frequency of 100Hz and calculates pressure change values.

[0015] Furthermore, the signal output terminal of the force sensor is electrically connected to the analog input interface of the control unit via a shielded cable.

[0016] Furthermore, the control unit compensates the stepping pulse frequency of the drive motor in real time based on the axial reaction force deviation. The compensation logic is as follows:

[0017]

[0018] in, The pulse frequency, This is the deviation of the axial reaction force. The theoretically preset pulse frequency, This is the proportional gain coefficient. This is the differential gain coefficient.

[0019] Based on the above technical features, the beneficial effects of the present invention are as follows:

[0020] (1) The present invention provides a micro-injection device with integrated precise measurement and control function of liquid medicine. By eliminating the gap nut pair, the physical dead zone in the transmission chain in the prior art can be eliminated, and the displacement lag problem in the start-up and fine-tuning stages can be solved.

[0021] (2) The present invention provides a micro-injection device with integrated precise drug metering control function. Through the pressure sensing component at the end of the syringe plunger, a closed-loop monitoring system for the entire process is realized. It can effectively sense and automatically compensate for flow deviation caused by pipeline pressure fluctuations or drug viscosity changes, ensure the uniformity of drug administration rate, and thus greatly improve the accuracy of drug dosage. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the structure of the present invention;

[0023] Figure 2 A schematic diagram illustrating the working principle of the device provided by the present invention.

[0024] In the diagram: 1. Syringe; 2. Closed-loop control system; 3. Control unit; 4. Drive motor; 5. Backlash-free nut assembly; 6. Force sensor. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0027] To better understand this invention, it should be noted that existing micro-injection devices typically use a motor to drive a lead screw to rotate. By converting rotational motion into linear displacement, the syringe plunger is pushed within the syringe barrel to move at a constant speed or in a programmed manner, thereby achieving continuous and stable drug infusion. Moreover, they mostly employ an open-loop control mode based on displacement, lacking real-time monitoring and feedback correction functions for the actual flow rate at the drug output end. When pressure fluctuations within the infusion tubing or changes in drug viscosity cause alterations in injection resistance, the system often fails to detect and promptly correct the thrust output. This not only affects the uniformity of the drug delivery rate but also exposes the precise control of the drug dosage to a high risk of fluctuation.

[0028] Example

[0029] Please refer to the above as well. Figures 1-2This invention provides a micro-injection device integrating precise drug measurement and control functions. The device includes a syringe 1, a closed-loop control system 2, a drive motor 4 electrically connected to the closed-loop control system 2, and a pressure sensing component. The pressure sensing component is connected to the drive motor 4. The output shaft of the drive motor 4 is connected to a lead screw via a coupling, and a backlash-free nut 5 is fitted on the lead screw. The pressure sensing component is connected between the backlash-free nut 5 and the plunger of the syringe 1, and is used to collect axial reaction force data generated by the plunger of the syringe 1 during the process of pushing the drug in real time. The closed-loop control system 2 dynamically adjusts the stepping pulse frequency output to the drive motor 4 based on the axial reaction force data and by comparing it with a preset characteristic curve.

[0030] It should be noted that the micro-injection device with integrated precise drug metering control function in this embodiment of the invention, during initial startup, eliminates mechanical backlash through the backlash-eliminating nut pair 5, achieving precise transmission while ensuring that the stepping pulses of the drive motor 4 are immediately converted into the linear displacement of the syringe plunger 1. During operation, the pressure sensing component detects pressure fluctuations within its chamber in real time. When the tubing resistance fluctuates due to changes in the physical properties of the drug solution, the control loop control system automatically adjusts the speed of the drive motor 4, thereby achieving dynamic compensation of the thrust output. This invention can effectively improve the drug delivery accuracy and flow rate uniformity of the micro-injection device in complex medical and experimental scenarios.

[0031] In detail, the output shaft of the drive motor 4 is connected to the power input end of the lead screw via a coupling.

[0032] In detail, the pressure sensing component is connected between the backlash-free nut assembly 5 and the physical contact surface of the syringe plunger 1.

[0033] Furthermore, the lead screw has a trapezoidal thread on its surface, and its lead deviation is controlled within ±0.005mm.

[0034] Furthermore, the coupling is a flexible diaphragm coupling, and the output shaft of the drive motor 4 is coaxial with and fixedly connected to the lead screw.

[0035] Furthermore, the gap-eliminating nut assembly 5 is connected to the tail of the syringe 1 plunger via a slider mechanism, and the displacement lag time during the start-up phase is less than 10ms.

