Diameter-controllable multi-layer coated multi-channel centrifugal microfluidic reactor

Abstract

The invention belongs to the technical field of microfluidics, and particularly relates to a diameter-controllable multi-layer coated multichannel centrifugal microfluidic reactor which comprises a machine body, a centrifugal microfluidic unit and a liquid accumulation unit, a multi-layer coated liquid drop preliminary forming unit in the centrifugal microfluidic unit comprises a driven shaft, the output end of a rotation driving unit is connected with the driven shaft, and the output end of the rotation driving unit is connected with the driven shaft. A cylindrical liquid injection cavity is formed in the center of the interior of the driven shaft, a plurality of annular liquid injection cavities are formed in the periphery of the cylindrical liquid injection cavity, micro-fluidic connectors with the same number as the vertical channels are connected to the lower portion of the driven shaft, and the micro-fluidic connectors communicate with the horizontal channels and the vertical channels correspondingly. Liquid intersections are arranged in the micro-fluidic joints, and a needle head is connected below each micro-fluidic joint; the liquid accumulation unit comprises a liquid accumulation cup. The liquid capsule has the advantages of high flux, low variable coefficient and accurate and controllable particle size, and can realize a multi-coating function.

Description

Technical Field

[0001] The present invention belongs to the field of microfluidics technology, and specifically relates to a multi-channel centrifugal microfluidic reactor with controllable diameter and multi-layer coating, which is suitable for application scenarios such as pharmaceutical engineering, biomedical testing, food, and environment that require high-throughput and high-precision fluid manipulation. Background Art

[0002] Microfluidics, a significant breakthrough in modern analytical science and biomedical engineering, is a key technology for building "labs on a chip" and realizing "micro-total analysis systems." Its core advantage lies in the precise manipulation of nanoliter to picoliter fluids through micrometer-scale fluid channels, enabling the miniaturization, automation, integration, and high-throughput operation of complex biological and chemical processes.

[0003] Droplet microfluidics, a key branch of the field, is a technological platform that enables the interaction of two or more immiscible fluids within microscale channels, generating and precisely manipulating discrete droplets. Its core characteristic is the transformation of macroscopic fluid manipulation into the precise control of monodisperse droplet units. This technology offers advantages such as low reagent consumption, rapid reaction speed, high throughput, and the ability to independently control the volume and composition of droplets (capsules). It is widely used in materials synthesis (such as the synthesis of microcapsules, microparticles, and microfibers), chemical and biochemical microreactors, drug development, clinical chemistry, immunodiagnosis, protein analysis, cell processing, molecular diagnostics, as well as environmental, biological, and food testing.

[0004] Currently, droplet microfluidics primarily achieves precise control over droplet (capsule) generation through manipulation of microchannel geometry and external energy. Microchannel geometries encompass a wide range of configurations, including T-junction, coaxial flow, flow focusing, and step emulsification. By adjusting these geometries and incorporating the fluid's physical properties (viscosity ratio, interfacial tension, wettability, density difference, and flow rate ratio), precise control of droplet (capsule) size is achieved, enabling adaptation to multiphase systems and the generation of multiple emulsions (W / O / W, O / W / O) or complex structures. External energy inputs primarily include, but are not limited to, electric fields, magnetic fields, and centrifugal forces. These energies act directly on the fluid interface, altering its physical properties (such as interfacial tension and contact angle) or mechanical state (distribution), effectively controlling the droplet (capsule) generation process. This flexible and proactive approach results in a low coefficient of variation (CV) in the generated droplets (capsules). In practical applications, a combination of these two approaches is often employed to achieve optimal results.

