WO2017206415A1

WO2017206415A1 - Electrophoresis system and method applicable to ion-sensitive field effect sensor

Info

Publication number: WO2017206415A1
Application number: PCT/CN2016/102072
Authority: WO
Inventors: 薛李荣; 孙伟; 朱春蓉
Original assignee: 张家港万众一芯生物科技有限公司
Priority date: 2016-06-03
Filing date: 2016-10-14
Publication date: 2017-12-07
Also published as: CN107462621B; CN107462621A

Abstract

An electrophoresis system applicable to an ion-sensitive field effect sensor, comprising a microfluid cavity, a biosensor, and an electrode. The biosensor is connected to the electrode by means of electrolyte; and an external circuit applies a voltage between the biosensor and the electrode. An electrophoresis method applicable to an ion-sensitive field effect sensor, comprising: applying a voltage to the electrode to form an electric field and driving a target cell or particle/molecule to move to a sensor test area, thereby implementing an effect of concentrating a particle/molecule to be tested and improving detection sensitivity and accuracy rate. The electrode also has a heating effect and can control amplification or dissection of DNA molecules, thus implementing flexible gene detection, achieving heavy use of chips, and the reducing detection costs.

Description

Electrophoresis system and method suitable for ion sensitive field effect sensor

Technical field

The present invention relates to the field of microfluidic electrophoresis, and more particularly to a method of concentrating particles and molecules to be detected by means of electrophoresis, and a sensor electrophoresis system for increasing the signal-to-noise ratio of an ion field effect sensor.

Background technique

A biochemical sensor is an analytical device that detects the type and concentration of targets such as particles and biomolecules. In the field of medical bioassays and chemical analysis, systems and methods that often use biosensors to quantify molecules in a target analyte sample are the cornerstone of modern analytical measurements.

In particular, integrated circuit based biochemical sensors, such as ion sensitive field effect transistors (ISFETs), have unique advantages. Due to the long-term effective effect of Moore's Law, the density of integrated circuits has been continuously increased in magnitude, the size of MOS devices has continued to decrease, the price-performance ratio of chips has been continuously improved, and the cost has continued to decline. For example, in recent years, the ISFET semiconductor gene sequencing technology developed by Ion Torrent Company of the United States has made great breakthroughs, achieving high-throughput parallel sequencing through large-scale integrated sensor circuit chips, which greatly reduces the price of gene sequencing and sequencing time, and improves the accuracy. More than 99.6%. A new generation of gene sequencing technology is revolutionizing the life sciences and the medical world.

However, when the size of the ISFET sensor device is reduced to deep submicron and nanometer scales, the sensor's ability to capture target particles/molecules is greatly reduced due to the large reduction of the microfluidic cavity above the sensor. In other words, the volume of the liquid sample that can be detected by the nanometer-scale sensor becomes small, so that the number of particles/molecules to be tested in the electrolyte becomes small and difficult to be detected, resulting in a significant decrease in the signal-to-noise ratio of the sensor. Second, when the microfluidic cavity above the sensor reaches the micro-nano scale, the molecular diffusion velocity is also greatly reduced (the diffusion rate is proportional to the fourth power of the microfluidic opening). For example, when a DNA molecule is used as a target molecule, it is difficult to reach the detection area of the surface of the nanosensor through the microfluidic inlet. The detection speed and sensitivity of the sensor are reduced, making it impossible to achieve reliable bioprobing.

Summary of the invention

In order to overcome the deficiencies of the prior art, the present invention discloses a design and a method for using an auxiliary electrophoresis system suitable for a nano-scale ion field effect sensor to greatly increase the directional movement of particles/molecules in the microfluid to the sensor surface, thereby improving the sensor. Signal-to-noise ratio, sensitivity, and detection speed.

