Centrifugal microfluidic chip with precise temperature control

Abstract

The application discloses a centrifugal micro-fluidic chip with precise temperature control, which comprises a passive circuit board, a substrate and a heating device, a first conductive element is arranged between the passive circuit board and the substrate, a plurality of reaction cavities are arranged in the substrate, the heating device is used for providing heat for the temperature rise of liquid in the reaction cavities, a first temperature detecting element is arranged in one of the reaction cavities, the first temperature detecting element can reduce the temperature of the liquid to be detected, the first temperature detecting element is connected with the first conductive element, and the passive circuit board and the substrate are connected with a centrifugal rotating shaft. The application can realize the precise control of the temperature of liquid in the chip, the accuracy is up to ±0.1 DEG C, and the temperature change response is fast. The temperature detecting element is embedded in only one reaction cavity, so that the temperature detecting element embedded in the cavity is prevented from directly contacting with the reaction liquid, cross contamination is avoided, and the accuracy of subsequent biochemical reaction and detection is influenced.

Description

Technical Field

[0001] This invention pertains to chips, specifically a centrifugal microfluidic chip for precise temperature control. Background Technology

[0002] With the advancement of medical technology, the demand for medical equipment has become increasingly diversified. Under these conditions, medical devices based on centrifugal microfluidic chip technology are constantly being developed and put into use. Centrifugal microfluidic chip technology utilizes the centrifugal force generated by rotation to drive liquids, eliminating the need for external pumps or connecting pipes. Different liquids can be processed on a single disk, such as sample extraction, sample pretreatment, reagent supply, metering, aliquoting, valve operation, mixing, incubation, washing, and analysis or preparative separation processes, to achieve unit operations and realize efficient miniaturized, parallel, and integrated analysis.

[0003] Temperature is an important parameter in biochemical research such as the synthesis of biological organic matter, polymerase chain reaction, and gene mutation detection. With the increasing application of centrifugal microfluidic chip technology in the field of biochemical analysis, the precise control of liquid temperature in the chip is becoming more and more important.

[0004] Existing liquid temperature control devices mostly employ non-contact temperature measurement schemes, such as infrared temperature sensing. Since the overall heating process involves the chip being externally heated and then the heat being conducted to the internal liquid to raise its temperature to the target temperature, infrared temperature sensing devices, limited by the principle of infrared sensing, can only measure the temperature of the chip's surface, not the actual temperature of the liquid within the chip's chamber. Using this temperature value as temperature control feedback may introduce errors and is easily affected by factors such as the uniformity of the chip surface and the thickness of the chamber walls. Furthermore, because centrifugal microfluidics involve rotation, non-contact solutions cannot record the real-time temperature of the chip during rotation. They can only read the temperature after the corresponding chamber on the chip has rotated to the temperature detection area and stopped for a certain period, thus limiting their application.

[0005] In summary, the accuracy and precision of liquid temperature control in existing chips need to be improved, and the slow response to temperature changes is an urgent problem to be solved. Summary of the Invention

[0006] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a centrifugal microfluidic chip with high accuracy, fast temperature change response and precise temperature control.

[0007] Technical Solution: The present invention discloses a centrifugal microfluidic chip for precise temperature control, comprising a passive circuit board, a substrate, and a heating device. A first conductive element is disposed between the passive circuit board and the substrate. Several reaction chambers are disposed within the substrate, and the heating device provides heat for heating the liquid within the reaction chambers. A first temperature sensing element is disposed within one of the reaction chambers and is connected to the first conductive element. Both the passive circuit board and the substrate are connected to the centrifugal rotation shaft. The purpose of embedding the temperature sensing element only within one liquid reaction chamber is to avoid direct contact between the embedded temperature sensing element and the reaction liquid, which could cause cross-contamination and affect the accuracy of subsequent biochemical reactions and detection.

[0008] Furthermore, the passive circuit board is connected to the control circuit board via a second conductive element, and the control circuit board is connected to the centrifugal turntable via a wireless power supply coil. The centrifugal turntable drives the centrifugal rotating shaft to rotate, thereby causing the centrifugal microfluidic chip to rotate.

[0009] Furthermore, the first conductive element and the second conductive element are metal spring pins or electrical connectors.

[0010] Furthermore, a liquid injection hole is provided on the reaction chamber, and a heating device is located below the reaction chamber. The heating device uses air heating or contact heating blocks, such as heating resistors, heating ceramic plates, heating wires, or Peltiers. A second temperature sensing element is installed inside the heating device.

