The invention relates to a microfluidic component for manipulating a fluid and to a microfluidic chip.
Microfluidics deals with the manipulation of fluids, i.e. liquids or gasses, in very constrained spaces. In the process, fluids are moved, mixed, separated or processed in any other manner. Micropumps deliver or meter fluids, microvalves determine a direction or movement mode of pumped fluids and micromixers enable targeted mixing of fluid volumes. Microfluidic components are used, inter alia, in biotechnology and medical engineering.
The German patent application DE 10 2008 002 336.1-12, which is a prior publication, has disclosed a microfluidic component in the form of a pinch valve, which has a first, second and third substrate, wherein the third substrate is made of an elastic material and arranged between the first and second substrate. Here, the first substrate adjoins the third substrate and has at least one first recess on the side adjoining the third substrate. The second substrate likewise adjoins the third substrate and has at least one second recess on the side adjoining the third substrate. Here, the first recess and the second recess are arranged at least partly opposite one another. For the purposes of this disclosure, this prior application is incorporated into the present application in its entirety.
The present invention provides a microfluidic component, more particularly a micropump, a microvalve or a micromixer, for manipulating a fluid, having a first substrate, a second substrate and a third substrate, which is arranged between the first substrate and the second substrate and made of an elastic material. At least one first recess is made in the side of the first substrate which faces the third substrate, said recess forming a first control chamber. At least one second recess is made in the side of the second substrate which faces the third substrate, said recess forming a fluid channel or a fluid chamber, which is for the fluid to be manipulated and at least in portions overlaps with the first control chamber. Additionally, a second control chamber, which is spatially separated from the first control chamber, and a control channel are made in the first substrate, with the control channel connecting the first control chamber to the second control chamber. The control chambers and the control channel form a closed system and are filled with a control fluid. At least one sidewall of the second control chamber is made of elastic material and can be deformed by an actuator, more particularly a mechanical activation member of an actuator, such that the internal volume of the second control chamber is reduced and, as a result thereof, the pressure in the control fluid increases.
The principle underlying the microfluidic component according to the invention is that the region of the third, elastic substrate arranged between the fluid channel or the fluid chamber and the first control chamber can, in the case of different pressures in the chambers, extend into the chamber with respectively lower pressure. By suitably arranging and configuring fluid channels or fluid chambers, this for example affords the possibility of implementing a micropump, a microvalve or a micromixer. Here, the first control chamber together with the second control chamber and the control channel interconnecting the two chambers forms a closed system, with a sidewall of the second control chamber being made of elastic material. As a result of the deformation of this sidewall, the internal volume of the second control chamber can be reduced and so the pressure in the closed system, and hence in the first control chamber as well, can be increased thereby. Here, the deformation of the deformable sidewall of the second control chamber required to activate the microfluidic component is implemented by an actuator, which can for example be driven electrically, magnetically, piezoelectrically or else by an electroactive polymer. Ultimately, the arrangement according to the invention leads to a spatial separation between the actuation system of the microfluidic component and the manipulation region of the fluid to be manipulated, i.e., for example, the valve region, the pump region or the mixing region. Only the first control chamber is arranged in the region of the actual micropump, the actual microvalve or the actual micromixer, while the second control chamber, which is acted upon by the actuation system, can be provided at any other position on a microfluidic chip, more particularly a biochip, on which the microfluidic component is implemented. It goes without saying that a plurality of microfluidic components according to the invention can also be arranged on one microfluidic chip.
This spatial separation between the actuation system and the actual manipulation location of the fluid enables an improved disentanglement of the control chambers and channels, which contain the control fluid in the chip, from the fluid chambers and channels, which hold the fluid to be manipulated in the chip. As a result of this it is, in turn, possible to position the second control chambers and hence the points of contact with the actuators at predefined, standardized positions of a microfluidic chip, and this makes it possible to activate different applications, i.e. different microfluidic components, using a standard actuation system.
It is also possible for a plurality of microfluidic components, e.g. microvalves, to be arranged on a chip with very small spacing between them. In the case of conventional actuation directly at the manipulation point there may be problems when designing the chip as a result of the actuation system, which is often relatively large. These problems are solved by separating the actuation system from the actual microfluidic components and the disentanglement of the chip enabled thereby.
