WO2000055618A2

WO2000055618A2 - Manifold

Info

Publication number: WO2000055618A2
Application number: PCT/DE2000/000768
Authority: WO
Inventors: Steffen Howitz; Mario Bürger; Lars Rebenklau
Original assignee: GeSIM Gesellschaft für Silizium-Mikrosysteme mbH
Priority date: 1999-03-15
Filing date: 2000-03-14
Publication date: 2000-09-21
Also published as: AU4099300A; WO2000055618A3; DE10080648D2

Abstract

The invention relates to a manifold with at least one microexamination chamber, especially for use in examinations carried out in the field of biology or genetic engineering, and with devices for supplying and discharging fluids. The aim of the invention is to provide a manifold with at least one microexamination chamber, especially for use in examinations carried out in the field of biology or genetic engineering, that is completely universal, can be structured at low costs and allows the combination of fluid, electric and mechanical components. To this end, the working chamber (A) extends through a sandwich multi-layer system that consists of a combination of layers produced by thin-film or thick-film technology. Said working chamber (A) can be firmly or reversibly closed by way of a glass lid. Devices for supplying and discharging fluids are provided in the form of trench structures in at least one of the layers of the sandwich multi-layer system. Said devices for supplying and discharging fluids are configured as several independent fluid circuits.

Description

Manifold

Manifold with at least one microscope chamber, in particular for biological or genetic engineering studies, with devices for supplying and discharging fluids.

In the fluidic microsystem, the manifold forms the system basis with which fluidic components are networked together to form the microsystem. The manifold has the task of keeping individual components mechanically defined, fluidly connecting them to one another and, if necessary, electrically coupling them. Such microsystems are created by combining sensors, actuators and electronic components on the manifold, with devices for supplying and discharging fluids being integrated at the same time.

Such a manifold usually consists of a composite of different materials, for example a silicon-glass composite, the fluid channels in the manifold, possibly chemical microsensors and other functional units, being structured in silicon before the glass-silicon composite is joined. If new microsystems are to be designed, then one assumes fixed geometric conditions of the components to be integrated and fits them

Manifold accordingly. The manifold is therefore changeable and fixed components are integrated. Customized manifolds for microfluidics in silicon-glass construction are currently customary on the market. The joining of the different materials into a composite is carried out with the aid of the known technology of anodic bonding. The choice of material is determined by the application and the technological know-how. Different material combinations are practically feasible.

A manifold can be produced from a silicon-glass composite by anodic bonding, which enables extremely short iteration times with a module concept that is easy to implement. The actual channel system is created by anodic bonding, which is extremely reliable and robust and can also be easily linked using conventional techniques. The advantages of a silicon-glass composite are high reagent compatibility and the possibility of realizing structure sizes down to the sub-μm range. The actual duct system is created by anodic bonding, which is extremely reliable and robust and can also be easily linked with conventional techniques.

The disadvantages of this technique can be seen in the fact that the material is relatively expensive and that the realization of a multi-level manifold is very complex.

Another possibility is to realize the manifold from a quartz-glass composite, which is an ideal pairing for capillary electrophoresis. However, the materials used are expensive and the joining of the materials is critical.

There is also the possibility of producing a glass-glass composite, the individual parts having to be joined by diffusion welding at high temperatures. The joining process is problematic here.

Another possibility for realizing a manifold is to implement a silicon-silicon composite. Extremely short iteration cycles are achieved here with a module concept that is easy to implement. The advantages of a silicon-silicon composite are high reagent compatibility and the possibility of realizing structure sizes down to the sub-μm range.

The disadvantage here is that the joining process is risky and time-consuming and that the materials used are expensive.

A manifold can also be produced from a polymethyl methacrylate (PMMA) or polydimethylsiloxane (PDMS). This material is very cheap and allows structuring down to the sub-μm range. The module concept is also easy to implement. The disadvantage, however, is the low resistance to organic solvents. The technology is also very expensive with very long iteration cycles. Since the manifolds are produced by capping from above and below, the technology is relatively complex and not very suitable for mass production.

If a fixed resist is used as an extremely cheap material for the production of the manifold, the joining technology is very simple and short iteration times can be realized. However, it is a disadvantage that the material swells when aqueous liquids are used and that the resistance to organic solvents is poor.

Furthermore, the so-called Low Temperature Cofiring Technology (LTCC) has become known, which is a further development of the classic thick-film hybrid technology. This technology is characterized by the use of individual layers of green ceramic. These layers are mechanically structured separately and provided with vias and electrical functional layers. After the lamination of the individual layers, that is to say the actual layer structure, this takes place in a subsequent technological step Burning out and sintering to a stable ceramic wiring carrier with several control levels.