[0011] Furthermore, the reaction chamber is connected to the injection chamber via a liquid flow channel, and the injection chamber is provided with an injection hole.

[0012] Furthermore, the first temperature sensing element is a thermistor, thermocouple, or resistance temperature detector (RTD). The two pins of the heating device are directly connected to corresponding solder points on the passive circuit board to control the interruption and duration of heating. The lower end of the first conductive element contacts a corresponding solder point on the passive circuit board of the lower half of the chip to transmit real-time liquid temperature information. The second temperature sensing element transmits real-time temperature information of the heating device to provide over-temperature protection.

[0013] Furthermore, the heating method can also employ non-contact hot air heating. The aforementioned passive circuit board and substrate are placed in a sealed, insulated cavity and connected to the heating device via an air duct. The heating device includes a hot air gun and a heating resistance wire, both of which are housed within the air duct. The hot air gun continuously supplies hot air into the insulated cavity, transferring heat to the liquid inside the chip reaction chamber through the hot air.

[0014] Furthermore, the substrate is made of PDMS, PMMA, or PC, all of which have good optical properties, high light transmittance, and good biocompatibility, and will not cause toxicity or damage to biological samples.

[0015] Working principle: The first temperature sensing element is located in the chamber containing the liquid. Its two pins transmit temperature information to the passive circuit board through the first conductive element, and then to the control circuit board through the passive circuit board. The control circuit board transmits the temperature information to the peripheral circuit through the wireless communication module. The peripheral circuit is used to control the operation of the overall device. It compares the received temperature information with the preset target temperature, and then transmits the control signal to the control circuit through the wireless communication module. The control circuit then transmits it to the passive circuit board to control the conduction and interruption of the heating device, so that the liquid temperature in the chamber is balanced and stabilized at the target temperature.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0017] 1. It can achieve precise control of the liquid temperature in the chip with an accuracy of up to ±0.1℃ and a fast response to temperature changes;

[0018] 2. The temperature sensing element is embedded only in one reaction chamber to avoid direct contact between the embedded temperature sensing element and the reaction liquid, which would cause cross-contamination and affect the accuracy of subsequent biochemical reactions and detection.

[0019] 3. By directly embedding the first temperature sensing element inside the reaction chamber, the actual conditions of the liquid being tested can be accurately reproduced;

[0020] 4. The first temperature sensing element is directly embedded inside the reaction chamber and can rotate with the substrate. It can directly read the core temperature of the liquid in the reaction chamber and is not affected by factors such as the uniformity of the substrate surface or the thickness of the chamber wall. There are no limitations on its use. It can perform temperature detection at any time, which greatly improves the control performance of the temperature control system and meets more application scenarios of centrifugal microfluidic chips. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention;

[0022] Figure 2 This is a connection diagram of the heating device 3 in Embodiment 1 of the present invention;

[0023] Figure 3 This is a top view of substrate 2 in Embodiment 1 of the present invention;

[0024] Figure 4 This is a connection diagram of the heating device 3 in Embodiment 2 of the present invention;

[0025] Figure 5 This is a top view of substrate 2 in Embodiment 3 of the present invention;

[0026] Figure 6 This is an enlarged view of point A in Embodiment 3 of the present invention;

[0027] Figure 7 This is a connection diagram of the heating device 3 in Embodiment 3 of the present invention;

[0028] Figure 8 This is a connection diagram of the heating device 3 in Embodiment 4 of the present invention;

[0029] Figure 9 This is a top view of substrate 2 in embodiment 4 of the present invention. Detailed Implementation

[0030] Example 1

[0031] like Figures 1-3 The centrifugal microfluidic chip is placed on the centrifugal turntable 11 via the centrifugal rotation shaft 7. The passive circuit board 1 is connected to the control circuit board 9 on the centrifugal turntable 11 via a second conductive element 8, which is an electrical connector to achieve precise temperature feedback. The control circuit board 9 communicates with the peripheral circuit 18 via the wireless communication module 10 to transmit control signals and temperature acquisition signals. The control circuit board 9 rotates synchronously with the centrifugal microfluidic chip. The centrifugal turntable 11 provides electrical energy to the control circuit board 9 wirelessly to achieve power transmission and temperature signal acquisition during centrifugal rotation.