[0005] The technology that uses centrifugal force to drive fluid flow is called centrifugal microfluidics. This technology has many significant advantages: first, its pumpless design simplifies the system structure and reduces complexity; second, by adjusting the rotational speed, it can achieve precise control of the droplet (capsule) particle size; finally, the centrifugal field can effectively eliminate bubble interference within the microchannel and reduce dead volume, thereby improving system stability and detection accuracy. With these advantages, centrifugal microfluidics has shown broad application prospects in multiple fields, especially in applications that require precise control of droplet (capsule) particle size, monodispersity, and high throughput, such as the preparation of emulsions, suspensions, and microcapsules. Currently, this technology has been widely used in materials synthesis, drug development, clinical chemistry, immunodiagnosis, protein analysis, cell processing, molecular diagnostics, as well as environmental, biological, and food testing. Traditional centrifugal microfluidic systems are typically implemented as a "lab-on-a-disc." This involves integrating various microchannel structures onto a circular rotating disk similar to a compact disc through micro-nanofabrication techniques such as photolithography or hot pressing, creating a single- or multi-layer disc-on-a-chip. Centrifugal force is then used to generate microdroplets (capsules) of the desired morphology. This structure played a crucial role in the early development of centrifugal microfluidics, becoming the mainstream choice for centrifugal systems due to its ease of rotational actuation and integrated operation. However, the disc-on-a-chip architecture faces several limitations in practical application and engineering translation. First, the complex channel design within the chip places extremely high demands on the precision and consistency of micro-nanofabrication processes, resulting in high manufacturing costs. Second, its limited ability to integrate and expand multifunctional modules inevitably presents a performance trade-off between achieving high throughput and highly monodisperse droplet (capsule) generation. Furthermore, the disc-on-a-chip architecture relies heavily on custom chips, which not only hinders rapid system iteration and flexible deployment but also limits its scalability during product development. Summary of the Invention

[0006] To address these technical issues, the present invention provides a multi-channel centrifugal microfluidic reactor with controllable diameter and multi-layer coating, namely a chip-free centrifugal multi-channel microfluidic reaction system. Based on four core concepts: a centrifugal force-driven mechanism, a combination of 3D-printed microchannels and a chip-free structural design, an open platform architecture, and external modular expansion, this system effectively addresses the core pain points of traditional technologies, including complex processes, rigid structures, slow iterations, and limited flexibility.

[0007] The present invention is implemented in this way, providing a multi-channel centrifugal microfluidic reactor with controllable diameter and multi-layer coating, including a body, a centrifugal microfluidic unit and a liquid accumulation unit, the centrifugal microfluidic unit can be arranged on the body in an upward and downward manner, the centrifugal microfluidic unit includes an upper support seat, a lower support seat, a rotation drive unit, and a multi-layer coated droplet preliminary formation unit, the inverted U-shaped upper support seat is fixedly connected to the lower support seat, the output end of the rotation drive unit passes through the upper support seat, the multi-layer coated droplet preliminary formation unit includes a driven shaft, the driven shaft is rotatably connected to the upper support seat and the lower support seat, the output end of the rotation drive unit is connected to the upper support seat and the lower support seat, and the output end of the rotation drive unit is connected to the upper support seat and the lower support seat. The driven shaft is connected to drive the driven shaft to rotate, and a cylindrical liquid injection cavity is provided in the center of the driven shaft, and the lower end of the cylindrical liquid injection cavity is connected to multiple horizontal channels. The periphery of the cylindrical liquid injection cavity is provided with multiple annular liquid injection cavities, and the lower end of the annular liquid injection cavity is provided with multiple vertical channels. Microfluidic joints with the same number as the vertical channels are connected below the driven shaft, and the microfluidic joints are respectively connected to the horizontal channels and the vertical channels, and a liquid intersection is provided in the microfluidic joints. A needle is connected below each microfluidic joint; the liquid accumulation unit includes a liquid accumulation cup, and the liquid accumulation cup is arranged on the body directly below the driven shaft.

[0008] Preferably, the machine body includes a profile frame, a linear guide rail is provided on the vertical profile of the profile frame, a slider is provided on the linear guide rail, one end of the upper support seat and the lower support seat is fixedly connected to the slider, and a linear rail clamp is provided on the linear guide rail below the slider.

[0009] Preferably, the rotation drive unit includes a motor, a coupling, an active synchronous wheel and a synchronous belt. A motor seat is provided on the upper support seat, the motor is arranged on the motor seat, the output end of the motor is connected to the coupling, the coupling passes through the upper support seat and is connected to the active synchronous wheel, and the synchronous belt is sleeved on the active synchronous wheel and the driven synchronous wheel on the driven shaft.

[0010] It is further preferred that a synchronous belt tensioning unit is also provided on the upper support seat, and the synchronous belt tensioning unit includes a tensioning block, an idler shaft and an idler. The tensioning block is installed on the upper surface of the upper support seat and is connected to the idler shaft. The lower end of the idler shaft rotates to connect the idler, and the idler is in contact with the synchronous belt.

