Differential thick-film amperometric glucose sensor with an enzyme-immobilized nitrocellulose membrane

A disposable glucose sensor based on a differential amperometric measuremen t is fabricated on activated carbon paste electrodes with the use of a gluc ose oxidase (GOx)-immobilized nitrocellulose (NC) membrane. Two identical t hree-electrode cells are screen-printed symmetrically on both faces of a si ngle polyester (PE) substrate. Both electrodes of the two-sided sensor stri p are covered with NC membranes incorporating a mediator (K-3[Fe(CN)(6)]), one membrane with GOx and the other with bovine serum albumin (i.e., no GOx ): the former serves as a glucose-sensing cell and the other as a reference cell. In the differential measurements between these two cells, the respon se signals toward various redox species other than glucose cancel out. Prio r to placing the NC membranes, the working carbon paste electrodes are pret reated by anodizing them in saturated sodium carbonate at 1.2 V (vs. SCE): the electrochemical reversibility of the mediator is found to be enhanced s ignificantly on such an activated electrode. The analytical performance of the proposed differential glucose sensor strip is demonstrated by measuring glucose values in normal and abnormal serum samples: 5.08 +/- 0.52 (found) vs. 5.10 +/- 0.46 (listed), and 16.56 +/- 1.71 (found) vs. 16.92 +/- 1.72 (listed).