Apparatus for analyzing liquid samples automatically and continually

An apparatus for mixing liquid reagents thereby to cause a reaction in which the reagents react chemically and for analyzing, by means of a sensor, a sample of liquid resulting from the reaction, comprising:

• a substrate having a micropump including an inlet conduit and an outlet conduit etched in the substrate and a pumping chamber etched in the substrate and connected to the inlet conduit and the outlet conduit, the pumping chamber having a volume which expands and contracts during a complete pump cycle;
• said substrate having a mixing chamber etched thereon and connected to said outlet conduit;
• said inlet conduit having an effective flow cross section different from that of said outlet conduit such that over the complete pump cycle net fluid flow is from the inlet conduit and out the outlet conduit;
• and
• a covering layer covering said substrate to seal said pumping chamber, said inlet conduit, said outlet conduit and said mixing chamber;
• wherein said pumping chamber contracts and expands such that a flow in the inlet conduit is laminar entering said pumping chamber and turbulent exiting said pumping chamber and a flow in the outlet conduit is laminar both entering and exiting said pumping chamber.