A device and method for detecting flatness of a microfluidic chip based on an optical system

Abstract

A device and method for detecting the flatness of a microfluidic chip based on an optical system relates to the field of optical instruments. The device solves the problem that the existing technology cannot detect the flatness of the internal flow channel and detection cavity of the microfluidic chip, resulting in insufficient stability of the detection results. Furthermore, the existing device relies on optical interference, microscopic imaging and other technologies to implement. The device includes a lever micrometer, a microfluidic chip, a hollow shaft rotating platform, etc.; the lever micrometer is placed above the microfluidic chip and an observation value is set so that the lever micrometer contacts the surface of the microfluidic chip; the lever micrometer and the hollow shaft rotating platform are respectively mounted on an optical flat plate; the optical adjustment frame and all mirrors in the mirror module are respectively mounted; the spectrometer, compensation plate and reflector of the mirror module are mounted on the same horizontal plane as the light source; the observation screen is mounted on the optical adjustment frame; and all optical adjustment frames are respectively mounted on the optical flat plate. The present invention is also suitable for application fields such as medical treatment and environmental monitoring.

Description

Technical Field

[0001] The present invention relates to the technical field of optical instruments, and in particular to a device and method for detecting the flatness of a microfluidic chip based on an optical system. Background Art

[0002] As a precision device for manipulating fluids in micron-scale channels, microfluidic chips have been widely used in biomedical testing, chemical analysis, drug screening and other fields. Its core advantage lies in the efficient processing and precise detection of trace samples through integrated design. For example, it plays a key role in scenarios such as gene sequencing and rapid diagnosis of pathogens. However, the performance of microfluidic chips is highly dependent on their structural accuracy. The surface flatness of microfluidic chips and the processing quality of internal flow channels and detection cavities directly affect the fluid flow characteristics, optical signal acquisition accuracy and the reliability of detection results. If there are micron-scale bumps on the chip surface or uneven internal flow channels, it may lead to abnormal fluid diffusion, insufficient reagent mixing or interference from light signal scattering, which may cause detection errors or even experimental failure.

[0003] Currently, flatness testing of microfluidic chips faces two major technical bottlenecks: surface flatness and internal structure inspection. Traditional contact measurement methods (such as stylus profilometers) offer high accuracy but require point-by-point scanning, resulting in low efficiency and potential damage to the chip surface. Non-contact optical measurement methods (such as laser confocal microscopy) are expensive and difficult to adapt to large-scale production scenarios. The flatness of the chip's internal flow channels and inspection cavities cannot be assessed through direct observation or simple contact methods. Instead, techniques such as optical interferometry and microscopy must be employed. However, existing solutions often suffer from complex optical path adjustments and weak anti-interference capabilities, resulting in unstable test results.

[0004] After analyzing and comparing existing surface flatness detection methods, Chinese patent publication number CN119784745A discloses a composite plate flatness detection method based on image processing. The detection method includes: first, collecting the surface image of the composite plate, dividing it into blocks and sub-blocks, evaluating the noise probability of each pixel point, and measuring the degree of noise interference. Within each block, the sub-blocks are paired according to the coordinates of the pixels, and several groups of pixels with the largest grayscale difference are selected. The distance between the sub-blocks is calculated based on the noise probability of the pixels. Secondly, the fuzzy membership is determined based on the sub-block distance, and the sub-block expansion operation is performed. The fuzzy entropy of the block is obtained by the difference in the mean of the fuzzy membership before and after expansion, and then the flatness of the block is determined to achieve the flatness detection of the composite plate. This detection method causes a large amount of calculation, is easily affected by human factors, is prone to calculation errors, etc., and cannot measure the surface flatness of the object being measured. The measured material is limited and the measurement process is time-consuming, etc., making it unsuitable for promotion and application. Summary of the Invention

[0005] The present invention aims to address two major technical bottlenecks in existing microfluidic chip flatness testing: surface flatness detection and internal structure detection. Traditional contact measurement, while highly accurate, requires point-by-point scanning, is inefficient and can damage the chip surface. Non-contact optical measurement is expensive and difficult to adapt to large-scale production scenarios. The flatness of the internal flow channels and detection cavities of microfluidic chips cannot be assessed through direct observation or simple contact methods, requiring reliance on optical interferometry and microscopic imaging. However, existing solutions often suffer from complex optical path adjustment and weak anti-interference capabilities, leading to insufficient stability in test results.

[0006] To solve the above technical problems, the present invention is achieved through the following technical solutions:

[0007] Solution 1: The present invention proposes a microfluidic chip flatness detection device based on an optical system, the device comprising a lever micrometer, a microfluidic chip, a hollow shaft rotating platform, a first light source, a real-time camera, a second light source, an optical adjustment platform, a mirror module, an observation screen, an optical flat plate, and an optical adjustment frame, wherein the mirror module comprises a beam splitter, a compensation plate, a first reflector, and a second reflector;

[0008] A lever micrometer is placed above the microfluidic chip and is provided with an observation value, so that the lever micrometer contacts the surface of the microfluidic chip; the lever micrometer and the hollow shaft rotating platform are respectively mounted on an optical plate; the first light source is connected to a real-time camera; the first light source and the second light source are respectively mounted on an optical adjustment frame; the optical adjustment frame is respectively connected to all mirrors in the mirror module; the spectrometer, the compensation plate, and the second reflector of the mirror module are mounted on the same horizontal plane as the second light source; the first reflector and the second reflector, the spectrometer, and the observation screen in the mirror module are on the same horizontal plane; the observation screen is mounted above the optical adjustment frame, which is a six-dimensional adjustment platform; and all optical adjustment frames are respectively mounted on the optical plate.

[0009] Furthermore, a preferred embodiment is provided in which the microfluidic chip, when mounted above the second reflector, is mounted on the surface of the microfluidic chip in the form of a slot card. When mounted on the surface of the hollow shaft rotating platform, the microfluidic chip is clamped and secured by a flat clamp. The microfluidic chip is implemented as a 16-channel chip with dimensions of 26 mm in radius and 3 mm in thickness.

[0010] Furthermore, a preferred embodiment is provided, wherein the lever micrometer includes a digital micrometer, a magnetic base and a universal fine-tuning magnetic meter frame, the digital micrometer is mounted on the universal fine-tuning magnetic meter frame through a fine-tuning nut, and the universal fine-tuning magnetic meter frame is mounted on the magnetic base through a fine-tuning knob; the rear end of the rear rod of the universal fine-tuning magnetic meter frame is connected to the magnetic base, the front end of the front rod of the universal fine-tuning magnetic meter frame is connected to the digital micrometer, and the rear rod and the front rod are connected through a fine-tuning knob.

