Patent Publication Number: US-11035833-B2

Title: Stacked layer-type member with integrated functional component

Description:
RELATED APPLICATIONS 
     This application is the national stage under 35 U.S.C. 371 of International Application No. PCT/IB2016/054643, filed Aug. 2, 2016, titled “STACKED LAYER-TYPE MEMBER WITH INTEGRATED FUNCTIONAL COMPONENT”, which claims priority to GB Application No. GB 1514135.1, filed Aug. 11, 2015, the entire contents of both of which are incorporated herein by reference. 
     The present invention relates to a fluidic valve, a method of manufacturing a fluidic valve, a sample separation apparatus, a planar member, and a method of manufacturing a planar member. 
     In liquid chromatography, a fluidic sample and an eluent (liquid mobile phase) may be pumped through conduits and a separation unit such as a column in which separation of sample components takes place. The column may comprise a material which is capable of separating different components of the fluidic sample. The separation unit may be connected to other fluidic members (like a sampler or an injector, a detector) by conduits. Before the fluidic sample is introduced into a separation path between a fluid drive unit (in particular a high pressure pump) and the separation unit, a predefined amount of fluidic sample shall be intaken from a sample source (such as a sample container) via an injection needle into a sample loop by a corresponding movement of a piston within a metering device. This usually occurs in the presence of a significantly smaller pressure than what the separation unit is run with. Thereafter, an injector valve is switched so as to introduce the intaken amount of fluidic sample from the sample loop of a metering path into the separation path between fluid drive unit and the separation unit for subsequent separation. 
     At various positions of a liquid chromatography device, fluidic valves are used. For instance, a mixing unit for mixing a mobile phase from various solvent compositions, the above mentioned pump and the above mentioned injector may comprise one or more fluidic valves for selectively enabling or disabling flow of fluid through one or more conduits. Hence, fluidic valves are useful in a sample separation apparatus. Although conventional fluidic valves are powerful fluidic tools, there is still room for improvement of fluidic valves in terms of compactness, robustness and dead volume. Moreover, also an improvement of compactness and robustness of other members (such as valves) with functional components (such as a movable valve body of a valve) is desirable. 
     DISCLOSURE 
     It is an object of the invention to provide a compact and robust member (in particular a valve) with functional component (in particular a movable valve body of a valve). 
     According to an exemplary embodiment of the present invention, a fluidic valve (in particular for a sample separation apparatus for separating a fluid, or more generally for any fluid processing device) is provided, wherein the fluidic valve comprises a stack of (in particular integrally) connected layer structures, a first conduit (in particular defining a lumen which may accommodate fluid) within the stack, a second conduit (in particular defining a lumen which may accommodate fluid) within the stack, a movable body within the stack (i.e. a body located within the stack which can move within and relative to the stack), and an actuator configured for actuating the movable body to selectively bring the movable body into a flow enabling configuration (in particular to move or allow to move the movable body to a flow enabling position) in which flow of fluid between the first conduit and the second conduit is enabled, or into a flow disabling configuration (in particular to move or allow to move the movable body to a flow disabling position differing from the flow enabling position) in which flow of fluid between the first conduit and the second conduit is disabled. 
     According to another exemplary embodiment of the present invention, a sample separation apparatus for separating a fluidic sample is provided, wherein the sample separation apparatus comprises a fluid drive unit configured for driving at least a part of a fluid comprising a mobile phase and the fluidic sample in the mobile phase along a separation path, a separation unit arranged within the separation path and configured for separating the fluidic sample into a plurality of fractions, and a fluidic valve having the above mentioned features configured for selectively enabling or disabling flow of at least a part of the fluid within or into the separation path. 
     According to another exemplary embodiment of the present invention, a method of manufacturing a fluidic valve (in particular for a sample separation apparatus for separating a fluid) is provided, wherein the method comprises forming a first conduit within a stack of layer structures, forming a second conduit within the stack, arranging a movable body within the stack, interconnecting the stack, and configuring an actuator for actuating the movable body to selectively bring the movable body into a flow enabling configuration in which flow of fluid between the first conduit and the second conduit is enabled, or into a flow disabling configuration in which flow of fluid between the first conduit and the second conduit is disabled. 
     According to still another exemplary embodiment of the present invention, a planar member is provided which comprises a stack of metallic (i.e. comprising or consisting of metallic material) layer structures connected to one another, in particular by diffusion bonding, and at least one nonmetallic (i.e. comprising or consisting of nonmetallic material) functional component integrated (for instance as an inlay) with (in particular within) the stack, in particular by diffusion bonding. 
     According to yet another exemplary embodiment of the present invention, a method of manufacturing a planar member is provided which comprises connecting a stack of metallic layer structures to one another by diffusion bonding (in particular in combination with soldering), and integrating at least one nonmetallic functional component with (in particular within) the stack, in particular by diffusion bonding. 
