Electrochemical enzyme-less urea sensor based on nano-tin oxide synthesized by hydrothermal technique.

Nano-Tin oxide was synthesized using hydrothermal method at 150 °C for 6 h and then thin films were deposited by electrophoretic method at an optimized voltage of 100 V for 5 min on electropolished aluminum substrate. Spherical particles of about 30-50 nm diameters are observed with partial agglomeration when observed under electron microscope, which are tetragonal rutile structure. XPS results showed peaks related to Sn 4d, Sn 3d, O 1s & C 1s with spin-orbit splitting of 8.4 eV for Sn 3d. Feasibility studies of enzyme less urea sensing characteristics of nano-tin oxide thin films are exhibited herein. The deposited films have been used for enzyme less urea sensing from 1 to 20 mM concentration in buffer solution. The sensors were characterized electrochemically to obtain cyclic voltammogram as a function of urea concentration and scan rate. The sensitivity is estimated as 18.9 μA/mM below 5 mM and 2.31 μA/mM above 5 mM with a limit of detection of 0.6 mM.