A magnetic control nucleic acid purification device based on a PCB coil array

Abstract

The application relates to a PCB coil array-based magnetic nucleic acid purification device, which comprises a microfluidic nucleic acid purification part, a multi-chamber structure, and microchannels between the chambers; an electromagnetic control part is arranged below the microfluidic nucleic acid purification part and comprises a PCB coil array, a control circuit and a permanent magnet; the control circuit is connected with the PCB coil array and is used for controlling the conduction of the PCB coils in the PCB coil array; the PCB coil array comprises a plurality of PCB coils, and each PCB coil is arranged below a corresponding chamber and microchannel; and the permanent magnet is arranged between the PCB coil array and the multi-chamber structure and is used for completing displacement under the driving of the conducted PCB coils. The application can realize the miniaturization and automation of nucleic acid purification equipment.

Description

Technical Field

[0001] This invention relates to the field of nucleic acid purification technology, and in particular to a magnetically controlled nucleic acid purification device based on a PCB coil array. Background Technology

[0002] Nucleic acid testing is an important means of biomedical diagnosis for pathogens, genetic diseases, and other conditions. Nucleic acid purification, as a key pre-test step, directly affects the accuracy and timeliness of test results. Traditional nucleic acid purification techniques, such as centrifugation column method and phenol / chloroform extraction method, have problems such as cumbersome operation, long time consumption, large reagent consumption, and easy contamination, which cannot meet the needs of point-of-care testing scenarios for portability, speed, and integration.

[0003] Existing magnetic bead-based nucleic acid purification technology has become a standard choice for instrumented applications due to its flexibility and ease of automation. However, traditional magnetic control methods using external permanent magnets or large electromagnetic coils suffer from drawbacks such as poor magnetic field uniformity, large equipment size, and low integration, making them unsuitable for the miniaturization requirements of portable testing instruments. By combining with microfluidic chips, the size of nucleic acid purification equipment has been further reduced. For example, existing four-chamber microfluidic chip structures utilize the movement of external permanent magnets to control the active transfer of magnetic beads for nucleic acid purification. However, the movement of the permanent magnets relies on mechanical drives such as stepper motor slides, which still suffers from insufficient flexibility in magnetic field control and a relatively large equipment size. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a magnetically controlled nucleic acid purification device based on a PCB coil array, which can realize the miniaturization and automation of nucleic acid purification equipment.

[0005] The technical solution adopted by this invention to solve its technical problem is: to provide a magnetically controlled nucleic acid purification device based on a PCB coil array, comprising:

[0006] The microfluidic nucleic acid purification section includes a multi-chamber structure, with the chambers connected by microchannels;

[0007] The electromagnetic control section, located below the microfluidic nucleic acid purification section, includes a PCB coil array, a control circuit, and a permanent magnet. The control circuit is connected to the PCB coil array and is used to control the conduction of the PCB coils in the PCB coil array. The PCB coil array includes multiple PCB coils, each of which is located below a corresponding chamber and microchannel. The permanent magnet is located between the PCB coil array and the multi-chamber structure and is used to complete displacement under the drive of the conducting PCB coils.

[0008] The multi-chamber structure is a four-chamber structure, which includes a lysis chamber, a first washing chamber, a second washing chamber, and an elution / amplification chamber connected sequentially by microchannels.

[0009] The multi-chamber structure has a mineral oil seal layer in the transition area between the chambers and the microchannels, as well as in the full reaction area within the chambers.

[0010] Each PCB coil in the PCB coil array is a 12-turn rectangular planar helical coil with an area of ​​2.6mm × 2.6mm and a wire width of 4mil.

[0011] The control circuit includes an analog switch chip, a Darlington transistor array chip, and multiple current-limiting resistors. The input terminal of the analog switch chip is connected to the output terminal of an external microcontroller, and the output terminal is connected to the input terminal of the Darlington transistor array chip. The multiple output terminals of the Darlington transistor array chip are respectively connected to multiple PCB coils in the PCB coil array through multiple current-limiting resistors. The multiple current-limiting resistors and the output terminals of the Darlington transistor array chip are connected to the positive terminal of an external power supply, and the tail ends of the multiple PCB coils are connected to the negative terminal of the external power supply.

[0012] The external power supply is equipped with a voltage adjustable module, which is used to adjust the input voltage.

[0013] The permanent magnet is a cylindrical permanent magnet with its upper surface in close contact with the cavity and microchannel.

[0014] The cylindrical permanent magnet has a diameter of 3 mm and a height of 3 mm, and its surface magnetic field strength is higher than that required for successful transfer of magnetic beads in manual nucleic acid purification experiments.

