Abstract:
A water analysis device with a pneumatically actuated multi-chamber peristaltic pump includes a base plate comprising a plurality of proximally open pump chambers disposed on a proximal side of the base plate. A pump membrane disposed on the proximal side of the base plate is configured to close the pump chambers. A cover plate is disposed on the pump membrane comprising a respective pneumatic actuator channel in a region of each of the pump chambers. The pneumatic actuator channel is configured to connect to an overpressure source which actuates the pump membrane. A connection channel formed as a groove on a distal side of the base plate is disposed between two of the pump chambers. A separate groove cover is disposed on the distal side of the base plate in a region of the groove. The separate groove cover closes a distal opening side of the groove.

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
       [0001]    This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2010/054333, filed on Mar. 31, 2010 and which claims benefit to European Patent Application No. 09168536.2, filed on Aug. 25, 2009. The International Application was published in German on Mar. 3, 2011 as WO 2011/023420 A1 under PCT Article 21(2). 
     
    
     FIELD 
       [0002]    The subject matter of the present invention refers to a water analysis device comprising a pneumatically operated multi-chamber peristaltic pump. 
       BACKGROUND 
       [0003]    In a water analysis device, liquids such as, for example, a water sample, a liquid dialysate, a liquid analyte, a rinsing liquid etc., are conveyed by pumps. If the analysis device is of a microfluidic design, peristaltic pumps are the pump type of choice. These comprise a plurality, for example, three, pump chambers which are successively filled and emptied so as to cause a unidirectional peristaltic pumping operation. 
         [0004]    A microfluidic multi-chamber peristaltic pump is described in U.S. Pat. No. 5,593,290 A which comprises three pump chambers that are formed on the proximal side of a base plate and are each closed with an elastic pump membrane. The adjacent pump chambers are interconnected by a connection channel formed in the base plate as a proximally open groove closed with an intermediate plate. In the region of the pump chambers, the intermediate plate has corresponding continuous openings. The proximal side of the intermediate plate is provided with the elastic pump membrane, on which a cover plate is fixed that comprises a pneumatic actuator channel for each pump chamber. 
         [0005]    Manufacturing this peristaltic pump is extremely intricate since the base plate and the intermediate plate must be aligned with each other with a tolerance of less than 0.1 mm. In order to provide that the respective overall volumes of the three pump chambers are as identical as possible, the intermediate plate is formed by a thin film. It is technically challenging to provide the continuous openings in the thin film with any accuracy. 
       SUMMARY 
       [0006]    An aspect of the present invention is to provide a water analysis device with a pneumatically operated multi-chamber peristaltic pump that is simpler to manufacture. 
         [0007]    In an embodiment, the present invention provides a water analysis device with a pneumatically actuated multi-chamber peristaltic pump which includes a base plate comprising a plurality of proximally open pump chambers disposed on a proximal side of the base plate. A pump membrane configured to be liquid-tight and elastic is disposed on the proximal side of the base plate. The pump membrane is configured to close the proximally open pump chambers. A cover plate is disposed on the pump membrane. The cover plate comprises a respective pneumatic actuator channel in a region of each of the proximally open pump chambers. The pneumatic actuator channel is configured so as to be connected to an over-pressure source configured to actuate the pump membrane. A connection channel is disposed between two of the proximally open pump chambers. The connection channel is formed as a groove on a distal side of the base plate. A separate groove cover is disposed on the distal side of the base plate in a region of the groove. The separate groove cover is configured to close a distal opening side of the groove. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The present invention is described in greater detail below on the basis of embodiments and of the drawings in which: 
           [0009]      FIG. 1  shows a schematic illustration of a water analysis device formed by a base module and an exchangeable cartridge module in which a pneumatically operated multi-chamber peristaltic pump is arranged; and 
           [0010]      FIG. 2  shows a longitudinal section of the peristaltic pump in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    In the water analysis device of the present invention, the connection channel between two pump chambers is formed as a groove on the distal side of the base plate. In the region of the connection channel groove, a separate groove cover is provided on the distal side of the base plate, which closes the distal opening side of the connection channel groove. The groove is thus now provided on the side of the base plate averted from the pump chambers. The groove may be closed with a simple groove cover. An intermediate plate with recesses or openings is no longer needed. The groove cover may be a large-surface body, for example, which covers the entire distal side of the base plate. No exact positioning of the groove cover is required, whereby the assembly is much facilitated. 
