Portable microorganism growth curve analyzer

Abstract

The invention discloses a portable microorganism growth curve analyzer, and belongs to the technical field of microorganism detection. A detection module of the analyzer adopts a multi-path wavelength-selectable LED light source and photodiode correlation type structure, is used for realizing real-time optical density detection of microorganism samples in a 6-pore plate and a 12-pore plate, and can automatically draw a growth curve; the X-axis moving module is composed of a sliding block structure driven by a stepping motor, and automatic scanning of multi-channel samples is achieved. The communication module supports Bluetooth and a USB interface, and can realize upper computer control and data export. According to the invention, high-precision, multi-channel and automatic microbial growth curve detection can be realized under a miniaturized structure, and the operation is simple and convenient; the method is suitable for various application scenes such as clinical medical examination, drug research and development, environment monitoring, food safety, water quality detection, pathogen monitoring of agriculture and animal husbandry, industrial fermentation and biological processing, public health monitoring, teaching and scientific research and the like.

Description

Technical Field

[0001] This invention relates to the field of biological detection instrument technology, and in particular to a portable microbial growth curve analyzer. Background Technology

[0002] Microorganisms have wide applications in environmental monitoring, water quality control, food safety, clinical diagnosis, biological research, and optimization of industrial fermentation processes. Their growth status is often dynamically analyzed through growth curves. Traditional microbial growth curve analysis usually relies on microscopic observation and manual counting, which are cumbersome, inefficient, and prone to errors, making it difficult to meet the modern demands for high throughput, real-time performance, and automation. Although some automated analytical instruments can achieve a certain degree of real-time monitoring and data recording, they suffer from problems such as high price, large size, and complex operation, which are not conducive to field deployment and use by grassroots units. In addition, existing equipment still has many shortcomings in terms of light source wavelength selection, environmental parameter adjustment, wireless communication, and integration, and lacks the ability to adapt to multiple types of microorganisms and their growth requirements. Currently, research in the field of portable microbial detection equipment is progressing steadily both domestically and internationally, with a particular focus on highly integrated, multifunctional, and multi-parameter fusion design schemes. Against this backdrop, developing a microbial growth curve analyzer that is compact, accurate, stable in operation, flexible in communication, and adaptable to different spectral and environmental conditions has become a key technological direction for meeting the needs of scientific research, teaching, and on-site testing. Based on the above-mentioned needs, this invention proposes a multifunctional microbial growth curve analyzer that integrates modules such as filter wheel control, LED multi-wavelength light source, automatic temperature control, Bluetooth communication, and data acquisition and analysis. This enables continuous monitoring and analysis of the microbial growth process, improves detection efficiency and data accuracy, and is suitable for various application scenarios such as laboratory and mobile testing. Summary of the Invention

