A Novel Urea Sensor Using CuO/ZnO Fabricated Diode

This work presents fabrication of a biodiode using ZnO and CuO for detection of urea. Before immobilization of urease (enzyme) electrical response was recorded by Keithley Source Meter (KSM) at voltages from -5.0 to +5.0 V in steps of 0.1 V and then 2 μI urease solution was immobilized by physical adsorption technique at the depletion width of the diode with the help of glutareldehyde as cross-linker. Electrochemical response of this diode for urea concentration from 0.1 to 100 mM was recorded by KSM at the same diode voltages. It is observed that the biodiode has urea sensitivity of 488 uA/mM/cm
²
, shelf life of 180 days under experiment and diode knee voltage of -2 V and breakdown voltage of -5 V. The fabricated CuO/ZnO biodiode could be used for measurement of other biomolecules also.