CN114415746A - Novel cascade microfluid intelligence control system - Google Patents
Novel cascade microfluid intelligence control system Download PDFInfo
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- CN114415746A CN114415746A CN202111429168.0A CN202111429168A CN114415746A CN 114415746 A CN114415746 A CN 114415746A CN 202111429168 A CN202111429168 A CN 202111429168A CN 114415746 A CN114415746 A CN 114415746A
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D16/00—Control of fluid pressure
- G05D16/20—Control of fluid pressure characterised by the use of electric means
- G05D16/2006—Control of fluid pressure characterised by the use of electric means with direct action of electric energy on controlling means
- G05D16/2013—Control of fluid pressure characterised by the use of electric means with direct action of electric energy on controlling means using throttling means as controlling means
- G05D16/2026—Control of fluid pressure characterised by the use of electric means with direct action of electric energy on controlling means using throttling means as controlling means with a plurality of throttling means
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Abstract
The invention provides a novel cascade microfluid intelligent control system, which is used for controlling an air source storage device in an air pressure valve box to obtain accurate and stable air pressure so as to drive microfluid in the air pressure valve box to reach a target flow rate and then output the microfluid. The system provided by the invention can realize the accurate control of the flow rate of the intelligent microfluid with high robustness, can reach the pressure of 250mbar in 100ms at most, and correspondingly can reach the microfluid flow rate with the accuracy of 0.1nl in 1s and the range of 0-100 nl/s. Meanwhile, the system precision reaches nl level, and the response time is controlled within 1s, so that the system can meet most of application environments, particularly biochemical application environments.
Description
Technical Field
The invention relates to an intelligent control system applied to the field of microfluid.
Background
With the continuous progress and development of science and technology, microfluidics technology is widely applied in the fields of chemistry, medicine, life science and the like. Among them, the microfluidic chip, also called "lab-on-a-chip", is an important component for implementing microfluidic control, and is also a hot spot in the research of the current microfluidic technology.
The traditional microfluid control system has a complex structure and difficult manufacturing process, and most components are not replaceable, so that the application range of the traditional microfluid control system is extremely limited. Meanwhile, the mainstream microfluidic control system is mostly manufactured commercially, is expensive in manufacturing cost and large in size, and the application range of the microfluidic control system is greatly limited.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the traditional microfluid control system has a complex structure and difficult manufacturing process, and most components are not substitutable, so that the application range of the traditional microfluid control system is extremely limited; meanwhile, the mainstream microfluidic control system is mostly manufactured commercially, is expensive in manufacturing cost and large in size, and the application range of the microfluidic control system is greatly limited.
In order to solve the technical problems, the technical scheme of the invention is to provide a novel cascade microfluid intelligent control system, which is used for controlling an air source storage device in an air pressure valve box to obtain accurate and stable air pressure so as to drive microfluid in the air pressure valve box to reach a target flow rate and then output the microfluid, and is characterized by comprising a control module operating a control algorithm, wherein the control algorithm adopts an integral cascade structure, the integral cascade structure controls the air pressure and the flow rate, the integral cascade structure generates and adjusts a driving air pressure value which enables the microfluid to reach the target flow rate according to the target flow rate and a real-time flow rate value of the microfluid fed back by a flow rate sensor in real time, the integral cascade structure generates a PWM driving signal according to the driving air pressure value, the PWM driving signal drives a pressure regulating component to regulate the air pressure for driving the microfluid, and the PWM driving signal is carried out based on the real-time air pressure value fed back by an air pressure sensor and the updated driving air pressure value And adjusting to eliminate the influence of the error in the air pressure loop on the flow rate loop in advance.
Preferably, the air pressure valve box comprises a storage bottle for storing the microfluid, the control module adjusts the air pressure in a through pipe communicated with the storage bottle to a target pressure through a pressure increasing valve and a pressure reducing valve, and after the adjusted air pressure drives the microfluid to flow, the flowing microfluid flows out from the fluid outlet through the through pipe.
