Patent Application
20080168942
The invention refers to transporting and focusing liquids and to crystal growth.
In chemical identification, mass spectroscopy is a well-established analytical method. Using “soft ionization” techniques like MALDI-MS (matrix-assisted laser desorption/ionization mass spectrometry) even large biomolecules and synthetic polymers are suitable for this analysis method.
Often the specimen to be analyzed is liquid. In another example the specimen is solid but has to be dissolved in a solvent for various reasons. With, for example MALDI-MS the analyte and a matrix are mixed first at a molecular level in an appropriate solvent and then co-crystallized on a suitable carrier plate for being analyzed within the MALDI instrument. The crystallization is performed by evaporation of the solvent. The remaining analyte is included in a crystal structure formed by the matrix on the surface of the carrier plate. When using only small volumes of liquids huge numbers of samples can be processed simultaneously.
However the quality of sample preparation for further processing or later analysis of the specimen is of importance in relation to the quality of the analysis results.
Various approaches to improve for example MALDI preparation like sample concentration and localization on the carrier plate, crystal grow, crystal distribution, crystal structure and crystal purity have been made. A further example can be found in DE 199 49 735, wherein a carrier comprises a not easily wettable or lyophobic carrier surface with an easily wettable or lyophilic anchor. The sample solution is arranged on that anchor. The evaporation process of a solvent and the well-defined lyophilic anchor in the lyophobic carrier surface leads to a well-defined structured crystal growth of the specimen on the area of the lyophilic anchor.
One object of the invention is to improve liquid transportation.
The object is solved by the independent claims. Preferred embodiments are subject of the dependant claims.
In an embodiment of the invention a device for transporting a liquid is provided, the device comprising a hollow space in a body. The hollow space might be adapted as a vessel. The hollow space or the vessel is adapted for receiving a liquid. Additionally the structure of the hollow space is adapted for generating a directed capillary effect. The directed capillary effect forces the liquid to flow along a specific direction. Thus the invention is usable for transporting a liquid, preferable to a specific place. The device might also be a vessel, the vessel comprising an aperture and being adapted for generating a directed capillary effect. The flow of a liquid within the hollow space along the direction given by directed capillary effect allows a concentration of the liquid in a well-defined area. Hence a liquid can be transported to a specific area and forced to remain there.
In a further aspect of the invention, the directed capillary effect can be used to build a mixing or reaction area and in another embodiment a microlab reaction chamber. In such embodiment the capillary effect is directed towards the mixing or reaction area, also being formed within the body respectively. The different solvent and the reactants are transported in the liquid to the mixing area or the reaction chamber. In an aspect of the invention the reaction chamber is connected to a plurality of vessels, some of them being adapted for generating a directed capillary effect towards the chamber.
Another object of the invention is to provide an improved crystal growth. In this embodiment of the invention, a device for crystal growth is provided. The device comprises a vessel or hollow space respectively in a body, the vessel comprising an orifice or an aperture to a surface of the body. The device is adapted for generating a directed capillary effect towards the orifice. The orifice is adapted for initializing crystal growth. A crystallization process normally is started due to evaporation of a liquid. Thus the device is adapted for evaporation of solvent in the area of the orifice. The loss of solvent is compensated by the directed capillary effect transporting liquid towards the orifice. Due to evaporation the remains of a solute form a growing crystal structure. The structure grown can be mono-crystalline or poly-crystalline.
In an embodiment of the invention, the device comprises a body with a first side and a second side. A hollow space is formed within the body having at least a first orifice on the first side. The hollow space is adapted for receiving a liquid. Furthermore an area of the first orifice is smaller than an area of the second orifice. Alternately a cross-section or an area of a cross-section is decreasing towards the first orifice.
In another aspect, the hollow space is adopted for creating different liquid shapes along the liquid-air interface of a droplet filled in the hollow space. A different liquid surface, for example created by different areas of the vessel can generate a directed capillary effect. The directed capillary effect will force the liquid towards the smaller area of the hollow space and thus towards the first orifice or aperture respectively. The driving force of the directed capillary effect is becoming zero as soon as the first liquid surface reaches the edge of the orifice or the surface of the body.
In an aspect of the device for crystal growth, the evaporation process of the solvent occurs at the liquid surface at all time, but starts significantly after one face of the liquid reaches the surface of the body. The process results in a crystal growth beginning at the surface in a very well defined area. This area will be within the orifice or the aperture of the vessel in the body. In an embodiment, the crystal is grown self-supporting, connected only along an edge of the aperture. This growth will allow access from two sides to the crystal and also improve different analysis and further processing techniques.
