EP2730335A1 - Microfluidic peristaltic pump, method and pumping system - Google Patents

Abstract

The peristaltic pump (100) has primary and secondary pumping chambers (20,50-52) that are operatively connected to the inflow channel (10) by the primary and secondary channels (30,60-62). A fluidic resistance of the primary channel is different from a fluidic resistance of the secondary channel. The channel is configured to produce a throttling function, such that the primary and secondary membranes (40) are deflected in a time sequence, when a pressure is applied in the inflow channel to produce a pumping function. Independent claims are included for the following: (1) a pumping system; and (2) a method for operating microfluidic peristaltic pump.

Description

State of the art

For the processing of microfluidic processes in miniaturized diagnostic systems (Labs-on-a-Chip, LOCs) u. a. also integrated micropumps on the LOC. In addition to the avoidance of contamination of external pumps with sample liquids, this results in particular the advantage that even very small amounts of sample and small pumping rates are low feasible.

From the state of the art, electroosmotic pumps, diaphragm pumps combined with valves, micromechanical peristaltic pumps, electrically actuated peristaltic pumps and thermo-pneumatically actuated peristaltic pumps are generally known as representatives of different designs.

The US Pat. No. 7,217,367 B2 describes a system for microfluidic chromatography using a microfluidic peristaltic pump. The individual pumping chambers of the pump are each controlled via an associated valve, so that the production cost increases accordingly.

Advantages of the invention

The microfluidic peristaltic pump defined in claim 1 and the pumping system defined in claim 11 has the advantage over conventional solutions that now only a single integrated valve or only by the action of the individual channels as throttles in the (pneumatic) path to the pumping chambers a single interface to the outside world is necessary for all pumping chambers, whereas in conventional pneumatic peristaltic pumps each pumping chamber must be individually actuated by means of an associated valve. Due to this simplification in the construction of the pump according to the invention results in both the LOCs and the external drive unit lower costs, as well as increased reliability. When using a layer structure with Polymer substrates and a polymer membrane is a particularly cost-effective realization of the smallest structures possible, which are necessary for the throttling of gases.

In contrast to known pumps, the number of pumping chambers can be arbitrarily increased, without additional interfaces to the outside or additional valves are necessary.

In contrast to known pumps, it is possible by a clever design of the pumping chambers and the integrated throttles to specifically activate or deactivate more than just a single pump via the switching frequency of the controlling valve. For example, one pump has a low-pass characteristic and is activated at low switching frequencies, and another pump has a high-pass characteristic and is activated at high switching frequencies. In this case, even with multiple pumps only a single valve or a single interface to the outside world is necessary.

By a (inflow) channel is meant a structure that realizes a tubular connection, and may be formed, for example, as a (microfluidic) flow channel in a layered construction or as a separate conduit, for example in the manner of a tube or a tube ,

According to a further embodiment of the microfluidic peristaltic pump according to the invention, the fluidic resistance of a channel at a constant cross section is determined essentially by its length. Thus, the channel acts as a (pneumatic) throttle, which is integrated in the channel, whereby the deflection of the diaphragm of a pumping chamber into defined cavities can be controlled in time by the integrated throttles.

According to a further embodiment of the microfluidic peristaltic pump according to the invention, the first membrane and the second membrane are formed from a polymer membrane. Here, only a single polymer membrane is used, wherein the individual membranes of the respective pumping chambers are realized by a local deflection of this polymer membrane. Thus, the two membranes can be formed as an integral component. The polymer membrane may be made of, for example, an elastomer, a thermoplastic elastomer, thermoplastics or a hot melt adhesive film. The thickness of the polymer membrane can be between 5 .mu.m and 300 .mu.m.

According to a further embodiment of the microfluidic peristaltic pump according to the invention, the first membrane and the second membrane can be deflected into a flow channel, which is formed in a first polymer substrate. For the realization of the microfluidic peristaltic pump according to the invention, as described above, the use of a polymeric layer structure in conjunction with a polymer membrane for the individual membranes of the pumping chambers offers significant advantages with regard to their cost-effective production. The polymer substrate may be formed from thermoplastics such as PC, PP, PE, PMMA, COP, COC. The thickness of the polymer substrate may be between 0.5 mm to 5 mm. The diameter of the channels for connection to the pumping chamber in a polymer substrate may be between 200 μm to 3 mm.