     In the context of this application, the term “fluid” may particularly denote any liquid and/or gaseous medium, optionally including also solid particles. Such a fluid may be or may comprise or may be to be mixed with fluidic sample, which is to be analyzed. Such a fluidic sample may comprise a plurality of fractions represented by molecules or particles which shall be separated, for instance small mass molecules or large mass biomolecules such as proteins. Separation of a fluidic sample into fractions may involve a certain separation criterion (such as mass, volume, chemical properties, etc.) according to which a separation can be carried out. Alternatively, the fluid may also be a mobile phase such as a solvent or a solvent composition (for instance composed of water and an inorganic solvent). 
     In the context of this application, the term “sample separation apparatus” may particularly denote any apparatus which is capable of separating different fractions of a fluidic sample by applying a certain separation technique. The actual separation can be carried out in a separation unit of the sample separation apparatus. The term “separation unit” may particularly denote a member of a fluidic path through which a fluidic sample is transferred and which is configured so that, upon conducting the fluidic sample through the separation unit, fractions or groups of molecules of the fluidic sample will be at least partly spatially separated according to the difference in at least one of their properties. An example for a separation unit is a liquid chromatography column which is capable of trapping or retarding and selectively releasing different fractions of the fluidic sample. 
     In the context of this application, the term “diffusion bonding” may particularly denote a connection technology for connecting stacked sheets or layers, in particular comprising metallic material, by a combination of the application of heat and high pressure. More specifically, diffusion bonding may be denoted as a solid-state welding technique, capable of joining similar and dissimilar materials including metals. It operates on the materials science principle of solid-state diffusion, wherein the atoms of two solid surfaces intermingle over time under elevated temperature (for instance in a range between 800° C. and 1200° C., for example 1100° C.). Diffusion bonding can be implemented by applying both high pressure and high temperature to the materials to be welded. 
     According to an exemplary embodiment, a highly compact flat and planar fluidic valve is provided which is highly appropriate for microfluidic high pressure applications. This can be achieved by bonding a stack of layer structures to one another and embedding a freely and controllably movable body therein, which can be conveniently and precisely controlled with low effort from an exterior of the stack by simply operating an actuator. Such a fluidic valve may be particularly advantageously manufactured by diffusion bonding of metallic layer structures. 
     According to another exemplary embodiment, a planar or flat and thus compact member is formed by diffusion bonding between metallic sheet material and nonmetallic material (which may be also configured as a sheet material or with a pronounced three-dimensional structure such as a ball). Surprisingly, connection of stacked metallic sheets by diffusion bonding allows to interleave or attach also one or more non-metallic structures without deterioration or damage of the manufactured planar member. Moreover, a correspondingly manufactured flat planar member shows a high robustness. 
     In the following, further exemplary embodiments of the fluidic valve, the sample separation apparatus, the planar member, and the methods will be explained. 
     In an embodiment, at least part of the layer structures is configured as a sheet, in particular a metal sheet (for instance steel or titanium). Metal sheets are very thin though robust and sufficiently bendable during manufacturing operation. Moreover, metal sheets are simply and reliably connectable by diffusion bonding. 
     In an embodiment, at least part of the layer structures is configured as a patterned layer having one or more recesses constituting at least part of the first conduit and the second conduit. Patterning layers, for instance by etching, punching, laser cutting, etc. is a simple and accurate way of defining fluidic conduits or channels in a layer stack. It allows to manufacture both straight and curved conduits, and even complex bifurcations and fluidic networks. 
     In an embodiment, the movable body is configured as a ball. By such a ball or sphere geometry, activation of the movable body by a piston-type actuator works reliably regardless of a rotation state of the movable body. 
     In an embodiment, the movable body is made of a ceramic material, sapphire, or ruby. Such materials are capable of withstanding high pressure values (of several hundred bar, for instance up to 1200 bar) which may occur in modern sample separation procedures (in particular in terms of high-performance liquid chromatography, HPLC) while at the same time being capable of providing a leakage free sealing with a seat in which the movable body may rest in a fluid flow disabling operation mode. Moreover, the mentioned materials are capable of withstanding the high temperature and pressure conditions during diffusion bonding of metal sheets. 
     In an embodiment, the movable body is configured for being forced to rest on a seat formed by at least a part of the layer structures by the actuator in the fluid disabling configuration (in particular fluid disabling position) and is configured for being released from the seat for being brought into the fluid enabling configuration (in particular for assuming the fluid enabling position) by the actuator. In order to drive the movable body into the seat, force or pressure may be applied from the actuator onto the movable body (either directly or preferably indirectly via a force transmission mechanism). In the absence of force or pressure applied from the actuator onto the movable body, the movable body is able to move out of the seat (for instance under the influence of flowing fluid which may lift the movable body out of the seat), thereby opening a fluid passage between the first conduit and the second conduit. 
