Abstract:
A wash system for a fluid handling system that permits simultaneous washing of a plurality of parallel fluid channels is disclosed. In one aspect of the invention, a specialized rotary wash valve is described. In another aspect of the invention a system which incorporates wash and selector valves is described which permits a plurality of separate fluid lines emerging from the selector valve to be washed simultaneously.

Description:
BACKGROUND OF THE INVENTION 
     The present inventions relate generally to rotary valve based fluid handling systems. More particularly, wash delivery systems that permit simultaneous washing of multiple output fluid paths from a rotary valve are described. 
     Recent advances in drug discovery have produced an overwhelming number of drug-like compounds to be tested for activity against protein targets. These drug-like compounds have various origins including natural products, and compounds produced through traditional organic syntheses and combinatorial syntheses. Typically, the drug-like compounds are archived in compound libraries at differing concentrations. Retrieval and dilution (e.g., normalization), of such compounds is generally performed with multiple precision metering devices attached to multiple distinct channels, with each channel being capable of independently performing a dilution. The precision metering devices are preferably capable of delivering very small (e.g. sub-microliter magnitude) precise amounts of the retrieved (and possibly diluted) compounds for testing. 
     In all liquid handling systems a cleansing of the fluid channels must be accomplished prior to the manipulation of the next compound. This cleansing can be achieved by washing the channels or, alternatively, by attaching a new disposable tip. Disposable tips are extremely expensive in the context of compound screening where an extensive library may contain as many as a million or more samples. Thus, washing the channels is generally preferred. However, the washing step can be a rate limiting factor in the liquid handling protocol. Accordingly, improved precision liquid handling systems that can incorporate simultaneous washing of a plurality of different fluid channels would be desirable. 
     SUMMARY OF THE INVENTION 
     To achieve the foregoing and other objectives, and in accordance with the purpose of the present invention, a wash system for a precision fluid handling system that permits simultaneous washing of a plurality of parallel fluid channels is disclosed. In one aspect of the invention, a specialized rotary wash valve is described. In another aspect of the invention a system that incorporates independent wash and selector valves which permits a plurality of separate fluid lines emerging from the selector valve to be washed simultaneously is described. 
     In one system aspect of the invention, independent wash and selector valves are utilized. The selector valve has a selector input port and a plurality of selector output ports. Each selector output port has an associated dispensing line. The selector valve has a number of different working positions which each make a fluidic connection between the selector input port and a particular one of the selector output ports. The wash valve has a wash fluid input port and a plurality of wash fluid output ports. Each wash output port has an associated wash line that is coupled to an associated dispensing line. In a first working position, the wash valve makes a fluidic connection between the wash fluid input port and the plurality of wash fluid output port. In a second working position the wash fluid input port is disconnected from the plurality of wash fluid output ports. With this arrangement, all of the dispensing lines may be washed in parallel by simply opening the wash valve. 
     In a preferred embodiment, both the wash valve and the selector valve are rotor based valves that have a rotor face plate that rotates relative to a stator face plate to make and decouple fluidic connections between their respective input and output ports. 
     In another aspect of the invention a unique rotary wash valve structure is described. In this embodiment the rotor face has a central recess and a multiplicity of angularly spaced grooves that extend radially outward from the central recess. The stator has a stator face that has a central passage that opens opposite the central recess of the rotor face and extends to the wash fluid input port. The stator also has a plurality of outer holes that each couple to an associated wash fluid output port. Each outer hole is aligned with an associated groove when the valve is disposed in a first position. The rotor face and stator are arranged such that when the valve is rotated to a second position, the outer holes do not have any fluidic connection with the grooves such that the outer holes are all substantially dead-headed at the rotor face. one embodiment, the only openings in the rotor face are the central recess and the multiplicity of grooves that extend radially outward from the central recess and the valve has just two operational positions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a schematic diagram of a fluid dispensing system that incorporates a parallel wash system in accordance with one embodiment of the present invention. 
     FIG. 2 is an exploded perspective view of a wash valve in accordance with one embodiment of the present invention with the rotor face situated in the wash position. 
     FIG. 3 is an exploded perspective view of the wash valve of FIG. 2 with the rotor face situated in the off position. 
     FIG. 4 is a diagrammatic view of the rotor face of the wash valve illustrated in FIG.  2 . 
     FIG. 5 is a diagrammatic view of the stator face of the wash valve illustrated in FIG.  2 . 
     FIG. 6 is a diagrammatic cross sectional side view of a selector valve highlighting one suitable plumbing arrangement between the wash lines and fluid lines of FIG.  2 . 
    
    
     DESCRIPTION OF THE INVENTION 
     Referring initially to FIG. 1, a precision fluid delivery system  15  that is well adapted for delivering a number of very small precise amounts of liquid using a multiplicity of distinct parallel channels is illustrated. The precision fluid delivery system  15  is based on a multi-channel rotary selector valve  20  and includes a wash valve  30  and a metering system  40  that meters fluids delivered by the selector valve  20 . For the purposes of illustration, a twelve-channel rotary selector valve  20  is shown. However, it should be apparent that the number of channels provided in the selector valve may be widely varied in accordance with the needs of a particular system. Rotary selector valves that are capable of delivering precise, very small volumes of liquid have been available for some time. By way of example, Rheodyne, Inc. of Rohnert Park Calif. produces a number of such rotary selector valves. One example is the RV350-106. 