[0011] Furthermore, a preferred embodiment is provided, in which the hollow shaft rotating platform includes a plane clamp, a rotating platform, and a supporting base plate, the plane clamp is installed above the rotating platform through screw threads, and the rotating platform is installed above the supporting base plate; the plane clamp includes a plane plate and two rotating telescopic pressure clamps, the two rotating telescopic pressure clamps are installed on the plane plate through two tension spring screws, and the two rotating telescopic pressure clamps are installed on opposite sides of the plane plate, 180 degrees apart.

[0012] Furthermore, a preferred embodiment is provided, wherein the optical adjustment frame includes a base, an adjustment knob, and a locking mechanism; the adjustment knob includes a reflector angle adjustment knob, a reflector translation adjustment knob, a coarse adjustment knob and a fine adjustment knob, and a second light source adjustment knob; the reflector angle adjustment knob is located on the back or side of the first reflector and the second reflector; the reflector translation adjustment knob is located on one side and is connected to the translation mechanism of the reflector; the coarse adjustment knob and the fine adjustment knob are both installed on the front panel or the side panel.

[0013] Furthermore, a preferred embodiment is provided, wherein the beam splitter is mounted on a fixture of an optical adjustment frame, and the beam splitter is adjusted to be perpendicular to the optical axis by the three-dimensional translation function of the optical adjustment frame, and the knob of the optical adjustment frame is locked to fix the position of the beam splitter;

[0014] Mounting the first reflector on a movable fixture on a six-dimensional adjustment stage, and using the translation function of the optical adjustment frame, positioning the reflector in the path of light reflected by the beam splitter, with its mirror surface forming a 45° angle with the beam splitter;

[0015] The second reflector is mounted on another fixing fixture of the optical adjustment frame. Through the translation and rotation functions of the optical adjustment frame, the second reflector is made to form a 45° angle with the beam splitter and correspond to the beam splitter, so that the light reflected by the second reflector and the light reflected by the beam splitter are in the same plane, forming clear and stable interference fringes. The knob of the six-dimensional adjustment stage is locked to fix the position of the second reflector.

[0016] Furthermore, a preferred embodiment is provided, in which the observation screen, the mirror module and the light source are integrated into a structure for detecting whether the flow channel inside the microfluidic chip and the inner surface of the detection cavity are flat.

[0017] Furthermore, a preferred embodiment is provided, wherein the device also includes a shock-absorbing foot pad, the optical plate is mounted on the shock-absorbing foot pad, the optical plate is also provided with a threaded hole, and a magnetic seat, a support base of a hollow shaft rotating platform, and seven optical adjustment frames are mounted on the threaded hole.

[0018] Furthermore, a preferred embodiment is provided, wherein the device further comprises shock-absorbing pads, which are respectively mounted at four oblique corners of the optical plate, and the threads on the shock-absorbing pads are mounted in the threaded holes of the optical plate.

[0019] Solution 2: A method for detecting the flatness of a microfluidic chip based on an optical system, the method being implemented based on any one of Solution 1, the method comprising the following steps:

[0020] Step 1: Install the lever micrometer, hollow shaft rotating platform, first light source, second light source, optical adjustment frame, mirror module and observation screen and adjust the angle and position;

[0021] Step 2: Place the microfluidic chip on the flat clamp and adjust the position and clamping force of the flat clamp to fix the microfluidic chip on the hollow shaft rotating platform. Set the initial reading to 0.010 mm, lock the magnetic base position, start the stepper motor on the hollow shaft rotating platform, and drive the microfluidic chip to rotate at a constant speed. Observe the reading changes of the lever dial indicator to ensure that the lever dial indicator can work properly and accurately measure the thickness change of the microfluidic chip surface.

[0022] Step 3: Start the real-time camera, set the shooting parameters, and observe the changes in the dial indicator reading in real time during the rotation of the microfluidic chip. The fluctuation range of the reading is recorded by the real-time camera. If the value change is within ±0.005mm, the surface flatness of the microfluidic chip is determined to be qualified; if it is out of the range, it indicates a surface defect. The surface roughness of the microfluidic chip is calculated based on the value on the lever dial indicator. The surface roughness value of the chip is determined by the difference between the maximum and minimum readings recorded.

[0023] Step 4. Accurately install the microfluidic chip on the second reflector in the form of a slot card, ensuring that the detection surface of the microfluidic chip is perpendicular to the optical path; use a six-dimensional optical adjustment frame to fine-tune the position and angle of the light source, beam splitter, compensation plate, first reflector, and second reflector; during the adjustment process, observe the interference fringes on the observation screen, and through continuous adjustment, the light beam emitted by the light source is split into two beams by the beam splitter, and is reflected by the first reflector and the second reflector respectively to form clear interference fringes on the observation screen; fine-tune the position of the first reflector to make the interference fringes clear and stable, and lock the optical adjustment frame knob to ensure that the position and angle of the optical system remain unchanged during the measurement process;

[0024] Step 5, calculating the position and value of the unevenness; observing the interference fringes displayed in real time on the observation screen to determine the state of the interference fringes; if the fringes are evenly distributed, it indicates that the internal flow channel and the detection cavity surface of the microfluidic chip are flat and the flatness is qualified; if the interference fringes are bent, twisted or the spacing suddenly changes, it indicates that the internal flow channel and the detection cavity surface of the microfluidic chip are uneven; by increasing or decreasing the light source of the compensation plate, the optical path is adjusted to meet the requirements of alternating light and dark and evenly distributed interference fringes, and then the flatness difference of the flow channel and the detection cavity plane of the microfluidic chip is calculated, thereby reflecting the flatness change of the object being measured.

[0025] The present invention is beneficial in that:

[0026] The present invention describes an optical-based microfluidic chip flatness detection device and method, developing a highly precise, efficient, and anti-interference detection device. By integrating mechanical measurement with optical interferometry, this device achieves high-precision detection of both the chip surface and its internal structure. This device not only fills a technological gap in microfluidic chip internal structure detection but also, through its automated rotating platform and real-time data acquisition, provides an efficient and reliable solution for quality control during chip production. This approach facilitates the large-scale application of microfluidic technology in fields such as precision medicine and environmental monitoring.

[0027] This invention utilizes a combination of elastic mechanics, statics, and optical interference principles to mechanically detect the flatness of microfluidic chips. This prevents surface unevenness and accurately detects whether the flow channels and detection cavities within the microfluidic chip meet required flatness. This device offers dual detection capabilities, high accuracy, ease of operation, safety, low cost, and portability.

[0028] The present invention is also suitable for large-scale applications in the fields of medical treatment, environmental monitoring, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a front view of a microfluidic chip flatness detection device based on an optical system as described in embodiment 1.