[0011] Preferably, a dividing plate is provided on the outer side of the portion of the driven shaft higher than the upper support seat, the dividing plate is provided with an array of strip holes, a photoelectric encoding sensor is provided on the upper support seat, and the dividing plate is within the sensing range of the photoelectric encoding sensor.

[0012] Preferably, a liquid injection bracket is connected to the upper support seat, and the liquid injection bracket extends above the driven shaft. A plurality of liquid injection joints are provided on the liquid injection bracket, and a liquid injection joint is provided above the cylindrical liquid injection cavity and the annular liquid injection cavity.

[0013] Preferably, an electric control panel and a touch screen are provided on the machine body, and the electric control panel is respectively connected to the touch screen and the rotation drive unit for signal communication.

[0014] Compared with the prior art, the advantages of the present invention are: 1) Significant cost-effectiveness, significantly reducing manufacturing costs and achieving effective integration of 3D printed parts (microfluidic connectors); 2) Modular design supports flexible functional expansion, facilitating rapid productization and large-scale production; 3) Possess excellent iterative capabilities and be able to quickly complete technology upgrades; 4) Demonstrates outstanding performance in droplet (capsule) generation: high throughput, low coefficient of variation, precise and controllable particle size, and the ability to achieve multiple coating functions; 5) The overall chipless design eliminates the need for micromachining microchannel operations during the processing process, eliminating complex and expensive processes such as lithography, etching, and bonding that require a clean room environment. This significantly reduces costs, simplifies operating procedures, and improves portability. While achieving the chipless goal, it still retains the characteristics of microscale precision control. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the overall structural diagram of the centrifugal microfluidic reactor provided by the present invention; Figure 2 This is a structural diagram of the centrifugal microfluidic unit in the present invention; Figure 3 This is a structural diagram of the fluid collection cup in the present invention; Figure 4 This is a diagram of the machine structure of the present invention; Figure 5 This is a cross-sectional view of the centrifugal microfluidic unit of the present invention; Figure 6 This is a cross-sectional view of the horizontal channel and the liquid intersection position in the present invention; Among them: 1-body, 101-profile frame, 102-linear guide, 103-slider, 104-linear rail clamp, 105-electric control board, 106-touch screen; 2-centrifugal microfluidic unit, 201-motor, 202-motor seat, 203-coupling, 204-linear rail mounting plate, 205-upper support seat, 206-lower support seat, 207-tension block, 208-idler shaft, 209-active synchronous wheel, 210-synchronous belt, 211-idler, 212-photoelectric encoding sensor, 213-indexing plate, 214-liquid injection connector, 215-microfluidic connector, 216-needle, 217-driven shaft, 218-cylindrical liquid injection chamber, 219-annular liquid injection chamber, 220-liquid intersection, 3-liquid accumulation unit, 301-base, 302-liquid accumulation cup. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0017] refer to Figures 1-6 The present invention provides a multi-channel centrifugal microfluidic reactor with controllable diameter and multi-layer coating, comprising a body 1, a centrifugal microfluidic unit 2 and a liquid accumulation unit 3. The centrifugal microfluidic unit 2 is movably arranged on the body 1, and the centrifugal microfluidic unit 2 comprises an upper support seat 205, a lower support seat 206, a rotation drive unit, and a multi-layer coated droplet preliminary formation unit. The inverted U-shaped upper support seat 205 is fixedly connected to the lower support seat 206, and the output end of the rotation drive unit passes through the upper support seat 205. The multi-layer coated droplet preliminary formation unit comprises a driven shaft 217, which is rotatably connected to the upper support seat 205 and the lower support seat 206. The output end of the rotation drive unit is connected to the driven shaft 217, driving the driven shaft 217 to rotate A cylindrical liquid injection chamber 218 is provided in the center of the driven shaft 217, and the lower end of the cylindrical liquid injection chamber 218 is connected to a plurality of horizontal channels. A plurality of annular liquid injection chambers 219 are provided on the periphery of the cylindrical liquid injection chamber 218, and a plurality of vertical channels are provided at the lower end of the annular liquid injection chamber 219. A microfluidic connector 215 having the same number as the vertical channels is connected below the driven shaft 217, and the microfluidic connector 215 is connected to the horizontal channel and the vertical channel respectively, and a liquid intersection 220 is provided in the microfluidic connector 215, and a needle 216 is connected below each microfluidic connector 215; the effusion unit 3 includes an effusion cup 302, and the effusion cup 302 is arranged on the body 1 directly below the driven shaft 217 through the base 301.