The invention is achieved by the following technical solutions:

The ion field effect sensor assisted electrophoresis system includes one or more microfluidic cavities, one or more biosensors in the microfluidic cavity, and one or more metal electrodes around the biosensor. The biosensor and the metal electrode are connected by an electrolyte; an external circuit applies a voltage between the biosensor and the metal electrode;

The biosensor is an ion sensitive field effect transistor ISFET, an exposed silicon channel ISFET, a junctionless ion sensitive field effect transistor, or a nanoscale ion sensitive field effect transistor;

The material of the metal electrode is one or alloy of aluminum, copper, silicide, silver, gold, platinum.

The metal electrode is a plate electrode, and the plate electrode is disposed above the microfluidic cavity of the ISFET, and a direct current voltage or an alternating voltage is applied to the plate electrode through an external circuit.

When it is a large-scale array of ISFETs, a flat-plate electrode is placed over the ISFET of the large-scale array.

Or the metal electrode is a ring electrode, which is a loop coil composed of one or more coils, and the width of the coil is 20 nm to 100 μm; preferably 1-10 coils.

a ring electrode is disposed at the inlet of the microfluidic cavity of the ISFET;

The ring electrode is a closed loop coil or a ring electrode having an opening;

The ring electrode is exposed to the electrolyte or buried in the dielectric insulating material;

In the case of large scale arrayed ISFETs, a ring electrode is placed at the entrance of the microfluidic cavity of each ISFET of the large scale array, and the connected ring electrodes are connected to each other to form a multi-grid metal grid and apply a voltage to the metal grid.

Or the metal electrode is a U-shaped electrode:

When the microfluidic cavity is parallel to the ISFET of the gate plate, a U-shaped electrode is added to one side of the ISFET exposed gate plate, and a DC voltage or an AC voltage is applied to the U-shaped electrode and the exposed gate plate of the ISFET through an external circuit. ;

Or the metal electrode is a double electrode composed of a rectangular parallelepiped electrode and a U-shaped electrode:

When the microfluidic cavity is parallel or perpendicular to the ISFET of the grid plate, the double electrode composed of the rectangular parallelepiped electrode and the U-shaped electrode surrounds the exposed gate plate of the ISFET, and a DC voltage is applied to the rectangular parallelepiped electrode and the U-shaped electrode through an external circuit. Or AC voltage.

The metal electrode is a micro-nano electrode having a width of 20 nm to 200 μm.

An electrophoresis method suitable for an ion-sensitive field effect sensor, characterized in that an external circuit applies a voltage between a biosensor and a metal electrode to form a potential difference, and electrophoresis is driven on the target molecule to concentrate it on the surface of the sensor for a period of time. After the voltage is interrupted, the sensor is activated for detection.

A method of voltage application is at the gate and electrode of a conventional metal gate ion sensitive field effect sensor Voltage is applied between them. Another method when the channel of the ion-sensitive field effect sensor is directly exposed to the solution (exposing the channel sensor) is to apply a voltage between the exposed channel of the sensor and the electrode. For non-junction type (no PN junction between channel and source/drain), the ion-sensitive field effect sensor can also be at the drain (or source) and electrode of the sensor if its channel portion is exposed to the solution. A voltage is applied between them.

The applied voltage is 10mV to 20V, the time is 10ms to 1000s, and the frequency is less than or equal to 50MHz;

When the dielectric constant of the molecule/particle to be tested differs from the dielectric constant of the solution, or the analyte is a cell, DNA, or protein, the AC voltage frequency is 50 Hz to 5000 Hz, and the molecule to be tested is concentrated to the ISFET by the dielectric electrophoresis principle DEP. Gate surface

When the molecule to be tested is a small nanoparticle or particle, or the dielectric constant of the molecule to be tested is relatively close to the dielectric constant of the electrolyte, the frequency of the alternating voltage is set at 500 Hz to 100000 Hz to realize the ACOX phenomenon of the alternating current permeation flow;

When the particle concentration of the solution to be tested is high and the conductivity is above 10 mS, the frequency of the alternating voltage is set in the range of 100000 Hz to 50 MHz, and the electrophoresis ACET is realized by the principle of alternating current electrothermal to concentrate the molecule to be tested.

