The present invention relates to a microfluidic platform having at least one means for initiating a movement of a liquid, in particular a sample liquid, between at least two locations of the microfluidic platform.
|
The term “microfluidic platform” in the present invention is meant to encompass all objects or devices in which sample liquids that are to be investigated or manipulated can be accommodated in cavities and can be transported by suitable means (for example, capillary forces acting in microchannels) to reaction locations that are provided accordingly.
|
In particular, the present invention encompasses microfluidic platforms such as, for example, sample carriers, test strips, biosensors or the like, which may be used for carrying out individual tests or measurements. For example, biological liquids (e.g., blood, urine or saliva) may be investigated on the one hand for pathogens or incompatibilities but also on the other hand for their content of, for example, glucose (blood sugar) or cholesterol (blood fat). For this purpose corresponding detection reactions or whole cascades of reactions take place on the microfluidic platforms.
|
For these, it is necessary for the biological sample liquid to be transported by suitable means to the reaction location or locations provided for this purpose. This transporting of the sample liquid may, for example, be effected by passive capillary forces (by corresponding capillary systems or microchannels) or by an active actuating system.
|
The active actuating system used may be, for example, injection or diaphragm pumps which may be located outside the microfluidic platform or on said platform.
|
Generally, microfluidic platforms have a sample application area of the order of a few millimetres in size for the application of a quantity of sample liquid of the order of a few microlitres, the sample liquid (e.g., blood) having to be transported through a microchannel or a microchannel system to corresponding sample utilisation areas or reaction locations. This transporting or this movement of the sample liquid should take place reliably and in a simple manner.
|
DE 10 2004 050 062 A1 describes, for example, microfluidic platforms of this kind, while a plurality of usable platforms may be joined together as an endless strip and may be individually detached from the strip for use. The sample liquid is transported here exclusively by means of capillary forces.
|
DE 20 2009 008 052 U1 describes a microfluidic platform, in which both capillary forces and also an active element in the form of a pressure source are used as means for initiating a movement of a sample liquid or for transporting said liquid. The device shown is intended to be able to control transport processes in the microfluidic system precisely and safely, while the manufacturing costs for the microfluidic platform are to be kept comparatively low.
|
The problem of the present invention is to provide an alternative microfluidic platform of the generic type, with which at least a portion of a liquid, in particular a sample liquid, can be transported between two locations on the microfluidic platform reliably and in an easily manageable manner.
|
The at least two locations may be, for example, on the one hand, a sample application area in which a sample liquid is applied, and on the other hand a sample utilisation area or reaction area to which the sample liquid is to be transported and undergo a specific detection reaction therein with suitable reagents. Both the sample application area and the sample utilisation area may be embodied as cavities.
|
The problem stated above is solved by the characterising features of claim
1. Advantageous embodiments or further features of the invention can be inferred from the respective subclaims.
|
The invention starts from a microfluidic platform with at least one means for initiating a movement of a liquid, in particular a sample liquid, between at least two locations of the microfluidic platform.
|
It is now provided according to the invention that the at least one means comprises at least one element of changeable volume and/or shape, which is mounted on at least one component movably connected to the microfluidic platform and, by movement of the component, can be brought into a position such that the element, by changing its volume and/or shape, causes the liquid located at the at least one location to be at least partly moved from this location to the at least one other location.
|
By this measure it is very easy to move a liquid between two locations of a microfluidic platform without the need for external equipment (e.g., external pumps) essentially independent of the microfluidic platform. Naturally, additional capillary channels may be provided on the microfluidic platform, in which the liquid is transported purely passively by capillary forces.
|
It has proved very convenient if the at least one element of changeable volume and/or shape can be brought, by movement of the component, into a position such that the element, by increasing in volume, at least partly fills at least one cavity or, by decreasing in volume, at least partly re-opens at least one cavity that has previously been formed by the element or such that, as the element changes shape, the volume of at least one cavity that is at least partly delimited by the element can be changed.
|
An essential feature here is therefore the element of changeable volume and/or shape. When it at least partly fills at least one cavity, having increased in volume, the cavity may preferably be a sample application area of the microfluidic platform.