[0030] Figure 2 This is a rear side view of a microfluidic chip flatness detection device based on an optical system as described in embodiment 1.

[0031] Figure 3 This is a right side view of the microfluidic chip flatness detection device based on an optical system described in embodiment 1.

[0032] Figure 4This is a left side view of a microfluidic chip flatness detection device based on an optical system as described in embodiment 1.

[0033] Figure 5 This is a top view of a microfluidic chip flatness detection device based on an optical system as described in embodiment 1.

[0034] Figure 6 This is a flow chart of a microfluidic chip flatness detection method based on an optical system as described in embodiment 2.

[0035] Among them, there are a digital micrometer 1, a magnetic base 2, a universal fine-tuning magnetic meter stand 3, a microfluidic chip 4, a plane clamp 5, a rotating platform 6, a supporting base 7, a first light source 8, a real-time camera 9, a second light source 10, a base 11, an adjustment knob 12, a locking mechanism 13, a spectrometer 14, a compensation plate 15, a first reflector 16, a second reflector 17, an observation screen 18, an optical flat plate 19, and a shock-absorbing foot pad 20. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the implementation methods of this application clearer, the technical solutions in the implementation methods of this application will be clearly and completely described below in combination with the drawings in the implementation methods of this application. Obviously, the described implementation methods are only part of the implementation methods of this application, not all of the implementation methods.

[0037] Implementation 1: This implementation proposes a microfluidic chip flatness detection device based on an optical system. Figures 1 to 5 This embodiment is described. The optical system-based microfluidic chip flatness detection device described in this embodiment includes: a digital micrometer 1, a magnetic base 2, a universal fine-tuning magnetic meter stand 3, a microfluidic chip 4, a plane clamp 5, a rotating platform 6, a supporting base 7, a first light source 8, a real-time camera 9, a second light source 10, a base 11, an adjustment knob 12, a locking mechanism 13, a spectrometer 14, a compensation plate 15, a first reflector 16, a second reflector 17, an observation screen 18, an optical flat plate 19, an optical adjustment stand, and a shock-absorbing foot pad 20.

[0038] The lever micrometer is above the microfluidic chip 4 and is set to a certain observation value so that the lever micrometer is in contact with the surface of the microfluidic chip 4; the lever micrometer and the hollow shaft rotating platform are respectively mounted on the optical plate 19; the first light source 8 is connected and installed with the real-time camera 9; the first light source 8 and the second light source 10 are respectively mounted on the optical adjustment frame; the optical adjustment frame and all the mirrors in the mirror module are respectively mounted; the spectrometer 14, the compensation plate 15, the second reflector 17 and the second light source 10 of the mirror module are mounted on the same horizontal plane; the first reflector 16 and the spectrometer 14 in the mirror module are on the same horizontal plane as the observation screen 18; the observation screen 18 is mounted on the optical adjustment frame; at the same time, all the optical adjustment frames are respectively mounted on the optical plate 19; all the optical adjustment frames are six-dimensional adjustment tables. The real-time camera 9 is installed behind the first light source 8 and is connected by a threaded connection. The first light source 8 is installed on an optical adjustment frame, which is a six-dimensional adjustment platform that can be adjusted in orientation on the X-axis, Y-axis, and Z-axis respectively. This allows the real-time camera 9 to capture the flatness of the microfluidic chip 4 and the value of the digital micrometer 1 in real time when the microfluidic chip 4 rotates. The first light source 8 is used to adjust the brightness so that the real-time camera 9 can have better clarity during the shooting process and will not have problems such as blurring or unclear vision. The light source consists of a first light source 8 and a second light source 10. The first light source 8 is installed to provide brightness adjustment for the real-time camera 9 when shooting the values ​​of the microfluidic chip 4 and the digital micrometer 1 during rotation, making them clearer; the first light source 8 is installed on the optical adjustment frame, and the first light source 8 can change its orientation due to the movement of the optical adjustment frame; the first light source 8 is connected to the real-time camera 9 in the form of a threaded connection at the rear; the wavelength of light emitted by the first light source 8 in the device is 560nm; the second light source 10 forms a whole with the mirror module and the observation screen 18 to detect whether the flow channel inside the microfluidic chip 4 and the inner surface of the detection cavity are flat; the second light source 10 is installed on the optical adjustment frame and fixed by threads; when the second light source 10 contacts the mirror module, the light source is divided into two beams of light; the wavelength of light emitted by the second light source 10 in the device is 632.8nm; the applied wavelength is not limited to this device, and the wavelength emitted by the light source can be changed according to changes in the flow channel, detection cavity, etc. of the microfluidic chip 4. The microfluidic chip 4 adopts 16 channels, a radius of 26mm and a thickness of 3mm; the microfluidic chip 4 needs to be tested for its surface flatness and the flow channel inside the microfluidic chip 4 and the plane flatness of the detection cavity; when the microfluidic chip 4 is tested for its surface flatness, the bottom is connected to the surface of the hollow shaft rotating platform and is clamped and fixed by the plane clamp 5 to prevent problems such as movement during rotation; when the microfluidic chip 4 is tested for the internal flow channel and the plane flatness of the detection cavity, it is installed above the second reflector 17 of the mirror module and installed on its surface in the form of a slot card to avoid problems such as falling off during the detection process; the device uses a 16-channel chip, but is not limited to chips of this size, and the type and size of the microfluidic chip can be changed at will.An observation screen 18 is mounted above the optical adjustment mount. The optical adjustment mount is a six-dimensional adjustment platform capable of azimuth adjustment along the X, Y, and Z axes. The observation screen 18 detects the flatness of the flow channel and detection cavity surfaces within the microfluidic chip 4 through light reflection. The observation screen 18 serves as the final observation and detection surface. The observation screen 18, along with the mirror module and the second light source 10, forms an integral unit for detecting the flatness of the flow channel and detection cavity surfaces within the microfluidic chip 4. Circular interference fringes can be detected on the surface of the observation screen 18, with varying interference fringes depending on the flatness of the microfluidic chip 4 and the wavelength and refractive index of the light. If the flow channel and detection cavity surfaces within the microfluidic chip 4 are flat, the interference fringes formed by the reflected light are uniformly distributed. Irregularities in the flow channel and detection cavity surfaces within the microfluidic chip 4 cause changes in the optical path length of the reflected light, resulting in bending, distortion, or variations in the spacing of the interference fringes. By observing and analyzing the interference fringes, the flatness of the surface can be determined. The optical plate 19 is mounted on shock-absorbing feet 20. A magnetic base 2, a support base plate 7, and seven optical adjustment mount bases 11 are mounted above the optical plate 19. The optical plate 19 is highly flat, lightweight, and easy to move. Its surface has been oxidized and treated to a black finish, making it both aesthetically pleasing and wear-resistant, and suitable for optical path construction environments. This design utilizes a surface array of M6 threaded holes with a 25mm pitch for convenient installation and fixation of optical components. The shock-absorbing feet 20 are mounted below the optical plate 19, at the four angled corners of the optical plate 19, with the threads on the shock-absorbing feet 20 installed within the threaded holes of the optical plate 19. The installation of the shock-absorbing feet 20 facilitates the movement and transportation of the entire device, and provides significant shock absorption during movement, preventing damage to the optical system.