[0003] The purpose of this invention is to provide a portable detection instrument for microbial growth curve analysis, aiming to solve the problems of low detection efficiency, poor integration, high cost, complex operation, and inability to achieve dynamic monitoring in existing technologies. This instrument integrates optical detection technology, temperature control technology, microfluidic technology, wireless communication technology, and intelligent data processing technology to achieve high-precision, real-time monitoring of microbial growth status and automatic dynamic curve plotting. This invention is achieved through the following technical solution: A portable microbial growth curve analyzer includes a main body, a casing of the main body and a fixed base forming the external frame of the entire device, and a flip-open upper cover hinged to the casing via a damping hinge; the main body includes: Detection module: The detection module consists of a multi-channel selectable wavelength LED light source group and its corresponding photodiodes, forming a through-beam optical path structure, which is used to perform real-time optical density detection on microbial samples placed in the well plate. X-axis moving module: The X-axis moving module consists of a stepper motor, a lead screw and a slider, and is used to drive the detection module to move along the X-axis to realize the detection of different holes in the multi-hole plate one by one. Plate holder assembly: Located inside the sample chamber of the fixed base, it is used to hold 6-well or 12-well microbial culture plates; Temperature control module: Located inside the upper cover, it consists of a heating plate and a temperature sensor. It is used to maintain the temperature of the upper cover above the ambient temperature to suppress condensation and improve detection accuracy. Integrated circuit control module: including microcontroller MCU, analog-to-digital converter ADC, LED constant current drive module, motor drive module and power input module, used to control the detection process and process data; Communication module: includes a USB interface and a Bluetooth module. The Bluetooth module supports communication with a host computer and can simultaneously support connections to up to 16 devices. The host computer software system is used to set the sampling frequency, temperature control parameters and detection plate type, and supports remote control of the device and export of detection data. Preferably, the LED light source group supports multi-wavelength output. The detection module includes 8 LED light sources and 8 corresponding photodiodes. The LED light sources are driven by a constant current driving chip. The light signal after passing through the sample is collected by the photodiodes and converted into an electrical signal. Preferably, the detection module further includes a photoelectric detection component, which is mounted on an L-shaped detection bracket. The LED light source group and the photodiode, i.e., the photosensor group, are respectively mounted at the upper and lower ends of the L-shaped detection bracket to form a through-beam optical path structure. The photoelectric detection component moves synchronously with the slider of the X-axis moving module to achieve point-by-point scanning of different holes in the perforated plate. The slider of the X-axis moving module is driven by a stepper motor and achieves precise displacement control through a lead screw drive. Preferably, the photoelectric detection component includes a light source board and a photoelectric signal acquisition board. The LED light source group is mounted on the light source board, which is fixed to one end of the stepper motor. The light source board is responsible for providing a stable constant current drive, enabling the light source group to emit 600nm wavelength light to illuminate the sample. After the emitted light passes through the sample, it is received by a photodiode at the opposite position. The photodiode is the receiver of the light signal and is called the "photosensor group". The photoelectric signal acquisition board is the processing center of the light signal. The photodiode is mounted on the photoelectric signal acquisition board, which is fixed to the other end of the stepper motor. The photoelectric signal acquisition board receives, amplifies, and converts the weak current signal generated by the photodiode into a stable voltage signal through its internal operational amplifier circuit, transimpedance amplifier, filter circuit, and high-sensitivity signal conditioning system. This signal is used for ADC acquisition by the main controller (MCU) to realize the detection of sample concentration changes, with a linear correlation coefficient >0.99. Preferably, the temperature control module uses a closed-loop control system to regulate the temperature of the heating plate, keeping its temperature within the range of ambient temperature +4℃ to 50℃. The heating plate has the dual functions of preventing condensation inside the flip cover and maintaining ambient temperature control, and is used to stabilize the ambient temperature between 25℃ and 40℃. Preferably, the host computer software is set to a sampling interval of 1 to 60 minutes and has the functions of automatically generating microbial growth curves, exporting detection data, and remotely upgrading firmware. The host computer software is connected to the analyzer via a wired serial port or wireless Bluetooth and can be set to continuous monitoring from 1 hour to 100 hours. Scattered light intensity is recorded every minute. After receiving the scattered light intensity data stream every minute, the software immediately executes a smoothing filtering algorithm to eliminate transient high-frequency noise and ensure the continuity of the data sequence. Subsequently, the filtered discrete points are used for nonlinear regression fitting (in this invention, the filtering algorithm is integrated into the real-time data stream of the host computer software, and in conjunction with the ADS8688 acquisition chip, ensures that the data can be continuously, stably, and accurately processed during high-frequency sampling (once per minute) and long-term monitoring, thereby supporting high-precision microbial growth curve plotting), accurately fitting it into the growth kinetic model. The classic Logistic growth kinetic model is adopted, and its functional form is... The software system employs the Levenberg-Marquardt LM iterative optimization algorithm to determine the maximum light intensity value of model parameter A. Maximum specific growth rate and During the lag phase, using this continuous and accurate fitting function, the software system automatically and dynamically plots a smooth and accurate microbial growth curve with time as the horizontal axis and scattered light intensity as the vertical axis. After the curve is plotted, the program automatically calculates the inhibition rate at each drug concentration using parameters such as the maximum light intensity extracted from the fitting model. Finally, based on the drug sensitivity test standards, the program automatically searches for the minimum drug concentration that meets the threshold of inhibition rate ≤ 90%~100%, and automatically determines it as the MIC value. Preferably, the detection module has a detection accuracy of ±1%, a coefficient of variation (CV) ≤ ±0.5% for consistency testing, a linear correlation coefficient (R²) greater than 0.99, and a temperature control accuracy of ±1℃ for the temperature control module. Preferably, after the analyzer is powered on, it automatically completes self-test and position initialization, and reports the status information to the host computer. The communication module supports Bluetooth serial port pass-through protocol, supports 16 devices to connect to the host computer in parallel, and supports power failure reconnection and historical data upload functions. Preferably, the cover further includes several connectors connected to a fixed base; the fixed base further includes several foot pads; the main body of the detection module is locked to the fixed base by fasteners; the upper cover is provided with a handle; the X-axis moving module includes two core driving components, a motor and a lead screw, which enable the detection module and the slider to move along the X-axis; an infrared position sensor is provided next to the X-axis, which is connected to the main controller and is used to detect the initial position of the slider of the X-axis moving module. Preferably, the orifice plate bracket assembly includes an orifice plate bracket, with an instrument support below the orifice plate bracket, and left and right support feet (with rubber pads at the bottom of the left and right support feet for adsorption) on both sides of the entire body; the X-axis moving module is locked to the orifice plate bracket by fasteners. Compared with the prior art, the beneficial effects of the present invention are as follows: The portable microbial growth curve analyzer of the present invention has the advantages of