Optimization of an ion microsensor using a crystallized membrane and an amorphous semiconductor as impedancemetric transducer

A new kind of sodium sensor was studied by impedance measurement. The sensi tive membrane is a fast ionic conductor (NASICON) coupled with an amorphous semiconductor (a-Si:H). Other materials were also used in a sandwich confi guration to improve the interface between the membrane and the electric con nection, A special multi-contact set-up was fabricated to identify the tran sducing phenomena and to optimize the design and the measuring parameter. F rom this study, it appeared that the best results were obtained with a non- symmetrical cell and by measurement of the real part of the impedance at a constant frequency. The range of sensitivity is similar to the one of poten tiometric sensors using such a membrane. (C) 1999 Elsevier Science S.A. All rights reserved.