According to a further embodiment of the microfluidic peristaltic pump according to the invention, the pump chambers may be formed as widenings. The widenings may extend, for example, into the polymer substrate. In this case, the cross-section of the pump chambers may be variable due to an expansion along one direction. The volume of a pumping chamber can be between 1 mm ³ to 1000 mm ³ .

According to a further embodiment of the microfluidic peristaltic pump according to the invention, the first pumping chamber may have substantially the same cross section as an inlet connected to the first pumping chamber, and the second pumping chamber may have substantially the same cross section as a drain connected to the second pumping chamber. As a result, the production of the pump chambers and the associated inlets and outlets can be simplified in an advantageous manner. The microfluidic peristaltic pump according to the invention can convey and move a fluid both in the direction from the inlet to the outlet and in a corresponding activation of the pumping chambers in the direction from the outlet to the inlet.

According to a further embodiment of the microfluidic peristaltic pump according to the invention, the first channel and the second channel may be formed in the polymer membrane. The channels are here by recesses in formed the polymer membrane, so that the height of the channels is determined by the thickness of the polymer membrane, which can be realized very shallow channels. The diameter of the channels in a polymer membrane can be between 1 .mu.m and 100 .mu.m.

According to a further embodiment of the microfluidic peristaltic pump according to the invention, the first channel and the second channel may be formed in a second polymer membrane. Preferably, the two polymer membranes are formed separately and spaced from each other at different levels. This has the particular advantage that a different polymer membrane than the polymer membrane responsible for the deflection of the pumping chambers can be used for the channels. For example, the polymer membrane for the channels may be chosen to be particularly thin (high fluidic resistance for the throttle channels) and the polymer membrane for the pumping chambers thicker (improved pumping reliability). In addition, the pumping unit can be made with the channels on a much smaller footprint, as the channels can also run over the pumping chambers.

According to a further embodiment of the microfluidic peristaltic pump according to the invention, the channels can be operatively connected to the pumping chambers via through-holes. In this design, in combination with the above-described separation of the polymer membranes for the channels and the pumping chambers, there are advantages in producing the structures for connecting channels and pumping chambers, since these can be realized by means of through-holes.

According to a further embodiment of the microfluidic peristaltic pump according to the invention, the feed channel can be formed in a third polymer substrate, which is arranged above the second polymer membrane. In this case, in particular in the case of separate polymer membranes of the channels and of the pump chambers, a stable and reliable connection of the inlet channel is ensured.

Furthermore, a pumping system is claimed, comprising a first microfluidic peristaltic pump and a second microfluidic pump, wherein the first and the second pump are connected to the inlet channel, and for the first and the second pump, the respective products of the fluidic resistance of a channel and the fluidic capacity of the associated pumping chamber from each other, wherein a pump has a low-pass characteristic and another pump has a high-pass characteristic. The following relationship applies: R _ij · C _ij ≠ R _{i + 1 j + 1} · C _{i + 1 j + 1} . The index i describes the respective pump of the pumping system and the index j describes the respective pumping chamber within the associated pump i. For example, a first pump has a low pass characteristic and is activated at low actuation frequency (s), and a second pump has a high pass characteristic and is activated at high actuation frequency (s).

Furthermore, a method for operating a microfluidic peristaltic pump is claimed, which has an inlet channel, a first pumping chamber, which is operatively connected to the inlet channel via a first channel, and a first membrane, a second pumping chamber, which operatively connected via a second channel with the inlet channel , and having a second membrane, wherein the fluidic resistance of the first channel is different from the fluidic resistance of the second channel, comprising the steps of realizing a throttling function of each channel, so that the respective membranes upon application of a pressure in the inlet channel in a time sequence for realizing a pumping function are deflected.

The claimed method has the advantage that due to the effect of the individual channels as throttles in the (pneumatic) path to the pumping chambers now only a single integrated valve or only a single interface to the outside world for all pumping chambers is necessary, while in conventional pneumatic peristaltic Pumps each pumping chamber must be individually actuated by means of an associated valve. Due to this simplification in the functioning of the associated pump according to the invention, both the LOCs and the external drive unit are subject to lower costs and increased reliability.