The wiring carriers created in this way are used as ceramic multi-chip modules (MCM-C), especially in high-frequency technology, although the three-dimensional shape and the integration of non-electrical functions are also increasingly being added. Another focus is the use of photo-structurable thick-film pastes.

However, studies on the use of buried channel systems are limited to the fluidic cooling of electronic LTCC multi-chip modules.

The invention is based on the object of creating a manifold with at least one microscope chamber, in particular for biological or genetic engineering investigations, which can be structured in a completely universal and cost-effective manner and which permits the combination of any desired fluidic, electrical and mechanical components.

The object on which the invention is based is achieved in a manifold of the type mentioned at the outset in that the working chamber extends through a sandwich-like multilayer arrangement which consists of a combination of layers produced in thick-film and thin-film technology, in that the working chamber is fixed or reversible by means of a glass cover is closed that the devices for supplying and discharging fluids are designed as buried structures in at least one of the levels of the sandwich-like multilayer arrangement and that the devices for supplying and discharging fluids are designed in the form of several mutually independent fluid circuits.

Such a manifold can be produced particularly inexpensively and allows the simple integration of a wide variety of functional units. The multilayer arrangement can consist of a stack of alternating glass and silicon layers, or of a stack of a large number of ceramic layers (multilayer ceramic).

If the ceramic layers are produced from an LTCC ceramic, particularly cost-effective production is made possible.

In continuation of the invention, the devices for supplying and discharging the fluids are designed as three-dimensionally intersecting fluid channels and can additionally be equipped with control valves, the membrane of the control valve should be made of silicon.

If the passage cross section of the control valves is designed to be switchable or controllable, simple metering of the fluids passed through the valves can be achieved. The control valves can be actuated pneumatically, fluidically or electrically, or also by changing the pressure in the fluid circuit.

A special embodiment of the invention can consist in the fact that each control valve is designed as a thermoelectric valve with a heating element, wherein it is also possible to arrange the heating element spatially separated from the control valve.

The heating element can be implemented particularly easily if it is designed as a printed interconnect.

A further development of the invention is characterized in that each control valve is equipped with a silicon membrane over the valve chamber, which is firmly connected at the edge to the LTCC ceramic.

In a further embodiment of the invention, the working chamber is provided with electrodes for generating an electrical field. These electrodes can advantageously be realized in that the microscope camera is provided with an internal metalization, which is electrically connected to the electrical connections of the manifold.

A further development of the invention is characterized in that a fluid connection strip is provided in which all fluid channels and hydraulic fluid channels and the fluid channels of the cooling circuit open. This fluid connection strip is advantageously arranged on an outer edge of the manifold.

Furthermore, an electrical connection strip is provided, in which all electrical functional connections are combined. This electrical connection strip should advantageously also be arranged on an outer edge of the manifold, it being particularly favorable for the user of the manifold if the electrical connection strip is arranged on the outer edge of the manifest, which is opposite the fluid connection strip.

It is also easily possible to provide several fluid circuits for one working chamber circuit, a valve circuit for controlling the working chamber circuit and a cooling circuit.

The invention enables complex, planar microfluidic manifolds to be implemented using the LTCC technology and the hybrid technology for integrating microfluidic components that have been produced with other than the LTCC technology. Such manifolds can be used for the purposes of cell therapy or pharmaceutical development / testing in biological test systems.

With the further developments and devices according to the invention formulated in the subclaims, the controlled fluid management in the LTCC-based microsystem is made possible, with flow rates of a few 10 picoliters per minute up to a few 10 mililiters per minute. Controlled fluid management here means the serial or parallel execution of functions. These functions concern the controlled heating and cooling of a working chamber as well as the exact temperature measurement by integrated temperature sensors. They concern a freely selectable number of microfluidic inflows and outflows in this working chamber. The rate of the liquids in these inlets and outlets can be regulated with the aid of microvalves or can be switched off completely or completely. The flow rate of the fluids in these channel systems can be measured online by means of integrated high-resolution flow sensors. Electrochemical (eg: pH electrodes) or micromechanical sensors (eg: pressure sensors) can be integrated into the microchannels. The working chamber is reversibly or irreversibly closed by substrates mounted on the top and bottom. These substrates preferably consist of the materials glass, silicon or a biocompatible polymer, it being possible for these substrates themselves to be carriers of electrically active microelectrodes (for example: micro-T sensor, micro heater). Due to the planar structure, the manifolds can be combined in combination with all microscopes (e.g. high-resolution fluorescence microscopes, light-optical microscopes, inverse microscopes, microscopes with optical or dielectric cell tweezers).