[0018] In this embodiment, a two-layer driven shaft 217 is used, that is, a cylindrical liquid injection cavity 218 and an annular liquid injection cavity 219 are provided, four horizontal channels, four vertical channels, four microfluidic connectors 215 and four needles 216 are provided.

[0019] During the preparation of multi-layer coated droplets or capsules using the centrifugal microfluidic reactor provided in this embodiment, a capsule outer phase liquid is injected into the fluid collection cup 302, and the centrifugal microfluidic unit 2 is lowered on the body 1 until the needle 216 penetrates below the liquid surface of the fluid collection cup 302. Then, liquid A and liquid B are injected into the annular liquid injection chamber 219 and the cylindrical liquid injection chamber 218. The rotary drive unit is activated, which drives the driven shaft 217 to rotate. When the driven shaft 217 rotates, the four microfluidic connectors 215 and the four needles 216 rotate. During the rotation, liquid A and liquid B inside the driven shaft 217 are ejected due to centrifugal force. The two liquids pass through the horizontal channel and the vertical channel, respectively, and enter the microfluidic connector 215. Two layers of coated liquid capsules are formed at the liquid intersection 220. The liquid capsules are ejected from the four needles 216 and enter the outer phase liquid of the fluid collection cup 302, forming three layers of coated outer phase liquid. The reaction is now complete.

[0020] If the driven shaft 217 chamber is modified to a three-layer structure, i.e., a cylindrical liquid injection chamber 218 and two annular liquid injection chambers 219, the ejected liquid capsule will be coated in three layers, and will be coated in four layers after entering the liquid collection cup 302. Similarly, the more layers the driven shaft chamber structure has, the more coating layers will be formed.

[0021] As a specific implementation method of the body 1, the body 1 includes a profile frame 101, a linear guide rail 102 is provided on the vertical profile of the profile frame 101, a slider 103 is provided on the linear guide rail 102, one end of the upper support seat 205 and the lower support seat 206 are fixedly connected to the slider 103 (through the linear rail mounting plate 204), and a linear rail clamp 104 is provided on the linear guide rail 102 below the slider 103.

[0022] When adjusting the position of the centrifugal microfluidic unit 2 on the body 1 , the position of the linear rail clamp 104 is adjusted, and then the slider 103 slides on the linear guide rail 102 , thereby changing and adjusting the position of the centrifugal microfluidic unit 2 .

[0023] As a specific implementation method of the rotation drive unit, the rotation drive unit includes a motor 201, a coupling 203, an active synchronous wheel 209 and a synchronous belt 210. A motor base 202 is provided on the upper support base 205, and the motor 201 is arranged on the motor base 202. The output end of the motor 201 is connected to the coupling 203, and the coupling 203 passes through the upper support base 205 and is connected to the active synchronous wheel 209. The synchronous belt 210 is sleeved on the active synchronous wheel 209 and the driven synchronous wheel on the driven shaft 217.

[0024] When the driven shaft 217 needs to be driven to rotate, the motor 201 is started, and the output shaft of the motor 201 drives the coupling 203, the active synchronous wheel 209, and the synchronous belt 210 to rotate, thereby driving the driven synchronous wheel on the driven shaft 217 to rotate, and finally driving the driven shaft 217 to rotate.

[0025] In order to ensure the accuracy of the rotational speed and thus ensure the accuracy of the particle size of the prepared liquid capsules, as an improvement to the technical solution, a synchronous belt tensioning unit is also provided on the upper support seat 205. The synchronous belt tensioning unit includes a tensioning block 207, an idler shaft 208 and an idler 211. The tensioning block 207 is installed on the upper surface of the upper support seat 205 and is connected to the idler shaft 208. The lower end of the idler shaft 208 is rotated to connect the idler 211, and the idler 211 is in contact with the synchronous belt 210.