In yet another embodiment of the invention, the hollow space is formed at least partly as a truncated cone. Such truncated cone automatically generates a directed capillary effect towards the smaller basis. The direction of the directed capillary effect is depending on the wall geometry as well as structure and wall material. In an embodiment of the invention, the wall of the hollow space comprises at least partly a coated layer wetting-hostile to a liquid or to a solute filled in the vessel or hollow space respectively. Alternately the wall might comprise a coated layer wetting-friendly towards the liquid or the solute. In such embodiments of the invention the coated layer is adapted being lyophobic, hydrophobic or lyophilic and hydrophilic.
The wetting behavior also generates a capillary effect directed towards the parts with greater liquid-friendly behavior. The directed capillary effect can be generated by geometry of the vessel, or structures and material on the vessel's walls.
In another embodiment of the invention, the vessel at least partly comprises a coated layer. The coated layer is adapted for being attractive to at least one content of a solute of the liquid filled in the vessel. Such layers can be used for example to restrain some contents of the liquid from any crystallization process. For example, the liquid might be purified of not wanted molecules, which are attracted towards the coated layer. Alternately the coated layer is adopted for being repellent to at least one content of a solute. In a further aspect of the invention the coated layer might comprises a gradual repellent or attractive behavior.
Specifically in an embodiment the invention, the wall of a truncated cone comprises at least partly a coated layer liquid-friendly or liquid-hostile to a solute filled in the truncated cone resulting in a directed capillary effect towards the smaller radius of the truncated cone.
Thus in the directed capillary effect can be controlled by the coating layer on the hollow space's walls. The coating can also be used in a tube, thereby generating a gradual capillary effect towards a specified direction, depending on the lyophobic or lyophilic behavior. In yet another embodiment of the invention, the hollow space comprises a cylindrical hollow space connected to a truncated conical hollow space. A basis of the conical hollow space is adapted of forming the orifice on the first side. In another embodiment of such invention, at least a part of the walls of such hollow space is coated with a wetting-friendly or wetting-hostile layer. For example the tube may be coated with a liquid-friendly layer to increase the directed capillary effect.
In a further embodiment of the invention, a cross-section of the hollow space is continuously decreasing towards the first orifice on the first side. A decreasing cross-section can generate a directed capillary effect almost independently of the hollow space's form.
In yet a further embodiment of the invention, the wall of the hollow space comprises a microstructure in the area of the first orifice. The microstructured area next to the first orifice improves the crystal growth at those areas as soon as evaporation of the solvent starts significantly.
In a further embodiment of the invention, the hollow space comprises a second orifice. The second orifice might be closed in yet another embodiment by a cover or a plate respectively. In a further embodiment, the cover comprises a foil, the foil comprising at least one of the following materials: stainless steel, gold, palladium or titanium. Plastics like PP, PEEK, or the like and polyimide or fluorpolymers are usable as well. Another material is DLC. In yet another embodiment of the invention, the cover might comprise a semi-permeable membrane.
The cover reduces or even prevents evaporation through the second orifice of the vessel. It will also prevent crystal growth on the walls of the vessel or hollow space between the second orifice and the surface of the liquid. In an embodiment of the invention, the cover comprises a lyophobic or wetting-hostile coating layer.
In an embodiment of the invention, the cover layer is adapted for reducing significantly any evaporation of the liquid filled in the hollow space, while maintaining pressure compensation at the same time. In another embodiment of the invention, the cover comprises a small orifice. The area of such orifice is much smaller than the area of the first orifice. The small orifice will compensate additional vapor pressure during filling a liquid into the hollow space. Still any significant evaporation of the liquid is prevented due to its small size.
Yet another embodiment, the first orifice comprises a structured collar thereby increasing the edge of the orifice. The increase of the edge will initialize a preferred crystal growth on that edge. In another embodiment the surface of the first side of the body near the first orifice is structured with grooves.
In a further embodiment the vessel comprises a second aperture on one side of a body. The second aperture is adopted for being connected to a removable supply chamber formed within a second body. Providing an additional supply chamber increases the flexibility in pre-processing and extends the volume available for crystal growth. The carrier comprising the grown crystal structure can be disconnected from the supply chamber and processed further. In an embodiment the supply chamber comprises an inlet area, the area being adapted for receiving a liquid.
For a well-defined crystal growth a vessel for a solvent is provided, the vessel is adapted for generating a directed capillary effect. Then the solvent is filled in the vessel. The directed capillary effect is forcing the solvent towards the first orifice of the vessel. There the solvent starts to evaporate significantly, thereby generating a crystal growth on the surface near the first orifice and especially along the meniscus of the liquid build at the first aperture. In an aspect, a self-supporting crystal is grown. In another aspect, a supply vessel is provided and connected to a second aperture of the vessel. Then a crystal is grown and the supply vessel is disconnected.