The microfluid diffusion distance L is 1 to 100 μm.

The metal electrode can be used as an electronic heating wire to heat the electrolyte in the microfluidic cavity by supplying a large current to the metal electrode, and the temperature is controlled at 20 ° C to 100 ° C to achieve the separation effect between the target molecule and the probe, so that the biosensor can It is reused.

Compared with the prior art, the ion field effect sensor electrophoresis system of the present invention has the advantages of forming an electric field after applying a voltage to the electrode, driving the target cell, or moving the particle/molecule to the sensor test area to realize concentration of the particle to be tested/ The role of the molecule to improve the sensitivity and accuracy of the detection; the electrode also has the function of heating, can control the amplification or exfoliation of the DNA molecule, realize flexible gene detection, and can realize the repeated use of the chip and reduce the detection cost.

The ion field effect sensor assisted electrophoresis system successfully solves the problem that the biosensor is difficult to detect low concentration ions/molecules and cannot be reused. Especially for DNA detection, on-chip DNA amplification (PCR) can be achieved by repeated heating and cooling to increase the number of DNA samples to be tested and improve detection sensitivity.

DRAWINGS

1 is a diagram showing a plate electrode and an exposed silicon channel ISFET forming electrophoresis system according to an embodiment of the present invention.

2(a) is a side view showing a ring electrode and an exposed silicon channel ISFET forming an electrophoresis system according to an embodiment of the present invention;

2(b) is a top plan view of a ring electrode and an exposed silicon channel ISFET forming electrophoresis system in accordance with an embodiment of the present invention.

3(a) is a side view of a ring electrode (with an opening) and a conventional metal gate ISFET forming an electrophoresis system according to an embodiment of the present invention;

Figure 3 (b) is a top plan view of a ring electrode (with openings) and a conventional metal gate ISFET forming an electrophoresis system in accordance with an embodiment of the present invention.

4(a) is a side view of an electrophoresis system formed by a buried ring electrode and a conventional metal gate ISFET of an embodiment of the present invention;

4(b) is a top plan view of an electrophoresis system formed by a buried ring electrode and a conventional metal gate ISFET of an embodiment of the present invention.

Figure 5 shows a plate electrode and ISFET large scale array forming electrophoresis system in accordance with an embodiment of the present invention.

Figure 6 (a) is a side view of a ring-shaped electrode and ISFET large-scale array forming electrophoresis system according to an embodiment of the present invention;

Figure 6 (b) is a top plan view of a ring electrode and ISFET large scale array forming electrophoresis system in accordance with an embodiment of the present invention.

Figure 7 (a) is a side view of a two-electrode and ISFET forming a horizontal direction electrophoresis system according to an embodiment of the present invention;

Figure 7 (b) is a plan view of a two-electrode and ISFET forming a horizontal electrophoresis system in accordance with an embodiment of the present invention.

8(a) is a side view of a horizontal electrode electrophoresis system formed by a dual electrode and an exposed silicon channel ISFET according to an embodiment of the present invention;

Figure 8 (b) is a top plan view of a two-electrode and exposed silicon channel ISFET forming a horizontal direction electrophoresis system in accordance with an embodiment of the present invention.

Figure 9 (a) is a side view of a single-electrode and exposed silicon channel ISFET forming a horizontal direction electrophoresis system in accordance with an embodiment of the present invention;

Figure 9 (b) is a top plan view of a single-electrode and exposed silicon channel ISFET forming a horizontal electrophoresis system in accordance with an embodiment of the present invention.

detailed description

In order to facilitate the understanding of those skilled in the art, the present invention will be further described below in conjunction with the embodiments and the accompanying drawings.

