Microfluidic device for identifying urinary tract infected Escherichia coli

Abstract

The present invention relates to the field of Escherichia coli identification, and discloses a microfluidic device for urinary tract infection Escherichia coli identification, the microfluidic device comprises a bearing disc and a transmission mechanism, a plurality of mounting grooves are formed in the circumferential direction of the bearing disc, and microfluidic chips are in clearance fit in the mounting grooves; the transmission mechanism comprises a gear unit and a driving unit, the gear unit comprises a central gear, the central gear is circumferentially engaged with a plurality of circumferential gears, the circumferential gears are detachably connected with the micro-fluidic chip, the number and position of the circumferential gears are in one-to-one correspondence with the number and position of the mounting grooves, and the central gear is detachably connected with the center of the bearing disc; the transmission mechanism has two modes, namely a centrifugal mode and an adjusting mode; in the adjusting mode, the central gear sequentially drives the circumferential gear and the micro-fluidic chip to rotate until the micro-fluidic chip is adjusted to a designed angle; in the centrifugal mode, the center gear drives the bearing disc to rotate. The centrifugal micro-fluidic chip is used for a centrifugal micro-fluidic chip and can change the flowing direction of liquid.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of Escherichia coli identification, and in particular to a microfluidic device for identifying Escherichia coli causing urinary tract infection. BACKGROUND

[0002] The identification of Escherichia coli relies on its unique biochemical phenotype and molecular characteristics, which distinguish it from most Enterobacteriaceae bacteria and non-Enterobacteriaceae bacteria, and are the basis for designing detection modules in microfluidic technology. Microfluidic chips can be customized to integrate targeted detection units according to the biochemical and molecular characteristics of Escherichia coli, without the need for extensive non-specific screening tests as in traditional methods, significantly reducing the time.

[0003] Ordinary microfluidics mainly rely on external micropumps, electric fields or capillary forces to control fluid flow, while centrifugal microfluidics uses centrifugal force to drive and control fluid, with a relatively simplified structure consisting mainly of a rotating motor and a disc chip. However, this also results in a single direction of liquid flow, which can usually only flow in one direction. With the development of technology, the requirement for identification is increasing, and single-direction flow has gradually failed to meet the identification requirements.

[0004] The microfluidic chip includes a mixing chamber, an amplification chamber, and a detection chamber. The mixing chamber is used to mix the lysis solution and the bacterial body thoroughly. The amplification chamber is used to amplify the uidA gene or virulence gene. The detection chamber is used to combine with the fluorescent probe to generate a signal. At the same time, the antibiotic solution in the drug sensitivity test chamber is mixed with the bacterial solution, and the drug resistance is determined by observing the bacterial growth signal (such as turbidity, fluorescence).

[0005] The centrifugal microfluidic of the prior art can make the liquid flow through different functional chambers in a predetermined order by designing a hierarchical threshold structure and a fluid path switching structure, without the need to change the centrifugal direction. However, if the number of chip chambers increases, the threshold structure and the fluid path gradually become complex, and the processing time and cost of the chip gradually increase. In order to ensure the accuracy of the results, the chip is usually a disposable consumable, so improving the finished product of the chip is not economical. SUMMARY

[0006] The present application aims to provide a microfluidic device for identifying Escherichia coli causing urinary tract infection, which is used for a centrifugal microfluidic chip and can change the direction of liquid flow.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a microfluidic device for identifying Escherichia coli causing urinary tract infection, comprising a supporting tray and a transmission mechanism, the supporting tray is circumferentially provided with a plurality of installation grooves, and a microfluidic chip is gap-fitted in each installation groove. The transmission mechanism comprises a gear unit and a driving unit, the gear unit comprises a central gear, a plurality of circumferential gears are circumferentially engaged with the central gear, the circumferential gears are detachably connected with the microfluidic chip, the number and position of the circumferential gears are one-to-one corresponding to the mounting slots, and the central gear is detachably connected with the center of the supporting tray; The transmission mechanism has two modes: centrifugal mode and adjustment mode; In the adjustment mode, the driving unit drives the gear unit to move, the central gear is separated from the center of the supporting tray, the circumferential gears are connected with the microfluidic chip, the central gear drives the circumferential gears and the microfluidic chip to rotate in turn, and the microfluidic chip is adjusted to the designed angle. In the centrifugal mode, the driving unit drives the gear unit to move, the central gear is connected with the center of the supporting tray, the circumferential gears are separated from the microfluidic chip, and the central gear drives the supporting tray to rotate.