While other objects and many of the intended advantages of embodiments of the present invention will be readily appreciated and become better understood by reference to the following description, the preferred embodiments in connection with the accompanied drawings are used therein for illustration purposes only. They do not limit the scope of protection. Features that are substantially or functionally equal or similar will be referred to with a same reference science.
The orifice or aperture 9 might comprise a circle with an area of some mm2. Specifically the area of the aperture is in the range of 0.005 mm2 to 5 mm2. To increase the edge of the orifice it may be structured. Crystallization process normally starts at the edges of the orifice. In this example the hollow space 20 is filled with a liquid L. The liquid L comprises a first surface near the orifice 9. An adhesion force between the liquid attractive wall 6 of the hollow space and the liquid L is directed upwards and results in a curvature of the liquid's surface.
The body 1 comprises a material, which is inert for the chemical components of the liquid L. For example the body 1 comprises plastics like polypropylene (PP), polyphenylensulfide (PPS), polyetherethercetone (PEEK) or polyethylene (PE). Other materials for examples metals, glass or ceramics might also be used. Within the body 1 a hollow shape 20 is arranged. The hollow shape is adapted to form a truncated cone and comprises two orifices 9 and 9a on opposite sides of the body 1. The first base of a truncated cone on the first side 2 comprises a smaller area as the second basis on the second side 2a. The sidewall 6 in the upper part of the truncated cone comprises a wetting-friendly coated layer to the liquid L. In other word the wall comprises an attractive layer to the liquid. This attraction results in an adhesion force between the wall and the liquid.
In addition the truncated cone also comprises a second coated layer 7 arranged on the sidewall of the truncated cone in the lower part. The second coated layer 7 is adapted for being lyophobic and therefore wetting-hostile to the liquid L. The resulting cohesion force repels the liquid, forming an at least partly curved liquid surface. In other words when connecting the liquid L to the sidewall, the liquid is repelled in the area of the coated layer 7 and attracted in the area 6 of the sidewall. Thus as one can see, the surface of the liquid droplet L comprises curvatures in the same directions. The surface connected to the liquid repellent coating layer 7 is arched outwards, while the surface near the orifice 9 is arching itself inwards. The curvature of both liquids' surfaces is depending on the radius of the surface and the vessel 20. Due to the liquid curvature, a force directed to the center of the liquid curvature is generated.
A layer 4 is placed on the second side of the body 1, thereby closing the second orifice of the truncated cone. The membrane 4 also comprises a wetting hostile coated layer on its inner surface. Furthermore it comprises a very small orifice 5. This orifice 5 will allow small amounts of air flowing into the area 20 thereby compensating the pressure difference between the empty area of the hollow space 20 and the outside. However the orifice 5 is too small to support significant evaporation from the surface 8 of the liquid droplet L. Instead of a small orifice a semi-permeable membrane can be used as well.
Due to evaporation the area 20 is filled with a vapor pressure and equilibrium results between the vapor pressure in the area 20 and the liquid droplet L. The vapor pressure within the area remains constant over time, and almost no solvent can evaporate through the small orifice. Crystal growth on the sidewalls and specifically on the coated layer 7 is thereby minimized. Solvent is evaporated mainly from the liquid's surface near the orifice 9. Solute crystals start to grow on the edge of the orifice 9. The loss of solvent normally lowers the surface of the liquid droplet L. However due to the directed capillary effect any liquid L filled into the truncated cone is transported upwards in direction to the orifice 9 with its smaller radius. The effect is increased by the liquid hostile layer 7. The force of the directed capillary effect is decreasing over time but remains in the same direction until all solvent is evaporated. Evaporation and therefore crystal growth also continues until all solvent is evaporated. During crystal growth, small crystals are swimming on the surface of the liquid within the aperture. These small crystals are used as seeds for further crystallization.
The continuous evaporation process of solvent further increases solute concentration in the remaining liquid. The crystals on the surface of the liquid are growing and start to connect to the edge of the aperture. Since not all liquid is evaporated by now, the directed capillary effect forces the liquid towards the aperture, thereby supporting the crystals structure building on its surface. In other words, the liquid's surface is used as a carrier during the crystal growth process. If all liquid is evaporated, the solute is now crystallized in a high concentration on the microstructures 3 and within the aperture as a self-supporting crystal.
The resulting structure after all liquid is evaporated can be seen in
Since the evaporation surface compared to the droplet volume is relatively low, a slow crystal growing can be generated and modified by adding additional solvent. Another aspect of the invention is given by the size of the aperture that basically controls the evaporation rate. Evaporation can also be controlled by temperature, vapor pressure or other parameters. The geometry of the hollow shape, for example the cone angle in
A more detailed view of the directed capillary effect can be seen in
After filling the liquid L into the cone the adhesion force is curving the surface of the liquid near the contact of the liquid's surface with the wall of the cone. The curvature is depending on the adhesion force to the wall and the cohesion pressure of the liquid. The adhesion force exists for both, the upper and the lower surface. If a droplet of liquid is placed within a normal capillary, having a constant cross section and a constant wetting behavior, the capillary pressure is equal but opposite on both faces of the liquid. The resulting forces along the capillary axis, given by the capillary pressure, are compensated and the droplet will not move.