The actuation of the microfluidic component implemented by deforming a sidewall of the second control chamber also leads to the actuator no longer needing to be integrated directly in the chip, but instead advantageously only being loosely connectable to the microfluidic component. Microfluidic components and the chips which carry them are often embodied as disposable cartridges, particularly in the case of application in the field of biotechnology or medical engineering. This loose connectability of the actuator to the microfluidic component and the separability of the two units after activation accompanying this make it possible to design the actuation system in the form of a reusable, preferably portable, control unit. In the case of an appropriate design of the chips, particularly in the case of appropriate arrangement of the second control chambers of the microfluidic components arranged on a chip, the control unit can even be used universally for different microfluidic chips, which significantly reduces the required financial expenditure. Here, the control unit can comprise a single actuator, optionally with a plurality of activation members, or else a plurality of actuators with respectively one or more activation members.
According to one embodiment of the invention, the second control chamber is formed by a third recess, which is made at a distance from the first control chamber in the side of the first substrate which faces the third substrate. The control channel can also likewise be formed by a recess which is made between the first and third recess in the side of the first substrate which faces the third substrate. These embodiments are advantageous from a manufacturing point of view in particular because the recesses can be implemented with little manufacturing complexity. However, it is also feasible for the second control chamber and/or the control channel not to be embodied as recesses in the side of the first substrate which faces the third substrate, but rather to be arranged in the interior of the first substrate. It is only the deformable sidewall of the second control chamber that has to be accessible from the outside.
According to a further embodiment of the invention, the deformable sidewall of the second control chamber is formed by the third substrate. By using the third substrate, which in any case has an elastic design, as a deformable sidewall of the second control chamber, a particularly simple design of the microfluidic component according to the invention is achievable, leading to relatively little production complexity. In order to actuate the microfluidic component, it is possible, on the one hand, to provide in the second substrate a passage opening which at least partly overlaps with the second control chamber and by means of which the actuator can directly act on the third substrate in a deforming manner. As an alternative thereto, provision can also be made on the side of the second substrate which faces away from the third substrate for a recess which at least partly overlaps with the second control chamber and the extent of which in the direction of the third substrate is set such that between the recess and the third substrate there is a web-like region of the second substrate, on which an actuator can act in a deforming manner. In this case, the deformation of the third substrate which serves as sidewall of the second control chamber is brought about indirectly via a deformation of the web-like region of the second substrate.
However, as an alternative thereto, the deformable sidewall of the second control chamber can also be formed directly by an outer wall of the first substrate.
The embodiments in which the actuator acts on a portion of the first or second substrate and not, or at least not directly, on the third substrate are particularly advantageous if relatively high restoring forces are required within the closed system filled with the control fluid.
Both gases and liquids can be used as control fluid. According to a preferred embodiment, air is used as control fluid, and so the microfluidic component is actuated pneumatically. This offers the advantage of being able to dispense with a complicated filling procedure for the control chambers and the control channel. In the case of using incompressible or almost incompressible liquids as control fluids, the volumes of the control chambers can be reduced compared to when they are filled with gases. However, on the other hand, this also results in higher flow resistances, which leads to an increase in the switching times.
If air is used as control fluid, then the microfluidic component can have an additional pressure compensation valve for compensating for the pressure difference at different heights (often also referred to as barometric pressure compensation), which pressure compensation valve, via a first pressure compensation channel (66), is connected to the first control chamber (4′), the second control chamber (8′) or the control channel (9′) and connected to the external surroundings via a second pressure compensation channel (67).
Further features and advantages of embodiments of the invention emerge from the following description with reference to the attached figures.
In detail:
In the figures, identical or functionally equivalent components are respectively denoted by the same reference sign.
At a distance to the first recess, a further recess 8 is provided in the first substrate 1 and forms a second control chamber 8′. Provided between the first recess 4 and the third recess 8, there is a fourth recess 9, which serves as control channel 9′ and connects the first control chamber 4′ to the second control chamber 8′ such that the two control chambers 4′ and 8′ together with the control channel 9′ form a closed system. The two control chambers are advantageously embodied such that the second control chamber 8′ has a larger internal volume than the first control chamber 4′. The control channel 8′ has a smaller cross section than the two control chambers 4′ and 8′. The two control chambers 4′ and 8′ and also the control channel 9′ are filled with a control fluid, which can have a gaseous or liquid embodiment. Air is advantageously used a control fluid because this makes it possible to dispense with a complicated filling procedure of the two control chambers 4′ and 8′ and of the control channel 9′.