compact structure, high detection accuracy, strong adaptability, high degree of automation, strong remote communication capability, and adaptability to multiple scenarios. It is particularly suitable for rapid detection and analysis of microorganisms in on-site testing, mobile experimental platforms, university teaching, grassroots scientific research units, and resource-constrained environments. Attached Figure Description To more clearly illustrate the technical details and operational processes in the embodiments of the present invention or the prior art, the accompanying drawings referenced in the description of the embodiments or the prior art will be briefly described below. These drawings are intended to provide intuitive visual assistance for the present invention and to deepen the understanding of the present invention. As an important part of the specification, they, together with the embodiments of the present invention, constitute a complete explanatory system. However, these drawings are not intended to limit the scope or content of the present invention; they are merely auxiliary illustrative materials. Figure 1 This is an overall structural diagram of the portable microbial growth curve analyzer provided in this embodiment of the invention; Figure 2 This is an external image of the portable microbial growth curve analyzer provided in an embodiment of the present invention; Figure 3This is an internal structural diagram of the portable microbial growth curve analyzer provided in the embodiment of the present invention, and an overall structural diagram of the instrument (side view). Figure 4 This is the rear view of the instrument; Figure 5 This is a block diagram of the portable microbial growth curve analyzer system provided in an embodiment of the present invention; Figure 6 This is a diagram of the host computer interface of the portable microbial growth curve analyzer provided in this embodiment of the invention; Figure 7 These are the consistency and linearity test results and related verification results of the portable microbial growth curve analyzer provided in this embodiment of the invention. Figure 8 This is the main control board circuit diagram; Figure 9 This is the circuit diagram of the motor drive board; Figure 10 Circuit diagram of photoelectric data acquisition board; Figure 11 Circuit diagram of the light source driver board; Figure 12 This is a graph showing the test results of the portable microbial growth curve analyzer provided in this embodiment of the invention for different carbon sources and pH values ​​of Saccharomyces cerevisiae and Yersinia lipolyticis po1g; Figure 13 This is a graph showing the test results of the portable microbial growth curve analyzer provided in this embodiment of the invention on the drug sensitivity test of Saccharomyces cerevisiae to 5-fluorocytosine and amphotericin B. tumefaciens. Figure 14 This is a schematic diagram of the connector and fixed base structure of the present invention. Among them, 1. Detection module, 101. LED light source group, 102. Photodiode, 103. Photoelectric detection component, 104. L-shaped detection bracket, 105. Light source board, 106. Photoelectric signal acquisition board, 107. Fastener lock; 2. Drive detection module, 201. Stepper motor, 202. Lead screw, 203. Slider; 3. Orifice plate bracket assembly, 301. Orifice plate bracket, 302. Left support foot, 303. Right support foot; 4. Temperature control module, 401. Heating plate, 402. Temperature sensor; 5. Integrated circuit control module; 6. Communication module; 7. Body; 8. Cover; 801. Connector; 9. Fixed base; 10. Top cover; 11. Power input interface; 12. Wired data communication interface; 13. Main power switch; 14. Infrared position sensor. Detailed Implementation The technical solutions in the embodiments of the present invention will be described in detail below, with the accompanying drawings for a clear and comprehensive explanation. Example 1 See Figures 1 to 5 A portable microbial growth curve analyzer includes a main body 7, a casing 8 and a fixed base 9 forming the external frame of the entire device, and a flip-open upper cover 10 hinged to the casing 8 via a damping hinge; the casing 8 also includes several connecting parts 801 connected to the fixed base 9; the fixed base 9 also includes several foot pads; the main body of the detection module 1 is fixed to the fixed base 9 by fastener locks 101; the upper cover 10 is provided with a handle; the main body 7 includes: Detection Module 1: Detection Module 1 consists of a multi-channel selectable wavelength LED light source group 101 and its corresponding photodiode 102, forming a through-beam optical path structure, used for real-time optical density detection of microbial samples placed in the well plate. X-axis movement module 2: The X-axis movement module consists of a stepper motor 201, a lead screw 202, and a slider 203. It is used to drive the detection module 2 to move along the X-axis to detect different holes in the perforated plate one by one. The X-axis movement module 2 includes two core driving components: a motor and a lead screw, which enable the detection module 1 and the slider 203 to move along the X-axis. An infrared position sensor is provided next to the X-axis and is connected to the main controller to detect the initial position of the slider 203 of the X-axis movement module 2. This module uses a high-precision stepper motor and lead screw transmission system combined with an infrared position sensor. Through closed-loop control with pulse calculation and real-time feedback, the infrared position sensor next to the X-axis provides a real-time feedback signal to the main controller when the system starts up, completing the absolute position calibration (i.e., zeroing) of the slider's initial position, thereby establishing a precise and repeatable X=0 reference point. Once the zero point is established, subsequent scanning and positioning of each well in the multi-well plate (in this embodiment, the light source consists of three identical lamps, which can simultaneously detect 6-well and 12-well microbial cell culture plates; the only difference is the order in which the light source illuminates and the detection sequence is executed, which can be selected in the host computer program) is achieved through precise pulse calculation: the main controller converts the well spacing into the number of pulses required by the stepper motor, and drives the detection module to perform high-precision relative displacement through a lead screw transmission system. This collaborative working mode, which uses sensor feedback (closed loop) for initial calibration and pulse calculation (open loop) for relative movement, achieves precise position control and initial position calibration. A key feature is the software-preset path and speed movement, ensuring accurate detection of each well, and a significant improvement lies in enhancing the system's repeatability and automation level. Orifice plate bracket assembly 3: Located inside the fixed base, used to hold 6-well or 12-well plates; Orifice plate bracket assembly 3, with orifice plate bracket 301, with instrument support 15 below orifice plate bracket 301, and left support foot 302 and right support foot 303 on the bottom of both sides of the entire body (rubber feet for adsorption at the bottom of the left and right support feet); X-axis moving module 2 is locked to orifice plate bracket 301 by fasteners; Temperature control module 4: Located inside the upper cover plate 10, it consists of a heating plate 401 and a temperature sensor 402, and is used to maintain the temperature of the upper cover plate 10 above the ambient temperature to suppress condensation and improve detection accuracy. Integrated circuit control module 5 includes a microcontroller (MCU), an analog-to-digital converter (ADC), an LED constant current drive module, a motor drive module, and a power input module, which are used to control the detection process and process data. Communication module 6 includes a USB interface and a Bluetooth module. The Bluetooth module supports communication with a host computer and can simultaneously support connections to up to 16 devices. The host computer software system is used to set the sampling frequency, temperature control parameters, and detection plate type, and supports remote control of the device and export of detection data. The sample chamber, located above the base, accommodates standard 12-well or 6-well microbial culture plates. The sample chamber is enclosed by a flip-top structure, with a heating plate and temperature sensor on the inner wall of the flip-top. A constant temperature is maintained via PID control to prevent condensation from interfering with the detection. LED light source modules and photodiodes are positioned at both ends of the L-shaped detection frame, forming a through-beam optical path structure. The detection module 1 also includes a photoelectric detection component 103, which is mounted on an L-shaped detection bracket 104. The LED light source group 101 and the photodiode 102, i.e., the photosensor group, are respectively mounted