[0039] The lever micrometer consists of a digital micrometer 1, a magnetic base 2 and a universal fine-tuning magnetic table frame 3. The digital micrometer 1 is installed on the universal fine-tuning magnetic table frame 3 and is connected by a fine-tuning nut. The precision of the digital micrometer 1 used in this embodiment is 0.001mm; when installed, the digital micrometer 1 is in close contact with the microfluidic chip 4, so that the reading of the digital micrometer 1 is displayed as 0.010mm. The reading is set to a fixed initial value to ensure that the surface flatness micro-variable is detected when the microfluidic chip 4 rotates in the later stage; according to the micro-movement of the set reading on the digital micrometer 1, the surface of the microfluidic chip 4 is detected to be qualified; according to the detection, if the value change of the digital micrometer 1 fluctuates within 0.005mm, it means that the surface of the microfluidic chip 4 meets the requirements; the universal fine-tuning magnetic table frame 3 is installed on the magnetic base 2 and is connected by the fine-tuning knob; the rear end of the rear rod of the universal fine-tuning magnetic table frame 3 is connected to the magnetic base 2, The front end of the front rod of the universal fine-tuning magnetic meter frame 3 is connected to the digital micrometer 1, and the rear rod is connected to the front rod by a fine-tuning knob. The fine-tuning knob and the fine-tuning nut can change the height and distance of the digital micrometer 1, so that the digital micrometer 1 has higher accuracy when measuring and has a wide range of applications. It can be adjusted accordingly according to different microfluidic chips 4; the magnetic base 2 is installed on the optical plate 19. The magnetic base 2 is mainly composed of a permanent magnet and a metal shell, and a switch device is provided at the bottom. The north and south poles of the magnet repel each other and opposite poles attract each other. When the switch or handle is turned, the direction of the internal magnet changes, and the digital micrometer 1 can be firmly fixed on the surface of the ferromagnetic material; the magnetic base 2 is installed to facilitate position adjustment, and the adjustment function of the universal fine-tuning magnetic meter frame 3 is used to easily adjust the position and angle of the digital micrometer 1 to meet the needs of different measurement positions and directions, thereby improving the flexibility and convenience of measurement.

[0040] The hollow shaft rotating platform is composed of a plane clamp 5, a rotating platform 6 and a supporting base plate 7; the plane clamp 5 is installed above the rotating platform 6 and is fixed by six screw threads; the rotating platform 6 is installed above the supporting base plate 7; the plane clamp 5 is composed of a plane plate and two rotating telescopic pressing clamps, the two rotating telescopic pressing clamps are installed on the plane plate through two tension spring screws, and the two rotating telescopic pressing clamps are installed on the opposite sides of the plane plate, 180 degrees apart; the length of the rotating telescopic pressing clamp is 50mm, which is to prevent the microfluidic chip 4 from being unclamped when the microfluidic chip 4 rotates, and the tension spring is used for installation. When the size of the microfluidic chip 4 changes, it can still be used, and the position of the rotating telescopic clamp can be rotated at will, which is convenient for application; the rotating platform 6 is rotated at a constant speed by a stepper motor, so that it drives the flat clamp 5 to rotate, and finally rotates the microfluidic chip 4; the rotating platform 6 is a hollow ring with a stepper motor placed in the hollow inside. Three knobs are installed on the top of the rotating platform 6, which respectively represent rotation acceleration, rotation deceleration and rotation switch; the rotating platform 6 is connected to the supporting base plate 7, and the supporting base plate 7 is connected to the optical plate 19, in order to make the entire hollow axis rotating platform stable and easy to install and transport.

[0041] The optical adjustment frame consists of a base 11, an adjustment knob 12 and a locking mechanism 13. The optical adjustment frame adopts a six-dimensional adjustment table, which can simultaneously adjust the movement of the X-axis, Y-axis and Z-axis, so that the second light source 10 of the optical system can be adjusted and tested in multiple directions. It is usually composed of an upper platform, a lower platform and a support structure connecting the two. The upper platform is used to install optical components, such as the first reflector 16, the second reflector 17, the spectrometer 14, etc. The lower platform is generally fixed on the optical plate 19 to provide stable support. The support structure includes multiple adjustable components to achieve six-dimensional adjustment functions. The three-dimensional translation adjustment along the three coordinate axes of X, Y and Z can make the optical components installed on the upper platform move slightly in the horizontal and vertical directions through a precise screw structure, with an accuracy of up to micrometers or even nanometers, ensuring accurate adjustment of the optical path length and the relative position of the optical components. The three-dimensional rotation adjustment around the X, Y and Z axes is achieved through precise rotation joints, which can accurately control the angle of the optical element. The adjustment range is usually within plus or minus ten degrees or even smaller, ensuring that the reflection and refraction angles of the light are accurate, thereby achieving stable interference fringes. The optical adjustment frame has the characteristics of high precision and high stability, which can effectively reduce the influence of external vibration and interference on the interferometer optical path. It has high adjustment resolution and good repeatability. The adjustment knob 12 includes an angle adjustment knob for the first reflector 16 and the second reflector 17, a translation adjustment knob for the first reflector 16, a coarse adjustment knob and a fine adjustment knob, and an adjustment knob for the second light source 10. The angle adjustment knobs for the first reflector 16 and the second reflector 17 are located on the back or side of the first reflector 16 and the second reflector 17, and are used to accurately adjust the angles of the first reflector 16 and the second reflector 17 so that the reflected light can accurately propagate along the set optical path, thereby achieving interference between the two beams of light. The interference fringes can be made clear and stable by fine-tuning the knob. The first reflector The translation adjustment knob 16 is located on one side and is connected to the translation mechanism of the first reflector 16; the purpose is to rotate the knob to make the first reflector 16 translate back and forth along the guide rail, change the optical path difference, and then observe the movement of interference fringes of different orders; the coarse adjustment knob and the fine adjustment knob are installed on the front panel or the side and are associated with the optical path adjustment mechanism; the coarse adjustment knob is generally larger, which is convenient for quickly adjusting the approximate position of the optical path; the fine adjustment knob is smaller and is used for fine adjustment based on the coarse adjustment; the coarse adjustment knob is used to quickly change the optical path so that the interference fringes appear roughly within the observation area; the fine adjustment knob is used for further precise adjustment so that the interference fringes reach the optimal state of clarity and stability to meet the accuracy requirements of experimental measurements; the light source adjustment knob is installed on the second light source 10 part or near it, and may include knobs for adjusting the light source brightness, focus and other functions; its function is to adjust the brightness of the light source so that the interference fringes have appropriate contrast for easy observation and measurement; adjust the focus state of the light source so that the light is incident on the microfluidic chip 4 in a suitable manner to optimize the interference fringe effect.The specific installation position and form of the adjustment knob 12 on the optical adjustment frame may vary, but the basic functions and effects are similar. They are all located on the back or side of the first reflector 16 and the second reflector 17. The application of this article is not limited to this design. The locking mechanism 13 consists of a base leveling locking structure, a relative position locking structure between the carriage and the guide rail, and a locking structure after the reflector angle is adjusted. The base of the base leveling locking structure is supported by three leveling screws. After leveling, the locking ring on the base can be tightened to keep the mount stable; the relative position locking structure between the carriage and the guide rail is coordinated between the carriage and the precision screw on the guide rail through a precision nut. When the screw rotates, the carriage can move back and forth; the relative position of the carriage and the guide rail is fixed by relying on the coordination of the screw nut and the friction between the carriage and the guide rail to maintain a stable position; the locking structure after the reflector angle is adjusted is that there are adjusting screws behind the first reflector 16 and the second reflector 17 for adjusting the mirror orientation. After the screws are adjusted to the angle, the angle is kept fixed by relying on the tightening force of the screws themselves and the coordination with the reflector bracket; in addition, there may also be locking structures on some components connected to external equipment, such as a connecting frame connected to a light source, which is fixed by tightening screws.