     In an embodiment, the actuator comprises a piston configured for axially moving (for instance for reciprocating)—when driven by a drive unit (such as an electric motor) or by the muscle force of a user—so as to selectively actuate the movable body to be transferred into the fluid enabling configuration (in particular to move into the fluid enabling position) or into the fluid disabling configuration (in particular a fluid disabling position) depending on an axial position of the piston. Such a reciprocating piston, which may move upwardly or downwardly under control of a user or a drive unit (such as a processor-controlled motor) of the fluidic valve or the sample separation apparatus, may assume two different functional positions, one relating to a fluid flow enabling operation mode and the other one relating to a fluid flow disabling operation mode of the fluidic valve. It is also possible that the fluid flow between the first conduit and the second conduit is enabled only to a certain degree by allowing the movable body to move out the seat only for a limited extent, defined by a correspondingly controllable piston position. 
     In an embodiment, the fluidic valve comprises a force transmission structure, in particular a force distribution structure, configured for transmitting, in particular for distributing, an actuation force from the actuator to the movable body. Such a force transmission structure may act as a force-travel transformer and as a mechanical interface between the piston and the movable body. 
     In an embodiment, the force transmission structure is elastic, i.e. has elastic properties. Therefore, force transmitted from the piston to the movable body can be applied to the movable body in a smooth and gentle way damping force peaks, since the elastic force transmission structure also functions as a damping element due to its elastic properties. 
     In an embodiment, the force transmission structure comprises an elastic membrane as at least one of the layer structures. Such an elastic membrane may be a thin bendable film being deformable when applying force or pressure by the piston. Such a membrane may, on the one hand, contribute to the sealing of the fluid flow channel between the first conduit and the second conduit and may, on the other hand, operate in a smooth way on the movable body. 
     In an embodiment, the force transmission structure comprises an elastic pad. For example, the elastic pad may be made of elastic polyurethane material. It may serve as a damping cushion for transmitting and spatially distributing force from the piston to the membrane, and from there to the movable body. In particular, the elastic pad may be arranged between the piston and the elastic membrane. 
     In an embodiment, the elastic pad has a larger lateral extension (i.e. a larger extension within a plane perpendicular to a motion direction of the piston) than at least one of the actuator and the movable body. The elastic pad may therefore balance out spatial inaccuracies concerning the relative position and orientation between piston and movable body. 
     In an embodiment, at least one of the layer structures is configured as a spring-type layer (for instance made of spring steel or a ceramic material). Such a spring-type layer may for example generate a biasing force biasing the movable body into a valve seat. Thus, such a spring-type layer may additionally contribute to the fluid-tight sealing between movable body and seat. Depending on its configuration and arrangement, the spring-type layer may bias the fluidic valve either into a normally open state (i.e. being open as a default state, thus enabling fluid flow in the absence of a piston force) or into a normally closed state (i.e. being closed as a default state, thus disabling fluid flow in the absence of a piston force). Surprisingly, the integration of a spring-type layer into a stack of layers connected to one another by diffusion bonding does not deteriorate the spring properties. 
     In an embodiment, the fluidic valve is configured as a non-return valve. Such a non-return valve (which may also be denoted as check valve or one-way valve) is a valve that (in particular when opened) allows fluid (i.e. liquid or gas) to flow through it in only one direction, but not in the opposite direction. 
     In an embodiment, at least a part of the stack of layer structures is connected to one another by diffusion bonding. Diffusion bonding can be implemented, according to an exemplary embodiment of the invention, by applying both high pressure and high temperature to the stacked sheets to be welded. Diffusion bonding can hence be advantageously applied to weld layered stacks of thin metal foils, which may also be recessed for conduit formation or the like. Surprisingly, conduit recesses within the stack can be advantageously maintained during diffusion bonding without deterioration. 
     In an embodiment, the fluidic valve according to an exemplary embodiment may be implemented at or in a mixing unit for mixing a mobile phase from various solvent compositions upstream of a fluid drive unit, and/or may be implemented at or in a fluid drive unit, and/or may be implemented at or in a proportioning valve, and/or may be implemented at or in an injector for injecting the fluidic sample into a mobile phase. Of course, fluidic valves according to exemplary embodiments of the invention may also be implemented in very different technical environments. 
     In an embodiment, a thickness of each of the layer structures may be in a range between 20 μm and 500 μm, in particular in a range between 50 μm and 200 μm. Preferably, outer layers of the stack may have a higher thickness (for instance between 150 μm and 250 μm) than interior layers of the stack (for instance between 50 μm and 150 μm). 
     Embodiments of the above described fluid valve may be implemented in conventionally available HPLC systems, such as the Agilent 1200 Series Rapid Resolution LC system or the Agilent 1100 HPLC series (both provided by the applicant Agilent Technologies—see the website www.agilent.com). 
     One embodiment of a sample separation apparatus, in which one or more of the above described fluidic valves may be implemented, comprises a pumping apparatus as fluid drive unit or mobile phase drive having a pump piston for reciprocation in a pump working chamber to compress liquid in the pump working chamber to a high pressure at which compressibility of the liquid becomes noticeable. This pumping apparatus may be configured to know (by means of operator&#39;s input, notification from another module of the instrument or similar) or elsewise derive solvent properties, which may be used to represent or retrieve actual thermal properties of fluidic content, which is anticipated to be in a sampling apparatus. 