at the upper and lower ends of the L-shaped detection bracket 104 and move synchronously with the slider 203 of the X-axis moving module 2 to achieve point-by-point scanning of different holes in the perforated plate. The slider 203 of the X-axis moving module 2 is driven by a stepper motor 201 and transmitted through a lead screw 202 to achieve precise displacement control, thereby realizing the detection of different holes one by one. The photoelectric detection component 103 includes multiple channels, each equipped with an LED and a corresponding photodiode, used to detect the optical density value at different wavelengths (such as OD600, OD680, etc.). The module output signal is transmitted to the ADC channel of the main control MCU for acquisition after passing through a transimpedance amplifier and filtering circuit. The photoelectric detection component 103 includes a light source board 105 (the LED light source group 101 is the emitter of light signals; it is a collection of LED light sources with multiple selectable wavelengths, mounted on the light source board 105. The light source board 105 is responsible for providing a stable constant current drive, enabling the light source group to emit light to illuminate the sample. After passing through the sample, the emitted light is received by the photodiode 102 at the opposite position. The photodiode 102 is the receiver of light signals, often referred to as a "photosensor group") and a photoelectric signal acquisition board 106 (the photoelectric signal acquisition board 106 is the processing center of the light signal; the photodiode 102 is mounted on this board. This board, through its internal operational amplifier circuit, transimpedance amplifier, filter circuit, and other high-sensitivity signal conditioning system, receives, amplifies, and converts the weak current signal generated by the photodiode into a stable voltage signal for the ADC acquisition of the main controller MCU). The light source board is fixed to one end of the stepper motor 201 and is used to emit 600nm wavelength light; the photoelectric signal acquisition board 106 is fixed to the other end of the stepper motor 201 and is used to receive the light signal transmitted through the sample; the light source board 105 controls the 600nm light to be lit with constant current, and the photoelectric signal acquisition board 106 receives and amplifies the photoelectric signal through an operational amplifier circuit to realize the detection of sample concentration change, with a linear correlation coefficient >0.99. Furthermore, the photoelectric detection component 103, through a transimpedance amplifier, differential amplifier circuit, and filter circuit, constitutes a high-sensitivity signal conditioning system that can convert weak optical signal current into a stable voltage signal. First, after the photodiode receives the optical signal, the transimpedance amplifier (TIA) converts the resulting weak current signal into a measurable voltage signal; this step is crucial for achieving the "current-to-voltage" conversion. Subsequently, this voltage signal passes through a differential amplifier circuit (used to efficiently suppress common-mode noise coupled in during transmission and enhance stability) and a filter circuit (used to remove high-frequency interference and purify the signal), ultimately forming a stable, high-precision analog voltage signal, which is then transmitted to the MCU's ADC port for sampling and digitization. The MCU core controller uses a high-performance 32-bit processor, responsible for acquisition control, data analysis, equipment status monitoring, and communication tasks, and can adjust the light source intensity via PWM. The innovative structure of this module is a system that converts optical signals into electrical signals, ensuring that the signal intensity acquisition is used to plot growth curves. In detail, the photoelectric acquisition board includes photodiodes, current-to-voltage conversion circuits, and operational amplifiers. These convert optical signals into electrical signals and amplify them. The signals are then interconnected with the ADS8688 chip on the main control board, allowing the microcontroller's ADC to acquire the signal strength and plot the growth curve. The board's innovation lies in its signal conversion and amplification circuit design, which improves the accuracy of signal acquisition. The core of the control system is an STM32 series MCU, responsible for adjusting LED light intensity, switching filter wheels, motor control, and signal acquisition and processing. The communication module supports Bluetooth 4.0 protocol, enabling remote communication with a host computer. Users can set sampling time, detection channels, temperature parameters, etc., via the host computer, and simultaneously achieve data recording, curve plotting, and export. The main control board uses an STM32VET6 as its core, connecting to an ADS8688 chip via an SPI communication interface to read the photodiode voltage signal. The acquired signal is output to the PC via a serial port (connected to USB and Bluetooth), and the LED lights and motor operation are controlled via terminal blocks. The board's innovative design integrates signal acquisition and control, achieving coordinated constant current source drive and motor operation. In actual detection, the MCU first sends commands to the motor drive board to precisely coordinate the X-axis movement, ensuring the slider and detection module accurately stop at the center of the target hole. Once the position is stable, the MCU immediately starts the LED constant current source drive via a PWM signal to ensure extremely high consistency in the light intensity emitted by the light source during sampling. Finally, the MCU synchronously uses the ADS8688 chip connected via the SPI interface for high-speed, precise voltage signal acquisition. The motor driver board uses an STM32F103C8T6 microcontroller as its core, connecting to the main control board via a serial port. It controls the stepper motor's operation through a TMC2660 stepper motor driver chip, using pulse calculation. The main control board (STM32VET6) determines the required linear displacement based on the spacing of the micro-hole plate and the lead screw pitch. The microcontroller (STM32F103C8T6) and TMC2660 chip on the motor driver board convert the linear distance into a precise pulse sequence. The step distance is calculated via pulses, and the position sensor collects the current position in real time, feeding it back to the microcontroller. The temperature control section controls the output power of the heating element by controlling the switching of a transistor using a PWM wave, achieving constant temperature control. The board's innovation lies in combining serial port command parsing with PWM control to achieve both motor operation and constant heating element temperature. The innovative implementation of this motor driver board utilizes the high integration capabilities of the STM32F103C8T6 microcontroller to unify the previously separate motion control and temperature control tasks. Specifically, the board first receives and distinguishes high-level commands from the main control board via serial port command parsing to determine whether motor operation or temperature control is required. If it's a motion command, the microcontroller coordinates with the TMC2660 driver chip to drive the stepper motor through pulse calculation for precise position control. If it's a temperature control command, the microcontroller activates a closed-loop algorithm (PID) and converts the calculated required heating power into a precise PWM duty cycle. This PWM wave directly controls the transistor's on / off state, thereby precisely adjusting the heating element's output power to achieve temperature control. This design, combining serial port command parsing with PWM control, allows the main control board to delegate complex real-time hardware management tasks to the driver board for centralized processing, ensuring efficient coordination and synchronization of motor operation and ambient temperature control in terms of timing and accuracy. The light source driver board uses the OC7141 constant current source driver chip. It receives PWM signals from the main control board to drive a 600nm LED light source, which illuminates the sample and is received by the photoelectric receiving board. Changes in sample concentration are recorded by analyzing the changes in the received signal intensity to plot microbial growth curves. The board's innovation lies in its constant current source drive, ensuring stable sample illumination. Firstly, the OC7141 constant current source driver chip was selected and integrated, rather than a simple resistor-limited current solution. This constant current source chip ensures that the current flowing through the LED remains constant regardless of power supply voltage fluctuations, ambient temperature changes, or LED temperature increases, effectively isolating the light intensity from these factors. Secondly, the board's design perfectly coordinates with the