A passage opening 10 is provided in the second substrate 2 and in the illustrated exemplary embodiment it is arranged exactly opposite the second control chamber 8′. A mechanical activation member 11, for example in the form of a tappet, of an actuator (not illustrated in any more detail) can act in a deforming manner on the elastic substrate 3 via this passage opening 10. In the exemplary embodiment illustrated in
In addition to the embodiments illustrated in
With reference to
The actuators and the activation members thereof can have very varied designs. Thus, it is conceivable to provide a shaft 50, which is operated via an electric motor 51, optionally also in conjunction with gear ratios, deflection apparatuses, levers or eccentric rods. Here, the shaft 50 can be provided with appropriately designed eccentric disks, which serve as activation members 42a-c. By way of example, such an actuation system can be used for micropumps with continuous or partly continuous operation and is illustrated in
If air is used as control fluid, the microfluidic component according to the invention can additionally have a pressure compensation valve, which serves for pressure compensation between the pneumatic system, consisting of the control chambers (4′, 8′) and the control channel (9′), and the external surroundings. A possible embodiment of such a pressure compensation valve is illustrated in
In accordance with the illustrated embodiment of the pressure compensation valve 60, the first substrate 1 has two recesses 61a and 61b on the side adjoining the third substrate 3 and these form fluid channels 61a′ and 61b′ for the control fluid, i.e. for air. Here, the recesses 61a and 61b are arranged adjacent to one another and separated by a web 62. In the second substrate 2, provision is made for a further recess 63, which is arranged on the side of the second substrate 2 which faces away from the third substrate 3, to be precise such that at least in portions it overlaps with the two recesses 61a and 61b. Here, the depth of the recess, i.e. the extent of the further recess 63 in the direction toward the elastic substrate 3, is set such that a web-like region 64 of the second substrate 2 emerges between the further recess 63 and the third substrate; this web-like region forms a deformable part of the outer wall of the second substrate 2. An activation member 65 of an actuator can act on the web-like region 64 of the second substrate 2 such that the web-like region 64 is pressed in the direction of the third substrate 3 and hence the third substrate 3 is pressed against the web 62 between the two recesses 61a and 61b. This in turn leads to the pressure compensation valve being closed.
In order to enable pressure compensation between the pneumatic system and the external surroundings, the recess 61a is connected to the external surroundings via a first pressure compensation channel 66. This is achieved by virtue of the fact that the first pressure compensation channel 66 extends up to the edge of the microfluidic component or, in the case of a chip, up to the edge of the chip. The recess 61b is connected to the pneumatic system, i.e. to one of the control chambers 4′ or 8′ or to the control channel 9′, via a second pressure compensation channel 67. As a result of this, there is pressure compensation between the pneumatic system and the external surroundings when the pressure compensation valve is open. Before the microfluidic component or chip is put into operation, i.e. actuated, the pressure compensation valve 60 can then be sealed so that reliable functioning is ensured.
In order to ensure certain sealing of the pressure compensation valve 60, an elastic mold 68, e.g. in the form of an elastomeric pad, can be arranged on the side of the activation member which faces the web-like region 64 of the second substrate 2.
On the other hand, in order to ensure that the pressure compensation valve 60 in the open state certainly allows an airflow between the external surroundings and the pneumatic system of the microfluidic component, the web 62 between the two recesses 61a and 62b can have a slightly bent embodiment (see
It goes without saying that, in addition to the embodiment of the pressure compensation valve 60 illustrated in
Finally,
It goes without saying that a pressure compensation valve can be actively sealed before the microfluidic component on the chip is put into operation. However, the pressure compensation valve (60), the activation member (65) and the control unit are advantageously configured such that the pressure compensation valve (60) is automatically closed during the insertion into the control unit. By way of example, this can be achieved by using spring-forced pins or else fixedly attached rubber buffers.
Number | Date | Country | Kind |
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102010001412.5 | Feb 2010 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2010/070908 | 12/30/2010 | WO | 00 | 8/1/2012 |