Valves traditionally used in high-pressure liquid chromatography (HPLC) systems typically operate under high-pressure (about 1 to 400 bar or higher) and allow switching between inlet and outlet ports or allow a single port to be selectively connected to one or more outlet ports. Due to the high-pressure requirements, large forces need to be applied to the components to maintain a seal between them, which has typically been implemented by using screws to hold the components in place. This method of affixing the components is effective and, depending on the size of the system and the screws, high holding-forces can be generated. In addition, this system works for valve systems that do not need maintenance often or for systems that do not need valve components changed or replaced. There are, however, disadvantages to using screws to provide the high forces necessary to ensure seal formation. First, it is difficult to apply the force directly and evenly between the various components, particularly when tightening and loosening the screws. Because the screws are distributed around the perimeter of a typical interface, it is inherently difficult to tighten the screws such that an even force is applied among the components unless all the screws are tightened simultaneously. Second, if the one or more components need to be removed repeatedly and often, it is time-consuming and possible to damage one or more of the components. Third, once screws are removed from the system, they are loose and subject to misplacement or loss.
Microfluidic devices can be used within HPLC or HPLC-like valves and devices to great effect (U.S. Pat. No. 6,702,256, which is incorporated herein by reference), solving the historically challenging process of connecting traditional fittings and equipment to microscale components. However, using screws to mount these devices is, for the above reasons, undesirable. Thus, for any system that requires frequent and(or easy exchange of parts (e.g., microfluidic devices and HPLC stators) it is preferable to use a method of mounting that does not use screws.
USPTO Backgrounds
USPTO Backgrounds