Metering device and method for operating such

The present invention relates to a metering device, a metering element and a method for operating such

The discovery and development of new substances and materials is a primary goal of the material sciences, of chemistry and pharmacy. However, the search for suitable compounds is often very costly and time-consuming. To be able to conduct this search more effectively and inexpensively, a systematic methodology which has become known under the name of “combinatory chemistry” had been introduced in the pharmaceutical and then also in other application fields years ago already. Here, several potentially interesting compounds are produced and analyzed in parallel. The advantage of this method is that automation is possible, which allows high processing speeds in a minimum of time.

To produce the material libraries required in this context, a large number of potentially interesting substances or their progenitor compounds must be positioned or metered at defined points of corresponding substrates. Because of the generally large number of substances to be metered, this is preferably done in a fully automatic manner. Conventional metering roboters utilize systems in which the substance to be metered is taken up by means of a syringe which is connected to a metering needle via a connection hose. The syringe as well as the connection hose and the metering needle are initially filled only with an operating fluid, the metering needle being filled with air at its end facing the metering orifice. For metering, the metering needle is dipped into the substance to be metered and the plunger of the syringe pulled out of the associated metering body. Due to the volume enlargement, the substance to be metered is drawn into the metering needle and into the connection hose. The air contained in the metering needle forms a buffer, so that contamination or mixing of the substance to be metered and the operating fluid is avoided. A disadvantage of such a metering system is that the air buffer present in the metering needle is compressible, and highly viscous media or suspensions can thus be metered only with difficulties.

It is an objective of the present invention to provide a metering device or a metering element and a method for operating the same that also allows the automated metering of highly viscous media.

The metering device or the metering element according to the present invention as well as the method for operating such have the advantage of allowing an automated metering of highly viscous media in a simple yet reliable manner. In the process, a metering element with a supply reservoir is used, which is open on one side and holds the substances to be metered and also includes a plunger which is axially displaceable and reversibly seals the opening of the supply reservoir, the plunger being provided with at least one metering orifice, preferably centrically positioned, for the metering of the substances deposited in the supply reservoir. The substances to be metered are first placed directly in the supply reservoir while the plunger is removed. This advantageously allows also solid materials or highly viscous media to be filled into the supply reservoir, which, due to the action of the vacuum pressure alone, cannot be aspirated into the storage reservoir through a metering needle provided at the plunger when the plunger is sealed.

To ensure reliable automated handling of plunger and storage reservoir, an accommodation is provided on the plunger and/or at the bottom of the storage reservoir as contact point for a mechanical gripping device.

The metering of the substances deposited in the storage reservoir advantageously takes place without the use of operating liquid.

The plunger is advantageously joined to a piston barrel which has a metering line for metering the deposited substances and is provided with an exchangeable metering needle at its end facing away from the plunger. The metering needle is connected to the piston barrel via a Luer lock closure, for instance. The exchangeability of the metering needle is advantageous if the metering needle becomes contaminated by foreign matter during the metering. Since each substance to be metered is advantageously assigned its own supply reservoir with a separate plunger, any possibility of contamination with foreign matter can be excluded.

In another advantageous specific embodiment, the metering device has several metering elements whose supply reservoirs have an essentially identical linear extension and different diameters. In this manner different volumes may be realized in the supply reservoirs without an adaptation of the automatic gripping device being necessary. It is especially advantageous in this case if the particular accommodation of the supply reservoir or the plunger is coded to detect the volume or the diameter of the associated supply reservoir.

In an especially advantageous specific embodiment, at least two substances are deposited in a supply reservoir, these substances being mixed in the supply reservoir prior to metering by a mixing device integrated in the supply reservoir or provided from the outside. Furthermore, once the vessel is sealed, the substances deposited in the supply reservoir are able to be degassed via the metering orifice penetrating the plunger. In addition, there is the advantageous possibility of subjecting the substances deposited in the supply reservoir to a chemical conversion prior to their metering.

FIG. 1 shows a plan view of a metering element as component of a metering device, in a schematic representation.

FIG. 2 shows a sectional view of the metering element illustrated in FIG. 1 .

FIGS. 3 a to 3 f show cross-sectional views of several variants of the metering element shown in FIGS. 1 and 2 .

The idea on which the present invention is based is to provide a metering device or a metering element that allows an efficient and automated metering of numerous substances required especially within the framework of combinatory material development for the compiling of combinatory material libraries.