[0042] The mirror module includes a beam splitter 14, a compensation plate 15, a first reflector 16, and a second reflector 17; the beam splitter 14 is installed on a fixture of a six-dimensional optical adjustment frame, and the three-dimensional translation function of the optical adjustment frame is used to make the center of the beam splitter 14 coincide with the optical axis of the optical path system, and the beam splitter 14 is adjusted to be perpendicular to the optical axis by using an angle measurement tool and the three-dimensional rotation function; the six-dimensional optical adjustment frame is fine-tuned to make the beam splitter 14 reach the optimal position and angle, and then the relevant knobs of the optical adjustment frame are locked to fix the position of the beam splitter 14; the first reflector 16 is installed on a movable fixture on the six-dimensional adjustment table, and the translation function of the optical adjustment frame is used to make the first reflector 16 located on the path of the light reflected by the beam splitter 14, and its mirror surface is at a 45-degree angle to the beam splitter 14, and an inclinometer can be used for precise measurement and adjustment; Connect the driving mechanism of the first reflector 16 to the six-dimensional optical adjustment frame so that the movement of the first reflector 16 can be controlled by the optical adjustment frame. At the same time, the fine-tuning function of the optical adjustment frame is used to accurately calibrate the position and angle of the first reflector 16 to ensure that its reflected light can accurately return to the beam splitter 14; the second reflector 17 is installed on another fixing fixture of the six-dimensional optical adjustment frame. Through the translation and rotation functions of the six-dimensional optical adjustment frame, the second reflector 17 is made to form a 45-degree angle with the beam splitter 14 and correspond to the beam splitter 14, ensuring that the two beams of light can accurately meet at the beam splitter 14; carefully fine-tune the optical adjustment frame so that the light reflected by the second reflector 17 and the light reflected by the beam splitter 14 are in the same plane, forming clear and stable interference fringes, and finally lock the corresponding knob of the adjustment stage to fix the position of the second reflector 17. During the installation process, feedback adjustment should be made continuously through optical path debugging and interference fringe observation, and the high-precision adjustment capability of the six-dimensional adjustment stage should be used to make the mirror system reach the best working state, so as to ensure that if the interference fringes are unclear or uneven after the installation of the microfluidic chip 4, the flow channel and detection cavity inside the microfluidic chip 4 are uneven, and the corresponding unevenness and uneven position can be calculated based on the interference fringes; the spectrometer 14 divides the incident light into two beams of light with roughly equal intensity, one beam of transmitted light is directed to the first reflector 16, and the other beam of reflected light is directed to the second reflector 17, so that the two beams have the same frequency and a stable phase difference, in order to generate interference The first reflector 16 reflects the light transmitted by the beam splitter 14, and changes the optical path of the light by moving along the guide rail, thereby changing the optical path difference between the two beams of light, causing the interference fringes to move, so as to observe and measure the interference phenomenon, and is used to measure the wavelength of light, small displacement, etc. to derive the plane flatness of the flow channel and control cavity inside the microfluidic chip 4; the second reflector 17 reflects the light reflected by the beam splitter 14, and meets the light reflected by the first reflector 16 again at the beam splitter 14. Since the two beams of light meet the coherence condition, interference will occur, forming interference fringes. The second reflector 17 provides a stable reflection light path for the generation of the interference phenomenon.The mirror module precisely controls the propagation path and optical path difference of light, causing stable interference between the two beams of light, thereby achieving precise measurement of physical quantities such as wavelength of light and tiny displacement, and thus calculating the detection of the flatness of the flow channel and control cavity inside the microfluidic chip 4. The compensation plate 15 is used to compensate for the optical path and eliminate chromatic aberration; making the optical paths of the two beams of light equal in different media. In the experiment, one beam of light passes through the spectroscope 14, then through the air to the reflector and then returns, while the other beam of light passes through the glass of the spectroscope 14 twice; the presence of the compensation plate 15 can compensate for the difference in the optical path of the latter beam of light in the glass and the optical path of the former beam of light in the air, ensuring that the optical path difference between the two beams of light is only related to the position of the first reflector 16 and the second reflector 17, and has nothing to do with the medium, thereby facilitating accurate measurement and observation of interference phenomena, and further determining that the flatness of the surface inside the microfluidic chip 4 is not affected by external factors; and for complex light, different Light of different wavelengths has different refractive indices in glass. Without compensation plate 15, the optical path difference of light of different wavelengths after passing through beam splitter 14, first reflector 16, and second reflector 17 would vary depending on the wavelength, resulting in blurred interference fringes. Compensation plate 15 ensures that the optical path difference of light of different wavelengths in both arms is equally compensated, allowing each wavelength to form clear interference fringes. This facilitates analysis of polychromatic light and allows calculation of whether the internal irregularities of microfluidic chip 4 are convex or concave, as well as the location and magnitude of the irregularities. The change in the interference fringes satisfies the relationship between the translation distance d and the number of fringe shifts N: d = Nλ / 2, where λ is the wavelength of the incident light.