Preferably, the air pressure sensor is used to check the actual pressure value in the through pipe in real time.
Preferably, a pressure release valve is further arranged in the air pressure valve box, and the control module releases the pressure in the through pipe through the pressure release valve to play a role in safety protection.
Preferably, the overall cascade structure is formed by cascading a main control loop and a secondary control loop.
Preferably, the real-time flow rate value is input to the main control loop as feedback, and the target flow rate is also input to the main control loop; the main control loop outputs a driving air pressure value which enables the microfluid to reach the target flow speed to the secondary control loop according to the real-time flow speed value and the target flow speed, the microfluid is driven by the adjusted air pressure to be output outwards at the adjusted flow speed, at the moment, the adjusted flow speed is fed back to the main control loop, and the main control loop adjusts the driving air pressure value output to the secondary control loop again according to the fed-back real-time flow speed value.
Preferably, the secondary control loop generates a PWM driving signal for driving the pressure regulating assembly according to the driving air pressure value and the real-time air pressure value, the pressure regulating assembly increases or decreases the air pressure value under the driving of the PWM driving signal, and feeds back the adjusted air pressure value to the secondary control loop, and the secondary control loop adjusts the PWM driving signal again according to the fed-back real-time air pressure value, so that the air pressure value approaches to the driving air pressure value output by the main control loop.
Preferably, the pressure regulating assembly comprises a pressure increasing valve driving circuit and a pressure reducing valve driving circuit which receive the PWM driving signal, and further comprises a pressure increasing valve and a pressure reducing valve which are driven by the pressure increasing valve driving circuit and the pressure reducing valve driving circuit.
Preferably, the primary control loop and the secondary control loop are based on an adaptive PID control algorithm:
for the main control loop, the self-adaptive PID control algorithm firstly calculates the error and the error change rate between the target flow rate and the real-time flow rate value, and then controls three control parameters k of the PID control loop through a fuzzy control strategy according to the error and the error change ratep、ki、kdAccurately defining, and outputting the regulated driving air pressure value by a PID controller;
for the secondary control loop, the self-adaptive PID control algorithm firstly calculates the error and the error change rate between the driving air pressure value and the real-time air pressure value, and then controls three control parameters k of the PID control loop according to the error and the error change rate and through a fuzzy control strategyp、ki、kdAnd (4) performing accurate definition, and outputting the regulated PWM driving signal by a PID controller. The fuzzy control strategy is set according to a large amount of actual test data in the early stage and by combining with the traditional fuzzy control strategy.
Preferably, the operation of the control algorithm and the viewing of the parameters are realized through a software interactive interface, and a software operating system is developed based on a Netbeans IDE platform and compiled by using a JAVA language.
Compared with the prior art, the invention has the following advantages:
(1) the system provided by the invention can realize the accurate control of the flow rate of the intelligent microfluid with high robustness, can reach the pressure of 250mbar in 100ms at most, and correspondingly can reach the microfluid flow rate with the accuracy of 0.1nl in 1s and the range of 0-100 nl/s. Meanwhile, the system precision reaches nl level, and the response time is controlled within 1s, so that the system can meet most of application environments, particularly biochemical application environments.
(2) The designed hardware has simple structure, the selected components have wide sources and high replaceability, and can be replaced or iterated automatically according to the difference of application environments. The overall volume and cost are greatly reduced compared to conventional commercial microfluidic control systems (e.g., the ELVEFLOW system in france).
(3) The software operating system is developed based on a Netbeans IDE platform and is compiled by using a JAVA language. The software system is reliable in open source and the operation interface is man-machine friendly. Meanwhile, due to the development characteristic, the whole software system has extremely high expansibility, and can be developed secondarily according to the subsequent use environment.