     The separation unit of the sample separation apparatus preferably comprises a chromatographic column (see for instance the webpage_en.wikipedia.org/wiki/Column_chromatography) providing the stationary phase. The column may be a glass or steel tube (for instance with a diameter from 50 μm to 5 mm and a length of 1 cm to 1 m) or a microfluidic column (as disclosed for instance in EP 1577012 or the Agilent 1200 Series HPLC-Chip/MS System provided by the applicant Agilent Technologies). The individual components are retained by the stationary phase differently and at least partly separate from each other while they are propagating at different speeds through the column with the eluent. At the end of the column they elute one at a time or at least not entirely simultaneously. During the entire chromatography process the eluent may be also collected in a series of fractions. The stationary phase or adsorbent in column chromatography usually is a solid material. The most common stationary phase for column chromatography is silica gel, surface modified silica gel, followed by alumina. Cellulose powder has often been used in the past. Also possible are ion exchange chromatography, reversed-phase chromatography (RP), affinity chromatography and expanded bed adsorption (EBA). The stationary phases are usually finely ground powders or gels and/or are microporous for an increased surface. 
     The mobile phase (or eluent) can be a pure solvent or a mixture of different solvents (such as water and an organic solvent such as ACN, acetonitrile). It can be chosen for instance to minimize the retention of the compounds of interest and/or the amount of mobile phase to run the chromatography. The mobile phase can also be chosen so that the different compounds or fractions of the fluidic sample can be separated effectively. The mobile phase may comprise an organic solvent like for instance methanol or acetonitrile, often diluted with water. For gradient operation water and organic solvent are delivered in separate bottles, from which the gradient pump delivers a programmed blend to the system. Other commonly used solvents may be isopropanol, tetrahydrofuran (THF), hexane, ethanol and/or any combination thereof or any combination of these with aforementioned solvents. 
     The fluidic sample may comprise but is not limited to any type of process liquid, natural sample like juice, body fluids like plasma or it may be the result of a reaction like from a fermentation broth. 
     The pressure, as generated by the fluid drive unit, in the mobile phase may range from 2-200 MPa (20 to 2000 bar), in particular 10-150 MPa (100 to 1500 bar), and more particularly 50-120 MPa (500 to 1200 bar). 
     The sample separation apparatus, for instance an HPLC system, may further comprise a detector for detecting separated compounds of the fluidic sample fluid, a fractionating unit for outputting separated compounds of the fluidic sample, or any combination thereof. Further details of such an HPLC system are disclosed with respect to the Agilent 1200 Series Rapid Resolution LC system or the Agilent 1100 HPLC series, both provided by the applicant Agilent Technologies, under the website www.agilent.com. 
     Embodiments of the invention can be partly or entirely embodied or supported by one or more suitable software programs, which can be stored on or otherwise provided by any kind of data carrier, and which might be executed in or by any suitable data processing unit. Software programs or routines can be preferably applied in or by the control unit. 
     In an embodiment, at least one of the at least one functional component is integrally connected with the stack of metallic layer structures, in particular by diffusion bonding. Such a functional component may be a non-metallic inlay which may be put into a recess of a metallic layer, for instance according to Damascene technology. By such an integrated connection, one or more of the metallic layer structures on the one hand and the respective functional component on the other hand are connected to one another so as to be fixed one other, in particular in an inseparable manner. Surprisingly, such an intimate connection between metallic and nonmetallic elements can be established with higher mechanical reliability and robustness by diffusion bonding. For example, a nonmetallic (for instance ceramic) valve seat layer may be connected to neighboring metallic conduit layers by diffusion bonding. 
     In an embodiment, at least one of the at least one functional component is movable within the stack of metallic layer structures. Additionally or alternatively to the previously described embodiment, the interconnection of the metallic layer structures together with the nonmetallic functional component(s) in between may be carried out in such a manner that the functional component remains a separate (and separately movable) body in the readily manufactured planar member regardless of the harsh conditions (such as high pressure and high temperature) which may act thereon during the manufacturing procedure. This for instance allows to manufacture a movable valve body from a nonmetallic material which may freely move within a stack of metallic sheets by diffusion bonding, which surprisingly deteriorates neither the integrity of the nonmetallic functional component in an interior of the planar member nor its capability of moving during operation. 
     In an embodiment, the planar member is configured as a high pressure resistant planar member, in particular capable of withstanding pressure of at least up to 1000 bar. It has been found surprisingly that even a connection of metallic sheets with nonmetallic structures by diffusion bonding results in an extremely robust planar member. Thus, the manufactured planar member may be used for applications in which high exterior and/or interior pressure is exerted to the planar member or parts thereof during operation. For example, the planar member may be configured and used as a fluidic valve having the above-mentioned features, which can be made subject to high pressure values of up to 1000 bar or more for example in the field of high performance liquid chromatography. 