[0043] In this embodiment, the flatness detection of the plane of the flow channel and the detection cavity inside the microfluidic chip 4 is mainly carried out by a system consisting of a second light source 10, a spectroscope 14, a compensation plate 15, a first reflector 16, a second reflector 17 and an observation screen 18. A beam of light emitted by the second light source 10 is divided into two beams of roughly equal light intensity by the spectroscope 14, one beam of light is directed to the first reflector 16, and the other beam of light is directed to the second reflector 17; when measuring the flatness of the flow channel and the detection cavity inside the microfluidic chip 4, the microfluidic chip 4 is usually placed on the optical path of the second reflector 17; when light is irradiated on the surface of the flow channel and the detection cavity inside the microfluidic chip 4, it will be reflected on the surface of the flow channel, and the reflected light and the light reflected back by the second reflector 17 will merge again at the spectroscope 14. When light meets the coherence condition, interference occurs. When the optical path difference between the two beams of light meets certain conditions, alternating light and dark interference fringes are formed. If the internal flow channel and detection cavity surface of the microfluidic chip 4 are perfectly flat, the optical path of the reflected light is uniform, and the interference fringes formed are evenly distributed circular interference fringes. If the internal flow channel and detection cavity surface of the microfluidic chip 4 have microscopic unevenness, this will cause the optical path of the reflected light to change. The convex parts of the flow channel surface and the detection cavity will increase the optical path, while the concave parts will reduce the optical path. This change in optical path can cause the interference fringes to bend, deform, or shift. In this case, by analyzing the shape, spacing, and movement of the interference fringes, information about the smoothness of the flow channel and detection cavity surface can be obtained. For example, the greater the degree of curvature of the stripes, the greater the height change of the surface of the flow channel and the detection cavity, and the worse the flatness; different interference patterns are formed, and the change in optical path difference is measured according to the movement of the interference stripes. By measuring the change in the spacing of the stripes, the height difference at different positions on the flow channel surface can be calculated, and then the contour information of the flow channel and the detection cavity surface can be obtained, and quantitative analysis of the flatness can be achieved; and the optical path of the bent, deformed or moving interference stripes can be adjusted by increasing or decreasing the light source of the compensation plate 15 to satisfy the interference stripes with alternating light and dark and uniform distribution, and then the flatness difference between the flow channel and the detection cavity plane of the microfluidic chip 4 is calculated, thereby reflecting the flatness change of the object being measured.The entire measurement method is more conducive to measuring the flatness of the flow channel and detection chamber inside the microfluidic chip 4. It has high sensitivity, non-contact measurement, full-field measurement, provides quantitative information, and is sensitive to the environment. The measurement method of the device is extremely sensitive to changes in optical path difference. Even if there are slight fluctuations or defects on the surface of the flow channel and detection cavity in the microfluidic chip 4, it will cause the optical path of the reflected light to change, thereby causing the movement or deformation of the interference fringes. By accurately measuring the changes in the interference fringes, surface morphology changes at the nanometer level or even smaller scales can be detected, which can meet the requirements of high-precision detection of the flow channel in the microfluidic chip 4. During the detection process, the device does not need to directly contact the flow channel and detection cavity in the microfluidic chip 4, avoiding the damage to the chip surface that may be caused by contact measurement. This is especially important for microfluidic chips 4 with small size and fine structure, and can ensure that the integrity and performance of the chip are not affected. It is also suitable for detecting some soft or fragile devices. bad microfluidic chip materials; it can also measure the entire surface of the flow channel and detection cavity in the microfluidic chip 4 to obtain full-field flatness information, and can simultaneously detect the planar flatness changes at different positions on the surface of the flow channel and detection cavity without the need for point-by-point scanning, which greatly improves the detection efficiency, and can intuitively observe the overall morphology and defect distribution of the surface of the flow channel and detection cavity; by analyzing the shape, spacing and movement of the interference fringes, it can not only qualitatively judge the flatness of the surface of the flow channel and detection cavity in the microfluidic chip 4, but also quantitatively calculate the height difference and contour information of the surface, give a specific flatness value, and provide accurate data support for the quality evaluation and improvement of the chip; it is relatively sensitive to environmental conditions (such as temperature, humidity, vibration, etc.). Under a stable experimental environment, the influence of environmental factors on the flow channel and detection cavity in the microfluidic chip 4 can be detected by monitoring the changes in the interference fringes, such as studying problems such as flow channel deformation caused by temperature changes.

[0044] Implementation method 2, see Figure 6 This embodiment describes a method for detecting the flatness of a microfluidic chip based on an optical system. The method includes the following steps:

[0045] Step 1: Before testing the flatness of the microfluidic chip's four surfaces, install the lever micrometer, hollow shaft rotating platform, light source (a helium-neon laser with a wavelength of 632.8 nm is used for its high stability and good coherence), optical adjustment mount, mirror module, and observation screen. Once completed, mount the light source on the optical adjustment mount, setting the initial angle at 45° to the horizontal to ensure optimal beam entry into the spectroscopic system. Use the optical adjustment mount's fine-tuning knob to precisely adjust the light source angle so that the beam propagates along the designed optical path, ensuring accurate subsequent spectroscopic and interference phenomena. Adjust each optical adjustment mount so that the lever micrometer is directly above the hollow shaft rotating platform, with the indicator perpendicular to the platform surface. Set the hollow shaft rotating platform's rotation speed to 5 rpm. This speed ensures clear camera data capture without excessive fluctuations in readings due to excessive rotation speed. The angles of the mirrors in the mirror module are adjusted so that the light beam emitted by the light source forms clear and accurate interference fringes on the observation screen 18 after a series of reflections and refractions, which indicates that the debugging of the entire optical system is completed.

[0046] Step 2. Carefully place the microfluidic chip 4 (such as 16 channels, radius 26mm, thickness 3mm) on the plane clamp 5, adjust the position and clamping force of the plane clamp 5, and firmly fix the chip on the hollow shaft rotating platform. Adjust the universal fine-tuning magnetic meter holder 3 so that the digital dial indicator 1 contacts the surface of the microfluidic chip 4. Note that the contact force should be moderate to avoid damaging the chip surface. Set the initial reading to 0.010mm, lock the position of the magnetic base 2, and ensure that the position of the dial indicator remains unchanged during the measurement process. Start the rotating platform stepper motor, drive the chip to rotate at a constant speed, observe the changes in the dial indicator reading, and ensure that the dial indicator can work normally and accurately measure the thickness changes on the chip surface.