         [0012]    The pump chambers can be closed with a single pump membrane or with separate pump membranes. 
         [0013]    In an embodiment of the present invention, the base plate can, for example, be an injection molded plastic part comprising all pump chambers and the connection channels in the form of grooves. Since the base plate has recesses only on the distal and the proximal sides of the base plate, remolding poses no problems. 
         [0014]    In an embodiment of the present invention, the groove cover can, for example, be a flexible cover film. The cover film is of limited flexibility so that it can adapt to irregularities on the distal side of the base plate. Leaks caused by irregularities; which would otherwise almost be inevitable with a rigid groove cover, are thereby avoided. Using a flexible cover film for the groove cover allows neglecting a high planarity on the distal side of the bas plate. 
         [0015]    In an embodiment of the present invention, the cover film can, for example, be transparent. The cover film is, for example, transparent to laser radiation used to weld the cover film to the base plate. The transparence of the cover film thus makes it possible to weld the cover film to the base plate by laser welding. This allows for a reliably fluid-tight fixing of the cover film by means of an automated and thus cost-efficient manufacturing process. 
         [0016]    In an embodiment of the present invention, the base plate and the cover film can, for example, be made from the same plastic material so that they have the same melting temperature. This facilitates the welding of the cover film to the base plate by laser welding. 
         [0017]    In an embodiment of the present invention, respective vertical channels can, for example, be provided between the connection channel of the distal side of the base plate and the pump chambers, which vertical channels are perpendicular to the connection channel and respectively connect the pump chambers to the connection channel. Since the vertical channels have the same demolding direction as the pump chambers on the proximal side and the connection channel groove on the distal side of the base plate, the base plate can readily be made by injection-molding a plastic material. 
         [0018]    In an embodiment of the present invention, the peristaltic pump can, for example, be a microfluidic peristaltic pump, wherein the pumping volume of a pump chamber is smaller than 10 μl. Observing the allowable tolerances is technically challenging, for example, with a microfluidic peristaltic pump, so that, for example, with respect to microfluidic peristaltic pumps, the present invention will lead to particular simplifications in the manufacture of a water analysis device using such a peristaltic pump. 
         [0019]    In an embodiment of the present invention, the water analysis device can, for example, be formed by a base module including all electric components and an exchangeable cartridge module comprising the entire fluidic system including the peristaltic pump. The cartridge module may be a one-way article that is replaced and discarded when depleted or damaged. 
         [0020]    In a schematic general view,  FIG. 1  illustrates a process water analysis device  10  used for a quasi-continuous quantitative determination of an analyte in water  11 . In the present case, the water analysis device  10  is fully immersed into the water  11  to be analyzed, i.e., it is designed as a so-called immersion probe. The water analysis device  10  is modular and is formed by a base module  12  containing all electric components and an exchangeable cartridge module  14  comprising the entire fluidic system which, in the present instance, is of microfluidic design. The cartridge module  14  is used only once and is replaced and discarded when depleted or in the event of a defect. 
         [0021]    The cartridge module  14  comprises a carrier liquid tank  16  connected to the pump inlet of a pneumatically operated multi-chamber peristaltic pump  18  via a liquid conduit. The pump outlet of the peristaltic pump  18  is connected to a dialysis element  20  via a liquid conduit, in which element the analyte migrates from the water  11  into the carrier liquid. 
         [0022]    A liquid conduit connects the dialysis element  20  to a measurement section  22 , with a reagent being introduced at some point along this liquid conduit, which reacts, for example, in a color changing manner with the analyte to be determined. The measurement section  22  is associated with an analysis device  24  on the side of the base module, which device may, for example, be designed as a photometer, and determines the extinction of the liquid in the measurement section  22 . The liquid is thereafter pumped into a waste tank  28 . 
         [0023]    The part of the peristaltic pump  18  on the side of the cartridge module is formed by a pump system whose actuation system is arranged in the base module  12 . The actuation system is formed by an overpressure accumulator  30  and a vacuum accumulator  32 , a pneumatic pump (not illustrated) that is connected to the overpressure accumulator  30  and the vacuum accumulator  32  and generates the necessary overpressure and vacuum, respectively, and three electrically switched change-over valves  34  that connect either the overpressure accumulator  30  or the vacuum accumulator  32  to the associated pump membrane of the peristaltic pump  18 . 
