The rate of flow above the sensitive area is lower if the liquid flows along it from the front (curvesb) because a region of relatively high back pressure and low turbulence is generated above the sensor cavity. (Quelle: bmb+f Forschungslandkarte Deutschland 1998)
This region is inside a circular cavity with a depth of 0.3mm and a diameter of 1.1mm at the bottom (Fig.2a). (Quelle: bmb+f Forschungslandkarte Deutschland 1998)
This is partly because the sensor itself disrupts the flow in its vicinity, but also because the chemically sensitive surface lies at the bottom of a cavity in the sensor chip casing where the exchange of liquid is partly obstructed. (Quelle: bmb+f Forschungslandkarte Deutschland 1998)