CN102101018A - Cascade high-pressure electro-osmosis pump - Google Patents

Abstract

The invention relates to the technical field of chemical analysis, which is a cascaded high-voltage electroosmotic pump, which contains a cationic capillary channel, an anionic capillary channel, a coupler, a high-voltage power supply, a working medium container and a platinum electrode. Anion-type capillary channels are connected alternately through couplers to construct a three-stage or multi-stage cascade electroosmotic pump; the positive voltage of the high-voltage power supply is applied to both ends of the cationic capillary channel, and the negative voltage of the high-voltage power supply is applied to the anion-type capillary channel Both ends; the capillary channel is a tubular or grooved channel constructed of rigid insulating material; the positive effect of the present invention is: the natural switching of the direction of the electric field and the output pressure are realized based on the way that the cationic capillary channel and the anionic capillary channel are alternately connected Effectively improve, minimize the number of electric field couplers used, and simplify the pump system.

Description

A cascaded high-pressure electroosmotic pump

technical field

The invention relates to the technical field of chemical analysis, in particular to a micro-flow high-pressure pump—a cascaded high-pressure electroosmotic pump, which can be used in systems such as capillary or nanoscale liquid chromatography, capillary ion chromatography, and the like.

Background technique

Capillary/nanoliter liquid chromatography (CLC) or capillary ion chromatography (CIC) has become one of the most concerned analytical techniques in recent years due to its advantages of high efficiency, solvent saving, and easy coupling with mass spectrometry (MS). The high-pressure infusion pump is one of the core components of the capillary liquid chromatography system. Its function is to deliver the mobile phase or eluent to the separation column system to complete the separation process of the sample. Since the flow range commonly used in capillary liquid chromatography systems is at the μL/min level, it is difficult for conventional mechanical infusion pumps to accurately deliver microliter and below μL/min due to micro-leakage of one-way valves and dynamic seals. Electroosmotic pump (EOP) is a new type of micropump that uses electroosmotic flow to realize liquid drive. It is characterized by high output pressure, and the change of flow rate and direction can be easily realized by changing the size and direction of the electric field. When other conditions remain unchanged, increasing the output pressure of the electroosmotic pump can be achieved by increasing the electric field intensity or increasing the applied voltage. The electroosmotic pump usually needs to apply a voltage of several thousand volts to tens of thousands of volts. This high pressure is not conducive to the safety of operators, especially in environments with relatively high humidity. But low voltage and high output pressure become a pair of contradictions. The solution is to use cascaded electroosmotic pumps, that is, use multi-stage pumps similar to multipliers in series, which is equivalent to connecting multiple pumps in series without increasing the applied voltage.

The cascade electroosmotic pump was first proposed by Takamura et al. It is an open-tube cascade electroosmotic pump constructed on a glass chip. Each pump body consists of 10 parallel channels followed by a single wide channel. composition. Applying a forward voltage across the narrow channel produces a forward electroosmotic flow, while applying an equal reverse voltage across the wide channel produces a reverse electroosmotic flow. Since the total electroosmotic flow generated in the narrow channel area is much larger than the electroosmotic flow in the wide channel, the net electroosmotic flow output from each stage of the electroosmotic pump is positive electroosmotic flow. Similarly, the output pressure of each electroosmotic pump is a positive output pressure, and the cascaded electroosmotic pumps can double the output pressure.

In order to overcome the inherent defect of the low output pressure of the above-mentioned open-tube cascade electroosmotic pump, Guan et al. proposed a cascade electroosmotic pump based on packed columns, and each stage of the pump includes two parts: a capillary packed column and an open-tube capillary. The capillary-packed column and the open-tube capillary are made of the same material, and the difference is that the former (capillary-packed column) has a filler, and the latter (open-tube capillary) is hollow; a positive voltage is applied to both ends of the capillary-packed column to generate a positive voltage. Directed electroosmotic flow, while applying an equal reverse voltage across the open capillary will produce a reversed electroosmotic flow. The open-tube capillary is only used to switch the direction of the electric field, but this design obviously increases the complexity of the system, and at the same time, the electroosmotic flow generated by it offsets the electroosmotic flow generated by a part of the capillary filled column.

Although the above two cascaded electroosmotic pumps are ingeniously designed, they have a common defect, that is, the existence of the reverse electroosmotic flow pump body. For example, wide channels and open-tube capillaries are used in the above designs, and the use of these pump bodies is only used to switch the direction of the electric field without benefiting the increase of electroosmotic flow or output pressure. However, adding a coupler (or called a connection joint) The number of will increase the complexity of the system.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a cascaded high-voltage electroosmotic pump, which can realize the natural switching of the electric field direction, minimize the use of couplers, and effectively increase the output pressure.