[0026] The tensioning block 207 includes a fixed tensioning block and a movable tensioning block. The fixed tensioning block is fixed on the upper support seat 205. The movable tensioning block is provided with a long hole, and the upper support seat 205 is provided with a threaded hole. The movable tensioning block is connected to the upper support seat 205 in a variably position by passing a fixed screw through the long hole on the movable tensioning block and the threaded hole on the upper support seat 205. A tensioning screw connected to both the fixed tensioning block and the movable tensioning block is provided between the fixed tensioning block and the movable tensioning block. By turning the tensioning screw, the distance between the fixed tensioning block and the movable tensioning block is adjusted, thereby adjusting the contact tightness between the idler wheel 211 and the synchronous belt 210, so that the synchronous belt 210 is always kept in a tensioned state.

[0027] In order to accurately control and adjust the rotational speed of the driven shaft 217, a dividing plate 213 is provided on the outer side of the part of the driven shaft 217 that is higher than the upper support seat 205, and an array of strip holes is provided on the dividing plate 213. A photoelectric encoding sensor 212 is provided on the upper support seat 205, and the dividing plate 213 is within the sensing range of the photoelectric encoding sensor 212.

[0028] The photoelectric encoding sensor 212 calculates the rotation speed of the driven shaft 217 by sensing the number of strip holes on the indexing plate 213 .

[0029] In order to facilitate the injection of liquid medium to form liquid capsules into the cylindrical liquid injection cavity 218 and the annular liquid injection cavity 219, as an improvement to the technical solution, an injection bracket is connected to the upper support seat 205, and the injection bracket extends above the driven shaft 217. A plurality of injection joints 214 are provided on the injection bracket, and an injection joint 214 is provided above each of the cylindrical liquid injection cavity 218 and the annular liquid injection cavity 219.

[0030] The diameter of the liquid medium in the channel of this embodiment is controllable, mainly based on the mechanical formula: , where F is the centrifugal force (unit: Newton, N), m is the mass of the object (unit: kilogram, kg), ω is the angular velocity of the object (unit: radians per second, rad / s), and r is the distance from the object to the center of the circle, that is, the radius of the circular motion (unit: meter, m); Reynolds number formula, Re = ρvL / μ, where ρ is the fluid density, v is the relative velocity of the fluid or object, L is the characteristic length, and μ is the fluid dynamic viscosity (unit: Pa·s); Stokes drag formula, F=6πηrv where η is the liquid viscosity, r is the characteristic dimension, and v is the relative velocity.

[0031] According to the above formula, the dripping droplets are subjected to centrifugal force, gravity, resistance between the liquid medium, and liquid surface tension during the rotation process. When the resultant force acting on the droplet equals the liquid surface tension, the droplet reaches the critical dripping point. The maximum centrifugal force calculated based on the speed range used in this experiment is much smaller than the liquid surface tension, so the centrifugal force can be ignored. The Reynolds number calculated by substituting the maximum speed of this device into its Reynolds number determines that the fluid state is laminar. The result calculated using the Stokes resistance formula for the speed range is greater than the liquid surface tension. Therefore, it can be concluded that the resistance between the liquid medium is the only factor other than gravity that determines the droplet reaching the critical dripping point during the rotation of this device. If the centrifugal force is ignored and the liquid surface tension does not change, the resistance between the liquid medium increases, and the mass of the water droplet decreases. According to the Stokes resistance formula F=6πηrv, the resistance between the liquid medium is proportional to the relative velocity. Therefore, it can be concluded that the greater the angular velocity, the smaller the mass of the dripping droplet.

[0032] In order to realize automatic control of the device, as an improvement of the technical solution, an electric control board 105 and a touch screen 106 are provided on the body 1, and the electric control board 105 is respectively connected to the touch screen 106 and the rotation drive unit for signal transmission.

[0033] Other components that need to be automatically controlled are also connected to the electric control board 105 by signal, such as the photoelectric encoding sensor 212.