     The rotary selector valve  20  has a selector input port  22  and a plurality of selector output ports  24 . Each selector output port  24  has an associated dispensing line  26 . The selector valve has a number of different working positions which each makes a fluidic connection between the selector input port  22  and a particular one of the selector output ports  24 . In the embodiment shown, the selector valve  20  has twelve working positions, one for each output port  24 . The input port  22  has an accompanying supply line  28  that is connected to a suitable metering device  40 . In the embodiment shown, the metering device takes the form of a syringe pump  40 , although as will be appreciated by those skilled in the art, any suitable metering device may be used. The use, control and operation of the selector valve  20  will not be described in detail herein since the selector valve may be operated in a wide variety of manners as will be well understood by those skilled in the art. 
     The wash valve  30  has a wash fluid input port  33  and a plurality of wash fluid output ports  35 . Each wash output port  35  has an associated wash line  37  that is coupled to an associated dispensing line  26  (from the selector valve  20 ). In a first working position, the wash valve  30  makes a fluidic connection between the wash fluid input port  33  and the plurality of wash fluid output ports  35 . In a second working position the wash fluid input port  33  is disconnected from the plurality of wash fluid output ports  35 . This can readily be accomplished by deadheading the output ports as will be described in more detail below with respect to FIGS. 2 and 3. With this arrangement, all of the dispensing lines  26  may be washed in parallel by simply opening the wash valve  30 . 
     Referring next to FIGS. 2 and 3, a representative rotary wash valve  30  will be described. The wash valve  30  includes a stator  50 , an independent stator face plate  52  and a rotor  55  having a rotor face  57 . The wash valve also includes a rotor housing  54  that couples to the stator  50 , a drive shaft  59  that co-axially carries the rotor  55  and a drive system  61 . The drive system (not shown in figures), which most commonly takes the form of a stepping motor, is provided to rotate the drive shaft and thus the rotor  55  relative to the stator face  52 . 
     The stator  50  and stator face plate each have an aligned central input channel  65 ,  66  that is fed by the wash valve input port  33 . They also include a plurality of aligned output channels  67 ,  68  that open into the wash valve output ports  35 . In the embodiment shown, the stator  50  and stator face plate  52  are individually formed for ease of manufacturing. In alternative embodiments they could be integrally formed. The stator and/or stator face input and output channels can, in theory, be routed in any manner desired. In the embodiment shown, they take the form of simple straight channels that extend substantially perpendicular to the rotor face  57 . 
     As best illustrated in FIG. 4, the rotor face  57  has a concentric central recess  70  and a plurality of angularly spaced radial channels or grooves  72  that extend radially outward from the central recess thereby forming landings or contact surfaces  73  between adjacent radial channels  72 . As with almost all rotary valves of the type illustrated, the rotor face  57  rests flush against the stator face  53  and preferably forms a substantially leak proof seal. In the embodiment shown, the rotor face has twelve radial channels  72  to match the number of dispensing and wash lines. However, the actual number of radial channels provided in any particular wash valve will depend highly on the desired number of independent wash lines. 
     As described above, in a first working position, the wash valve  30  makes a fluidic connection between the wash fluid input port  33  and the plurality of wash fluid output ports  35 . The wash fluid enters the stator input channels  65  through the fluid input port  33  and pass through the stator face input channel  66  into the central recess  70  in the rotor face  57 . In the first working position, the radial channels  72  are all aligned with corresponding output channels  68  in the face  57 . This makes a good fluidic connection between the wash fluid input port  33  and each of the fluid output ports  35 . 
     In the second working position the rotor is rotated such that the stator face output channel  67  are deadheaded against the contact surfaces  73  in the rotor face  57 . This effectively decouples the wash fluid input port  33  from all of the wash fluid output ports  35 . Also, deadheading the wash valve allows the syringe pump to still accurately aspirate through the selector valve. 
     Referring next to FIG. 6, a suitable arrangement for plumbing the wash lines  37  to the dispensing lines  26  will be described. In the embodiment shown, the wash lines  37  make a simple “T” or “Y” type connection  80  (or any other suitable connection) with the dispensing lines external to the selector valve. When the dispensing lines are being simultaneously washed, the selector valve is typically closed (although this is not an absolute requirement). Thus, in the washing mode, the wash fluid passes directly from the wash lines  37  to the dispensing lines  26 , thereby simultaneously flushing all of the dispensing lines. In the embodiment shown, each wash line is connected to a single unique dispensing line. However, it should be appreciated that in some alternative embodiments, the wash lines  37  could be coupled to more than on dispensing line  26 . 
     The described wash valve and/or wash system can be used in a wide variety of precision fluid delivery systems. In the context of the compound screening systems referred to in the background of this application, the described valve system architecture can provide an order of magnitude higher throughput for compound retrieval and dilution than most conventional delivery systems. This has the potential to facilitate significant improvements in the throughput of such compound screening systems. 
     Although only a few embodiments of the present invention have been described in detail, it should be understood that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Although a particular wash valve construction has been illustrated and described, it should be appreciated that the geometry of the respective stator and rotor faces, the routing of the input and output lines within the stator/stator face, and the general construction of the rotary valve may all be widely varied without departing from the scope of the invention. 
     Further, the selector valve used within the described wash system, as well as the wash line plumbing into the selector valve can be widely varied. As suggested above, the plumbing between the wash lines and the dispensing lines can be external to the selector valve. Alternatively, the selector valve can be constructed to have internal washing capabilities and/or internal connections between the dispensing and wash lines. Therefore, the present examples are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope of the appended claims.