|
If this sample application area contains sample fluid that has been introduced previously, this sample liquid is displaced out of the sample application area, in accordance with the increase in the volume of the element into the sample application area, and can be transported in the direction of a sample utilisation area, for example.
|
The element which thus changes its volume and to a certain extent its shape as well, is thus a component for producing a kind of overpressure pump for transporting a sample from a sample application area to a sample utilisation area.
|
Conversely, however, it is also possible that the element decreases in volume and at least partly frees up at least one cavity that has previously been at least partly filled by the element. In this case, a vacuum is formed by the volume that has been freed up in the cavity. If the cavity is fluidically connected (for example, via corresponding microchannels) to a sample utilisation area and the latter is in turn connected to a sample application area, this initiates transfer of a sample liquid that has been delivered to the sample application area, in the direction of the sample utilisation area or in the direction of the said freed-up cavity.
|
In this case the element of changeable volume and/or shape thus serves as a kind of vacuum pump for transporting the sample liquid.
|
Finally, it is also possible for the element to be changeable only in its shape and for it to at least partially define a cavity in a specific position. A sample application area may, for example, be part of the cavity, which is at least partially delimited by the element of changeable shape. If the element of changeable shape, which may, for example, be configured as a membrane, is then pushed into the cavity, the volume of the cavity bounded by the element of changeable shape is reduced.
|
This produces a kind of manual diaphragm pump, which is integrated in the microfluidic platform and in turn is able to initiate transport of the sample liquid to a sample utilisation area that is fluidically connected to the sample application area.
|
With the reduction in pressure on the membrane-like element that is changeable in shape, the volume of the cavity that is at least partly bounded by this element is increased again, so that it is possible to transport a liquid in the opposite direction, i.e., back towards the cavity that is at least partly bounded by the element. Corresponding applications may be envisaged.
|
It has proved very advantageous if the component is embodied as a cover and in at least one position covers at least one cavity. Expediently, the cover-like component may be arranged to cover the microfluidic platform at least from two opposite sides.
|
If the cavity is a sample application area, for example, the movement of the cover-like component triggers a dual function, so to speak. On the one hand, the transporting of a sample solution applied to the sample application area is brought about by the element of changeable volume and/or shape, and on the other hand at the same time the sample application area is covered and in this way subsequent contamination of the sample liquid, for example, by the user or by contamination of the environment by the sample liquid, is reliably prevented.
|
The microfluidic platform can be configured to be particularly easy to handle if the cover-like component is connected to the microfluidic platform so as to be slidable or pivotable therewith.
|
Expediently, at least one sealing means may be provided such that, in the at least one position of the cover-like component that covers at least one cavity, the covered cavity is outwardly sealed off. This reinforces the effect of the element of changeable volume and/or shape.
|
It is very useful if the sealing means is provided on the cover-like component on the side facing the at least one cavity that is to be covered. Alternatively, the sealing means could also be provided on the microfluidic platform, specifically around the cavity that is to be covered. The sealing means used may be, for example, a film-like seal which can correspondingly be adhered to the area that is to be sealed off. However, other shapes of seal are also possible, such as, for example, lip-like seals.
|
According to an advantageous further feature of the invention, it is envisaged that the cover-like component has at least one cavity or opening, in which the at least one element of changeable volume and/or shape is at least partially held. In this way, the element can easily be carried with it during movement of the cover-like component.
|
In particular, it is expedient if the element of changeable volume and/or shape is compressed in a first position of the cover-like component that opens up the cavity and the cover-like component can be moved into a second position in which the cavity is sealingly covered and the element of changeable volume and/or shape has relaxed into the cavity, the cavity being fluidically connected to at least one other cavity, particularly a sample utilisation area.
|
The cavity may advantageously be embodied as a sample application area of a technical medical measuring instrument, for example, a biosensor, a test strip or the like. When the element of changeable volume and/or shape expands into the sample application area after corresponding movement of the cover-like component, the sample liquid is forced in the direction of the sample utilisation area.
|
It may be envisaged according to another embodiment of the invention that, in a first position of the cover-like component, the element of changeable volume and/or shape is relaxed into a cavity of the microfluidic platform and the cover-like component can be brought into a second position, sealingly covering the cavity, in which the element of changeable volume and/or shape has opened up the cavity and has been compressed, while the cavity of the microfluidic platform is fluidically connected to at least one other cavity, particularly to a sample utilisation area and a sample application area.