Claims

1. A multi-channel centrifugal microfluidic reactor with controllable diameter and multi-layer coating, characterized in that: The invention comprises a body (1), a centrifugal microfluidic unit (2) and a liquid accumulation unit (3), wherein the centrifugal microfluidic unit (2) is arranged on the body (1) so as to be movable up and down, and the centrifugal microfluidic unit (2) comprises an upper support seat (205), a lower support seat (206), a rotation drive unit, and a multi-layer coated droplet preliminary formation unit, wherein the inverted U-shaped upper support seat (205) is fixedly connected to the lower support seat (206), and the output end of the rotation drive unit passes through the upper support seat (205), and the multi-layer coated droplet preliminary formation unit comprises a driven shaft (217), and the driven shaft (217) is rotationally connected to the upper support seat (205) and the lower support seat (206), and the output end of the rotation drive unit is connected to the driven shaft (217), driving the driven shaft (217) to rotate, and the interior of the driven shaft (217) A columnar liquid injection cavity (218) is provided in the center, the lower end of the columnar liquid injection cavity (218) is connected to a plurality of horizontal channels, a plurality of annular liquid injection cavities (219) are provided on the periphery of the columnar liquid injection cavity (218), the lower end of the annular liquid injection cavity (219) is provided with a plurality of vertical channels, a microfluidic connector (215) having the same number as the vertical channels is connected below the driven shaft (217), the microfluidic connector (215) is communicated with the horizontal channels and the vertical channels respectively, and a liquid intersection (220) is provided in the microfluidic connector (215), and a needle (216) is connected below each microfluidic connector (215); the liquid accumulation unit (3) includes a liquid accumulation cup (302), and the liquid accumulation cup (302) is provided on the body (1) directly below the driven shaft (217).

2. The multi-channel centrifugal microfluidic reactor with controllable diameter and multi-layer coating according to claim 1, characterized in that: The machine body (1) includes a profile frame (101), a linear guide rail (102) is provided on the vertical profile of the profile frame (101), a slider (103) is provided on the linear guide rail (102), one end of the upper support seat (205) and the lower support seat (206) are fixedly connected to the slider (103), and a linear rail clamp (104) is provided on the linear guide rail (102) below the slider (103).

3. The multi-channel centrifugal microfluidic reactor with controllable diameter and multi-layer coating according to claim 1, characterized in that: The rotation drive unit comprises a motor (201), a coupling (203), a driving synchronous wheel (209) and a synchronous belt (210); a motor base (202) is provided on the upper support base (205); the motor (201) is arranged on the motor base (202); an output end of the motor (201) is connected to the coupling (203); the coupling (203) passes through the upper support base (205) and is connected to the driving synchronous wheel (209); and the synchronous belt (210) is sleeved on the driving synchronous wheel (209) and the driven synchronous wheel on the driven shaft (217).

4. The multi-channel centrifugal microfluidic reactor with controllable diameter and multi-layer coating according to claim 3, characterized in that: A synchronous belt tensioning unit is also provided on the upper support seat (205), and the synchronous belt tensioning unit includes a tensioning block (207), an idler shaft (208), and an idler (211). The tensioning block (207) is mounted on the upper surface of the upper support seat (205) and is connected to the idler shaft (208). The lower end of the idler shaft (208) is rotatably connected to the idler (211), and the idler (211) is in contact with the synchronous belt (210).

5. The multi-channel centrifugal microfluidic reactor with controllable diameter and multi-layer coating according to claim 1, characterized in that: A dividing plate (213) is provided on the outer side of a portion of the driven shaft (217) that is higher than the upper support seat (205), and an array of strip holes is provided on the dividing plate (213). A photoelectric encoding sensor (212) is provided on the upper support seat (205), and the dividing plate (213) is within the sensing range of the photoelectric encoding sensor (212).

6. The multi-channel centrifugal microfluidic reactor with controllable diameter and multi-layer coating according to claim 1, characterized in that: A liquid injection bracket is connected to the upper support seat (205), and the liquid injection bracket extends above the driven shaft (217). A plurality of liquid injection joints (214) are provided on the liquid injection bracket, and a liquid injection joint (214) is provided above each of the columnar liquid injection cavity (218) and the annular liquid injection cavity (219).

7. The multi-channel centrifugal microfluidic reactor with controllable diameter and multi-layer coating according to claim 1, characterized in that: An electric control panel (105) and a touch screen (106) are provided on the machine body (1), and the electric control panel (105) is respectively connected to the touch screen (106) and the rotation drive unit for signal transmission.

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