Development of needle-type glucose sensor with high selectivity

An amperometric needle-type glucose biosensor employing rhodium as electrocatalyst for hydrogen peroxide detection is described. A novel transducer design is based on electrodeposition of rhodium particles on the external wall of the needle which serves as the working electrode and an external Ag/AgCl reference/counter electrode. Electropolymerized 1,3-diaminobenezene (1,3-phenylenediamine) is employed as a protective layer for the rhodium particles as well as an interference eliminating layer. This configuration uses the rhodium electrocatalyst in its most active dispersed form and ensure good mechanical rigidity. At the same time, because of the large working surface area, it provides a large sensitivity for the sensor response. The use of rhodium electrocatalyst allows detection of H2O2 at low working potential of + 0.25 V. Electrophoretic deposition of enzyme on the needle surface followed by cross-linking with glutaraldehyde was chosen for the immobilization of glucose oxidase (GOD) on the needle surface. Nafion was used as external diffusion control and additional interference eliminating layer, which extend the linear range of the sensor response to over 25 mM glucose concentration. These biosensors demonstrated diminished response to interference from oxidizable compounds present in body fluids and a life time of at least 3 months. (C) 1998 Elsevier Science S.A. All rights reserved.