[0008] The beneficial effects of the scheme are: 1. The supporting tray is mainly used for mounting the microfluidic chip, so as to drive the microfluidic chip to rotate, thereby achieving the centrifugal effect. In order to realize the effect of changing the flow direction of fluid, the transmission mechanism is provided in the scheme, the central gear drives the circumferential gears in turn, thereby driving a plurality of microfluidic chips on the supporting tray to rotate synchronously to the set angle, since the centrifugal force is always away from the center of the supporting tray, the effect of changing the flow direction of liquid is realized.

[0009] 2. Since the transmission mechanism is a gear structure, if the supporting tray drives the transmission mechanism to rotate together, the gears will collide with each other and be easily damaged, therefore, in the scheme, the transmission mechanism and the supporting tray are designed in a separated manner, they are connected only when the angle needs to be adjusted, and they are separated when centrifugal rotation is needed, thereby ensuring the reliability of the transmission mechanism.

[0010] 3. The circumferential gears drive the microfluidic chip to rotate, thereby adjusting the angle of the microfluidic chip, reducing the threshold structure of the microfluidic chip and simplifying the fluid path, controlling the cost of the microfluidic chip, simplifying the structure of the microfluidic chip, and improving the reliability of the microfluidic chip.

[0011] Further, the driving unit comprises a vertical driving member, a moving plate is connected to the upper end of the output shaft of the vertical driving member, and the central gear and the circumferential gears are both rotationally arranged on the moving plate; A rotating through hole is vertically formed in the center of the supporting tray, a rotating motor is arranged at the central position of the central gear, a rotating part is arranged on the output shaft of the rotating motor, the rotating part and the rotating through hole are in sliding connection, in the centrifugal mode, the rotating part is inserted into the rotating through hole and drives the rotating through hole to rotate synchronously, and in the adjustment mode, the rotating part exits the rotating through hole.

[0012] Further, the fixed plate is further included, the supporting tray is supported on the fixed plate, the supporting tray and the fixed plate are rotationally connected, the output shaft of the rotating motor is provided with a fixed part, and the fixed part is located below the rotating part; a fixed through hole is vertically formed on the fixed plate, and the fixed through hole and the fixed part are slidingly connected; In the adjustment mode, the vertical driving part drives the moving plate and the rotating motor to move upward, so as to drive the fixed part to move upward and insert into the fixed through hole and gap fit with the rotating through hole, and the rotating part moves upward and exits the rotating through hole. In the centrifugal mode, the vertical driving part drives the moving plate and the rotating motor to move downward, so as to drive the fixed part to move downward and exit the fixed through hole, and the rotating part moves downward and inserts into the rotating through hole.

[0013] Further, the base is further included, a plurality of limiting columns and a plurality of circumferential rotating shafts are vertically arranged on the base, the number and position of the circumferential rotating shafts correspond to the circumferential gear one by one, the circumferential rotating shafts pass through the moving plate and the circumferential gear in sequence, and the circumferential rotating shafts and the moving plate and the circumferential gear are slidingly connected; In the centrifugal mode, the moving plate moves downward, and the limiting columns pass through the moving plate and the central gear in sequence, so as to limit the rotation of the central gear; In the adjustment mode, the moving plate moves upward, and the limiting columns and the central gear are separated.

[0014] Further, the bottom of the mounting groove is circumferentially provided with a lower inclined tooth, the lower surface of the microfluidic chip is provided with an upper inclined tooth matched with the lower inclined tooth, in the adjustment mode, the circumferential gear drives the microfluidic chip to rotate, so that the microfluidic chip moves up and down along the surface of the lower inclined tooth; after rotation, the upper inclined tooth is re-engaged with the lower inclined tooth.

[0015] Further, the output shaft of the rotating motor is provided with a pressing plate at the upper end; In the centrifugal mode, the moving plate drives the pressing plate to move downward, the lower surface of the pressing plate is in contact with the upper surface of the supporting tray, and the rotating motor drives the supporting tray to rotate through the pressing plate.