|
According to this further feature, during the movement of the cover-like component, a sample liquid applied to the sample application area is transported towards the cavity that has been opened up, i.e., therefore towards the sample utilisation area as well.
|
In order to ensure easy movement of the cover-like component it is expedient that the element of changeable volume and/or shape should have bevels on the side facing the cavity. According to yet another further feature of the invention, the element of changeable volume and/or shape is of membrane-like configuration and the cover-like component can be brought into a position, in which at least one cavity is sealingly covered and in which the membrane-like element at least partly defines a cavity, while by applying pressure to the membrane-like element it is possible to reduce the volume of the cavity which is thereby at least partly restricted. This further feature makes it possible in particular to produce a diaphragm pump which is virtually integrated in the cover-like component.
|
It is naturally also possible for the microfluidic platform advantageously to comprise a plurality of cavities and for a plurality of elements that are changeable in volume and/or shape to be provided, which are mounted on the at least one component that is movably connected to the microfluidic platform. In this way, for example, a plurality of (possibly different) sample liquids can be applied, for example, to several sample application areas and with a movement of the component a movement of the sample liquid in the manner described previously can be initiated.
|
However, the invention does not relate only to a microfluidic platform as described, but also to a method of initiating a movement of a liquid, particularly a sample liquid, between at least two locations of a microfluidic platform, in particular using a microfluidic platform according to the invention.
|
According to the invention the method comprises at least the following steps:
at least one cavity is sealingly covered with at least one component that is movably connected to the microfluidic platform
at least one element of changeable volume and/or shape, mounted on the at least one component which is movably connected to the microfluidic platform, is changed in its volume and/or shape such that a liquid contained in the at least one cavity is at least partly moved out of the cavity or in that a liquid is moved at least in the direction of this cavity.
at least one cavity is sealingly covered with at least one component that is movably connected to the microfluidic platform
at least one element of changeable volume and/or shape, mounted on the at least one component which is movably connected to the microfluidic platform, is changed in its volume and/or shape such that a liquid contained in the at least one cavity is at least partly moved out of the cavity or in that a liquid is moved at least in the direction of this cavity.
|
The method according to the invention very reliably allows the initiation of a movement of a liquid between at least two locations of a microfluidic platform.
|
In an advantageous embodiment of the method, it may be envisaged, for example, that the at least one element of changeable volume and/or shape is brought, by the movement of the component, into a position such that, with an increase in volume, the element at least partly fills the at least one cavity, or, with a decrease in volume, at least partly frees up the at least one cavity which has previously been at least partly filled by the element or, with a change in the shape of the element, the volume of at least one cavity at least partly defined by the element is changed.
|
In particular, three further features of the method according to the invention may advantageously be envisaged.
|
It may be envisaged that the element of changeable volume and/or shape is compressed in a first position of the cover-like component that opens up the cavity, and the cover-like component is brought into a second position in which the cavity is sealingly covered and the element of changeable volume and/or shape relaxes into the cavity, the cavity being fluidically connected to at least one other cavity, particularly a sample utilisation area.
|
However, the method may advantageously be embodied so that the element of changeable volume and/or shape in a first position of the cover-like component is relaxed into a cavity of the microfluidic platform and the cover-like component is brought into a second position that sealingly covers the cavity, in which the element of changeable volume and/or shape has freed up the cavity again and has been compressed, the cavity of the microfluidic platform being fluidically connected to at least one other cavity, particularly to a sample utilisation area and a sample application area.
|
A third advantageous embodiment of the method may provide that the element of changeable volume and/or shape is of membrane-like configuration and the cover-like component is brought into a position, in which at least one cavity is sealingly covered and in which the membrane-like element delimits the at least one cavity at least partly, while as a result of pressure on the membrane-like element the volume of the at least one cavity that is thereby limited at least in parts is reduced.