     In an embodiment, the at least one nonmetallic functional component comprises or consists of at least one of group consisting of an inorganic material, a ceramic material, a metal oxide, and a hard material (such as a hard plastic material). Examples of nonmetallic materials which are appropriate for diffusion bonding are zirconium oxide, aluminum oxide, sapphire, ruby. In particular, a ceramic may be an inorganic, nonmetallic solid comprising metal, nonmetal or metalloid atoms primarily held in ionic and covalent bonds. The crystallinity of ceramic materials ranges from highly oriented to semi-crystalline, and often completely amorphous. 
     In an embodiment, the at least one nonmetallic functional component comprises at least one of the group consisting of a seat of a fluidic valve, a movable body of a fluidic valve, and a spring element. However, many other applications are possible. 
     In an embodiment, the described planar member may be configured as a fluidic valve having the above described features. In particular, the stack of metallic layer structures of the planar member may correspond to the stack of connected layer structures (optionally including the conduits) of the fluidic valve, and the at least one nonmetallic functional component of the planar member may correspond to the movable body and/or a valve seat of the fluidic valve. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Other objects and many of the attendant advantages of embodiments of the present invention will be readily appreciated and become better understood by reference to the following more detailed description of embodiments in connection with the accompanying drawings. Features that are substantially or functionally equal or similar will be referred to by the same reference signs. 
         FIG. 1  illustrates a sample separation apparatus according to an exemplary embodiment of the invention. 
         FIG. 2  shows a fluidic valve according to an exemplary embodiment. 
         FIG. 3  shows constituents of a fluidic valve according to an exemplary embodiment. 
         FIG. 4  shows a detailed view of a part of a fluidic valve according to an exemplary embodiment. 
         FIG. 5  and  FIG. 6  show cross-sectional views of planar members according to exemplary embodiments of the invention manufactured using diffusion bonding and illustrated before a connection between various layer structures. 
     
    
    
     The illustration in the drawing is schematic. 
     Before describing the figures in further detail, some basic considerations of the present invention will be summarized based on which exemplary embodiments have been developed. 
     According to an exemplary embodiment of the invention, a high pressure valve is provided which can be manufactured in diffusion bonded sheet-metal technology. According to this technology, microfluidic planar structures can be interconnected by diffusion welding to thereby obtain a high pressure robust planar microfluidic valve. In such an embodiment, it is also possible to bond ceramic components (and/or components from other nonmetallic materials) with other structures in a high pressure resistant manner. In particular, sapphire balls or spheres can be mounted in a movable way within a planar layer structure prior to a diffusion welding procedure, which can be carried out subsequently to obtain a bonding without damage or deterioration. This allows to manufacture a non-return valve in a planar layer structure architecture. 
     In the event of high pressure load, high forces may be exerted to membrane type outer layers of planar structures. Under certain circumstances, it may be possible that such kind of membranes cannot withstand such forces without deterioration or damage. However, when mechanically supporting such membranes from an exterior position with a hydraulic counterforce, the forces acting onto the membrane from an exterior position and from an interior position, may at least partially compensate each other. In an embodiment, such a counterpart can be generated by a cushion type elastic member (for instance from polyurethane). An external piston may be implemented as actuator for the valve and may exert a force onto the elastic member which can be translated or conveyed into an interior of the stacked layer or laminate type valve, to act on the membrane. By an appropriate dimensioning, this architecture allows to obtain a force-distance transducer reducing the required actuation force for the valve. 
     In an embodiment, it is also possible to combine a force-opened valve with a pin (for instance made of sapphire) arranged in an inlet channel region of the valve, which pin may be actuable via a membrane system from an exterior position of the valve. 
     Advantageously, a spring type element may be arranged within the planar structure so as to equip the valve with a certain degree of elasticity. Such a spring element may be made of a metal alloy (keeping its spring properties even after a bonding procedure) or from an elastic ceramic foil. 
     Referring now in greater detail to the drawings,  FIG. 1  depicts a general schematic of a sample separation apparatus  10  configured as a liquid chromatography system. A high pressure pump as a fluid drive unit  20  receives a mobile phase from a solvent supply  25 , typically via a degasser  27 , which degases the solvent and thus reduces the amount of dissolved gases in the mobile phase. The fluid drive unit  20  drives the mobile phase through a separation unit  30  (such as a chromatographic column) comprising a stationary phase. A sampling unit or sample injector  40  can be provided between the mobile phase drive or fluid drive unit  20  and the separation unit  30  in order to subject or add (often referred to as sample introduction) a fluidic sample into the mobile phase. A fluidic valve (or a combination of valves) denoted as injector valve  92  is switchable between different switching positions (or combinations of positions), one of which relating to an intake of fluidic sample within the sample injector  40  at a low pressure, while another switching position relates to an introduction of previously intaken fluidic sample into a main path or separation path between fluid drive unit  20  and separation unit  30  for separation of the fluidic sample under high pressure provided by the fluid drive unit  20 . The stationary phase of the separation unit  30  is configured for separating compounds of the sample liquid. A detector  50  is provided for detecting separated compounds or fractions of the fluidic sample. A fractionating unit  60  can be provided for collecting separated compounds of fluidic sample individually. 