[0016] Further, the rotating through hole is a regular hexagonal section, the central axis of the regular hexagon is taken as a boundary, the section of the rotating part is half of the regular hexagonal section, and the profile of the remaining edges of the rotating part is matched with the shape of the rotating through hole, except for the edge where the central axis is located; The pressing plate is cross-shaped, and the pressing plate is used for locally covering the supporting tray.

[0017] The scheme has the following effects: 1. The vertical driving part is used to realize the switching between the centrifugal mode and the adjustment mode, and specifically: In the centrifugal mode, the vertical driving part drives the moving plate and the rotating motor to move downward, the fixed part moves downward and exits the fixed through hole, and the rotating part moves downward and inserts into the rotating through hole; the limiting columns pass through the moving plate and the central gear in sequence, so as to limit the rotation of the central gear and the rotating motor, and the output shaft of the rotating motor drives the rotating through hole, the supporting tray and the microfluidic chip to rotate through the rotating part.

[0018] In the adjustment mode, the vertical driving member drives the moving plate and the rotary motor to move upward, and the rotating part moves upward to exit the rotating hole; the limiting column and the center gear are separated, the fixed part moves upward to insert the fixed hole and cooperates with the rotating hole gap, and since the fixed hole is arranged on the fixed plate, the fixed hole limits the rotation of the output shaft of the rotary motor, when the rotary motor starts, the output shaft reversely drives the rotary motor to rotate, thereby sequentially driving the center gear, the circumferential gear and the microfluidic chip to rotate.

[0019] 2. The rotary motor is used to drive the supporting tray to rotate and drive the center gear to rotate. Since the rotary motor or its rotating shaft must be fixed to achieve the rotation effect, the supporting tray and the center gear cannot rotate at the same time, thereby ensuring that the supporting tray will not rotate when the circumferential gear drives the microfluidic chip to rotate, thereby preventing the two structures from colliding and being damaged, and ensuring the durability.

[0020] 3. When the circumferential gear drives the microfluidic chip to rotate, a transmission shaft is usually arranged on the circumferential gear, the transmission shaft is inserted into the bottom of the microfluidic chip, thereby driving the microfluidic chip to rotate, the insertion depth is greater than the thickness of the lower inclined tooth, thereby ensuring that the transmission shaft will not come out of the bottom of the microfluidic chip; the lower inclined tooth cooperates with the upper inclined tooth to position the microfluidic chip, ensuring that the position of the microfluidic after rotation is consistent with the designed position, that is, the angle is fine-tuned through this structure.

[0021] During rotation, the microfluidic chip moves up and down along the surface of the lower inclined tooth, thereby assisting the liquid in the microfluidic chip to mix in the up-down direction, thereby increasing the accuracy of the results; at the same time, the transmission shaft is located below the supporting tray, which is not convenient for cleaning, and dust is easy to accumulate over time. Through the up-down movement of the microfluidic chip, the dust on the upper end of the transmission shaft is shaken off, thereby ensuring the flatness of the contact surface, ensuring the synchronization of rotation, thereby ensuring the accuracy of the rotation angle.

[0022] 4. The eccentricity of the chip during centrifugation is the main reason for the loss of control of liquid movement and the rupture of the chip. To prevent the chip from being eccentric, the output shaft of the rotary motor must first be prevented from being eccentric; the following measures are taken in this scheme: 1) The moving plate is guided by arranging a circumferential shaft, thereby ensuring that the output shaft of the rotary motor will not be skewed, even if eccentricity occurs during centrifugation, after the guide plate slides on the circumferential shaft during mode switching, the eccentricity is corrected; 2) Since the cross-section of the rotating part is half of a regular hexagon, when the output shaft of the rotating motor is misaligned, the gap between the rotating part and the rotating through hole increases, causing the bearing plate to start to shake. The rotation of the bearing plate and the pressure plate is no longer synchronized. By observing the shaking of the bearing plate or the change in the part of the bearing plate that is not covered by the pressure plate, even if rotational eccentricity is found, the operator is reminded to make adjustments in time, thereby ensuring the accuracy of the assessment results. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of Example 1; Figure 2 This is a top three-dimensional view of the pressure plate and the output shaft of the rotary motor in Example 1; Figure 3 This is a bottom-view 3D view of the pressure plate and the output shaft of the rotary motor in Example 1; Figure 4 This is a schematic cross-sectional view of the rotating part in Example 1; Figure 5 This is a three-dimensional view of the pressure plate in Example 2. Detailed Implementation