|
Further advantages and embodiments of the invention will be illustrated by means of embodiments by way of example, which are described in more detail with the aid of the accompanying drawings, wherein
|
FIG. 1 a is a diagrammatic representation of a microfluidic platform according to the invention (preferred embodiment) in sectional view along section line A from
FIG. 1
b with an element of changeable volume and/or shape compressed,
|
FIG. 1
b is a plan view of the microfluidic platform according to
FIG. 1
a,
|
FIG. 1
c is a view of the microfluidic platform according to
FIG. 1
a, in which a movable cover has already been partly pushed along,
|
FIG. 1
d is another view according to
FIG. 1
a, wherein the cover of the microfluidic platform has been pushed along to the end stop, with the element of changeable volume and/or shape expanded,
|
FIG. 2
a is a second embodiment of a microfluidic platform according to the invention in a diagrammatic sectional view along section line A in
FIG. 2
b, with the element of changeable volume and/or shape relaxed,
|
FIG. 2
b is a plan view of the microfluidic platform according to
FIG. 2
a,
|
FIG. 2
c is a representation of the microfluidic platform according to
FIG. 2
a, wherein a cover of the microfluidic platform has already been partly moved along, with the element of changeable volume and/or shape having already been compressed,
|
FIG. 2
d is also a representation according to the view in
FIG. 2
a, wherein the cover of the microfluidic platform has been pushed along to the end stop,
|
FIG. 2
e is a view of the microfluidic platform in the position shown in
FIG. 2
d from above,
|
FIG. 3
a is a third embodiment of a microfluidic platform according to the invention in a lateral sectional view along section line A from
FIG. 3
b with the element of changeable volume and/or shape undeformed,
|
FIG. 3
b is a view of the microfluidic platform according to
FIG. 3
a from above,
|
FIG. 3
c is a view of the microfluidic platform according to
FIG. 3
a, wherein a cover of the microfluidic platform has been pushed along to the end stop,
|
FIG. 3
d is a view of the microfluidic platform according to the view in
FIG. 3
c, wherein the element of changeable volume and/or shape (membrane) has been pressed down (deformed),
|
FIG. 3
e is a plan view of the microfluidic platform in the position according to
FIG. 3
d,
|
FIG. 4 is a fourth embodiment of a microfluidic platform according to the invention in diagrammatic plan view.
|
Reference will be made first to
FIG. 1
a to
d. A microfluidic platform in the form of a biosensor
1 is shown. The biosensor
1 comprises a base member
10 only part of which is shown, namely the area that is relevant to the invention. The base member
10 is a comparatively flat component which is rectangular in plan view (cf.
FIG. 1
b) and which is provided, in the detail shown, with a sample application area
100 and a sample utilisation area
101. The sample application area
100 and the sample utilisation area
101 are formed, in plan view, by substantially circular cavities.
|
The sample application area
100 serves for the application of a sample liquid P (shown by dashed lines) which is connected via a microchannel
102 to the sample utilisation area
101. The sample utilisation area
101 may, for example, contain reagents, so that sample liquid P entering the sample utilisation area
101 causes corresponding detection reactions for detecting a particular analyte. The sample utilisation area
101 in turn may be provided, via a microchannel
103, with other cavities or venting means (not shown in detail).
|
The cavity of the sample application area
100 is opened upwards to receive the sample P. The sample utilisation area
101 and also the microchannels
102,
103 are covered at the top by a thin cover film
14 which may, for example, be adhered to the base member
10. On the left hand side, the base member
10 is movably connected to a movable cover
11 which is substantially rectangular in outline, in plan view. The cover
11 has an upper cover part
110, a lower cover part
111 and a rear cover wall
112. The above-mentioned parts of the cover
11 may be both connected to one another in multiple sections and also formed in one piece.
|
It can be seen that the left-hand end of the base member
10 is accommodated between the upper part
110 and the lower part
111 of the cover
11. In
FIGS. 1
a and
1
b the cover
11 is in an extended position, in which it does not cover the sample application area
100, i.e., exposes it, so that a sample liquid P can be added to the sample application area
100 from above.
|
It is also apparent that a substantially circular recess
113 has been provided in the upper cover part
110, in which an element
12 of changeable volume and/or shape is held. The element
12 may be adhesively attached to the upper cover part
110 on its upper side, for example. Preferably, the element
12 of changeable volume and/or shape is made of compressible or deformable synthetic material, for example, foam or rubber.
