1. Field of the Invention
The invention relates in general to a flow cell with at least two inlet channels. Each of the inlet channels is connectable with a reservoir and controllable by means of valves. The inlet channels end in an inlet chamber. The inlet chamber has a common discharge channel.
2. Description of Related Art
Flow cells are known to be used in micro systems for chemical analysis techniques. This concerns planar micro systems having substrates of glass, silicium, plastic or other materials. These systems are also known under the name “Lab on a chip”. They have built-in micro-valves, channels for fluid transport, and reservoirs for fluid. The channel structure can be produced by etching, milling, boring, die-casting, hot embossing, and other methods.
It is a disadvantage of prior systems that the latest transported fluid always remains in the chamber where it pollutes the next fluid to be transported. Rather long dead times are required before an analysis can be made with a new fluid. The first mentioned fluid remains in corners and dead spaces making complete removal extremely difficult. This is especially common when more than two inlet channels are utilized.
In an infusion arrangement as shown in U.S. Pat. No. 5,431,185, it is disclosed that drugs are added to the infusion solution via three inlet channels, the channels being controllable by valves. Pollution is avoided because the continuously incoming infusion solution acts as rinsing fluid.
Previous flow cells included multiple inlet channels, one or several discharge channels, and a cell structure constituted by a single line channel. In a flow cell structure having a single line channel, a shift of fluid ingress into the flow cell from a first inlet channel to inlet channels more advanced in the flow cell would result in a dead space volume in the channel portion extending between more advanced inlet channels and the initial inlet channel. Significant disadvantages result from this dead space volume, such as, increased rinsing time and impurities in the fluid leaving the flow cell at discharge channel. The previous flow cells suffered these disadvantages and dead end spaces resulted in the flow cell which were difficult to rinse out causing long rinsing times and creating the risk of impure fluid volumes.
It can be seen that there is a need for a flow cell having an endless loop manifold to avoid and eliminate dead end spaces, reduce rinsing times, and improve fluid purity.