Comparison of Urea Determination in Biological Samples by EnFETs Based on pH and pNH4 Detection

In this paper urea biosensors based on detection of pH and ammonium ions are presented. As transducers pH-sensitive ion-selective field effect transistors (ISFETs) and chemically modified FETs (ChemFETs) snsitive to ammonium ions were used.Results concerning urea determination by the bisensors in blood plasma and in dialysate show that the biosensors can be applied for urea monitoring in the effluent dialysate. However in the case of pNH 4 based EnFETs a special pre-treatment (dilution with tris/HCl buffer) of the samples is necessary.