     While the mobile phase can be comprised of one solvent only, it may also be mixed from plural solvents, as indicated schematically in a detail of the solvent supply  25  shown in  FIG. 1 . Two different solvents (such as water and an organic solvent) are stored in solvent containers  82 ,  84  and are supplied to a mixing unit  86  in which the two solvents are mixed at a mixing point  88 . Two fluidic valves  90 , which may selectively open or closed and may be configured according to an exemplary embodiment of the invention, may be located between the solvent containers  82 ,  84  and the mixing point  88 . 
     The mixing might be a low pressure mixing and provided upstream of the fluid drive unit  20 , so that the fluid drive unit  20  already receives and pumps the mixed solvents as the mobile phase. Alternatively, the fluid drive unit  20  may be comprised of plural individual pumping units, with plural of the pumping units each receiving and pumping a different solvent or mixture, so that the mixing of the mobile phase (as received by the separation unit  30 ) occurs at high pressure and downstream of the fluid drive unit  20  (or as part thereof). The composition (mixture) of the mobile phase may be kept constant over time, the so called isocratic mode, or varied over time, the so called gradient mode. 
     As can be taken from a further detail of the fluid drive unit  20  illustrated in  FIG. 1 , the fluid drive unit  20  may be composed of two serially arranged piston pump units  94 ,  96  each having a piston  66 ,  68  reciprocating within a respective pump housing  62 ,  64 . Operation of the piston pump units  94 ,  96  may be synchronized or coordinated. A respective one of two fluidic valves  90 , which may selectively open or closed and may be configured according to an exemplary embodiment of the invention, is located upstream of the piston pump unit  94  and between the piston pump unit  94  and the piston pump unit  96 . 
     The above description shows that one or multiple fluidic valves  90  (which may be in particular On/Off valves or non-return valves) may be implemented in a fluid processing apparatus, such as the sample separation apparatus  10  operating in accordance with the principle of liquid chromatography. 
     A data processing unit or control device  70 , which can be a PC or workstation or an instrument-embedded micro-processor, can be coupled (as indicated by the dotted arrows) to one or more of the devices in the sample separation apparatus  10  in order to receive information and/or control operation. For example, the control device  70  may control operation of the fluid drive unit  20  (for instance setting control parameters) and receive therefrom information regarding the actual working conditions (such as output pressure, flow rate, etc. at an outlet of the pump). The control device  70  may also control operation of the solvent supply  25  (for instance setting the solvent/s or solvent mixture to be supplied) and/or the degasser  27  (for instance setting control parameters such as vacuum level) and may receive therefrom information regarding the actual working conditions (such as solvent composition supplied over time, flow rate, vacuum level, etc.). The control device  70  may further control operation of the sample injector  40  (for instance controlling sample injection or synchronization sample injection with operating conditions of the fluid drive unit  20 ). The separation unit  30  may also be controlled by the control device  70  (for instance selecting a specific flow path or column, setting operation temperature, etc.), and send—in return—information (for instance operating conditions) to the control device  70 . Accordingly, the detector  50  may be controlled by the control device  70  (for instance with respect to spectral or wavelength settings, setting time constants, start/stop data acquisition), and send information (for instance about the detected sample compounds) to the control device  70 . The control device  70  may also control operation of the fractionating unit  60  (for instance in conjunction with data received from the detector  50 ). The injector valve  92  and the fluidic valve  90  are also controllable by the control device  70  for selectively enabling or disabling specific fluidic paths within sample separation apparatus  10 . 
       FIG. 2  shows a fluidic valve  90  according to an exemplary embodiment of the invention which is configured as a non-return valve. The fluidic valve  90  can be implemented in the way as described above referring to  FIG. 1 , or at any other desired position within the sample separation apparatus  10  or in any other fluidic member or device. For instance, it may also be possible to configure the injector valve  92  from one or more fluidic valves  90  as shown in  FIG. 2  or having an adapted configuration. 
     The fluidic valve  90  shown in  FIG. 2  comprises a stack of connected layer structures  200 , for instance made of steel or titanium. Each of the layer structures  200  may have, for instance, a thickness in a range between 20 μm and 500 μm. The various layer structures  200  may be bonded to one another to form a planar laminate. During manufacture of the fluidic valve  90 , the stack of layer structures  200  is connected to one another by diffusion bonding so as to obtain a flat and planar high pressure robust configuration. Since the layer structures  200  are configured as sheets (some of them as metal sheets), the fluidic valve  90  is plate-shaped and hence very flat, thereby obtaining a vertically compact arrangement. As will be described below in further detail, some of the layer structures  200  are configured as patterned layers having recesses. 