[0047] Step three, start the rotating platform stepper motor and drive the chip to rotate at a constant linear speed of 0.1mm / s. The real-time camera 9 synchronously shoots the chip surface and the micrometer value, and records the fluctuation range of the reading during the rotation. If the value of the digital micrometer changes within ±0.005mm, the chip surface flatness is determined to be qualified; if it exceeds this range, it indicates that there is a defect on the chip surface. For example, in one test, the reading fluctuation range is ±0.003mm, indicating that the surface flatness of the chip is qualified under this detection method. According to the value on the lever micrometer, the unevenness of the surface of the microfluidic chip 4 can be obtained by calculating the difference in readings of adjacent measuring points. Assuming that 10 points are measured on a certain circumference, the maximum difference in adjacent point readings is 0.002mm, which means that the surface unevenness corresponding to the two points on the circumference is 0.002mm.

[0048] Step 4. Accurately install the microfluidic chip 4 in the form of a slot card above the second reflector 17, ensuring that the detection surface of the chip is perpendicular to the optical path, and the position of the chip is stable and will not move during the measurement process. Use a six-dimensional optical adjustment frame to fine-tune the position and angle of the second light source 10, the spectrometer 14, the compensation plate 15, the first reflector 16, and the second reflector 17. During the adjustment process, observe the interference fringes on the observation screen 18. Through continuous adjustment, the 632.8nm light beam emitted by the light source is divided into two beams by the spectrometer, and is reflected by the first reflector 16 and the second reflector 17 respectively to form clear interference fringes on the observation screen 18. Fine-tune the position of the first reflector 16 so that the interference fringes are clear and stable (such as uniform circular fringes), and lock the adjustment frame knob to ensure that the position and angle of the optical system remain unchanged during the measurement process.

[0049] Step 5: Calculate the location and value of the unevenness based on the degree of fringe distortion, light wavelength, refractive index, and other parameters (e.g., deriving the surface height difference from the fringe offset). Carefully observe the interference fringes displayed in real time on the observation screen 18 to determine their state. If the fringes are evenly distributed, such as appearing as evenly spaced circular rings, the surface of the flow channel and detection cavity within the chip is flat and meets the required flatness standards. If the interference fringes are curved, twisted, or exhibit sudden changes in spacing, this indicates unevenness within the flow channel and detection cavity. Curved, deformed, or shifted interference fringes can be adjusted by increasing or decreasing the optical path length of the light source on the compensation plate 15 to achieve evenly distributed interference fringes with alternating light and dark patterns. Calculate the location and value of the unevenness based on the degree of fringe distortion, light wavelength, refractive index, and other parameters (e.g., deriving the surface height difference from the fringe offset). The flatness difference between the flow channel and detection cavity surfaces of the microfluidic chip 4 is then calculated, reflecting the flatness variation of the object being measured. Based on the degree of fringe distortion, the wavelength of light (632.8nm), the refractive index of air (approximately 1.00029), and other parameters, the position and value of the unevenness can be calculated using the formula Δh=λ•ΔN / 2n, where Δh is the surface height difference, λ is the wavelength, ΔN is the fringe offset, and n is the refractive index. For example, when the fringe is observed to be offset by 3 fringe spacings, the calculated surface height difference is 632.8×10 -9 ×3 / 2×1.00029≈9.49×1 0-7 m=0.949μm.

[0050] Step 6. After the test experiment is completed, turn off the power of the device first. Carefully remove the microfluidic chip 4 on the carrier, taking care not to damage the chip. In accordance with laboratory regulations, place the chip in a suitable container for proper handling, such as cleaning and storage. Clean the device and gently wipe the surface of the optical element with a clean cloth to remove dust and stains. Check the various components of the device to ensure that there is no damage or looseness. If any parts are found to be damaged or need to be replaced, repair and replace them in time, such as adding appropriate amount of lubricating oil to mechanical parts such as the hollow shaft rotating platform. Place the device in a suitable location and take protective measures to prevent dust and other impurities from entering the inside of the device so that it can operate normally the next time it is used.

[0051] Those skilled in the art will understand that the above are only preferred embodiments of the present invention, and the features described in the various embodiments and / or technical solutions of the present disclosure can be combined or coupled in various ways, even if such combinations or couplings are not explicitly described in the present disclosure. They are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

[0052] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, the present invention is intended to include such changes and modifications as fall within the scope of the present invention and its equivalents.

Claims

1. A microfluidic chip flatness detection device based on an optical system, characterized in that: The device comprises a lever micrometer, a microfluidic chip (4), a hollow shaft rotating platform, a first light source (8), a real-time camera (9), a second light source (10), an optical adjustment platform, a mirror module, an observation screen (18), an optical flat plate (19), and an optical adjustment frame, wherein the mirror module comprises a beam splitter (14), a compensation plate (15), a first reflector (16), and a second reflector (17); A lever micrometer is placed above the microfluidic chip (4) and is provided with an observation value, so that the lever micrometer contacts the surface of the microfluidic chip (4); the lever micrometer and the hollow shaft rotating platform are respectively mounted on an optical plate (19); the first light source (8) is connected to the real-time camera (9); the first light source (8) and the second light source (10) are respectively mounted on an optical adjustment frame; the optical adjustment frame is respectively connected to all mirrors in the mirror module; wherein the spectrometer (14), the compensation plate (15) and the second reflector (17) of the mirror module are mounted on the same horizontal plane as the second light source (10); the first reflector (16) and the second reflector (17) in the mirror module, the spectrometer (14) and the observation screen (18) are on the same horizontal plane; the observation screen (18) is mounted above the optical adjustment frame, which is a six-dimensional adjustment platform; and all optical adjustment frames are respectively mounted on the optical plate (19); The microfluidic chip (4) needs to be tested for surface flatness and the flow channel inside the microfluidic chip (4) and the plane flatness inside the detection cavity; when the microfluidic chip (4) is tested for surface flatness, the bottom is connected to the surface of the hollow shaft rotating platform and is clamped and fixed by the plane clamp (5); when the microfluidic chip (4) is tested for internal flow channel and the plane flatness inside the detection cavity, it is installed above the second reflector (17) of the mirror module and installed on its surface in the form of a slot card.

2. The microfluidic chip flatness detection device based on an optical system according to claim 1, characterized in that: When the microfluidic chip (4) is mounted above the second reflector (17), it is mounted on the surface of the microfluidic chip (4) in the form of a slot card. When the microfluidic chip (4) is mounted on the surface of the hollow shaft rotating platform, it is clamped and fixed by a plane clamp. The microfluidic chip (4) adopts a 16-channel chip with a size of 26 mm in radius and 3 mm in thickness.