[0024] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings include: tray 1, mounting groove 11, mounting through hole 12, center groove 13, rotating through hole 14, wedge block 15, base 2, vertical drive component 21, moving plate 22, center column 23, limiting column 24, circumferential rotating shaft 25, fixing plate 3, support 31, ring structure 32, center hole 33, side plate 4, center gear 51, circumferential gear 52, transmission shaft 53, rotary motor 6, output shaft of rotary motor 61, rotating part 62, fixing part 63, pressure plate 7.

[0025] Example 1 Example 1 is basically as follows Figures 1-4 As shown: A microfluidic device for identifying Escherichia coli in urinary tract infections, comprising a tray 1 and a transmission mechanism, such as... Figure 2 As shown, the support tray 1 is disc-shaped, and four circular mounting slots 11 are opened circumferentially on the support tray 1. A microfluidic chip (not shown in the figure) is fitted in the mounting slot 11 with clearance. The microfluidic chip includes a chip body and a tray (not shown in the figure). The tray and the mounting slot 11 are fitted with clearance. The chip body is accommodated in the tray. A regular hexagonal groove is opened on the lower surface of the tray. A mounting through hole 12 is opened at the bottom of the mounting slot 11. The mounting through hole 12 has a circular cross-section, which is the circumcircle of the regular hexagonal groove.

[0026] A circular central groove 13 is formed at the center of the bearing tray 1, and a regular hexagonal rotating through hole 14 is formed at the bottom of the central groove 13. The regular hexagon is an inscribed hexagon of the circular cross section of the central groove 13, and the rotating through hole 14 penetrates the bearing tray 1. As Figure 1 shown, the transmission mechanism includes a transmission box, the transmission box is provided with a gear unit and a driving unit, the transmission box is surrounded by a base 2, a fixed plate 3 and four side plates 4, the connection mode is welding or bolt connection, the fixed plate 3 is located above the base 2, the side plates 4 are located between the base 2 and the fixed plate 3, the driving unit includes a vertical driving part 21, the vertical driving part 21 is bolted to the base 2, the output shaft of the vertical driving part 21 is bolted to a moving plate 22, the vertical driving part 21 is a gas cylinder, the moving plate 22 is a disc, and the gear unit is arranged on the moving plate 22; The gear unit includes a central gear 51, four circumferential gears 52 are circumferentially engaged with the central gear 51, a transmission shaft 53 is vertically and integrally formed on the upper surface center of the circumferential gear 52, the upper end of the transmission shaft 53 is a regular hexagonal section and matches the regular hexagonal groove shape of the lower surface of the tray. The number and position of the circumferential gears 52 correspond one-to-one to the mounting slots 11. A rotating motor 6 is screw-connected to the central gear 51, and a rotating part 62 and a fixed part 63 are sequentially arranged on the output shaft 61 of the rotating motor from top to bottom, as Figure 1 、 Figure 3 、 Figure 4 shown, the central axis of the regular hexagonal section of the rotating through hole 14 is taken as a boundary, the cross section of the rotating part 62 is half of the regular hexagonal section, except for one side where the central axis is located, the profiles of the remaining sides of the rotating part 62 match the shape of the rotating through hole 14, and the rotating part 62 and the rotating through hole 14 are in sliding connection; the fixed part 63 is a strip-shaped block, the distance between the fixed part 63 and the rotating part 62 is greater than the hole length of the rotating through hole 14, and the rotating through hole 14 limits the fixed part 63 from entering the interior of the rotating through hole 14; a central column 23, two limiting columns 24 and four circumferential rotating shafts 25 are vertically and integrally formed on the base 2, the number and position of the circumferential rotating shafts 25 correspond one-to-one to the circumferential gears 52, the circumferential rotating shafts 25 sequentially pass through the moving plate 22 and the circumferential gears 52, and the circumferential rotating shafts 25 are in sliding connection with the moving plate 22 and the circumferential gears 52; the central column 23 is inserted into the central surface of the central gear 51 and is in rotational connection with the central gear 51.