For realizing above-mentioned object, the technical scheme that the present invention takes is:

A cascaded high-voltage electroosmotic pump, which contains a cationic capillary channel, an anionic capillary channel, a coupler, and a high-voltage power supply. One-stage or multi-stage cascaded electroosmotic pumps; the positive voltage of the high-voltage power supply is applied to both ends of the cationic capillary channel, and the negative voltage of the high-voltage power supply is applied to both ends of the anion-type capillary channel.

The alternate connection of cationic capillary channels and anionic capillary channels of the three-stage cascaded electroosmotic pump through couplers is as follows: the first cationic capillary channel is the first-stage pump of the three-stage cascade electroosmotic pump, and the second cationic The type capillary channel is the third-stage pump of the three-stage cascade electroosmotic pump, and a positive voltage is applied to both ends of the two channels; the anion-type capillary channel is the second-stage pump of the three-stage cascade electroosmotic pump, and the two ends Negative voltage; after applying an electric field, both the first cationic capillary channel and the second cationic capillary channel generate electroosmotic flow from the positive electrode to the negative electrode, while the anionic capillary channel generates electroosmotic flow from the negative electrode to the positive electrode.

The cationic capillary channel or the anionic capillary channel is a channel constructed of a rigid insulating material with an effective inner diameter of 1-750 μm, and the channel is tubular or groove-shaped; the particle size of the particles filled in the channel is 100 nm-10 μm or Monolithic fillers constructed by in situ polymerization.

The cationic capillary channel includes a strong cationic capillary channel whose surface functional group is sulfonic acid group -SO3- and a weak cationic capillary channel whose surface functional group is phosphoric acid group ^-PO3- or carboxylic acid group ^-COO- or ^-SiO- .

The anion-type capillary channel includes strong anion-type capillary channel whose surface functional group is quaternary amine group-R ₄ N ⁺ and weak anion-type capillary channel whose surface functional group is tertiary amine-R ₃ N or secondary amine-R ₂ N.

The coupler is a stainless steel two-way or a stainless steel three-way.

The positive effect of a kind of cascaded high-voltage electroosmotic pump of the present invention is:

A three-stage or multi-stage cascaded electroosmotic pump is constructed by using cation-exchange monolithic columns and anion-exchange monolithic columns alternately. After an electric field is applied, the cationic capillary channel generates an electroosmotic flow from the positive electrode to the negative electrode, while the anionic capillary channel generates electroosmotic flow. Electroosmotic flow from the negative electrode to the positive electrode; since there is no backflow in the system, the total output pressure is approximately equal to the sum of the three-stage pumps, that is, the total output pressure of the three-stage or multi-stage cascaded electroosmotic pump is equal to the cationic capillary channel and the anion In this way, the output pressure can be multiplied without increasing the applied voltage.

Description of drawings

Fig. 1 is a structural schematic diagram of a cascaded high-voltage electroosmotic pump (three-stage cascaded electroosmotic pump) of the present invention;

Fig. 2 is an effect diagram of a cascaded high-voltage electroosmotic pump (three-stage cascaded electroosmotic pump) of the present invention;

The labels in the figure are:

1. The first cationic capillary channel; 2. Anionic capillary channel;

31. The first coupler; 32. The second coupler;

33. The third coupler; 4. The second cationic capillary channel;

5. Output capillary channel; 6. High voltage power supply;

7. Working medium container; 8. Platinum electrode.

Detailed ways

A specific embodiment of a cascaded high-voltage electroosmotic pump of the present invention is given below in conjunction with the accompanying drawings, however, the implementation of the present invention is not limited to the following examples.

See attached drawing 1. A cascaded high-voltage electroosmotic pump, which is a three-stage cascaded electroosmotic pump, comprising a first cationic capillary channel 1, an anionic capillary channel 2, a coupler, a second cationic capillary channel 4, an output capillary channel 5, High voltage power supply 6, working medium container 7 and platinum electrode 8. Take several cationic capillary channels of a certain length (such as 10-20 cm) and several sections of anionic capillary channels of a certain length (such as 10-20 cm), and connect the cationic capillary channels and anionic capillary channels alternately. Such as building a three-stage cascaded electroosmotic pump, its structure is as follows: the positive pole of the high voltage power supply 6 is connected to the platinum electrode 8 and the coupler 32 respectively; the negative pole of the high voltage power supply 6 is connected to the coupler 31 and the coupler 33 respectively; One end of the cationic capillary channel 1 is inserted into the working medium container 7 so as to be connected to the platinum electrode 8; the other end of the first cationic capillary channel 1 is connected to one end of the anionic capillary channel 2 through the first coupler 31; the second One end of the dication capillary channel 4 is connected to the other end of the anion capillary channel 2 through the second coupler 32 ; the other end of the second cation capillary channel 4 is connected to the output capillary channel 5 through the third coupler 33 .