main control board's PWM signals, allowing the MCU to precisely calibrate and adjust the light source intensity by adjusting the PWM duty cycle. This embodiment also includes an infrared position sensor for calibrating the initial position of the slider, improving system repeatability and automation. The entire unit is compact, with a handle and cushioned feet for easy portability in the field or for teaching purposes. The sample chamber is the core area for microbial detection, and its design directly affects the accuracy and reliability of the test. The sample chamber is made of highly transparent material with excellent optical transmittance, ensuring that light can pass through the sample without attenuation. The sample chamber is designed as a sealed structure to prevent interference from external gases or liquids, ensuring the stability of the testing environment. Furthermore, the sample chamber is equipped with a shaker motor or oscillation module, enabling automatic mixing of the sample and preventing microbial precipitation from affecting the test results. The sample chamber is made of highly transparent material with excellent optical transmittance. Its sealed structure prevents interference from external gases or liquids. It is equipped with a shaker motor or oscillation module for automatic sample mixing. The sample chamber is compatible with standard 12-well and 6-well microbial culture plates and includes an internal temperature sensor for multi-point temperature control and detection. The LED light source module 101 is a key component for optical density detection. This invention employs a multi-wavelength selectable LED light source, supporting multi-wavelength output. This multi-wavelength design can meet the detection needs of various microorganisms at different growth stages. For example, the growth curves of some bacteria under blue light (450nm) and red light (620nm) may differ significantly. Multi-wavelength light sources allow for a more comprehensive analysis of microbial growth characteristics. The LED light source module adopts a replaceable structure design (the detection module includes 8 LED light sources and their corresponding 8 photodiodes, and the structure can be switched to detect 6-well, 12-well, or 96-well detection according to user needs). The device supports simultaneous detection of multiple channels and can realize parallel monitoring of multiple samples, thereby greatly improving detection efficiency. The photoelectric detection module is a key component that converts optical signals into electrical signals. The photoelectric detection module of this invention includes multiple channels, each equipped with an LED and a corresponding photodiode, used to detect optical density values ​​at different wavelengths. The module output signal is transmitted to the ADC channel of the main control MCU for acquisition after passing through a transimpedance amplifier and filtering circuit. Specifically, the detection module 1 includes 8 LED light sources and 8 corresponding photodiodes. The LED light sources are driven by a constant current driver chip, and the optical signal transmitted through the sample is acquired by the photodiodes and converted into an electrical signal. To improve detection accuracy, the photoelectric detection module employs a high-sensitivity signal conditioning system, including a transimpedance amplifier, differential amplifier circuit, filter circuit, and resistors, capacitors, and connectors that make up these circuits. These circuits convert weak optical signal current into a stable voltage signal, ensuring signal stability and accuracy. Furthermore, the photoelectric detection module also exhibits good linearity and repeatability, accurately reflecting changes in the growth state of microorganisms. The temperature control module is a crucial component for ensuring a stable testing environment. In this invention, the temperature control module is located inside the upper cover and includes a heating plate and a temperature sensor. The temperature control module 4 employs a closed-loop control system to regulate the temperature of the heating plate, maintaining it within the range of ambient temperature +4°C to 50°C. The heating plate 401 serves the dual function of preventing condensation inside the flip cover and maintaining ambient temperature control, effectively stabilizing the ambient temperature between 25°C and 40°C and suppressing condensation formation inside the flip cover. The temperature control module employs a PID algorithm for intelligent control, achieving a temperature control accuracy of ±1℃. This high-precision temperature control system avoids detection errors caused by temperature fluctuations, ensuring the accuracy of the test results. Furthermore, the temperature control module also possesses the ability to rapidly heat up and cool down, adapting to the growth requirements of different microorganisms. The X-axis movement module is a key component for realizing multi-channel automatic scanning. The X-axis movement module of this invention includes a stepper motor, a lead screw, and a slider, which is used to drive the detection component to move along the X-axis direction to realize the detection of different holes in the multi-hole plate one by one. The X-axis movement module employs a high-precision stepper motor and lead screw drive system, enabling precise position control. Through software control, the X-axis movement module can move along a preset path and speed, ensuring accurate detection of each hole. Furthermore, the X-axis movement module is equipped with an infrared position sensor to calibrate the initial position of the slider, further improving the system's repeatability and automation level. The control system is the core of the entire instrument, responsible for coordinating the operation of each module. The control system of this invention uses a high-performance 32-bit STM32 series MCU as the core controller, responsible for adjusting LED light intensity, wired and wireless communication, motor control, and signal acquisition and processing. The control system acquires signals from the photoelectric detection module via an analog-to-digital converter (ADC) and processes them digitally. Through an LED constant current drive module, the control system can precisely control the intensity of the LED light source, ensuring the stability of the detection signal. Furthermore, the control system also controls the movement of the X-axis motion module via a motor drive module, enabling multi-channel automatic scanning. The control system also features equipment status monitoring, enabling it to monitor the instrument's operating status in real time and report the status information to the host computer. Through the host computer software, users can remotely control the instrument's operation, set sampling time, detection channels, temperature parameters, etc., and perform data recording, curve plotting, and export. The communication module is a key component for enabling communication between the instrument and the host computer. The communication module of this invention supports Bluetooth 4.0 wireless communication and standard USB serial communication. The host computer, through a custom communication protocol, can perform functions such as remote operation control, parameter setting, real-time data reading, curve generation, data storage and export, and device status feedback. The Bluetooth module supports communication with a host computer, allowing up to 16 devices to connect simultaneously via Bluetooth. This multi-device connectivity enables the instrument to meet the needs of multiple users operating at the same time, improving work efficiency. Furthermore, the communication module supports power-off reconnection and historical data upload functions, ensuring data integrity and security. The host computer software system is a crucial interface for user interaction with the instrument. The host computer software of this invention supports setting sampling time intervals from 1 to 60 minutes and has functions such as automatically generating microbial growth curves, exporting data, and remotely upgrading firmware. The host computer software connects to the analyzer via a wired serial port or wireless Bluetooth and can be set to continuous monitoring from 1 hour to 100 hours. Users can remotely control the instrument by setting parameters such as sampling frequency, temperature control parameters, and detection plate type through the host computer software. The host computer software also features data logging, curve plotting, and export functions, allowing users to easily view and analyze test results. Furthermore, the host computer software supports wireless firmware upgrades, enabling users to improve the instrument's performance and functionality through software updates. Upon power-up, the analyzer automatically completes self-tests and position initialization, and reports its status information to the host computer. The communication module supports Bluetooth serial port pass-through protocol, supports parallel connection of up to 16 devices to the