     The fluidic valve  90  comprises a first conduit  202  (in the shown embodiment an inlet channel) configured as a recess within the stack and a second conduit  204  (in the shown embodiment an outlet channel) configured as a further recess within the stack. The function of the first conduit  202  and of the second conduit  204  can also be exchanged in each embodiment described in this application, i.e. the first conduit  202  may also function as outlet channel (i.e. may be connected to a fluidic drain), whereas the second conduit  204  may also function as inlet channel (i.e. may be connected to a fluidic source). The fluidic valve  90  may be configured or operate to function as a one-way valve, i.e. enabling only a fluid flow from the fluid inlet to the fluid outlet, or may be configured or operate to function as a two-way valve, i.e. enabling a flow from the first conduit  202  towards the second conduit  204 , or from the second conduit  204  towards the first conduit  202 . When the fluidic valve  90  is in an open state, fluid (in particular a liquid) is enabled to flow from the first conduit  202  into the second conduit  204 . When the fluidic valve  90  is in a closed state, fluid is disabled to flow from the first conduit  202  into the second conduit  204 . 
     For switching the fluidic valve  90  between the closed state and the open state, a movable body  206  (such as a ball or sphere, but which may alternatively be configured as a pin or any other structure, and which may be preferably made of sapphire material) is located within the stack and can be moved from an exterior of the stack by an actuator  208 . The movable body  206 , made of sapphire, is configured for being forced to rest on a seat  210  (which may be made of a ceramic material, preferably ZrO 2  or a composition of ZrO 2  and Y 2 O 3 ) which is formed as well as part of the layer structures  200 . The actuator  208  is here embodied as a movable piston and may be made from a magnetic material so as to be movable by correspondingly powering a solenoid or electromagnet (not shown). The closed position of the valve  90  can be initiated by a downward motion of the piston according to  FIG. 2  so that the piston actuator  208  sealingly presses the movable body  206  into seat  210 . The open position of the valve  90  can be initiated by an upward motion of the piston according to  FIG. 2  so that the piston actuator  208  releases the movable body  206  and no longer presses the latter against the seat  210 , thereby allowing a fluid flow. 
     The motion of the movable body  206  may hence be triggered or effected by a motion of the actuator  208 . In the fluid disabling position, the movable body  206  sealingly sits on the seat  210  and thereby prevents flow of fluid between the first conduit  202  and the second conduit  204 . However, in the absence of a vertical pressing force from the actuator  208  onto the movable body  206  against the seat  210 , the movable body  206  is free to be released from the seat  210  and can therefore assume the fluid enabling position in which fluid may flow from the first conduit  202  through a central through hole in the seat  210  into the second conduit  204 . To accomplish its actuation function, the actuator  208  comprises the piston which is configured for axially moving (see double arrow  280 ) so as to selectively actuate the movable body  206  to move into the fluid enabling position or into the fluid disabling position depending on an axial position of the piston. 
     More precisely, the fluidic valve  90  is configured for actuating the movable body  206  using a force transmission mechanism located between piston actuator  208  and movable body  206  to selectively move into a flow enabling position (i.e. an upper position of the actuator  208  according to  FIG. 2 ) in which flow of fluid between the first conduit  202  and the second conduit  204  is enabled, or into a flow disabling position (i.e. a lower position of the actuator  208  according to  FIG. 2 ) in which flow of fluid between the first conduit  202  and the second conduit  204  is disabled. In order to apply spatially distributed pressure to the movable body  206 , an elastic force transmission structure  212  of the force transmission mechanism is arranged between the actuator  208  and the movable body  206  and is configured for transmitting an actuation force from the actuator  208  to the movable body  206 . More specifically, the force transmission structure  212  serves as a force distribution or spreading structure distributing or spreading the force applied via a relatively small contact surface  282  of the piston actuator  208  to a larger contact surface of an elastic membrane  214  of the force transmission structure  212 , wherein the membrane  214  acts directly on the movable body  206 . The force transmission structure  212  thus comprises the flexible or elastic membrane  214  as one of the layer structures  200  and comprises an elastic pad  216  (for instance made of elastic polyurethane material). The elastic pad  216  is arranged between the actuator  208  and the elastic membrane  214 . As can be taken from  FIG. 2 , the elastic pad  216  has a larger lateral extension, D, than a smaller lateral extension, d, of the actuator  208 . The elastic pad  216  acts as a hydraulic medium to distribute the piston pressure homogeneously on the elastic membrane  214  and supports the elastic membrane  214 . The force transmission structure  212  acts as a force-travel transformer. The bulky elastic pad  216 , exerting a counterforce on the elastic membrane  214 , also mechanically stabilizes the sensitive elastic membrane  214  which might otherwise get torn or break in the presence of a high pressure of for instance 1200 bar. 
     From bottom to top, the stacked layer laminate according to  FIG. 2  comprises a bottom cover sheet  230 , covered with a patterned sheet  232  in which a recess  218  forms part of the first conduit  202  and being, in turn, covered with a seal sheet  234  in which a further recess  236  is provided which forms another part of the first conduit  202  and being, in turn, covered with a spacer layer  238  (composed of a central ceramic body  240  constituting the seat  210  and a surrounding spacer annulus  242 ). The spacer layer  238  is covered by a patterned seal layer  244  having a central recess  246  partially for accommodating the movable body  206  and partially for forming a fluidic interface between the first conduit  202  and the second conduit  204 . A further patterned sheet  248  has a recess which constitutes the second conduit  204 . A patterned spacer sheet  250  is arranged on top of the further patterned sheet  248 . The spacer sheet  250  is covered by the elastic membrane  214 . A central portion of the elastic membrane  214  is covered by and elastically coupled to the elastic pad  216 , whereas an annularly surrounding portion of the elastic membrane  214  is immovably sandwiched between the spacer sheet  250  and a top cover sheet  252 . The actuator  208  configured as reciprocating piston (i.e. being capable to move upwardly or downwardly) is longitudinally guided by a guide body  254  having an accommodation recess in which the actuator  208  is accommodated. The bottom cover sheet  230  and the top cover sheet  252  are thick metal sheets functioning as a casing and mechanically stabilizing the fluidic valve  90 . 