[0032] The centrifugal microfluidic chip has a diameter of 120 mm and a thickness of 3.5 mm. It includes a passive circuit board 1, a substrate 2, and a heating device 3. The substrate 2 is made of PMMA and has a reaction chamber 5 for storing liquid. The heating device 3 is located directly below the reaction chamber 5 and is a contact heat block. The temperature probe of the first temperature sensing element 6 is located inside the reaction chamber 5. Its two pins transmit the temperature detection information to the passive circuit board 1 in the lower half of the chip through a first conductive element 4, which is an electrical connector. The first temperature sensing element 6 is a thermocouple or a resistance temperature detector (RTD). A liquid injection hole 12 is provided on the reaction chamber 5.

[0033] Example 2

[0034] like Figure 4 The remaining structure of this embodiment is the same as that of Embodiment 1, except that the heating device 3 is an annular structure with a central hole, and the second temperature sensing element 15 is placed at the central hole of the heating device, with the gap filled with thermally conductive silicone grease, to measure the real-time temperature of the heating device and provide over-temperature protection. The substrate 2 is made of PDMS.

[0035] Example 3

[0036] like Figures 5-6The centrifugal microfluidic chip is placed on a centrifugal turntable 11 via a centrifugal rotation shaft 7. The passive circuit board 1 is connected to the control circuit board 9 on the centrifugal turntable 11 via a second conductive element 8, which is a metal spring pin. The control circuit board 9 communicates with the peripheral circuit 18 via a wireless communication module 10 to transmit control signals and temperature acquisition signals. The control circuit board 9 rotates synchronously with the centrifugal microfluidic chip, and the centrifugal turntable 11 provides power to the control circuit board 9 wirelessly. The centrifugal microfluidic chip has a diameter of 120 mm and a thickness of 3.5 mm, and includes a passive circuit board 1, a substrate 2, and a heating device 3. The substrate 2 is made of PDMS material and has three reaction chambers 5 for storing liquid. Each reaction chamber 5 has a radius of 4 mm and a depth of 2 mm.

[0037] like Figure 7 The reaction chamber 5 contains a first temperature sensing element 6 (NTC thermistor), R 25 =54kΩ, B value 3950, the temperature probe is 4mm long, and its two pins are connected to the first conductive element 4 placed on the substrate 2. The first conductive element 4 is a metal spring pin, and its lower end is in contact with the solder joint on the passive circuit board 1 to complete the signal collection. Below the reaction chamber 5 is the heating device 3, which uses annular ceramic heating elements with inner and outer diameters of 3mm and 7mm, respectively. The operating voltage and power are 5V and 2.5W, respectively. Its two pins are directly connected to the passive circuit board 1 below for power supply. The second temperature sensing element 15 (NTC thermistor), the same as the first temperature sensing element 6, is placed in the middle of the annular ceramic heating element, and its two poles are directly connected to the passive circuit board 1 below. The reaction chamber 5 is connected to the injection chamber 14 through the liquid flow channel 13, and the injection chamber 14 is provided with an injection hole 12. The relevant reaction liquid to be heated is injected through injection hole 12. The room temperature is 25℃. The target temperature of the heating program of the peripheral circuit 18 is set to 95℃. After the heating program is started, the liquid in the chamber is heated to 30℃ in 5 seconds, to 60℃ in 19 seconds, and to the target temperature of 95℃ in 34 seconds. After the liquid in the chamber reaches the target temperature in real time, the peripheral circuit 18 controls the heating device 3 to turn on and off to stabilize the temperature near the target temperature. The substrate 2 is made of PC.

[0038] Example 4

[0039] The rest of the structure in this embodiment is the same as in embodiment 3, the only difference being that the heating device 3 uses non-contact heating. Figures 8-9The centrifugal turntable 11 and the centrifugal microfluidic chip are placed inside a sealed, insulated cavity 16. A hot air gun 301, a heating resistance wire 302, and a gas circulation duct 17 are placed outside the cavity 16. The hot air blown from the hot air gun 301 provides the necessary heat to raise the temperature of the liquid inside the reaction chamber 5. With the room temperature at 25°C and the target temperature set to 60°C, the external circuit's heating program is activated. The fan of the hot air gun 301 starts, and the heating element begins heating, providing continuous hot air into the insulated cavity 16. After 45 seconds, the liquid in the reaction chamber 5 on the centrifugal microfluidic chip is heated to the target temperature of 60°C. Once the real-time temperature of the liquid in the reaction chamber 5 reaches the target temperature, the external circuit 18 controls the on / off state of the heating element of the hot air gun 301 to stabilize the temperature near the target temperature.