host computer, and supports power-off reconnection and historical data upload functions. The portable microbial growth curve analyzer of this invention has broad application prospects. It is suitable for laboratory, teaching, and field microbial monitoring scenarios, and can meet various needs such as food safety testing, biopharmaceutical process control, environmental monitoring, scientific research and teaching, medical and health care, and industrial fermentation process optimization. Example 2 In food safety testing, this instrument can quickly detect the microbial content in food to ensure food safety; in biopharmaceutical processes, it can monitor the growth status of microorganisms in real time to optimize production processes; in environmental monitoring, it can detect the types and quantities of microorganisms in water and soil to assess environmental quality; in scientific research and teaching, it can be used as a teaching tool to help students better understand the laws of microbial growth; in the optimization of industrial fermentation processes, it can serve as a data source for optimizing fermentation medium parameters, enabling one-click curve measurement, high yield, low consumption, and increased profits. Consistency testing is an important means of evaluating the repeatability and stability of an instrument. The portable microbial growth curve analyzer of this invention performed excellently in consistency testing. Test results show that the instrument exhibits high consistency in multiple detections of the same sample, with a detection accuracy of ±1% and a repeatability CV ≤ ±0.5%. This high consistency and repeatability ensure the reliability and accuracy of the instrument in practical applications. Linearity testing is an important indicator for evaluating the detection capability of an instrument. The linearity test results of the portable microbial growth curve analyzer of this invention within different concentration ranges demonstrate that the instrument exhibits good linearity. The test results show that the linear correlation coefficients at wavelengths such as OD600 and OD680 are all higher than 0.99, indicating that the instrument can accurately detect microbial samples of different concentrations. Specifically, a portable microbial growth curve analyzer was used to detect the growth curves of *Saccharomyces cerevisiae* S288C and *Yersinia lipolytica* po1g in different culture media with pH 4-8. Simultaneously, growth curves were measured in media with different carbon sources such as glucose, sucrose, galactose, and glycerol. Through simultaneous detection in 12 wells, complete growth kinetic parameters of the two yeasts under different pH and carbon sources can be obtained in a single batch. Compared to the traditional Erlenmeyer flask + offline OD method, the time is reduced by more than 70%, reagent consumption is reduced to 1 / 20, and the closed system avoids evaporation and contamination, with a CV < 5%. This provides a precise and reproducible basis for subsequent scale-up fermentation from 5 L to 50 m³. Specifically, the susceptibility of Saccharomyces cerevisiae S288C to 5-fluorocytosine / amphotericidal B was detected using a portable microbial growth curve analyzer. Pure colonies of Saccharomyces cerevisiae S288C with appropriate morphology and size were picked from solid plates using a sterile inoculation loop. The bacterial culture was adjusted to 0.5 MCF using a turbidimeter, and then added to RPMI-1640 medium containing 0, 0.0625, 0.125, 0.25, 1, 2, 4, 8, 16, 32, and 64 μg / mL 5-fluorocytosine, respectively, or to medium containing 0, 0.25, 0.5, 1, 2, and 48 μg / mL 5-fluorocytosine, respectively. In RPMI-1640 medium containing amphotericin B, 12-well detection plates (in this example, the detection plate and culture plate are the same plate, but different names are used depending on the application) were injected, sealed, and continuously monitored at 37°C for 48 hours, recording the scattered light intensity every minute. After receiving the scattered light intensity data stream every minute, the software immediately executed a smoothing filtering algorithm to eliminate transient high-frequency noise and ensure the continuity of the data sequence. Subsequently, the filtered discrete points were used for nonlinear regression fitting, accurately fitting them into the growth kinetic model. The classic Logistic growth kinetic model was adopted, with the functional form as follows: The software system employs the Levenberg-Marquardt (LM) iterative optimization algorithm to accurately determine the model parameter A (maximum light intensity). (Maximum specific growth rate) and (Lapse period). Using this continuous and accurate fitting function, the software system automatically and dynamically plots a smooth and accurate microbial growth curve with time as the horizontal axis and scattered light intensity as the vertical axis. After the curve is plotted, the program automatically calculates the inhibition rate at each drug concentration using parameters such as the maximum light intensity extracted from the fitting model. Finally, based on drug susceptibility testing standards, the program automatically searches for the minimum drug concentration that meets the inhibition rate threshold of ≤90% to 100%, and automatically determines it as the MIC value. This program improvement integrates complex signal processing and biological parameter extraction into an automated process, effectively eliminating errors caused by manual calculation and visual interpretation, and greatly improving the accuracy, objectivity, and efficiency of drug susceptibility testing. The accuracy of the curves in this invention stems from the extreme guarantee of data input quality: by employing a constant current source drive and a multi-stage signal conditioning system (including transimpedance amplifiers and hardware filtering), the scattered light intensity data collected every minute is ensured to be highly stable and pure before entering the algorithm. The software system utilizes this high-quality data to perform digital smoothing filtering in real time, and then uses the LM iterative optimization algorithm to accurately fit the data to the classic Logistic growth kinetic model Y(t). The biggest program improvement is reflected in the automatic determination of MIC: the program no longer relies on the original endpoint data, which is easily affected by instantaneous fluctuations, but instead extracts the fitted model parameter A (i.e., the maximum light intensity) as a more stable final biomass. This approach, integrating high-precision hardware, complex fitting algorithms, and objective determination logic based on fitted parameters into a portable automated process, effectively eliminates human error and significantly improves the accuracy, objectivity, and overall automation level of drug sensitivity testing. The portable microbial growth curve analyzer of this invention features a compact structure, high detection accuracy, strong adaptability, high degree of automation, strong long-distance communication capability, and versatility for various scenarios. It integrates optical detection technology, temperature control technology, microfluidic technology, wireless communication technology, and intelligent data processing technology, enabling high-precision, real-time monitoring of microbial growth status and automatic dynamic curve plotting. This instrument is particularly suitable for rapid detection and analysis of microorganisms in field testing, mobile experimental platforms, university teaching, grassroots research units, and resource-constrained environments. Specifically, in terms of communication, a Bluetooth 4.0 module supporting the Bluetooth serial port pass-through protocol enables remote operation control and parameter setting with the host computer, supporting parallel connections for up to 16 devices. Power-off reconnection and historical data upload functions ensure the integrity of long-term monitoring data. Regarding intelligent data processing, the high-performance STM32VET6 MCU handles the underlying system intelligence, including automatic self-testing and position calibration after power-on, as well as precise coordination between high-precision ADC acquisition, constant current source drive, and motor operation. The host computer software provides application-layer intelligence, automatically receiving real-time data and dynamically plotting growth curves. Based on these curves, it automatically performs complex data analysis tasks such as determining the minimum concentration with an inhibition rate ≤90%~100% (i.e., MIC value calculation), greatly improving experimental efficiency and data reliability. It should be clarified that the mentioned embodiments are merely some examples of the present invention, and not an exhaustive list of all possible implementations. Within the scope of the present invention, any other embodiments obtained based on the embodiments of the present invention without creative modifications should be considered to fall within the protection scope of the present invention.