|
In order to move the sample liquid P applied to the sample application area
100, or at least some of said liquid P, towards the sample utilisation area
101, the biosensor
1 shown operates as follows:
|
After the sample liquid P has been placed in the sample application area
100 (
FIG. 1
a) the movable cover
11 is pushed to the right in the direction of the base member
10 (
FIG. 1
c, first process step S
1). As this happens the cavity of the sample application area
100 is covered by the upper cover part
110, so that the sample liquid P located in the sample application area
100 can no longer escape upwards or outwards from the sample application area
100. More precisely, the cavity of the sample application area
100 is substantially sealingly covered. A sealing covering of the sample application area
100 by the cover
11 is reinforced by a seal
13 which is mounted on, preferably adhered to, the underside of the upper cover part
110, facing the sample application area
100. The seal
13 is preferably of a film-like configuration and has a substantially rectangular shape, in plan view, which surrounds the recess
113 of the upper cover part
110. Only a substantially circular recess is required, to enable the element
12 of changeable volume and/or shape to pass through.
|
In the position shown in
FIG. 1
c, the cavity of the sample application area
100 is already substantially sealed off, but the element
12 of changeable volume and/or shape is still in a compressed or tensioned state.
|
If the cover
11 is now pushed further to the right (
FIG. 1
d, second process step S
2) the element
12 held in the cover
11 moves into congruence with the sample application area
100 and is able to relax into its cavity (cf. reference numeral
12′ and arrow). The expanded element
12′ substantially fills the cavity of the sample application area
100 or is only slightly smaller than it. As a result of the expansion or increase in volume of the element
12 into the sample application area
100 the sample liquid P contained therein is displaced into the microchannel
102 and hence also into the cavity of the sample utilisation area
101 (cf. P′).
|
Depending on the dimensions of the cavities of the sample application area
100, sample utilisation area
101 and the microchannels
102,
103, the sample liquid P′ displaced into the sample utilisation area
101 also passes through the microchannel
103 into other cavities (not shown in detail) which in some cases may also be needed for other subsequent reactions. Also, as the sample liquid P is displaced by the element
12 expanding into the cavity of the sample application area
100, the additional seal
13 essentially prevents sample liquid P from escaping outwards from the cover
11.
|
In the embodiment shown the cover
11 is designed so that it is held in the opened position (
FIGS. 1
a, b) by suitable latching or fixing means (not shown) in the position illustrated and the cover
11 can only be moved after a specific force has been overcome. After the cover
11 has been closed (
FIG. 1
d) this is no longer possible, with the result that reliable closing of the sample application area
100 by the biosensor
1 used once is guaranteed. However, it would be possible to make the movement described above reversible, by equipping the element
12 with suitable bevels, for example.
|
In the embodiment shown in
FIGS. 1
a to
d, the element
12 of changeable volume and/or shape acts virtually as an overpressure pump for initiating a movement of the sample liquid P between the sample application area
100 and at least the sample utilisation area
101.
|
FIGS. 2
a to
e now show a second embodiment of a microfluidic platform according to the invention in the form of a biosensor
2. The biosensor
2 also comprises a base member
20 comparable in shape to the base member
10, and provided at its left-hand end with a substantially circular cavity
200. The cavity
200 is connected via a microchannel
202 with the substantially circular cavity of a sample utilisation area
201. The sample utilisation area
201 is in turn connected via a microchannel
203 to the substantially circular cavity of a sample application area
204. The sample application area
204 is upwardly open and allows a sample liquid P to be introduced (cf.
FIG. 2
a).
|
However, for this purpose the microchannels
202,
203 and also the sample utilisation area are closed off at the top by a cover film
24 which is, for example, adhered to the base member
20. On the left-hand side of the base member
20 a cover
21 is movably connected thereto. The cover
21 is in an extended position, in the position shown in
FIGS. 2
a to
2
b, and in turn comprises an upper cover part
210, a lower cover part
211 and a rear cover wall
212. These parts may in turn be joined together in several sections or may be constructed in one piece. In the upper cover part
210 is formed a substantially circular cavity
213 in which, in turn, a substantially circular element
22 of changeable volume and/or shape is held. The element
22 substantially fills the cavity
200 of the base member
20 in the position of the cover
21 shown in
FIGS. 2
a and
b.