[0036] In some embodiments, the slider mechanism includes a linear slide rail and a U-shaped clamping block. The linear slide rail is fixed on a backlash-eliminating nut, and the U-shaped clamping block is engaged with the tail of the syringe 1 push rod. The inner wall of the clamping block is provided with a rubber shock-absorbing pad, and the axial clearance is eliminated by pre-tightening force.

[0037] Furthermore, the backlash-free nut assembly 5 includes a mating main nut and a secondary nut, with a preload spring connecting the main nut and the secondary nut. The preload spring is always in a compressed state, generating an axial preload force. The threaded right side of the main nut is made to fit with the threaded surface of the lead screw, while the threaded left side of the auxiliary nut is made to fit with the threaded surface of the lead screw, thereby eliminating the physical dead zone in the transmission chain through the bidirectional preload structure.

[0038] Furthermore, the axial backlash-eliminating torque generated by the backlash-eliminating nut assembly 5 satisfies the formula:

[0039]

[0040] in, For preload, The mean diameter of the leadscrew. For thread helix angle, It is the equivalent friction angle.

[0041] It should be noted that by eliminating the backlash in the backlash-eliminating nut assembly 5, the displacement hysteresis time of this device during the startup phase is reduced from 150ms in conventional devices to less than 10ms, thereby fundamentally solving the problem of inaccurate response during micro-step frequency switching.

[0042] Furthermore, the pressure sensing component includes a force sensor 6, which employs a full-bridge strain gauge structure. Its sensing surface is perpendicular to the axis of the syringe plunger 1, enabling it to collect in real time the axial reaction force experienced by the syringe plunger 1 during the process of propelling the liquid medication. The signal output terminal of the force sensor 6 is electrically connected to the analog input interface of the control unit 3 via a shielded cable.

[0043] In some embodiments, the rear end face of the force sensor 6 is rigidly fixed to the output end seat of the backlash-free nut pair 5 by a positioning bolt. The center of the sensing end face of the force sensor 6 is provided with a hemispherical force transmission head. The force transmission head is inserted into the spherical recess at the bottom of the U-shaped clamping block to form a rotating pair. The two flanges of the U-shaped clamping block are provided with elastic pressure plates, which are used to radially limit the tail of the syringe 1 push rod during axial movement, ensuring that the hemispherical force transmission head always stays on the push rod axis and preventing lateral displacement under high pressure.

[0044] Furthermore, the closed-loop control system 2 includes a control unit 3, which acquires real-time pressure data at a sampling frequency of 100Hz and calculates the pressure change value. In detail, the control unit 3 integrates a high-speed processor and a drive circuit for the drive motor 4. When the viscosity of the medicine increases or a minor blockage occurs in the infusion line, causing an increase in output resistance, the force sensor 6 senses the axial reaction force. It will deviate from the preset characteristic curve. Next, the control unit 3 determines the axial reaction force deviation based on the deviation amount. Real-time compensation of the stepping pulse frequency of drive motor 4 The compensation logic is as follows:

[0045]

[0046] in, The pulse frequency, This is the deviation of the axial reaction force. The theoretically preset pulse frequency, This is the proportional gain coefficient. This is the differential gain coefficient.

[0047] It should be noted that the proportional gain coefficient Based on the linear progression of the drug solution viscosity, for drug solutions with a viscosity greater than 2 mPa·s, take... The upper limit value is set within a preset range to enhance response sensitivity. Differential gain coefficient. To suppress instantaneous pressure overshoot caused by piston static friction during the startup phase, it is achieved by setting the gain attenuation coefficient within 50ms before startup.

[0048] It should be noted that control unit 3 sets a threshold. Execution exception differentiation, specifically, when If the value exceeds 15% of the baseline curve for three consecutive sampling cycles, it is determined to be a pipeline blockage, triggering an alarm and forcibly reversing the drive motor 4 by 1-2 step angles to release local pressure, and then stopping the output. At the same time, the control unit 3 sets a dynamic threshold shielding zone within the first 2mm of the push rod's travel, automatically deducting the nonlinear interference force caused by the deformation of the syringe plug.

[0049] It should be noted that the preset characteristic curve is generated as follows: under no-load and load conditions, a full-stroke thrust scan is performed on the standard syringe 1 in advance to obtain the reference value of the thrust change with displacement, and it is stored in the EEPROM of the control unit 3. The preset characteristic curve is realized through a multi-dimensional lookup table. Its input dimensions include the syringe 1 specification (5ml / 10ml) and the drug viscosity grade. During the initialization phase, the system reads the selected specification and retrieves the corresponding displacement-thrust reference envelope from the lookup table as the zero point reference for dynamic compensation.