[0027] An abutment 31 is integrally formed on the upper surface of the fixed plate 3, and the supporting tray 1 is supported on the abutment 31, an upper convex annular structure 32 is integrally formed on the upper surface of the abutment 31, an annular groove is opened on the lower surface of the supporting tray 1 and matches the annular structure 32, the annular structure 32 and the annular groove are in rotational connection, circumferential holes are opened on the fixed plate 3 for the circumferential rotating shafts 25 to pass through, a central hole 33 is opened at the central position of the fixed plate 3 for the output shaft 61 of the rotating motor to pass through, the central hole 33 is in the shape of a strip that matches the fixed part 63, and the cross section of the central hole 33 can cover the cross section of the mounting through hole 12.

[0028] As Figure 1As shown, the upper end of the output shaft 61 of the rotary motor is bolted with the pressing plate 7, and the pressing plate 7 is used to partially cover the pressure-bearing disc. Figure 2 As shown, the pressing plate 7 is cross-shaped, and the pressing plate 7 is used to partially cover the pressure-bearing disc and press the microfluidic chip when the pressure-bearing disc rotates.

[0029] The use method of the microfluidic device for identifying Escherichia coli causing urinary tract infection is as follows: 1. In the centrifugal mode, the vertical driving part 21 drives the moving plate 22 and the rotary motor 6 to move downward, the fixed part 63 moves downward to exit the fixed through hole, the rotating part 62 moves downward to insert into the rotating through hole 14; the limiting column 24 passes through the moving plate 22 and the center gear 51 in sequence, thereby limiting the rotation of the center gear 51 and the rotary motor 6, the moving plate 22 drives the pressing plate 7 to move downward, the lower surface of the pressing plate 7 contacts the upper surface of the supporting disc 1, the output shaft 61 of the rotary motor drives the rotating through hole 14, the supporting disc 1 and all the microfluidic chips to rotate synchronously through the rotating part 62, and at the same time, the rotary motor 6 drives the supporting disc 1 to rotate through the pressing plate 7.

[0030] 2. In the adjustment mode, the vertical driving part 21 drives the moving plate 22 and the rotary motor 6 to move upward, the rotating part 62 moves upward to exit the rotating through hole 14; the limiting column 24 and the center gear 51 are separated, the fixed part 63 moves upward to insert into the fixed through hole and gap fit with the rotating through hole 14, since the fixed through hole is arranged on the fixed plate 3, the fixed through hole limits the rotation of the output shaft 61 of the rotary motor through the fixed part 63, when the rotary motor 6 is started, the output shaft reversely drives the rotary motor 6 to rotate, thereby sequentially driving the center gear 51, the circumferential gear 52 and the microfluidic chip to rotate, until the microfluidic chip is adjusted to the designed angle.

[0031] Example 2 Example 2 is based on example 1: as shown, Figure 5 As shown, the bottom of the installation groove 11 is circumferentially integrally formed with lower inclined teeth, the lower inclined teeth are formed by circumferentially arranging a plurality of inclined blocks 15, the upper surfaces of the inclined blocks 15 are inclined in the same direction along the circumferential tangent line, the lower surface of the tray of the microfluidic chip is integrally formed with upper inclined teeth matched with the lower inclined teeth, in the adjustment mode, the circumferential gear 52 drives the microfluidic chip to rotate, the lower inclined teeth are arranged in the same direction as the rotation direction of the microfluidic chip, that is, the lower inclined teeth will not hinder the rotation of the microfluidic chip, the microfluidic chip moves up and down along the surface of the lower inclined teeth, and after rotation, the upper inclined teeth and the lower inclined teeth re-maintain cooperation.