3. The microfluidic chip flatness detection device based on an optical system according to claim 1, characterized in that: The lever dial gauge comprises a digital dial gauge (1), a magnetic base (2) and a universal fine-tuning magnetic gauge frame (3); the digital dial gauge (1) is mounted on the universal fine-tuning magnetic gauge frame (3) via a fine-tuning nut; the universal fine-tuning magnetic gauge frame (3) is mounted on the magnetic base (2) via a fine-tuning knob; the rear end of the rear rod of the universal fine-tuning magnetic gauge frame (3) is connected to the magnetic base (2), the front end of the front rod of the universal fine-tuning magnetic gauge frame (3) is connected to the digital dial gauge (1), and the rear rod and the front rod are connected via a fine-tuning knob.

4. The microfluidic chip flatness detection device based on an optical system according to claim 1, characterized in that: The hollow shaft rotating platform comprises a plane clamp (5), a rotating platform (6), and a supporting base plate (7); the plane clamp (5) is mounted on the rotating platform (6) via screw threads, and the rotating platform (6) is mounted above the supporting base plate (7); the plane clamp (5) comprises a plane plate and two rotating telescopic pressing clamps, the two rotating telescopic pressing clamps are mounted on the plane plate via two tension spring screws, and the two rotating telescopic pressing clamps are mounted on opposite sides of the plane plate and are arranged 180 degrees apart.

5. The microfluidic chip flatness detection device based on an optical system according to claim 1, characterized in that: The optical adjustment frame comprises a base (11), an adjustment knob (12), and a locking mechanism (13); the adjustment knob (12) comprises a reflector angle adjustment knob, a reflector translation adjustment knob, a coarse adjustment knob and a fine adjustment knob, and a second light source adjustment knob; the reflector angle adjustment knob is located on the back or side of the first reflector (16) and the second reflector (17); the reflector translation adjustment knob is located on one side and is connected to the translation mechanism of the reflector; the coarse adjustment knob and the fine adjustment knob are both mounted on the front panel or the side panel.

6. The microfluidic chip flatness detection device based on an optical system according to claim 1, characterized in that: The beam splitter (14) is mounted on a fixture of an optical adjustment frame, and the beam splitter (14) is adjusted to be perpendicular to the optical axis through the three-dimensional translation function of the optical adjustment frame, and the knob of the optical adjustment frame is locked to fix the position of the beam splitter (14); The first reflector (16) is mounted on a movable fixture on a six-dimensional adjustment table, and through the translation function of the optical adjustment frame, the first reflector (16) is located on the path of the light reflected by the beam splitter (14), and its mirror surface forms an angle of 45° with the beam splitter (14); The second reflector (17) is mounted on another fixing fixture of the optical adjustment frame. Through the translation and rotation functions of the optical adjustment frame, the second reflector (17) is made to form a 45° angle with the beam splitter (14) and correspond to the beam splitter (14), so that the light reflected by the second reflector (17) and the light reflected by the beam splitter (14) are in the same plane, forming clear and stable interference fringes. The knob of the six-dimensional adjustment stage is locked to fix the position of the second reflector (17).

7. The microfluidic chip flatness detection device based on an optical system according to claim 1, characterized in that: The observation screen (18), the mirror module, and the second light source (10) are integrated into a structure for detecting whether the flow channel inside the microfluidic chip (4) and the inner surface of the detection cavity are flat.

8. The microfluidic chip flatness detection device based on an optical system according to claim 3, characterized in that: The optical flat plate (19) is also provided with a threaded hole, on which a magnetic base (2), a supporting base of a hollow shaft rotating platform, and seven optical adjustment frames are mounted.

9. The microfluidic chip flatness detection device based on an optical system according to claim 8, characterized in that: The device further comprises a shock-absorbing foot pad (20), which is respectively mounted at four oblique angles of the optical plate (19), and the threads on the shock-absorbing foot pad (20) are mounted in the threaded holes of the optical plate (19).

10. A method for detecting the flatness of a microfluidic chip based on an optical system, characterized in that: The method is implemented based on any one of claims 1 to 9, and comprises the following steps: Step 1: Install the lever micrometer, the hollow shaft rotating platform, the first light source (8), the second light source (10), the optical adjustment frame, the mirror module and the observation screen (18) and adjust the angle and position; Step 2: Place the microfluidic chip (4) on the plane clamp (5), adjust the position and clamping force of the plane clamp (5) so that the microfluidic chip (4) is fixed on the hollow shaft rotating platform; set the initial reading to 0.010 mm, lock the position of the magnetic base (2), start the stepper motor on the hollow shaft rotating platform, drive the microfluidic chip (4) to rotate at a constant speed, and observe the reading change of the lever micrometer to ensure that the lever micrometer can work normally and accurately measure the thickness change of the surface of the microfluidic chip (4); Step 3: Start the real-time camera (9), set the shooting parameters, observe the reading change of the dial indicator in real time during the rotation of the microfluidic chip (4), and record the fluctuation range of the reading through the real-time camera (9); if the value change is within ±0.005mm, it is determined that the surface flatness of the microfluidic chip (4) is qualified; if it is out of the range, it indicates a surface defect; the surface roughness of the microfluidic chip (4) is calculated based on the value on the lever dial indicator; the surface roughness value of the chip is determined by the difference between the maximum reading and the minimum reading recorded; Step 4, accurately install the microfluidic chip (4) in the form of a slot card above the second reflector (17), ensuring that the detection surface of the microfluidic chip (4) is perpendicular to the optical path; use a six-dimensional optical adjustment frame to fine-tune the position and angle of the second light source (10), the spectroscope (14), the compensation plate (15), the first reflector (16), and the second reflector (17); during the adjustment process, observe the interference fringes on the observation screen (18), and through continuous adjustment, the light beam emitted by the light source is divided into two beams by the spectroscope (14), and is reflected by the first reflector (16) and the second reflector (17) respectively to form clear interference fringes on the observation screen (18); fine-tune the position of the first reflector (16) so that the interference fringes are clear and stable, and lock the optical adjustment frame knob to ensure that the position and angle of the optical system remain unchanged during the measurement process; Step 5, calculate the position and value of the unevenness; observe the interference fringes displayed in real time on the observation screen (18) to determine the state of the interference fringes; if the fringes are evenly distributed, it indicates that the internal flow channel and the detection cavity surface of the microfluidic chip (4) are flat and the flatness is qualified; if the interference fringes are bent, twisted or the spacing suddenly changes, it indicates that the internal flow channel and the detection cavity surface of the microfluidic chip (4) are uneven; adjust the optical path by increasing or decreasing the light source of the compensation plate (15) to meet the requirements of alternating light and dark and evenly distributed interference fringes, and then calculate the flatness difference between the flow channel of the microfluidic chip (4) and the detection cavity plane, thereby reflecting the flatness change of the object being measured.

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