With wetting friendly behavior for the cone's sidewall, the attraction to the wall tries to wet the surface's wall with the liquid L. Hence the curvature of the liquid's surface near the contact of the liquid's surface with the cone's sidewall is arching inwards. In a greater distance of the sidewall the cohesion force of the liquid, acting as counterpoise, is trying to flatten the liquid's surface. In a tube capillary comprising a big radius, this results in a strong liquid curvature on the contact area between the capillary's sidewall and the liquid's surface and an almost planar surface in the remaining liquid's surface. However, if the radius of the capillary is decreasing, the area of the liquid curvature in relation to the projected surface P will increase.
Due the cone angle α, the area of the projection onto plane P of the upper surface of the liquid is much smaller than the projection onto plane P′ of the lower liquid's surface. On the other hand, the relation of the liquid surface compared to the area of the projection P is much higher for the upper surface then for the lower surface. The stronger curvature for the upper surface leads to a bigger area relation when compared to the projection.
The capillary pressure is now trying to reduce the liquid's surface. Due to van de Waals and other forces on atomic level, the liquid tries to reduce its surface to a minimum. The easiest way is to reduce the curvature of the liquid's surface. This will result in a force Fi and Fa respectively. The upper surface is drawn by the force Fi upwards, the force Fa draws the lower surface downwards. However, due to the stronger curvature for the upper surface the relation between the liquid's surface and the projected area is bigger than for the lower surface. In other words the upper surface might reduce its surface energy more efficiently, since its curvature is stronger. The different relations for the upper and lower surface lead to different values for the force Fi and Fa. Both forces, which compensate each other in the case of a normal tube with constant diameter are now different, resulting in a force directed upwards. The droplet will be forced in the direction of the smaller radius of the truncated cone or the direction wherein the relation of the liquids area compared to the radial projection is increasing.
The directed capillary effect can be enhanced by the lyophobic area 7 as seen in
The carrier comprises a truncated cone formed in the body 1 with its sidewall 6. The cone comprises an angle of roughly 90°. On the surface 2 of the carrier plate 1 small elevations are arranged around the aperture. Furthermore those elevation comprise a layer attractive to a solute's content of the solvent. The cone comprises a lower basis with a second orifice. This basis is adapted for being connected to a pre-processing unit 11, which is used as a supply chamber for solvent or solute.
The pre-processing unit 11 comprises a connector 10 adopted for a tight connection with the truncated cone of the carrier 1. It further comprises a pre-processing and supply area 12. The sidewall of the supply area includes a coated layer, which comprises a gradual wetting behavior. The behavior supports a directed capillary effect towards the connector 10 and the truncated cone in the carrier plate 1. A further inlet area 129 is connected to the chamber 12. In this embodiment of the invention the solvent can be mixed with the solute in the pre-processing area 12. It is also possible to fill the chamber through the inlet area 129.
For example the chamber 12 is connected to the carrier 1. Then a solute is filled up through the inlet area 129. Any further pre-processing is performed. Then the chamber is filled up with solvent through the area 129 until the solvent reaches the connector 10. Then the directed capillary effect forces the solvent towards the aperture 9. Due to evaporation a crystal structure is growing between the edge of the aperture 9. Solute is also concentrated on the surface due to the attraction.
The form of the cone as well as the orifice is flexible. The pre-processing device 11 can be disconnected after the crystallization process has been terminated. This embodiment is useful for MALDI environments wherein the pre-processing and the final analysis occur on different places. Also different solvents can be filled into the chamber, and even additional chemical reaction can be performed.
A further embodiment of the invention is shown in
The device according to
A top view of different apertures for the crystallization process can be seen in
A further aspect of the invention is found in
A side view of an alternate embodiment of the invention can be seen in
Another example can be seen in
A further embodiment is shown in
A further example with a different orifice is seen in
These various embodiments can be used simultaneously, for example in an automatic processing and analysis tooling. Injecting liquid into a pre-processing chamber or the evaporation process is then controlled by software running on the analysis system. A plurality of such transporting and crystal growth devices can be arranged on a well plate or similar structures. The crystallization area is well defined, since mixing of solvent and specimen is now performed inside the vessel and not on the surface, on which in a later stage the evaporation process occurs. Mixing behavior becomes better and the crystal structure is improved. The features of the example shown herein can be combined without neglecting the scope of protection.