The invention will be explained in more detail using an exemplary embodiment.

In the accompanying drawings:

Figure 1 is a plan view of an inventive manifold of a microscope chamber.

2 shows a plan view of a middle buried layer of the manifold with electrical functional assemblies and electrical external connections;

Fig. 3 shows a first fluid level for supplying the fluid for Chamber of Labor;

4 shows a second fluid level with a hydraulic circuit for actuating the functional assemblies and valves; and

Fig. 5 shows a third fluid level with a cooling circuit for the manifold.

1 to 5, an embodiment of a manifold according to the invention with a microscope chamber K or working chamber A is shown. The manifold here consists of a ceramic base body in LTCC technology, the microscopy chamber K, which is formed by a glass cover (not shown) in a central hole in the ceramic body, and the hybrid-integrated microsensors and microactuators, the electrical and fluidic connection elements. A fluid connection strip FL is provided for the fluid connection for all required functions, which is connected to the fluid channels FK and the hydraulic channels HF of the manifold. The flui connection strip FL is arranged along an edge of the manifold. The opposite edge of the manifold is connected to an electrical connection strip EL for connecting the electrical components of the manifold. This significantly improves the handling of the manifold.

The ceramic base body BK consists of individual ceramic layers with a thickness of 150 to 200 μm and contains three fluid circuits (FIGS. 3 to 5) which have different functions. The first fluid circuit is the working chamber circuit, which combines all the fluidic channels that lead into or out of the working chamber. The second circuit is the valve circuit (FIG. 4) which summarizes all the channels that are required for filling and operating the thermoelectric silicon microvalves. The third fluid circuit is the cooling circuit KK (FIG. 5), with the aid of which the temperature in the working chamber can be kept constant even in the event of any electrical heat loss. Conversely, the cooling circuit KK prevents the flow of heat from a possibly high microscope chamber K or working chamber A to the thermoelectric microvalves V.

In the manufacturing process of the manifold, each ceramic layer is mechanically structured separately in the unsintered state and provided with vias and electrical functional layers by means of screen printing. After the lamination of the individual layers, in a subsequent technological step, the burnout and sintering takes place to form a stable ceramic multilayer structure. In addition to mechanical and electrical functions, this structure also fulfills microfluidic functions.

The manifold shown in FIGS. 1 to 5 consists of 16 ceramic individual layers with a microscope chamber K, the fluidic working chamber circuit has 3 fluid inlet channels and a fluid outlet channel, as well as two valve circuits and a cooling channel that encompasses the working chamber A. All fluidic circuits are arranged on an area of 45x45 mm ² , crossing three-dimensionally.

Two of the fluid inlet channels in the working chamber circuit have an integrated silicon-based microvalve V, which allows the setting of a defined closing rate in the range from 0 to a few 100 microliters per minute. This microvalve V is designed as a thermoelectric valve, in which the actuator of the thermoelectric valve is geometrically separated from its place of action of the Si membrane. The LTCC allows the construction of a microfluidic hydraulic circuit, which separates the heater and the microchannel to be switched. The advantage is that the channel fluid is not heated when valve V is switched. The switching process itself takes place by heating an actuator fluid circuit (valve circuit), the expansion of which deforms the Si membrane at valve V and the valve seat is closed or opened. The heater of the valve can also benefit from the KK cooling circuit through the integration in the manifold, which makes valve V faster in its switching dynamics. If, for example, a normally open valve is used to activate the actuator fluid has to cool down in order to release the valve seat, you only have to wait until the actuator fluid is cool enough again, which can be accelerated by the cooling circuit.

For online detection of the flow rate, a flow sensor is integrated in each of the microchannels FK, which can be designed, for example, as a miniaturized electrocaloric flow sensor F.

In the exemplary embodiment, the cooling duct comprises the working chamber A and, in another position, overlapping three dimensions, has a thick-film heater comprising the working chamber.

By using external pumps, a cooling fluid for active cooling can be pumped through the manifold. The thick film heater allows the fluid in the working chamber A to be heated in the temperature range from room temperature to 100 ° C with settling times of approx. 1 minute. The cooling fluid circulating in the cooling circuit KK prevents, on the one hand, the heating of the manifold when heating is required in the working chamber A. On the other hand, the cooling duct also thermally decouples the micro heater and the working chamber. This is important because the silicon microvalves used in the exemplary embodiment each have a thermoelectric actuator which must be heated to approximately 42 to 45 ° C. during operation.