[0032] The above-mentioned are only embodiments of the present application, and common technical solutions and / or common knowledge of the scheme are not described in detail. It should be pointed out that, for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, and these will not affect the effect and practicality of the patent. The protection scope claimed in the present application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A microfluidic device for identifying Escherichia coli in urinary tract infections, characterized in that: Includes a support tray and a transmission mechanism. The support tray has several mounting slots on the circumferential direction, and microfluidic chips are fitted into the gaps in the mounting slots. The transmission mechanism includes a gear unit and a drive unit. The gear unit includes a central gear, which is circumferentially meshed with several circumferential gears. The circumferential gears and the microfluidic chip are detachably connected. The number and position of the circumferential gears correspond one-to-one with the mounting slots. The central gear and the center of the support tray are detachably connected. The transmission mechanism has two modes: centrifugal mode and regulating mode; In adjustment mode, the drive unit drives the gear unit to move, the central gear separates from the center of the support tray, the circumferential gear connects to the microfluidic chip, and the central gear drives the circumferential gear and the microfluidic chip to rotate in sequence until the microfluidic chip is adjusted to the design angle; In centrifugal mode, the drive unit moves the gear unit, the central gear is connected to the center of the tray, the circumferential gear is separated from the microfluidic chip, and the central gear drives the tray to rotate.

2. The microfluidic device for identifying Escherichia coli in urinary tract infections according to claim 1, characterized in that: The drive unit includes a vertical drive component, and a movable plate is connected to the upper end of the output shaft of the vertical drive component. The central gear and the circumferential gear are both rotatably mounted on the movable plate. The tray has a vertically opening rotating through hole in the center, and a rotary motor is located at the center of the central gear. The output shaft of the rotary motor has a rotating part, which is slidably connected to the rotating through hole. In centrifugal mode, the rotating part is inserted into the rotating through hole and drives the rotating through hole to rotate synchronously. In adjustment mode, the rotating part is removed from the rotating through hole.

3. The microfluidic device for identifying Escherichia coli in urinary tract infections according to claim 2, characterized in that: It also includes a fixed plate, a support plate is supported on the fixed plate, the support plate and the fixed plate are rotatably connected, the output shaft of the rotary motor is provided with a fixing part, the fixing part is located below the rotating part; the fixed plate has a vertical fixing through hole, the fixing through hole and the fixing part are slidably connected; In adjustment mode, the vertical drive unit drives the moving plate and the rotary motor to move upward, thereby driving the fixed part to move upward and insert into the fixed through hole and make clearance fit with the rotating through hole, and the rotating part moves upward and exits the rotating through hole; In centrifugal mode, the vertical drive unit moves the moving plate and the rotary motor downwards, thereby causing the fixed part to move down and exit the fixed through hole, and the rotating part to move down and insert into the rotating through hole.

4. The microfluidic device for identifying Escherichia coli in urinary tract infections according to claim 3, characterized in that: It also includes a base, on which several limiting posts and several circumferential rotating shafts are vertically provided. The number and position of the circumferential rotating shafts correspond one-to-one with the circumferential gears. The circumferential rotating shafts pass through the moving plate and the circumferential gears in sequence, and the circumferential rotating shafts, the moving plate, and the circumferential gears are slidably connected. In centrifugal mode, the moving plate moves downward, and the limiting post passes through the moving plate and the central gear in sequence, thereby restricting the rotation of the central gear; In adjustment mode, the moving plate moves upward, and the limit post and the center gear separate.

5. A microfluidic device for identifying Escherichia coli in urinary tract infections according to claim 4, characterized in that: The bottom of the mounting slot is provided with a downward helical tooth, and the lower surface of the microfluidic chip is provided with an upper helical tooth that cooperates with the downward helical tooth. In the adjustment mode, the circumferential gear drives the microfluidic chip to rotate, so that the microfluidic chip moves up and down along the surface of the downward helical tooth; after rotating to the position, the upper helical tooth and the lower helical tooth re-mesh.

6. A microfluidic device for identifying Escherichia coli in urinary tract infections according to claim 5, characterized in that: A pressure plate is provided at the upper end of the output shaft of the rotary motor; In centrifugal mode, the moving plate moves the pressure plate downward, and the lower surface of the pressure plate contacts the upper surface of the support tray. The rotary motor drives the support tray to rotate together through the pressure plate.

7. A microfluidic device for identifying Escherichia coli in urinary tract infections according to claim 6, characterized in that: The rotating through hole has a regular hexagonal cross section. With the central axis of the regular hexagon as the boundary, the cross section of the rotating part is half of the regular hexagon. Except for the side where the central axis is located, the contours of the other sides of the rotating part match the shape of the rotating through hole. The pressure plate is cross-shaped and is used to partially cover the pressure plate.

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