[0050] It is worth noting that, taking an experimental environment with a constant temperature of 25℃ and a drug solution viscosity of 1.2 mPa·s as an example, the device of the present invention was compared with an existing open-loop device, and the experimental data are shown in the table below:

[0051] Target dosing rate (μL / min) Actual average flow rate (μL / min) of existing equipment The actual average flow rate (μL / min) of the device of this invention Existing device error rate (%) Error rate (%) of the device of the present invention 0.10 0.082 0.099 18.0 1.0 0.50 0.465 0.498 7.0 0.4 1.00 0.952 0.999 4.8 0.1 5.00 4.880 5.002 2.4 0.04

[0052] As shown in the table above, under ultra-micro drug delivery conditions, such as 0.10 μL / min, the device provided by this invention can reduce the error rate from 18.0% to 1.0% through the gap elimination process and dynamic pressure feedback process.

[0053] It should be noted that, through the combination of mechanical structure and control algorithm, the embodiments of the present invention achieve more precise control of the injection volume of medicine in complex and ever-changing medical environments. The backlash-free nut assembly 5 solves the problem of displacement response lag in the transmission chain from a physical perspective. The force sensor 6 with a full-bridge strain gauge structure and the high-frequency sampling closed-loop control system 2 can build a more intelligent dynamic compensation system. The device provided by the present invention can not only automatically adapt to medicines from different years, but also respond and release pressure in a timely manner when pipeline abnormalities occur, thereby ensuring the continuity, uniformity and safety of the medical infusion process.

[0054] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0055] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A micro-injection device integrating precise drug metering control function, comprising a syringe (1), characterized in that, Also includes: A closed-loop control system (2) and a drive motor (4) and a pressure sensing component electrically connected to the closed-loop control system (2), wherein: The output shaft of the drive motor (4) is connected to the lead screw via a coupling, and the lead screw is fitted with a backlash-free nut pair (5). The pressure sensing component is connected between the gap-free nut pair (5) and the syringe (1) push rod, and is used to collect the axial reaction force data generated by the syringe (1) push rod in real time during the process of pushing the liquid medicine; The closed-loop control system (2) dynamically adjusts the stepping pulse frequency output to the drive motor (4) based on the axial reaction force data and by comparing it with a preset characteristic curve.

2. The micro-injection device according to claim 1, characterized in that, The lead screw has a trapezoidal thread on its surface, and its lead deviation is controlled within ±0.005mm.

3. The micro-injection device according to claim 2, characterized in that, The coupling is a flexible diaphragm coupling, and the output shaft of the drive motor (4) is coaxial with and fixedly connected to the lead screw.

4. The micro-injection device according to claim 1, characterized in that, The gap-eliminating nut assembly (5) is connected to the tail of the syringe (1) push rod via a slider mechanism, and the displacement lag time during the start-up phase is less than 10ms.

5. The micro-injection device according to claim 1, characterized in that, The backlash-free nut assembly (5) includes a main nut and a secondary nut that cooperate with each other. A preload spring is connected between the main nut and the secondary nut, and the preload spring is always in a compressed state.

6. The micro-injection device according to claim 5, characterized in that, The axial clearance-eliminating torque generated by the clearance-eliminating nut pair (5) satisfies the formula: in, For preload, The mean diameter of the leadscrew. For thread helix angle, It is the equivalent friction angle.

7. The micro-injection device according to claim 6, characterized in that, The pressure sensing component includes a force sensor (6), which adopts a full-bridge strain gauge structure and whose sensing surface is perpendicular to the axis of the syringe (1) push rod.

8. The micro-injection device according to claim 7, characterized in that, The closed-loop control system (2) includes a control unit (3), which acquires real-time pressure data at a sampling frequency of 100Hz and calculates the pressure change value.

9. The micro-injection device according to claim 8, characterized in that, The signal output terminal of the force sensor (6) is electrically connected to the analog input interface of the control unit (3) via a shielded cable.

10. The micro-injection device according to claim 8, characterized in that, The control unit (3) compensates the stepping pulse frequency of the drive motor (4) in real time according to the axial reaction force deviation. The compensation logic is as follows: in, The pulse frequency, This is the deviation of the axial reaction force. The theoretically preset pulse frequency, This is the proportional gain coefficient. This is the differential gain coefficient.

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