The fluidically usable working chamber A is created by covering the central hole on both sides, which extends through all the ceramic individual layers, with a glass substrate. In the exemplary embodiment, one of the glass substrates is irreversible and one is reversibly connected to the manifold. The irreversible glass substrate consists of a 500 μm thick Pyrex glass plate. This also has a temperature sensor T that extends into the working chamber A. As a result, the temperature of the fluid in the working chamber A can be determined continuously at any time. The reversibly mounted glass substrate can be placed on the manifold in a thickness from 150 μm, which can also be used to perform confocal microscopy on biological objects in the working chamber.

It is also possible to have the reversibly integrable glass substrate covered with biological material before it is installed in the manifold.

In order to be able to build up an electric field in the working chamber A with a special field geometry, the working chamber is provided with an inner hole metallization. This inner hole metallization can be designed as electrodes that extend over the entire bore depth of the working chamber. With these electrodes, an electric field acting on biological cells to be examined can be generated.

Manifold

Reference list

A working chamber K microscope chamber

FL fluid connector

V valve

F flow sensor

EL electrical terminal strip T temperature sensor

FK fluid channel

KK cooling circuit

HF hydraulic fluid channel

E electrode

Claims

Manifold patent claims

1. Manifold with at least one microscope chamber or working chamber, in particular for biological or genetic engineering studies, with devices for supplying and discharging fluids, characterized in that the working chamber (A) extends through a sandwich-like multilayer arrangement, which consists of a combination of layers produced in thick-film and thin-film technology, the working chamber (A) is firmly or reversibly closed by means of a glass cover, the devices for supplying and discharging fluids are designed as buried structures in at least one of the layers of the sandwich-like multilayer arrangement and that the devices for supplying and discharging fluids are designed in the form of a plurality of independent fluid circuits.

2. Manifold according to claim 1, so that the sandwich-like multilayer arrangement consists of a stack of alternating glass and silicon layers.

3. Manifold according to claim 1, characterized - shows that the sandwich-like multilayer arrangement consists of a stack of a plurality of ceramic layers.

4. Manifold according to claim 3, so that the ceramic layers are made of an LTCC ceramic.

5. Manifold according to one of claims 1 to 4, d a d u r c h g e k e n n z e i c h n e t that the devices for

The supply and discharge of the fluids are designed as three-dimensionally intersecting fluid channels.

6. Manifold according to claim 5, d a d u r c h g e k e n n - z e i c h n e t that the fluid channels with control valves

(V) are equipped.

7. Manifold according to claim 6, d a d u r c h g e k e n n z e i c h n e t that the membrane of the control valve (V) consists of silicon.

8. Manifold according to claim 6 and 7, so that the passage cross-section of the control valves (V) is switchable or controllable.

9. Manifold according to one of claims 1 to 8, d a d u r c h g e k e n n z e i c h n e t that the control valves (V) are pneumatically, fluidically or electrically actuated.

10. Manifold according to claim 9, so that the control valves (V) can be actuated by a change in pressure in the fluid circuit.

11. Manifold according to one of claims 1 to 10, characterized in that each control valve (V) is designed as a thermoelectric valve with a heating element.

12. Manifold according to claim 11, so that the heating element is arranged spatially separated from the control valve (V).

13. Manifold according to claim 12, d a d u r c h g e k e n n z e i c h n e t that the heating element is designed as a printed interconnect.

14. Manifold according to one of claims 1 to 13, so that each control valve (V) is equipped with a silicon membrane above the valve chamber, which is firmly connected at the edge to the LTCC ceramic.

15. Manifold according to one of claims 1 to 14, so that the working chamber (K) is provided with electrodes (E) for generating an electric field.

16. Manifold according to claim 15, so that the working chamber (A) is provided with an internal metallization that is electrically connected to the electrical connections of the manifold.

17. Manifold according to one of claims 1 to 16, d a d u r c h g e k e n n z e i c h n e t that a fluid connection bar (FL) is provided in which all fluid channels and hydraulic fluid channels and the fluid channels of the cooling circuit open.

18. Manifold according to claim 17, d a d u r c h g e k e n n z e i c h n e t that fluid connection strip is arranged on an outer edge of the manifold.

19. Manifold according to one of claims 1 to 18, characterized in that an electrical terminal block (EL) is provided in which all the electrical functional connections are combined.

0. Manifold according to one of claims 1 to 29, d a d u r c h g e k e n n z e i c h n e t that several fluid circuits are provided for a working chamber circuit, a valve circuit for controlling the working chamber circuit and a cooling circuit.