Drawings
FIG. 1 is a schematic diagram of a system provided by the present invention;
FIG. 2 is a schematic view of a pneumatic valve box controlled by the present invention;
FIG. 3 is a schematic diagram of an adaptive PID control flow;
FIG. 4 is a pressure increasing valve/reducing valve drive circuit diagram;
FIG. 5 is a pressure sensor driving circuit diagram;
FIG. 6 is a flow rate sensor drive circuit;
FIG. 7 shows the results of the air pressure stability test;
figure 8 illustrates the flow rate control behavior.
Detailed Description
The sizes, proportions and the like shown in the drawings in the specification are only schematic, are used for matching with the contents described in the specification, are not used for limiting the implementation conditions of the invention, and do not influence the efficacy of the invention. The positional relationships such as "upper", "lower", "inner" and "outer" in the present specification are for convenience of description only and are not intended to limit the implementable scope of the present invention, and variations in the relative relationships thereof are considered to be within the implementable scope of the present invention without substantial changes in the technical contents.
The novel cascade microfluid intelligent control system provided by the invention is used for controlling the air pressure valve box shown in figure 2 to obtain accurate and stable air pressure so as to drive microfluid provided by an air source to reach a target flow rate and then output.
As shown in fig. 2, in the present embodiment, the air pressure valve box includes a storage bottle 4 for storing the microfluid, the control module adjusts the air pressure in a through pipe 7 communicating with the storage bottle 4 to a target pressure through a pressure increasing valve 1 and a pressure reducing valve 2, and the adjusted air pressure drives the microfluid to flow, and then the flowing microfluid flows out from the fluid outlet 3 through the through pipe 7. An air pressure sensor 6 for checking the actual pressure value in the through pipe 7 in real time is also arranged in the air pressure valve box, and a pressure release valve 5 is arranged. The control module releases the pressure in the through pipe 7 through the pressure release valve 5, and the safety protection effect is achieved.
In order to realize the control of the pneumatic valve shown in fig. 2, with reference to fig. 1, the novel cascaded microfluidic intelligent control system provided by the present invention includes the aforementioned control module, in this embodiment, the control module is implemented based on a microprocessor, and a control algorithm is operated in the control module. In the present invention, air pressure is used to drive microfluidic flow. Thus, the entire control algorithm contains two process variables, air pressure and flow rate, respectively, where flow rate is the primary process variable and air pressure is the secondary process variable. The air pressure and flow rate are independent of each other and affect each other, making the control process more complicated. In this case, the control algorithm of the present invention adopts an integral cascade structure to eliminate the influence of the error in the air pressure loop on the flow rate loop in advance, as shown in fig. 1, the control algorithm of the present invention is formed by cascading a main control loop and a secondary control loop, wherein:
the control module collects a real-time flow rate value of the microfluid output by the air pressure valve box through the flow rate sensor, the real-time flow rate value is input into the main control loop as feedback, and the main control loop also inputs a target flow rate. The main control loop outputs a driving air pressure value which enables the microfluid to reach the target flow rate to the secondary control loop according to the real-time flow rate value and the target flow rate, and meanwhile, the control module collects the real-time air pressure value through the air pressure sensor 6 to be used as feedback input of the secondary control loop. The secondary control loop generates a PWM driving signal for driving a pressure increasing valve driving circuit or a pressure reducing valve driving circuit according to the driving air pressure value and the real-time air pressure value, the PWM driving signal is input into the pressure increasing valve driving circuit or the pressure reducing valve driving circuit, and then the control module controls a pressure increasing valve 1 or a pressure reducing valve 2 through the pressure increasing valve driving circuit or the pressure reducing valve driving circuit to achieve the purpose of increasing the air pressure value or reducing the air pressure value, the adjusted air pressure value is fed back to the secondary control loop, and the PWM driving signal is adjusted by the secondary control loop according to the fed-back real-time air pressure value again to overcome the influence of external pressure interference, so that the air pressure value approaches to the driving air pressure value output by the main control loop. And the microfluid is driven by the adjusted air pressure to be output outwards at the adjusted flow rate, at the moment, the adjusted flow rate is fed back to the main control loop, and the main control loop regulates the driving air pressure value output to the secondary control loop again according to the fed back real-time flow rate value.