Claims

1. A portable microbial growth curve analyzer, characterized in that, The main body (7), the casing (8) of the main body (7), and the fixed base (9) constitute the external frame of the whole machine. The flip-open upper cover (10) is hinged to the casing (8) through a damping hinge. The main body (7) includes: Detection module (1): The detection module (1) consists of a multi-channel selectable wavelength LED light source group (101) and its corresponding photodiode (102), forming a through-beam optical path structure, which is used to detect the optical density of microbial samples placed in the well plate in real time. X-axis moving module (2): The X-axis moving module consists of a stepper motor (201), a lead screw (202) and a slider (203), which is used to drive the detection module (2) to move along the X-axis direction to realize the detection of different holes in the multi-hole plate one by one; Plate holder assembly (3): The sample chamber is located inside the fixed base and is used to place 6-well or 12-well microbial culture plates; Temperature control module (4): Located inside the upper cover plate (10), it consists of a heating plate (401) and a temperature sensor (402) to maintain the temperature of the upper cover plate (10) above the ambient temperature to suppress condensation and improve detection accuracy; Integrated circuit control module (5): including microcontroller MCU, analog-to-digital converter module ADC, LED constant current drive module, motor drive module and power input module, used to control the detection process and process data; Communication module (6): includes a USB interface and a Bluetooth module. The Bluetooth module supports communication with the host computer and can support up to 16 devices connected at the same time. The host computer software system is used to set the sampling frequency, temperature control parameters and detection plate type, and supports remote control of the equipment and export of detection data.