|
It is also apparent that the element
22 has a bevel
220, which is provided on the side facing the cavity
200 and in the direction of movement, i.e., on the right (cf. the arrows) in the Figures.
|
In the embodiment shown in
FIG. 2,
FIG. 2
a shows a first process step (S
1′) in which the cavity
200 is substantially filled by the element
22. In a second step S
2′ (
FIG. 2
c) the cover
21 is pushed to the right in the direction of the base member
20. The pushing is assisted by the bevel
220. At the same time the element
22 is compressed by the opening edge of the cavity
200 and moved out of the cavity
200 (cf. arrow and reference numeral
22′). The volume of the element
22 thus decreases at the same time. Obviously, as in the case of the embodiment shown in
FIG. 1, combined forms are possible in which there is a certain change of shape in addition to a change of volume of the element
22 that occurs primarily.
|
As in the embodiment according to
FIG. 1, a film-like seal
23 is also provided in the embodiment shown in
FIG. 2, this seal
23 surrounding the cavity
213 of the upper cover part
210. The seal
23 reinforces the sealing action of the cover
21, with the result that during the compression of the element
22 into the compressed state (
22′) and hence opening up of the volume of the cavity
200, underpressure is produced in the cavity
200 and hence the sample liquid P is aspirated out of the sample application area
204 in the direction of the cavity
200 fluidically connected thereto. As the sample utilisation area
201 is provided in front of the cavity
200 in the direction of flow of the sample liquid P, the sample liquid P passes from the sample application area
204 through the microchannel
203 initially to the sample utilisation area
201.
|
In the embodiment shown in
FIG. 2, the element
22 of changeable volume and/or shape thus acts as a virtual vacuum pump for transferring sample liquid P from the sample application area
204 to the sample utilisation area
201 (cf. P′ in
FIGS. 2
c and
d).
|
Also provided in the embodiment shown in
FIG. 2 are latching means (not shown in detail) which hold the cover
21 in the open position shown in
FIG. 2
a or
b and enable the cover to be moved along only by the application of a certain releasing force. Similarly in the closed position of the cover
21 shown in
FIG. 2
d, suitable means are provided for ensuring that the cover
21 is held in this position. However, in this embodiment too, applications are conceivable in which repeated opening and closing of the cover
21 is desirable. Here (as in the embodiment shown in
FIG. 1) particular value would be placed on the suitable choice of material for the element
22 of changeable volume and/or shape, to enable this element to perform the reversible movements, repeatedly if necessary.
|
FIGS. 3
a to
e show a third embodiment of a microfluidic platform according to the invention. A biosensor
3 is shown which in turn shows a base member
30 comparable in shape with the base members
10 and
20 and a cover
31 that is movably connected thereto. The base member
30 of the biosensor
3 is in turn shown only partly (in the region of the cover
31) and comprises there a sample application area
300 for the application of a sample liquid P which is fluidically connected through a microchannel
302 to a sample utilisation area
301. From the sample utilisation area
301 runs another microchannel
303 which is able to connect the sample utilisation area
301 to other cavities or venting devices (not shown in detail). The sample utilisation area
301 and the microchannels
302 and
303 are covered at the top by a suitable cover film
34.
|
The cover
31 comprises an upper part
310, a lower part
311 and a rear wall
312, similarly to the other embodiments.
|
Also provided in the upper cover part
310 is a substantially circular through-opening
313. An element
32 of changeable volume and/or shape in the form of a membrane-like part is mounted in the upper part of the through-opening
313, preferably by adhesive bonding or welding.
|
Moreover, on the underside of the upper cover part
310 there is also provided a film-like seal
33 which surrounds the opening
313. In this embodiment as well, suitable means (not shown in detail) are provided which secure the cover
31, preferably by latching, in its open position shown in
FIGS. 3
a and
b or in its closed position (
FIGS. 3
c and
d).
|
If the cover
31 is now pushed to the right, in the direction of the base member
30, until it reaches the end stop, by the application of a releasing force (step S
1″,
FIG. 3
c), the opening
313 of the cover
31 is brought into approximate congruence with the sample application area
300. In this position a volume V is formed by the opening
313 and the cavity of the sample application area
300, this volume V being delimited at the top by the membrane-like element
32.