The first cationic capillary channel 1 is the first-stage pump of the three-stage cascade electroosmotic pump, and the second cationic capillary channel 4 is the third-stage pump of the three-stage cascade electroosmotic pump. The forward voltage of the high-voltage power supply 6 is connected to the platinum electrode 8 and the working medium container 7 as the positive pole, the end of the first cationic capillary channel 1 connected to the working medium container 7 is the positive pole, and the other end connected to the first coupler 31 is positive. is the negative pole; the anion-type capillary channel 2 is the second-stage pump for the three-stage cascaded electroosmotic pump, and the negative voltage of the high-voltage power supply 6 is applied to the two ends of the anion-type capillary channel 2: the first coupler 31 and the second coupler The two ends of the second cationic capillary channel 4 are applied with a positive electric field, the end connected to the second coupler 32 is the positive pole, and the end connected to the third coupler 33 is the negative pole. After an electric field is applied, both the first cationic capillary channel 1 and the second cationic capillary channel 4 generate electroosmotic flow from the positive electrode to the negative electrode, while the anionic capillary channel 2 generates electroosmotic flow from the negative electrode to the positive electrode.

The cationic capillary channel or the anionic capillary channel 2 is a channel constructed of a rigid insulating material with an effective inner diameter of 250 μm, and the channel is tubular or grooved; the particle size of the particles filled in the channel is 100 nm to 10 μm (usually The particle size used is 3μm or 5μm) or a monolithic filler constructed by in-situ polymerization.

The cationic capillary channel can be strong cationic (surface functional group is sulfonic acid group -SO ^3- ) or weak cationic capillary channel (surface functional group is phosphoric acid group -PO ^3- or carboxylic acid group -COO ^- or -SiO ^- ). The anionic capillary channel 2 can adopt strong anionic (surface functional group is quaternary amine group-R ₄ N ⁺ ) or weak anionic capillary channel (surface functional group is tertiary amine group-R ₃ N or secondary amine group-R ₂ N ). The coupler adopts a stainless steel two-way or a stainless steel three-way. The high-voltage power supply 6, the working medium container 7 and the platinum electrode 8 can adopt existing products without special requirements.

If a cascaded electroosmotic pump with four or more stages is constructed, it can be realized by increasing the number of stages in which cationic capillary channels and anionic capillary channels are alternately connected.

See attached drawing 2. Using the above-mentioned three-stage cascaded electroosmotic pump, when the applied voltage is 4 kV, the total output pressure is approximately equal to the sum of the individual output pressures of the three-stage pumps.

Claims (6)

1. cascade high voltage electroosmotic pump, contain cationic capillary channel, anionic capillary channel, coupler and high voltage source, it is characterized in that, alternately connect three grades or the multi-stage cascade electroosmotic pump that makes up by coupler for utilizing cationic capillary channel, anionic capillary channel; The forward voltage of high voltage source is applied to cationic capillary channel two ends and the negative voltage of high voltage source is applied to anionic capillary channel two ends.

2. a kind of cascade high voltage electroosmotic pump according to claim 1, it is characterized in that, cationic capillary channel of described three-stage cascade electroosmotic pump and anionic capillary channel alternately being connected to by coupler: the first cationic capillary channel is the first order pump of three-stage cascade electroosmotic pump, the second cationic capillary channel is the third level pump of three-stage cascade electroosmotic pump, and two passage two ends all apply forward voltage; The anionic capillary channel is the second level pump of three-stage cascade electroosmotic pump, and its two ends apply negative voltage; After applying electric field, the first cationic capillary channel and the second cationic capillary channel all produce the EOF from the positive pole to the negative pole, and produce the EOF from the negative pole to the positive pole in the anionic capillary channel.

3. a kind of cascade high voltage electroosmotic pump according to claim 1 and 2, it is characterized in that, described cationic capillary channel or anionic capillary channel are that effective internal diameter is the passage of the rigid insulation material construction of 1～750 μ m, and passage is a tubular-type or groove-shaped; The particle diameter of filler particles is 100 nm～10 μ m or the monoblock type filler that makes up by the in-situ polymerization mode in the passage.

4. a kind of cascade high voltage electroosmotic pump according to claim 3 is characterized in that, described cationic capillary channel comprises that surface functional group is sulfonic group-SO ₃ ^-Strong cation type capillary channel and surface functional group be phosphate-PO ₃ ^-Or carboxylic acid group-COO ^-Or-SiO ^-Weak cation type capillary channel.

5. a kind of cascade high voltage electroosmotic pump according to claim 3 is characterized in that, described anionic capillary channel comprises that surface functional group is quaternary amine base-R ₄N ⁺Reinforcing yin essence ionic capillary channel and surface functional group be tertiary amine-R ₃N or secondary amine-R ₂The weak anionic type capillary channel of N.

6. a kind of cascade high voltage electroosmotic pump according to claim 1 and 2 is characterized in that, described coupler is stainless steel two logical or stainless steel threeways.

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