The application of the above-described integral cascade structure enables the entire control algorithm to integrate multiple sensors to monitor two process variables in the system, enabling the entire system to effectively cope with the practical application of multi-parameter multivariable. In the invention
The main control loop and the secondary control loop in the invention are both based on an adaptive PID control algorithm, and in combination with FIG. 3, for the main control loop, the adaptive PID control algorithm firstly calculates the error and the error change rate between the target flow rate and the real-time flow rate value, and then controls three control parameters k of the PID control loop through a fuzzy control strategy according to the error and the error change ratep、ki、kdAnd (4) performing accurate definition, and outputting the regulated driving air pressure value by a PID controller. For the secondary control loop, similar to the main control loop, the self-adaptive PID control algorithm firstly calculates the error and the error change rate between the driving air pressure value and the real-time air pressure value, and then controls three control parameters k of the PID control loop according to the error and the error change rate and through a fuzzy control strategyp、ki、kdAnd (4) performing accurate definition, and outputting the regulated PWM driving signal by a PID controller. The fuzzy control strategy is set according to a large amount of actual test data in the early stage and by combining with the traditional fuzzy control strategy.
The pressure increasing valve driving circuit of the present invention is the same as the pressure reducing valve driving circuit, and includes a 12V voltage source V1, a capacitor C1, a diode D1, an inductor L1, a resistor R1, a transistor M1, and a resistor R2, as shown in fig. 4. The pressure sensor driving circuit of the invention is shown in fig. 5, and comprises a driving chip Microchip PIC24FJ128GA010, a 5V voltage source V2, a resistor R3, a resistor R4 and a 5V voltage source V3. The flow rate sensor driving circuit of the invention is shown in fig. 6 and comprises an operational amplifier, a 3.3V voltage source V4, a resistor R5, a resistor R6, an 8V voltage source V5 and a driving chip Microchip MCP 601.
Other components used in the present invention are shown in table 1 below:
TABLE 1 Intelligent component table for microfluid control system
| Component and device | Model number |
| Pressure sensor | GE UNIK 5000 series |
| Flow rate sensor | ELVEFLOW MFS |
| Microprocessor | PIC24FJ128G010 |
| Pressure relief valve | Norgren 1002 |
| Pressure increasing/reducing valve | Norgren Flatprop |
| Through pipe | PEEK 0.15/0.25 |
The system provided by the invention is simultaneously provided with a corresponding software interactive interface. The software operating system is developed based on a Netbeans IDE platform and compiled by using a JAVA language. The Netbeans IDE is an open source platform for software operating system development, and can be installed in operating systems such as Windows, MacOS and Linux. The system uses Microchip MPLAB X to develop a microprocessor part in embedded hardware, the Microchip XC16 compiler is used to compile related codes, and real-time data is transmitted through a USB serial port. The software system is reliable in open source and the operation interface is man-machine friendly. Meanwhile, due to the development characteristic, the whole software system has extremely high expansibility, and can be developed secondarily according to the subsequent use environment. The software system can monitor the whole hardware in real time, and the real-time pressure and the microfluid flow rate are displayed on a human-computer interaction interface in an image form. The user can set the target flow rate in the software system and can manually set the relevant control parameters.
Claims (10)
1. A novel cascade microfluid intelligent control system is used for controlling an air source storage device in an air pressure valve box to obtain accurate and stable air pressure so as to drive microfluid in the air pressure valve box to reach a target flow rate and then output the microfluid, and is characterized by comprising a control module running a control algorithm, wherein the control algorithm adopts an integral cascade structure which controls the air pressure and the flow rate, the integral cascade structure generates and adjusts a driving air pressure value which enables the microfluid to reach the target flow rate according to the target flow rate and a real-time flow rate value of the microfluid fed back by a flow rate sensor in real time, the integral cascade structure generates a PWM driving signal according to the driving air pressure value, a PWM driving signal is driven by a PWM driving signal driving pressure regulating assembly to regulate the air pressure for driving the microfluid, and the driving signal is regulated based on the real-time air pressure value fed back by the air pressure sensor and the updated driving air pressure value, thereby eliminating the influence of the error in the air pressure loop on the flow velocity loop in advance.