The required structures in the polymer substrates and membranes can be produced for example by milling, injection molding, hot stamping, stamping or laser structuring.

Brief description of the drawings

• Fig. 1: eine schematische Ansicht einer erfindungsgemäßen mikrofluidischen peristaltischen Pumpe,
• Fig. 2: eine Draufsicht einer mikrofluidischen peristaltischen Pumpe gemäß einer ersten Ausführungsform der vorliegenden Erfindung,
• Fig. 3: eine Schnittansicht der mikrofluidischen peristaltischen Pumpe von Fig. 2 entlang der Linie A-A,
• Fig. 4: eine Schnittansicht der mikrofluidischen peristaltischen Pumpe von Fig. 2 entlang der Linie B-B,
• Fig. 5: eine Draufsicht einer mikrofluidischen peristaltischen Pumpe gemäß einer zweiten Ausführungsform der vorliegenden Erfindung, und
• Fig. 6: eine Schnittansicht der mikrofluidischen peristaltischen Pumpe von Fig. 5 entlang der Linie C-C.

The present invention will be explained with reference to the accompanying drawings. It shows

• Fig. 1 FIG. 2: a schematic view of a microfluidic peristaltic pump according to the invention, FIG.
• Fig. 2 FIG. 2: a top view of a microfluidic peristaltic pump according to a first embodiment of the present invention, FIG.
• Fig. 3 FIG. 3: a sectional view of the microfluidic peristaltic pump of FIG Fig. 2 along the line AA,
• Fig. 4 FIG. 3: a sectional view of the microfluidic peristaltic pump of FIG Fig. 2 along the line BB,
• Fig. 5 FIG. 2: a plan view of a microfluidic peristaltic pump according to a second embodiment of the present invention, and FIG
• Fig. 6 FIG. 3: a sectional view of the microfluidic peristaltic pump of FIG Fig. 5 along the line CC.

Embodiments of the invention

Fig. 1 shows a schematic view of a microfluidic peristaltic pump 100 according to the invention in connection with the course of a pumping operation of the pump 100 according to the invention.

The inventive microfluidic peristaltic pump 100 is supplied via two pneumatic inputs 5 and 8 with compressed air for actuating the n pumping chambers 20, 50, 51, 52 and atmospheric pressure or vacuum. The pneumatic inputs 5 and 8 are each separated by a first valve 1 and a second valve 2 from an inlet channel 10, which is divided into n channels 30, 60, 61, 62. The inlet channel 10 and the channels 30, 60, 61, 62 may be formed independently of one another as a microfluidic flow channel in a layer structure or as a separate line, for example in the manner of a tube or tube. Each channel 30, 60, 61, 62 has a specific fluidic resistance R ₁ to R _n , wherein $${\mathrm{R}}_{\mathrm{1}}<{\mathrm{R}}_{\mathrm{2}}<...<{\mathrm{R}}_{\mathrm{i}}<...{\mathrm{R}}_{\mathrm{n}}\mathrm{for\; i}=\mathrm{1}...\mathrm{n}\mathrm{,}$$

The channels 30, 60, 61, 62 are connected to the n pumping chambers 20, 50, 51, 52, which are separated from the feeding channels by a flexible membrane 40, for example a polymer membrane. The pumping chambers 20, 50, 51, 52 are fluidly connected to each other. To the first pumping chamber 20 is also a fluidic inlet 200 and to the n-th pumping chamber 52, a drain 300 is connected. The pumping chambers 20, 50, 51, 52 are designed as widenings. Alternatively, the Pumping chambers 20, 50, 51, 52 have the same cross-section as the inlet 200 or as the drain 300.