|
At the same time the volume V is sealed off to the outside by the cover
31, the sealing action being further reinforced by the above-mentioned seal
33.
|
If in a further step the membrane-like element
32 is pressed down (S
2″,
32′,
FIG. 3
d), the volume V is reduced (V′). The consequence of this is that the sample liquid P located under the membrane-like element
32 is pumped through the microchannel
302 into the sample utilisation area
301 (P′).
|
In the embodiment shown in
FIG. 3 the element
32 of changeable volume and/or shape thus acts as a virtual manual diaphragm pump. It should be pointed out that after the release of the pressure on the element
32′ the latter returns to its original shape (
32). As a result, the volume situated under the membrane-like element
32 is naturally increased again, so as to obtain a bidirectional pumping mechanism (which may be desirable in certain cases).
|
Finally it should be pointed out that the embodiments shown in
FIGS. 1 to 3 always show only one element of changeable volume and/or shape which is held in a cover. However it is thoroughly possible and advantageous if one or more covers are provided which are movably connected to the microfluidic platforms and a plurality of elements of changeable volume and/or shape are held in the covers. This makes it possible to initiate a plurality of pumping operations simultaneously, by a movement of the cover or covers.
|
Thus
FIG. 4 describes an embodiment of a biosensor
4 which comprises a base member
40 with a plurality of sample application areas
400 and a plurality of sample utilisation areas
401. The sample utilisation areas
401 are connected to the sample application areas
400 by corresponding microchannels
402. A suitable cover film
403 is provided for covering the microchannels
402 and the sample utilisation areas
401. No venting means are shown.
|
Moreover, a cover
41 is slidably connected to the base member
40 and has a plurality of elements
42 of changeable volume and/or shape which may, for example, be configured in the manner of the element
12 shown in
FIG. 1. If the cover
41 is slid to the right in the direction of the base member
40, the elements
42 move into a position of congruence with the sample application areas
400, expand into them and displace a sample liquid that has been introduced into them in the direction of the microchannels
402 or the sample utilisation areas
401. Thus, by one movement of the cover
41, three pumping operations can be initiated simultaneously.
|
It is, of course, possible to provide a movable connection of the above-mentioned covers with the base members of the microfluidic platforms by some other method. For example, instead of a sliding movement, a rotary or hinged movement may also be provided.
|
The microfluidic platforms
1 to
4 described are preferably made of plastics, using the known plastics processing methods, particularly injection moulding. The films
14,
24,
34 and
403 that cover the cavities and microchannels formed in the base members
10 to
40 may be, for example, self-adhesive films or films provided with hot-melt adhesives which are laminated onto the surface of the base members. Alternatively it is also possible, of course, to use fixed covers for the covering, attached to the base members for example by UV adhesion, ultrasound welding, laser welding or high frequency welding.
|
LIST OF REFERENCE NUMERALS
1 biosensor
10 base member
100 sample application area
101 sample utilisation area
102 microchannel
103 microchannel
11 cover
110 upper cover part
111 lower cover part
112 rear wall of cover
113 recess in upper cover part
12, 12′ element of changeable volume and/or shape
13 seal
14 cover film
2 biosensor
20 base member
200 cavity in the base member
201 sample utilisation area
202 microchannel
203 microchannel
204 sample application area
21 cover
210 upper cover part
211 lower cover part
212 rear wall of cover
213 cavity in the upper cover part
22, 22′ element of changeable volume and/or shape
220 bevel of the element of changeable volume and/or shape
23 seal
24 cover film
3 biosensor
30 base member
300 sample application area
301 sample utilisation area
302 microchannel
303 microchannel
31 cover
310 upper cover part
311 lower cover part
312 rear wall of cover
313 opening of the upper cover part
32 element of changeable volume and/or shape
33 seal
34 cover film
4 biosensor
40 base member
400 sample application areas
401 sample utilisation areas
402 microchannels
403 cover film
41 cover
42 element of changeable volume and/or shape
43 seal
P, P′ sample liquid
S1,S2 process steps
S1′,S2′ process steps
S1″,S2″ process steps
V, V′ volume limited by membrane