     It should be said that many alternatives are possible concerning the configuration of  FIG. 2 . For instance, it is possible to provide two membranes  214  sandwiching the movable body  206  (for instance from a top side and from a bottom side) and being actuable by two pistons (for instance from a top side and from a bottom side). 
       FIG. 3  shows an explosive view of constituents of a planar fluidic valve  90  according to another exemplary embodiment of the invention. 
     According to the embodiment of  FIG. 3 , one of the layer structures  200  is configured as a spring-type layer  300  which may be made for instance of a spring-type steel or ceramic material. The movable body  206  rests on top of the spring-type layer  300  and biases the fluidic valve  90  into a normally open state. In other words, the spring force of the spring-type layer  300  keeps the movable body  206  away from the seat  210 . Only when the piston actuator  208  (not shown in  FIG. 3 ) presses the movable body  206  onto the seat  210 , the fluidic valve  90  is converted into the closed state. The spring-type layer  300  hence strengthens the elastic properties of the fluidic valve  90  and contributes to a biasing of the fluidic valve  90  into the open position. 
     According to  FIG. 3 , the seat  210  is illustrated as a full layer with a central recess. However, it may be advantageous to configure the seat  210  as ceramic inlay to be inserted into a central recess of a metallic layer (see reference numeral  242  in  FIG. 2 ) in Damascene technology and to integrally fix this structure by diffusion bonding. An advantage of such a configuration is that fitting issues and thermal stress induced by different thermal expansion properties of the ceramic material of the seat  210  on the one hand and vertically surrounding metallic material on the other hand can be suppressed. 
     Referring to  FIG. 3 , the components according to reference numerals  212  (hydroformed bellow),  250  (spacer sheet),  300  (spring-type layer, for instance made of steel) and the movable body  206  (such as a sapphire ball) can be bonded with valve manifold. Alternatively, at least a part of these components may also form a separate mounted assembly. 
       FIG. 4  shows a detailed view of a part of a fluidic valve  90  according to an exemplary embodiment of the invention. 
     In the embodiment according to  FIG. 4 , the metallic material of the top cover sheet  252  presses against PEEK (Polyetheretherketone) material of the flexible membrane  214 . Furthermore, the ceramic body  240  is made of a combination of ZrO 2  and Y 2 O 3 . 
       FIG. 5  show a cross-sectional view of a planar member, here configured as part of a fluidic valve  90 , according to an exemplary embodiment of the invention manufactured using diffusion bonding. The illustration according to  FIG. 5  relates to a situation before a connection between various layer structures. 
     The planar member comprises a stack of metallic layer structures  200 , for instance made of steel or titanium, and being connected to one another by diffusion bonding. If desired, the connection strength may be further improved by connecting the metallic layer structures  200  by soldering (and additionally, if desired, by adhesive). Additionally, a nonmetallic functional component  206 , which can be made of zirconium oxide, is immovably integrated within the stack. The nonmetallic functional component  206  may be configured as a valve seat. The nonmetallic functional component  206  according to  FIG. 5  is integrally connected with the stack of metallic layer structures  200  by diffusion bonding. The nonmetallic functional component  206  according to  FIG. 5  is embedded in one of the metallic layer structures  200  in accordance with Damascene technology. The planar member of  FIG. 5  is configured as a high pressure resistant planar member  90  which is capable of withstanding pressure of at least up to 1000 bar. 
       FIG. 6  show a cross-sectional view of a planar member, configured as part of a fluidic valve  90 , according to another exemplary embodiment of the invention manufactured using diffusion bonding. The illustration according to  FIG. 6  relates to a situation before a connection between various layer structures. 
     A main difference between the embodiment of  FIG. 5  and the embodiment of  FIG. 6  is that according to  FIG. 6  the nonmetallic functional component  206  may be configured to be movable within the layer structures  200 , in particular as a movable valve body. The nonmetallic functional component  206  according to  FIG. 6 , which can be made of sapphire or ruby, is embedded within a void within the stack of metallic layer structures  200  by diffusion bonding. The dimension of the void is larger than a dimension of the functional component  206 . Correspondingly, the nonmetallic functional component  206  according to  FIG. 6  is movable within the void of the stack of metallic layer structures  200  after completion of the manufacturing procedure of the planar member. 
     It should be noted that the term “comprising” does not exclude other elements or features and the term “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims shall not be construed as limiting the scope of the claims.