The valves 1 and 2 are switched so that either the pneumatic access 5 or 8 is connected to the underlying fluidic network (instead of two valves 1 and 2, a single switching valve can be used). Is connected to the access 1, an overpressure and access 8 to atmosphere and transfer the excess pressure to the fluidic network, so, the different fluidic resistors R _i in the channels 30, 60, 61, 62 means that the flexible polymer membrane 40 in the pumping chambers 20, 50, 51, 52 deflects delayed in time and the fluid is pumped in the direction of the drain 300 until the last pumping chamber 52 has been fully deflected. The channels 30, 60, 61, 62 with the fluidic resistors R _i thus act as pneumatic throttles, wherein instead of air and another Aktuierungsmedium can be used, for example a mineral oil.

If the valves 1 and 2 are subsequently switched over, then the restoring forces of the polymer membrane 40 in the respective pumping chambers 20, 50, 51, 52 in connection with the different fluidic resistances R _{i will} cause the polymer membrane 40 to relax in the reverse order, so that the fluid displaced in the direction of the drain 300 can not run back and new fluid is drawn in from the direction of the inlet 200. Subsequently, by switching over the valves 1, 2, the next cycle can be started.

In another embodiment, not shown, the port 8 is not at atmospheric pressure, but negative pressure in order to perform the retraction of the polymer membranes 40, 70 faster and more reliable.

Fig. 2 shows a top view of a microfluidic peristaltic pump 100 according to a first embodiment of the present invention. Fig. 3 shows a sectional view of the microfluidic peristaltic pump of Fig. 2 along the line AA, and Fig. 4 shows a sectional view of the microfluidic peristaltic pump of Fig. 2 along the line BB. Referring to Figs. 2 to 4 The first embodiment of the microfluidic peristaltic pump according to the invention will now be described. These and the embodiment described below preferably have lateral dimensions of 10 × 10 mm ² to 200 × 200 mm ^{2 of} the pump.

The microfluidic peristaltic pump 100 consists of a three-layer structure of a first polymer substrate 80 and a second polymer substrate 90, which are separated from each other by a flexible polymer membrane 110. The first polymer substrate 80 has a pneumatic access 5, which is connected via an inlet channel 10 with three channels 30, 60, 61. The channels 30, 60, 61 are formed by recesses in the polymer membrane 110, so that the height of the channels 30, 60, 61 defined by the thickness of the polymer membrane 110, which can realize very shallow channels. The fluidic resistance of the channels 30, 60, 61 is determined in this embodiment by their different lengths.

The channels 30, 60, 61 terminate in connection channels 31, 32, 33 in the second polymer substrate 90. The pump chambers 20, 50, 51 each have a membrane 40, 70, 71 which contains the pumping chamber from a flow channel 150 in the first polymer substrate 80 separates, in which the deflected membrane 40, 70, 71 extends. An overpressure leads through the mechanism to a time-delayed deflection of the diaphragm 40, 70, 71 below the connection channels 31, 32, 33. For this purpose, the membranes 40, 70, 71 in the direct vicinity of the connection channels 31, 32, 33 not with connected to the second polymer substrate 90. In the region between the connection channels 31, 32, 33, however, the polymer membrane is connected to the second polymer substrate 90 such that the displacement units of the pump 100 are pneumatically isolated. The membranes 40, 70, 71 are integrally formed with each other to the polymer membrane 110 and form a single component.

In another embodiment, not shown, the fluidic resistances R _i , not as a parallel but as a series circuit realized, ie, the pumping chambers are connected through the channels with fluidic resistances R _{i one} behind the other.

Fig. 5 shows a plan view of a microfluidic peristaltic pump 100 according to a second embodiment of the present invention, and Fig. 6 shows a sectional view of the microfluidic peristaltic pump 100 of Fig. 5 along the line CC. Referring to Fig. 5 and 6 The second embodiment of the microfluidic peristaltic pump according to the invention will now be described.

In contrast to the first embodiment, the second embodiment has an additional polymer membrane 120 and an additional polymer substrate 130. The additional polymer substrate 130 has a pneumatic access 5. The channels 30, 60, 61 are not located in the polymer membrane 110, but are formed in the second polymer membrane 120 and thus in another plane. The fluidic connection to the pumping chambers 20, 50 via through holes 140, 141, 142 in the second polymer substrate 90. This embodiment has the particular advantage that for the channels 30, 60, 61, a different polymer membrane 120 than that for the deflection of the pumping chambers 20th , 50 responsible polymer membrane 110 can be used. For example, the second polymer membrane 120 may be selected to be particularly thin (high fluidic resistance for the channels 30, 60, 61) and the polymer membrane 110 thicker (improved pumping reliability). In addition, the pumping unit including the channels 30, 60, 61 can be produced on a significantly smaller base area, since the channels 30, 60, 61 can also run over the pumping chambers.

