Differential setup of light-addressable potentiometric sensor with an enzyme reactor in a flow channel

The light-addressable potentiometric sensor (LAPS) was combined with an enzyme reactor in a fluidic channel. The fluidic channel was mounted on the sensor plate and the enzyme reactor was connected to the fluidic channel. The enzyme reactor was filled with glass beads as enzyme carrier modified by urease which catalyzed production of ammonia depending on the concentration of urea. Double-channel LAPS measurement was performed at the both side of upper and lower stream of the enzyme reactor which realized a differential measurement and eliminated the drift component of the measurement.