Example 1

The invention is illustrated in the structure of an ion sensitive field effect sensor as shown in FIG. The channel of this ion-sensitive field effect sensor is directly exposed to the solution, referred to as the exposed channel ISFET sensor. As shown in Figure 1, this ISFET can be implemented in a standard CMOS process using a polysilicon layer as the channel for the ISFET. And the solution cavity is realized above the channel. Another method is to use the upper single crystal silicon as a channel on a silicon wafer on an SOI (silicon-on-insulator) insulating film to realize the exposed silicon channel ISFET shown in FIG. Such an ISFET structure can also use other materials as channels, such as Ge锗, SiGe, graphene film, MoS2 film, WSe2 film, and the like. In this embodiment, a plate electrode is added at a position above the microfluidic cavity of the exposed channel ISFET, and a DC voltage or an AC voltage having a frequency of 0 Hz to 50 MHz and a size of 10 mV to 20 V is applied to the plate electrode through an external circuit.

The voltage applied to the plate electrode by the external circuit is greater than the voltage of the ISFET gate, forming a potential difference, driving the target molecule to electrophoresis, concentrating it onto the sensing surface, improving the sensitivity of the sensor detection, accuracy, and reducing the detection time (mainly waiting) Measuring the diffusion time of the molecule). After a period of time (such as 10ms to 1000s), the electrophoresis voltage is interrupted to prevent the voltage from affecting the detection result, and the sensor is activated for detection.

In addition, the electrolyte can be heated in the microfluidic cavity by supplying a large current to the electrode, and the temperature is controlled at 20 ° C to 100 ° C to achieve the separation effect of the target molecule and the probe, so that the biosensor can be reused. The ion field effect sensor assisted electrophoresis system successfully solves the problem that the biosensor is difficult to detect low concentration ions/molecules and cannot be reused. Especially for DNA detection, on-chip DNA amplification (PCR) can be achieved by repeated heating and cooling to increase the number of DNA samples to be tested and improve detection sensitivity.

Further here, the method of using the voltage and amplitude of the electrophoresis setting for different test electrolytes is described in detail. Depending on whether the applied voltage is DC or AC, the basic principles of electrophoresis and the range of applicable electrolytes will vary. For example when the DC voltage is a DC electrophoresis principle (DCEK), the intensity of the voltage needed to reach approximately ¹⁰⁵ V / m in order to effectively drive charged molecules. For example, when the height of the microfluidic cavity is 10 microns, the required voltage is about 1 volt. However, when the cavity is large, a large voltage will be required to drive the electrophoresis, and a high voltage may cause an electrochemical reaction, such as electrolysis of water to generate bubbles, which affects the accuracy of detection. In this case, an AC voltage or AC-DC combination can be used. In this case, the following AC electrophoresis principles (ACEK) are used.

The specific implementation of the AC electrophoresis principle is further subdivided into three cases, both of which require the plate electrode shown in FIG. 1 and the gate of the ISFET shown in FIG. 1 to form an asymmetric solid structure, thereby achieving uneven distribution as shown in FIG. Electric field. When the dielectric constant of the molecule/particle to be tested is different from the dielectric constant of the solution, a relatively low frequency AC voltage (such as 50 Hz to 5000 Hz) may be used to concentrate the molecule to be tested to the ISFET by the Dielectrophoresis Principle (DEP). Gate surface. This design is especially suitable for electrophoretic concentration of relatively large organic molecules such as cells, DNA, proteins, and the like. The voltage required for DEP electrophoresis is generally large, at least a few volts.

When the molecule to be tested is small, such as tiny nanoparticles or particles, or the dielectric constant of the molecule to be tested is close to the dielectric constant of the solution, the dielectrophoresis principle will fail. At this time, in the same structural design of Figure 1, it can be mentioned The AC voltage is high to achieve AC electroosmotic flow (ACEO). ACEO also requires an asymmetric electric field distribution with a smaller voltage amplitude than DEP. The frequency is generally set at several hundred Hz to 10WHz.