         [0024]    The peristaltic pump  18  is shown in detail in  FIG. 2 . The peristaltic pump  18  comprises a plastic material base plate  40  which has its proximal side provided with three pump chambers  41 ,  42 ,  43  as spherical recesses having a proximal opening. On the proximal side  44  of the base plate  40 , a liquid-tight and elastic pump membrane  46  is arranged that closes the openings of the three pump chambers  41 ,  42 ,  43 . The pump membrane  46  is formed from a fluorinated or partly fluorinated elastomer, for example, a material known by the name Viton, and has a thickness of 0.1 to 0.4 mm. As an alternative, the pump chambers  41 ,  42 ,  43  could also be closed with a separate individual pump membrane. Such a membrane may be formed by a circular membrane with an annular bead at the edge. 
         [0025]    Proximal of the pump membrane  46 , a cover plate  48  is applied onto the pump membrane  46 , wherein the cover plate  48  has three pneumatic actuator channels  51 ,  52 ,  53  which are approximately perpendicular to the base plane of the base plate  40 , each being aligned with the respective pump chamber  41 ,  42 ,  43  and ending approximately in the center of the pump chamber openings. 
         [0026]    From each pump chamber  41 ,  42 ,  43 , two vertical channels  60 - 65  respectively extend transversely to the base plane of the base plate  40  to the distal side of the base plate  40 . Each pump chamber  41 - 43  has a respective vertical inlet channel  60 ,  62 ,  64  and a respective vertical outlet channel  61 ,  63 ,  65 . The vertical outlet channel  61  of the first pump chamber  41  is connected to the vertical inlet channel  62  of the second pump chamber  42  through a horizontal connection channel  71 . The vertical outlet channel  63  of the second pump chamber  42  is connected to the vertical inlet channel  64  of the third pump chamber  42  through another horizontal connection channel  73 . The two connection channels  71 ,  73  are each formed as a distally open groove  70 ,  72  on the distal side of the base plate  40 . In the region of the connection channels  71 ,  73 , the distal side of the base plate  40  is covered by a separate groove cover  80  which is formed by a flexible transparent cover film  80  and distally covers the two connection channel grooves  70 ,  72 . 
         [0027]    The base plate  40  and the cover film  80  are made from the same plastic material so that they have the same melting point, and they are welded together fluid-tightly by laser welding or ultrasound welding. Heat sealing or thermal bonding can alternatively be used. 
         [0028]    The vertical inlet channel  60  in the first pump camber  41  forms the pump inlet and the vertical outlet channel  65  of the third pump chamber  43  forms the pump outlet. 
         [0029]    By correspondingly switching the associated change-over valve  34 , pneumatic overpressure can be applied onto the proximal rear side of the pump membrane  46  through the actuator channels  51 ,  52 ,  53  so that the contents of the respective pump chamber  41 ,  42 ,  43  is expelled. By changing over the change-over valve  34 , vacuum can be applied from the vacuum accumulator  32  onto the proximal rear side of the pump membrane  46  so that the same is withdrawn into the initial position illustrated in  FIG. 2 , whereby the respective pump chamber  41 ,  42 ,  43  is filled. 
         [0030]    By filling the first pump chamber  41  and by subsequently filling the second pump chamber  42  while the first pump chamber  41  is emptied at the same time, and by subsequently filling the third pump chamber  43  while the second pump chamber  42  is emptied at the same time, a peristaltic pumping of the liquid from the pump inlet to the pump outlet is realized. 
         [0031]    The absolute pressure in the overpressure accumulator  30  is at approximately 2.0 bar, and the absolute pressure in the vacuum accumulator 32 is at approximately 0.5 bar. 
         [0032]    The largest diameter of the pump chambers 41-43 is 1.0 to 5.0 mm, the vertical height is 0.1 to 2.0 mm, so that he pump chambers 41-43 have a volume of approximately 1.0 to 20 μl, respectively. 
         [0033]    The present invention is not limited to embodiments described herein; reference should be had to the appended claims.