2. The novel cascade microfluid intelligent control system of claim 1, wherein the pneumatic valve box comprises a storage bottle for storing microfluid, the control module adjusts the pneumatic pressure in a through pipe communicated with the storage bottle to a target pressure through a pressure increasing valve and a pressure reducing valve, and after the adjusted pneumatic pressure drives the microfluid to flow, the flowing microfluid flows out from a fluid outlet through the through pipe.
3. The novel cascaded microfluidic intelligent control system of claim 2, wherein said air pressure sensor is used to check the actual pressure value in the through-pipe in real time.
4. The novel cascaded microfluidic intelligent control system of claim 3, wherein a pressure release valve is further disposed in the pneumatic valve box, and the control module releases the pressure in the through pipe through the pressure release valve to achieve a safety protection effect.
5. The novel cascaded microfluidic smart control system of claim 1, wherein said monolithic cascaded structure is formed by cascading a primary control loop and a secondary control loop.
6. The novel cascaded microfluidic smart control system of claim 5, wherein said real-time flow rate value is fed back to said main control loop, said main control loop also feeding said target flow rate; the main control loop outputs a driving air pressure value which enables the microfluid to reach the target flow speed to the secondary control loop according to the real-time flow speed value and the target flow speed, the microfluid is driven by the adjusted air pressure to be output outwards at the adjusted flow speed, at the moment, the adjusted flow speed is fed back to the main control loop, and the main control loop adjusts the driving air pressure value output to the secondary control loop again according to the fed-back real-time flow speed value.
7. The novel cascaded microfluidic intelligent control system of claim 6, wherein the secondary control loop generates a PWM driving signal for driving the pressure regulating assembly according to the driving air pressure value and the real-time air pressure value, the pressure regulating assembly increases or decreases the air pressure value under the driving of the PWM driving signal, and feeds back the adjusted air pressure value to the secondary control loop, and the secondary control loop adjusts the PWM driving signal according to the fed back real-time air pressure value again, so that the air pressure value approaches to the driving air pressure value output by the main control loop.
8. The novel cascaded microfluidic intelligent control system of claim 7, wherein said pressure regulating assembly comprises a pressure increasing valve driving circuit and a pressure reducing valve driving circuit for receiving said PWM driving signal, and further comprises a pressure increasing valve and a pressure reducing valve driven by said pressure increasing valve driving circuit and said pressure reducing valve driving circuit.
9. The novel cascaded microfluidic intelligent control system of claim 1, wherein said primary control loop and secondary control loop are based on adaptive PID control algorithm:
for the main control loop, the self-adaptive PID control algorithm firstly calculates the error and the error change rate between the target flow rate and the real-time flow rate value, and then controls three control parameters k of the PID control loop through a fuzzy control strategy according to the error and the error change ratep、ki、kdAccurately defining, and outputting the regulated driving air pressure value by a PID controller;
for the secondary control loop, the self-adaptive PID control algorithm firstly calculates the error and the error change rate between the driving air pressure value and the real-time air pressure value, and then controls three control parameters k of the PID control loop according to the error and the error change rate and through a fuzzy control strategyp、ki、kdAnd (4) performing accurate definition, and outputting the regulated PWM driving signal by a PID controller. The fuzzy control strategy is set according to a large amount of actual test data in the early stage and by combining with the traditional fuzzy control strategy.
10. The novel cascaded microfluidic smart control system of claim 1, wherein said control algorithm is operated and parameters are viewed through a software interface, and said software operating system is developed based on a Netbeans IDE platform and compiled using JAVA language.
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