[0040] The aforementioned centrifugal microfluidic chips can all be used for nucleic acid detection. The nucleic acid detection reagents employ RAA isothermal amplification technology, with reaction parameters set at 39℃ and a reaction time of 20 min, based on a reaction isothermal control system with an accuracy of ±0.1℃. The specific steps include:

[0041] Step 1: After mixing the nucleic acid sample to be analyzed and the nucleic acid detection reagent, use a pipette to inject the reagent into the corresponding injection chamber 14 through each injection hole 12 of the microfluidic chip. The injection holes 12 of the microfluidic chip fit tightly with the pipette tip, which is conducive to sealing and ensures that there is no liquid leakage in the injection holes 12 after the microfluidic chip is finished and the pipette tip is removed. After the sample is added, seal with tape.

[0042] Step 2: Place the sealed microfluidic chip on the centrifuge platform, adjust its position and fix it, and adjust the rotation speed so that the reagent in the injection chamber 14 enters the corresponding reaction chamber 5 through centrifugation.

[0043] Step 3: After centrifugation, set the target temperature of the external circuit heating program to 39℃. After starting the heating program, the liquid in reaction chamber 5 will be heated to 39℃ in 9 seconds. After the real-time temperature rise of the liquid in reaction chamber 5 reaches the target temperature, the external circuit controls the heating device to turn on and off to stabilize the temperature near the target temperature.

[0044] Step 4: Turn on the fluorescence detection system and record the changes in fluorescence intensity in real time. After 20 minutes of reaction, complete the fluorescence detection based on RAA isothermal amplification technology.

Claims

1. A centrifugal microfluidic chip for precise temperature control, characterized in that: The device includes a passive circuit board (1), a substrate (2), and a heating device (3). A first conductive element (4) is disposed between the passive circuit board (1) and the substrate (2). Several reaction chambers (5) are disposed inside the substrate (2). The heating device (3) is used to provide heat for heating the liquid in the reaction chambers (5). A first temperature detection element (6) is disposed inside one of the reaction chambers (5). The first temperature detection element (6) is connected to the first conductive element (4) and can rotate with the substrate (2) to directly read the core temperature of the liquid in the reaction chamber (5). The passive circuit board (1) and the substrate (2) are both connected to a centrifugal rotating shaft (7). The reaction chamber (5) is provided with a liquid injection hole (12), and the heating device (3) is located below the reaction chamber (5); The heating device (3) is equipped with a second temperature detection element (15); The passive circuit board (1) and substrate (2) are set inside the insulation cavity (16) and connected to the second heating device through the air duct (17); The second heating device includes a hot air gun (301) and a heating resistance wire (302). The hot air gun (301) and the heating resistance wire (302) are both arranged in the air duct (17). The hot air gun (301) can continuously supply hot air to the heat preservation cavity (16). The two pins of the heating device (3) are directly connected to the corresponding solder joints on the passive circuit board (1) to control the interruption and duration of heating; the lower end of the first conductive element (4) is in contact with the corresponding solder joint on the passive circuit board (1) of the lower half of the chip to transmit real-time temperature information of the liquid. The substrate (2) is made of PDMS, PMMA or PC.

2. The centrifugal microfluidic chip for precise temperature control according to claim 1, characterized in that: The passive circuit board (1) is connected to the control circuit board (9) via the second conductive element (8), and the control circuit board (9) is connected to the centrifugal turntable (11) via the wireless power supply coil (10).

3. The centrifugal microfluidic chip for precise temperature control according to claim 2, characterized in that: The first conductive element (4) and the second conductive element (8) are metal spring pins.

4. A centrifugal microfluidic chip for precise temperature control according to claim 2, characterized in that: The first conductive element (4) and the second conductive element (8) are electrical connectors.

5. A centrifugal microfluidic chip for precise temperature control according to claim 1, characterized in that: The heating device (3) is a heating ceramic plate, a heating wire or a Peltier.

6. A centrifugal microfluidic chip for precise temperature control according to claim 1, characterized in that: The first temperature sensing element (6) is a thermistor.

7. A centrifugal microfluidic chip for precise temperature control according to claim 1, characterized in that: The first temperature sensing element (6) is a thermocouple or a resistance temperature detector.

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