The pumping chambers 20, 50 can be treated as fluidic capacitances C _i . In a further embodiment, not shown, a first pump can be designed so that the product of the capacitances C _i with the resistors R _{i is} large. A second pump is designed so that R _i * C _{i is} small. In this way, short reaction times result for the first pump and short reaction times for the second pump. This leads advantageously to the fact that only the second pump works for fast switching frequencies of valves, but at low switching frequencies, both pumps. Thus, it is possible with only a single pneumatic interface to selectively connect the pump and to expand the possibilities for the realization of microfluidic processes.

Claims (12)

Microfluidic peristaltic pump (100) comprising
an inlet channel (10),
a first pumping chamber (20), which is operatively connected to the inlet channel (10) via a first channel (30), and a first membrane (40),
a second pumping chamber (50), which is operatively connected to the inlet channel (10) via a second channel (60), and a second membrane (70),
wherein the fluidic resistance of the first channel (30) is different from the fluidic resistance of the second channel (60), and wherein each channel (30, 60) realizes a throttling function such that the respective membranes (40, 70) upon application of a pressure in the inflow channel (10) are deflected in a time sequence for realizing a pumping function. Microfluidic peristaltic pump according to claim 1, characterized in that the fluidic resistance of a channel (30, 60) is determined at a constant cross section substantially by its length. Microfluidic peristaltic pump according to claim 1 or 2, characterized in that the first membrane (40) and the second membrane (70) are formed from a polymer membrane (110). Microfluidic peristaltic pump according to one of claims 1 to 3, characterized in that the first membrane (40) and the second membrane (70) are deflected into a flow channel (150) which is formed in a first polymer substrate (80). Microfluidic peristaltic pump according to one of claims 1 to 4, characterized in that the pumping chambers (20, 50) are formed as widenings. Microfluidic peristaltic pump according to one of claims 1 to 5, characterized in that the first pumping chamber (20) has substantially the same cross-section as an inlet (200) connected to the first pumping chamber (20). and the second pumping chamber (50) has substantially the same cross-section as a drain (300) connected to the second pumping chamber (50). Microfluidic peristaltic pump according to one of claims 3 to 6, characterized in that the first channel (30) and the second channel (60) are formed in the polymer membrane (110). Microfluidic peristaltic pump according to one of claims 1 to 6, characterized in that the first channel (30) and the second channel (60) in a second polymer membrane (120) are formed. A microfluidic peristaltic pump according to claim 8, characterized in that the channels (30, 60, 61) are operatively connected to the pumping chambers (40, 70, 71) via through-holes (140, 141, 142). Microfluidic peristaltic pump according to claim 8 or 9, characterized in that the inlet channel (10) in a third polymer substrate (130) is formed, which is arranged above the second polymer membrane (120). A pumping system comprising a first microfluidic peristaltic pump according to any one of claims 1 to 10 and a second microfluidic pump according to any one of claims 1 to 10, characterized in that the first and second pumps are connected to the inflow channel, and for the first and second the second pump differentiates the respective products from the fluidic resistance of a channel (30, 60) and the fluidic capacity of the associated pumping chamber (20, 50), one pump having a low-pass characteristic and another pump having a high-pass characteristic. Method for operating a microfluidic peristaltic pump, having an inlet channel (10),
a first pumping chamber (20), which is operatively connected to the inlet channel (10) via a first channel (30), and a first membrane (40),
a second pumping chamber (50), which is operatively connected to the inlet channel (10) via a second channel (60), and a second membrane (70),
wherein the fluidic resistance of the first channel (30) is different from the fluidic resistance of the second channel (60), comprising the steps of: Realizing a throttle function of each channel (30, 60) such that the respective diaphragms (40, 70) are deflected upon application of a pressure in the inflow passage (10) in a timed sequence for realizing a pumping function.

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