ACEO is suitable for liquids with lower salt concentration. If the concentration of the particles to be tested is high and the conductivity is high (for example, above 10 mS), ACEO will no longer be effective. At this time, the voltage frequency is again increased to a range of 10 WHz to 50 MHz, and electrophoresis (ACET) is performed by an alternating current electrothermal principle to concentrate the molecules to be tested.

The various electrophoresis principles and voltage setting methods mentioned above are also applicable to the following cases. The text will not be repeated later.

Example 2

As shown in FIG. 2, a ring electrode is added at the entrance of the microfluidic cavity exposing the silicon channel ISFET, and a DC voltage or AC having a frequency of 0 Hz to 50 MHz and a size of 10 mV to 20 V is applied to the ring electrode through an external circuit. Voltage. Other specific embodiments are the same as in the first embodiment.

Comparing the plate electrode added in the microfluidic cavity of Example 1, the ring electrode of Example 2 can conveniently and accurately control the size of the microfluidic diffusion L (the size of the previous design L is 8 to 12 microns), thereby controlling the electrode pair micro The magnitude of the voltage applied to the solution in the fluid chamber prevents the water electrolysis from being generated due to excessive voltage, which has an effect on the detection result. The ion field effect sensor assisted electrophoresis system efficiently concentrates the ions/molecules to be measured, and does not affect the detection result, that is, high accuracy.

Example 3

As shown in FIG. 3, a ring electrode is also added at the entrance of the microfluidic cavity of the conventional metal gate ISFET, and a DC voltage having a frequency of 0 Hz to 50 MHz and a size of 10 mV to 20 V is applied to the ring electrode through an external circuit. Or AC voltage. The external circuit applies a voltage to the ring electrode that is greater than the voltage of the metal gate, forms a potential difference, and electrophoretically drives the target molecule to concentrate it onto the sensing surface. Other specific embodiments are the same as in the first embodiment.

The ion field effect sensor-assisted electrophoresis system can be applied not only to exposed silicon channel ISFETs, but also to conventional metal gate ISFETs. This conventional ISFET structure also includes the case where the polysilicon gate is directly exposed to the solution, and is also applicable to the electrophoresis system of the present invention.

Example 4

As shown in Figure 4, a ring electrode is also added at the entrance of the microfluidic cavity of a conventional metal gate ISFET. Unlike the case where the ring electrode is exposed to a solution in Example 3, this example buryes the ring electrode in a dielectric insulating material such as silicon oxide (which may also be alumina, titanium oxide, etc.). The reason is the high concentration of salt at more than 5 mmol/L In the solution, the metal material of the ring electrode is easily dissolved in the solution. Moreover, the salt solution having a higher concentration has a higher conductivity and is easy to shield the electric field generated by the ring electrode. Since the ring electrode is not exposed to the solution, the effect of the DC voltage is greatly reduced. Therefore, an alternating current voltage having a frequency of 100 Hz to 50 MHz and a size of 10 mV to 20 V is applied to the ring electrode through an external circuit. Other specific embodiments are the same as in the first embodiment.

The method of adding a ring electrode in this example is mainly for detecting a high concentration salt solution in the field of medicine and biological monitoring. Example 2-3 is mainly for water quality testing such as drinking water and swimming water.

Example 5

As shown in FIG. 5, since ISFET sensor chips require simultaneous detection of multiple targets in real time and large-scale arrays to greatly reduce the statistical error of detection, there are large-scale arrayed ISFETs on the chip. Therefore, in this example, a large plate electrode is added above the ISFET array, and a DC voltage or an AC voltage having a frequency of 0 Hz to 50 MHz and a size of 10 mV to 20 V is applied to the plate electrode through an external circuit. Other specific embodiments are the same as in the first embodiment.

This example is applied to ion array sensors of large scale arrays.