2. The portable microbial growth curve analyzer according to claim 1, characterized in that, The LED light source group (101) supports multi-wavelength output. The detection module (1) includes 8 LED light sources and 8 corresponding photodiodes. The LED light sources are driven by a constant current driving chip. The light signal after passing through the sample is collected by the photodiodes and converted into an electrical signal.

3. The portable microbial growth curve analyzer according to claim 1, characterized in that, The detection module (1) also includes a photoelectric detection component (103). The photoelectric detection component (103) is installed on an L-shaped detection bracket (104). The LED light source group (101) and the photodiode (102), i.e. the photosensor group, are respectively installed at the upper and lower ends of the L-shaped detection bracket (104) to form a through-beam optical path structure. They move synchronously with the slider (203) of the X-axis moving module (2) to achieve point-by-point scanning of different holes in the perforated plate. The slider (203) of the X-axis moving module (2) is driven by a stepper motor (201) and transmitted through a lead screw (202) to achieve precise displacement control.

4. The portable microbial growth curve analyzer according to claim 3, characterized in that, The photoelectric detection assembly (103) includes a light source board (105) and a photoelectric signal acquisition board (106). An LED light source group (101) is mounted on the light source board (105), which is fixed to one end of a stepper motor (201). The light source board (105) provides a stable constant current drive, enabling the light source group to emit 600nm wavelength light to illuminate the sample. After passing through the sample, the emitted light is received by a photodiode (102) at the opposite position. The photodiode (102) is the receiver of the light signal and is called a "photosensor group." The photoelectric signal acquisition board (106) 106) is the processing center of optical signal. The photodiode (102) is mounted on the photoelectric signal acquisition board (106). The photoelectric signal acquisition board (106) is fixed at the other end of the stepper motor (201). The photoelectric signal acquisition board (106) receives, amplifies and converts the weak current signal generated by the photodiode into a stable voltage signal through its internal operational amplifier circuit, transimpedance amplifier, filter circuit and high-sensitivity signal conditioning system. This signal is used for the ADC acquisition of the main controller (MCU) to realize the detection of sample concentration changes. The linear correlation coefficient is >0.

99.

5. The portable microbial growth curve analyzer according to claim 1, characterized in that, The temperature control module (4) uses a closed-loop control system to regulate the temperature of the heating plate, keeping its temperature within the range of ambient temperature +4℃ to 50℃. The heating plate (401) has the dual functions of preventing condensation inside the flip cover and maintaining ambient temperature control, and is used to stabilize the ambient temperature between 25℃ and 40℃.

6. The portable microbial growth curve analyzer according to claim 1, characterized in that, The host computer software is set to a sampling interval of 1 to 60 minutes and has the functions of automatically generating microbial growth curves, exporting detection data, and remotely upgrading firmware. The host computer software is connected to the analyzer via a wired serial port or wireless Bluetooth and can be set to continuous monitoring from 1 hour to 100 hours. The curve generation process is as follows: The scattered light intensity is recorded once every minute; after receiving the scattered light intensity data stream once every minute, the software immediately executes a smoothing filtering algorithm to eliminate transient high-frequency noise and ensure the continuity of the data sequence. Subsequently, the filtered discrete points were used for nonlinear regression fitting, accurately fitting them into the growth kinetics model. The Logistic growth kinetics model was adopted, with the following functional form: ; The system employs the Levenberg-Marquardt LM iterative optimization algorithm to determine the maximum value of model parameter A (light intensity). Maximum specific growth rate and During the lag phase, using this continuous and accurate fitting function, the software system automatically and dynamically plots a smooth and accurate microbial growth curve with time as the horizontal axis and scattered light intensity as the vertical axis. After the curve is plotted, the program automatically calculates the inhibition rate at each drug concentration using the maximum light intensity parameter extracted from the fitting model. Finally, based on the drug sensitivity test standards, the system automatically searches for the minimum drug concentration that meets the threshold of inhibition rate ≤ 90%~100%, and automatically determines it as the MIC value.

7. The portable microbial growth curve analyzer according to claim 1, characterized in that, The detection accuracy of the detection module (1) is ±1%, the coefficient of variation (CV) of the consistency test is ≤ ±0.5%, the linear correlation coefficient (R²) is greater than 0.99, and the temperature control accuracy of the temperature control module is ±1℃.

8. The microbial growth curve analyzer according to claim 1, characterized in that: After powering on, the analyzer automatically completes self-test and position initialization, and reports the status information to the host computer. The communication module supports Bluetooth serial port pass-through protocol, supports 16 devices to connect to the host computer in parallel, and supports power failure reconnection and historical data upload functions.

9. The microbial growth curve analyzer according to claim 1, characterized in that: The cover (8) also includes several connectors (801), which are connected to the fixed base (9); the fixed base (9) also includes several foot pads; the main body of the detection module (1) is fixed to the fixed base (9) by fastener lock (107); the upper cover plate (10) is provided with a handle; the X-axis moving module (2) includes two core driving components, a motor and a lead screw, which enable the detection module (1) and the slider (203) to move along the X-axis; an infrared position sensor (14) is provided next to the X-axis, which is connected to the main controller and is used to detect the initial position of the slider (203) of the X-axis moving module (2).

10. The microbial growth curve analyzer according to claim 1, characterized in that: The orifice plate bracket assembly (3) is provided with an orifice plate bracket (301), and an instrument support (15) is located below the orifice plate bracket (301). The bottom of both sides of the entire body (7) is provided with a left support foot 302 and a right support foot (303). The X-axis moving module (2) is locked to the orifice plate bracket (301) by fasteners.

Images