At the core of the metering device is one or a plurality of metering element(s) as shown in FIGS. 1 and 2 by way of example. Metering element 10 includes a supply reservoir 12 in which one or a plurality of substances to be metered is able to be deposited. Supply reservoir 12 is made of a material that is in essence chemically inert, for instance glass, PTFE or PVC. Supply reservoir 12 preferably has a cylindrical design, one end of supply reservoir 12 being open and able to be sealed by a plunger 14 . To ensure that supply reservoir 12 can be sealed independently of plunger 14 , supply reservoir 12 has a thread 13 impressed on the outer wall of supply reservoir 12 , preferably in the region of its opening.

Preferably at its side facing the substance to be metered, plunger 14 is provided with a seal 15 which is mechanically fixated, for instance, and thus designed to be exchangeable. On its side facing away from the substance to be metered, plunger 14 goes over into a piston barrel 16 , which preferably has four suitable ribs for improved guidance. Plunger 14 and piston barrel 16 are preferably made of stainless steel or a chemically inert polymer such as PTFE or PVC.

A special feature of the metering element is that, in contrast to conventional metering syringes known especially from the medical field, the metering of the deposited substances is implemented via a cutout 18 of plunger 14 . To this end, piston barrel 16 joined to plunger 14 has a metering line 20 through which a substance to be metered is able to be transported from supply reservoir 12 through cutout 18 . On its side facing away from plunger 14 , piston barrel 16 has, for instance, a mechanical fixation device 22 for a metering needle 24 . Mechanical fixation device 22 is preferably implemented as Luer lock closure.

To ensure automated metering in a short time cycle, an accommodation or fitted region 26 , 28 , which is used as contact point for a mechanical gripping device, is provided on supply reservoir 12 on its side lying across from the orifice, and/or on plunger 14 or piston barrel 16 on its side facing away from the substance to be metered.

For metering, each substance or substance mixture to be metered is preferably assigned a separate metering element. This effectively avoids intermixing or cross-contamination of the substances. To fill metering element 10 , its plunger 14 is first removed and the substance deposited in open supply reservoir 12 . Plunger 14 is then inserted into supply reservoir 12 , the air present there being able to escape via metering line 20 . Plunger 14 is preferably introduced to such that the entire air in supply reservoir 12 is displaced. Should the deposited substance be a substance that reacts with air, the substance may be supplied in a protective gas apparatus, or a substance already deposited may be degassed in a conventional manner through metering line 20 .

Another possibility is to fill a plurality of substances and possibly solvents into supply reservoir 12 one after another and to then mix them together, either with the aid of an external agitator such as a magnetic stirrer, or with the aid of a stirring device provided in supply reservoir 12 , for instance glass balls.

The metering of the deposited substances or substance mixtures is implemented in that metering element 10 is gripped by a mechanical gripping device at accommodations 26 , 28 , brought to the metering location, where the deposited substances or substance mixtures are metered by pressure on plunger 16 or supply reservoir 12 .

The metering element thus includes at least one metering element 10 , at least one gripping device and at least one control unit to control the gripping device.

In another specific embodiment, metering element 10 is additionally used as chemical reactor. To this end, the substances deposited in supply reservoir 12 of metering element 10 are subjected to a chemical reaction prior to being metered. Metering element 10 may have a corresponding heating, stirring or cooling device for this purpose. However, these devices may just as well be designed in such a way that they are temporarily affixable or are merely available upon demand.

FIGS. 3 a through 3 f show a number of variants of metering element 10 , which differ especially with regard to the possible metering volumes. Notwithstanding different volumes of supply reservoirs 12 , the linear extension of metering element 10 is kept largely constant. Different volumes are achieved by selecting appropriate diameters of supply reservoir 12 . In this way metering elements 10 having different metering volumes may be utilized for the metering one after another without an adaptation of the mechanical gripping device being required. Moreover, it is possible to design accommodations 26 , 28 such that they have markings to identify the metering volume, so that the mechanical gripping device is automatically adapted to the corresponding metering volume of the presently mounted metering element.

The metering element illustrated in FIG. 3 a is shown with metering needle 24 removed; it becomes clear that, instead of metering needles, other metering devices such as pourers may be mounted as well or that the metering element is permanently connectable to a sealed metering or reaction apparatus. The metering element shown in FIG. 3 f is connected not to a metering needle, but instead to a hollow line or a piston having a wider diameter. This may be a component of an overall apparatus.

The described metering device is suitable for, in particular, the metering of highly viscous media such as suspensions or dispersions.