Non-Invasive Potentiometric Sensor for Measurement of Blood Urea in Human Subjects Using Reverse Iontophoresis

Abstract

A Screen printed potentiometric urea biosensor is developed to monitor the blood urea level non-invasively using reverse iontophoresis (RI). The working electrode is screen printed using graphitic carbon paste, reference and RI electrodes are screen printed using silver/silver chloride (Ag/AgCl) paste. Urease enzyme is immobilized in the polypyrrole (PPy) matrix of the working electrode using optimized cyclic voltammetry parameters to obtain maximum sensor performance. Electrochemical and material characterizations conducted in the Screen Printed Reference Electrodes (SPRE) are examined to ensure their stability and retention of their properties. The developed screen printed sensors exhibited sensitivity of 35.07 mV/decade and showed liner response for the range, 10 μM to 5 mM with a correlation co-efficient of 0.995. Interference studies with KCl, NaCl and MgCl2 solutions are performed and it was found that sensor performance is unaffected due to interference ions. The urea sensor is further validated by conducting clinical investigations on 15 human subjects. A correlation is established between blood urea level and transdermal extracted urea level and the correlation co-efficient is found to be 0.391.