Using a single structure for three sensor operations and two actuator operations

In many process control applications, a set of separate existing sensor str uctures is placed in the environment of interest and not much attention is being paid to the integration of these structures and even less to the poss ibility of combining the measurement results obtained from these sensor str uctures. However, a new trend in chemical sensing is the development of sen sor arrays and the use of more than one transduction principle applied to t he same selective layer (J. Janata, M. Josowicz, Chemical sensors, Anal. Ch em. 70 (1998) 179R-208R). An integrated sensor structure with the highest l evel of integration was developed and tested. The structure with a size of 1 mm(2) can be accessed by only four contacting leads. By scheduling this s tructure in different modes, several sensing modes are selected for determi ning electrolyte conductivity, temperature and hydrogen peroxide concentrat ion, where the latter one represents one example of many species that can b e determined amperometrically. In addition, two actuator functions using th e same single structure were tested as well: the local environment was ther moresistively heated and a local pH gradient was created by the electrolysi s of water. The two actuator operations together with the three sensor oper ations makes the structure an excellent starting point for many local exper iments, which will lead to the determination of more environmental paramete rs than the number of sensors present in the array. (C) 1998 Elsevier Scien ce S.A. All rights reserved.