Example 6

As shown in Figure 6, a ring electrode is added to the inlet of the microfluidic cavity of each ISFET on a large scale array. The connected ring electrodes can be connected to each other, and all of the ring electrodes form a multi-grid metal grid. A voltage is then applied to the metal grid. Other specific embodiments are the same as in the first embodiment.

This example is equally applicable to ion array sensors of large scale arrays.

Embodiments 5 and 6 are applicable not only to conventional metal gate ISFETs, but also to nanoscale ISFETs, exposed silicon channel ISFETs, and the like.

Example 7

As shown in FIG. 7, two electrodes are added in parallel with the exposed gate plate of the conventional metal gate ISFET, one electrode is a rectangular parallelepiped electrode as shown in FIG. 7, and the other electrode is a U-shaped electrode as shown in FIG. . Two electrodes surround the ISFET exposed gate plate in the middle. Applying a DC voltage or AC voltage with a frequency of 0 Hz to 50 MHz and a size of 10 mV to 20 V to the two electrodes through an external circuit, driving the target molecules to electrophoresis, and concentrating the target molecules in the microfluidic cavity to the two electrodes On the surface of the grid plate. Other specific embodiments are the same as in the first embodiment.

Example 8

As shown in FIG. 8, two electrodes are added at a position parallel to the gate plate of the exposed silicon channel ISFET, one electric The pole is shown as a rectangular parallelepiped electrode, and the other electrode is a U-shaped electrode as shown in FIG. Two electrodes surround the ISFET exposed gate plate in the middle. Apply a frequency of 0 Hz to the two electrodes through an external circuit.

50MHz, DC voltage of 10mV ~ 20V or AC voltage. An electric field is formed around the electrode to electrophoretically drive the target molecule, and the target molecules in the microfluidic cavity are concentrated onto the surface of the grid plate surrounded by the two electrodes. Other specific embodiments are the same as in the first embodiment.

Example 9

As shown in Figure 9, a U-shaped electrode is added to the side of the gate plate that exposes the silicon channel ISFET. A DC voltage or an AC voltage having a frequency of 0 Hz to 50 MHz and a size of 10 mV to 20 V is applied to the rectangular plate electrode and the gate plate exposed by the polysilicon ISFET through an external circuit, and the potential difference formed is electrophoretically driven to the target molecule, and the microfluidic cavity is driven. The target molecules in the concentration are concentrated onto the surface of the grid plate. Other specific embodiments are the same as in the first embodiment.

Examples 1-6 are applicable to ISFETs in which the microfluidic cavity is perpendicular to the grid plate, and Examples 7-9 are applicable to ISFETs in which the microfluidic cavity is parallel to the gate plate.

The above embodiments are merely illustrative of the technical idea of the present invention, and the scope of protection of the present invention is not limited thereto. Any changes made on the basis of the technical solutions according to the technical idea proposed by the present invention fall within the scope of protection of the present invention. within. Techniques not covered by the present invention can be implemented by existing techniques.

Claims

An electrophoresis system suitable for an ion-sensitive field effect sensor, comprising: a microfluidic cavity, a biosensor, an electrode; the biosensor is located in a microfluidic cavity, and the biosensor and the electrode are electrolyzed a liquid connection; an external circuit applies a voltage between the biosensor and the electrode.
The electrophoresis system according to claim 1, wherein said biosensor is an ion sensitive field effect transistor ISFET, an exposed channel ISFET, a junctionless ion sensitive field effect transistor, or a nanoscale ion sensitive field effect transistor;

The material of the electrode is one of aluminum, copper, silicide, silver, gold, platinum or alloy.
The electrophoresis system according to claim 1 or 2, wherein the electrode is a plate electrode, and the plate electrode is disposed above the microfluidic cavity of the biosensor, and a direct current is applied to the plate electrode through an external circuit. Voltage or alternating voltage;