[0015] Beneficial effects

[0016] By adopting the above-mentioned technical solution, this invention has the following advantages and positive effects compared with the prior art: This invention employs an integrated structure where the microfluidic nucleic acid purification section and the electromagnetic control section are stacked vertically. By correspondingly placing PCB coils below each chamber and microchannel, precise zonal control of the magnetic field is achieved, driving the permanent magnet to move stably along a preset trajectory. This replaces the traditional stepper motor slide mechanical drive method, significantly reducing the size and weight of the equipment, and lowering system complexity and mechanical failure rate. Simultaneously, the electromagnetic control method allows for fully automated control of magnetic bead transfer through programming, eliminating the need for manual intervention, improving nucleic acid purification efficiency and result consistency, and meeting the miniaturization and integration requirements of portable point-of-care testing instruments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the microfluidic nucleic acid purification section in an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of a magnetically controlled nucleic acid purification device based on a PCB coil array according to an embodiment of the present invention. Detailed Implementation

[0019] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0020] Embodiments of the present invention relate to a magnetically controlled nucleic acid purification device based on a PCB coil array, such as... Figure 1 and Figure 2 As shown, it includes:

[0021] The microfluidic nucleic acid purification section A includes a multi-chamber structure, with the chambers connected by microchannels;

[0022] The electromagnetic control section B, located below the microfluidic nucleic acid purification section A, includes a PCB coil array, a control circuit, and a permanent magnet 1. The control circuit is connected to the PCB coil array and is used to control the conduction of the PCB coils in the PCB coil array. The PCB coil array includes multiple PCB coils 2, each of which is located below a corresponding chamber and microchannel. The permanent magnet 1 is located between the PCB coil array and the multi-chamber structure and is used to complete displacement under the drive of the conducting PCB coils.

[0023] In this embodiment, the electromagnetic control part B realizes the movement of the permanent magnet by sequentially turning on the PCB coil 2 at intervals. The movement of the permanent magnet 1 can realize the transfer of the magnetic beads in the multi-chamber structure to different chambers, thereby replacing the traditional stepper motor control method.

[0024] In this embodiment, the multi-chamber structure of the microfluidic nucleic acid purification section A is a four-chamber structure. The four-chamber structure includes a lysis chamber A1, a first washing chamber A2, a second washing chamber A3, and an elution / amplification chamber A4, which are connected sequentially by microchannels. Key areas of the multi-chamber structure (e.g., the transition areas between the chambers and the microchannels, and the total reaction areas within the chambers) are sealed with mineral oil to prevent contamination.

[0025] In this embodiment, the PCB coil array has a double-layer structure, wherein each PCB coil 2 is located below the corresponding cavity and microchannel, respectively. Figure 1Taking the four-chamber configuration as an example, the PCB coil array includes eight PCB coils, which are respectively placed below the lysis chamber, the first washing chamber, the second washing chamber, the elution / amplification chamber, and the microchannels connecting each chamber. Each PCB coil is a 12-turn rectangular planar solenoid coil with an area of ​​2.6mm × 2.6mm and a wire width of 4mil.

[0026] The control circuit in this embodiment includes an analog switch chip 3, a Darlington transistor array chip 4, and multiple current-limiting resistors 5. The input terminal of the analog switch chip 3 is connected to the output terminal of an external microcontroller (not shown in the figure), and the output terminal is connected to the input terminal of the Darlington transistor array chip 4. The multiple output terminals of the Darlington transistor array chip 4 are respectively connected to multiple PCB coils 2 in the PCB coil array through multiple current-limiting resistors 5. The multiple current-limiting resistors 5 and the output terminals of the Darlington transistor array chip 4 are connected to the positive terminal of an external power supply (not shown in the figure), and the tail ends of the multiple PCB coils 2 are connected to the negative terminal of the external power supply.

[0027] In this embodiment, the analog switch chip 3 uses a 74HC4051 chip, and the Darlington transistor array chip 4 uses a ULN2803 chip. The data selection pins S0, S1, and S2 of the 74HC4051 chip output 3-bit binary numbers (000 to 111) representing high and low levels through the general-purpose I / O ports PA0, PA1, and PA2 of an external STM32 embedded microcontroller, achieving conduction control of 8 signals. The output signals of the 74HC4051 chip serve as 8 input signals for the ULN2803 chip, controlling the conduction of its output circuit. The output circuit of the ULN2803 chip includes a loop consisting of a PCB coil, a current-limiting resistor, and an external power supply. The external power supply in this loop can be a voltage-adjustable module. Thus, by adjusting the resistance value of the current-limiting resistor and the voltage value output by the voltage-adjustable module, the current in the PCB coil can be adjusted. Tests showed that when the input voltage is 3.2V and the current-limiting resistor is 1Ω (power 1 / 2W), the coil current can reach 330mA. At this time, the magnetic field strength on the coil surface is about 1mT, and no additional heat dissipation structure is required.

[0028] In this embodiment, to achieve the best magnetic bead movement effect, the upper surface of the permanent magnet is in close contact with the chamber and microchannel. The movement of cylindrical permanent magnets of different sizes was tested to determine the appropriate size for this coil array structure. Test results showed that tall, elongated permanent magnets had a high center of gravity and were prone to tipping over when the next coil was turned on, making stable movement to the target position impossible. Thin, flat permanent magnets, while not tipping over, were easily bounced off by the magnetic field generated by the next coil, or experienced movement jamming or abnormal trajectories. Flat permanent magnets with a large bottom area and heavy mass lacked sufficient driving magnetic force to achieve reliable displacement. Ultimately, this embodiment selected an N52 cylindrical permanent magnet with a diameter of 3mm and a height of 3mm. Its surface magnetic field strength reaches 360-370mT, higher than the 300mT required for successful transfer of magnetic beads in manual nucleic acid purification experiments. The magnetic force meets the requirements for magnetic bead manipulation, and this permanent magnet can complete displacement under the drive of the PCB coil array, adapting to the transfer of magnetic beads within the microfluidic chip.