When it is a large-scale array of biosensors, one of the plate electrodes is disposed above the large-scale array of biosensors;

The electrode is a micro-nano scale electrode having a width of 20 nm to 200 μm.
The electrophoresis system according to claim 1 or 2, wherein the electrode is a ring-shaped electrode and is a toroidal coil composed of one or more coils having a width of 20 nm to 100 μm;

The ring electrode is disposed at an inlet of the microfluidic cavity;

The ring electrode is a closed loop coil or a ring electrode having an opening;

The ring electrode is exposed to the electrolyte or buried in the dielectric insulating material;

In the case of a large-scale array of biosensors, one of the ring electrodes is disposed at the inlet of the microfluidic cavity of each biosensor of the large-scale array, and the connected ring electrodes are connected to each other to form a multi-grid metal grid. Applying a voltage to the metal grid;

The electrode is a micro-nano scale electrode having a width of 20 nm to 200 μm.
The electrophoresis system according to claim 1 or 2, wherein

The electrode is a U-shaped electrode:

When the microfluidic cavity is parallel to the ISFET of the gate plate, a U-shaped electrode is added to one side of the ISFET exposed gate plate, and a DC voltage is applied to the U-shaped electrode and the ISFET exposed gate plate through an external circuit or AC voltage;

Or the electrode is a double electrode composed of a rectangular parallelepiped electrode and a U-shaped electrode:

When the microfluidic cavity is parallel or perpendicular to the ISFET of the gate plate, the rectangular parallelepiped electrode and the U-shaped electrode are composed The two electrodes surround the exposed gate plate of the ISFET, and apply a DC voltage or an AC voltage to the rectangular parallelepiped electrode and the U-shaped electrode through an external circuit;

The electrode is a micro-nano scale electrode having a width of 20 nm to 200 μm.
An electrophoresis method suitable for an ion-sensitive field effect sensor, characterized in that an external circuit applies a voltage between a biosensor and an electrode to form a potential difference, and electrophoretically drives the target molecule to concentrate it on the surface of the ISFET gate. After the time, the voltage is interrupted and the sensor is activated for detection.
The electrophoresis method according to claim 6, wherein the voltage is applied by applying a voltage between the gate and the electrode of the conventional metal gate ion-sensitive field effect sensor; or the channel and the electrode exposed by the ISFET Apply a voltage between them; or apply a voltage between the drain/source and the electrode of the non-junction ISFET that exposes the channel.
The electrophoresis method according to claim 6 or 7, wherein the applied voltage has a magnitude of 10 mV to 20 V, a time of 10 ms to 1000 s, and a frequency of 50 MHz or less;

When the dielectric constant of the molecule/particle to be tested differs from the dielectric constant of the solution, or the analyte is a cell, DNA, or protein, the AC voltage frequency is 50 Hz to 5000 Hz, and the molecule to be tested is concentrated to the ISFET by the dielectric electrophoresis principle DEP. Gate surface

When the molecule to be tested is a small nanoparticle or particle, or the dielectric constant of the molecule to be tested is relatively close to the dielectric constant of the electrolyte, the frequency of the alternating voltage is set at 500 Hz to 100000 Hz to realize the ACOX phenomenon of the alternating current permeation flow;

When the particle concentration of the solution to be tested is high and the conductivity is above 10 mS, the frequency of the alternating voltage is set in the range of 100000 Hz to 50 MHz, and the electrophoresis ACET is realized by the principle of alternating current electrothermal to concentrate the molecule to be tested.
The electrophoresis method according to claim 6 or 7, wherein the microfluid diffusion distance L is from 1 to 100 μm.
The electrophoresis method according to claim 6 or 7, wherein the electrolyte in the microfluidic cavity is heated by supplying a large current to the metal electrode, and the temperature is controlled at 20 ° C to 100 ° C to reach the target molecule and the probe. The effect of the separation allows the biosensor to be reused.