[0029] When purifying nucleic acid using the magnetically controlled nucleic acid purification device based on a PCB coil array according to this embodiment, the following steps are included:

[0030] Step S1: Add the biological sample to be processed, magnetic beads, and nucleic acid lysis reagent into the lysis chamber of the microfluidic nucleic acid purification section to complete nucleic acid lysis and binding of the magnetic bead-nucleic acid complex;

[0031] Step S2: The STM32 embedded microcontroller outputs a 3-bit binary signal to control the 74HC4051 chip to select the corresponding channel. After power amplification by the ULN2803 chip, the PCB coils in the PCB coil array are driven to conduct sequentially according to the preset timing interval.

[0032] Step S3: The PCB coils are sequentially turned on to generate an alternating magnetic field, which drives the permanent magnet to move along the microchannel trajectory from the lysis chamber to the first washing chamber, the second washing chamber and the elution / amplification chamber in sequence, thereby driving the magnetic bead-nucleic acid complex to complete the impurity washing and nucleic acid elution process;

[0033] Step S4: Collect the purified nucleic acid in the elution / amplification chamber, or proceed directly to the subsequent nucleic acid amplification reaction.

[0034] It is easy to see that this invention adopts an integrated structure in which the microfluidic nucleic acid purification section and the electromagnetic control section are stacked one on top of the other. By placing PCB coils under each chamber and microchannel, precise zonal control of the magnetic field is achieved, driving the permanent magnet to move stably along a preset trajectory. This replaces the traditional mechanical drive method of stepper motor slide table, significantly reducing the size and weight of the equipment, and lowering system complexity and mechanical failure rate. At the same time, the electromagnetic control method can achieve fully automated control of magnetic bead transfer through programming, without manual intervention, improving nucleic acid purification efficiency and result consistency, and adapting to the miniaturization and integration requirements of portable point-of-care testing instruments.

Claims

1. A magnetically controlled nucleic acid purification device based on a PCB coil array, characterized in that, include: The microfluidic nucleic acid purification section includes a multi-chamber structure, with the chambers connected by microchannels; The electromagnetic control section, located below the microfluidic nucleic acid purification section, includes a PCB coil array, a control circuit, and a permanent magnet. The control circuit is connected to the PCB coil array and is used to control the conduction of the PCB coils in the PCB coil array. The PCB coil array includes multiple PCB coils, each of which is located below a corresponding chamber and microchannel. The permanent magnet is located between the PCB coil array and the multi-chamber structure and is used to complete displacement under the drive of the conducting PCB coils.

2. The magnetically controlled nucleic acid purification device based on a PCB coil array according to claim 1, characterized in that, The multi-chamber structure is a four-chamber structure, which includes a lysis chamber, a first washing chamber, a second washing chamber, and an elution / amplification chamber connected sequentially by microchannels.

3. The magnetically controlled nucleic acid purification device based on a PCB coil array according to claim 1, characterized in that, The multi-chamber structure has a mineral oil seal layer in the transition area between the chambers and the microchannels, as well as in the full reaction area within the chambers.

4. The magnetically controlled nucleic acid purification device based on a PCB coil array according to claim 1, characterized in that, Each PCB coil in the PCB coil array is a 12-turn rectangular planar helical coil with an area of ​​2.6mm × 2.6mm and a wire width of 4mil.

5. The magnetically controlled nucleic acid purification device based on a PCB coil array according to claim 1, characterized in that, The control circuit includes an analog switch chip, a Darlington transistor array chip, and multiple current-limiting resistors. The input terminal of the analog switch chip is connected to the output terminal of an external microcontroller, and the output terminal is connected to the input terminal of the Darlington transistor array chip. The multiple output terminals of the Darlington transistor array chip are respectively connected to multiple PCB coils in the PCB coil array through multiple current-limiting resistors. The multiple current-limiting resistors and the output terminals of the Darlington transistor array chip are connected to the positive terminal of an external power supply, and the tail ends of the multiple PCB coils are connected to the negative terminal of the external power supply.

6. The magnetically controlled nucleic acid purification device based on a PCB coil array according to claim 5, characterized in that, The external power supply is equipped with a voltage adjustable module, which is used to adjust the input voltage.

7. The magnetically controlled nucleic acid purification device based on a PCB coil array according to claim 1, characterized in that, The permanent magnet is a cylindrical permanent magnet with its upper surface in close contact with the cavity and microchannel.

8. The magnetically controlled nucleic acid purification device based on a PCB coil array according to claim 1, characterized in that, The cylindrical permanent magnet has a diameter of 3 mm and a height of 3 mm, and its surface magnetic field strength is higher than that required for successful transfer of magnetic beads in manual nucleic acid purification experiments.

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