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

In many process control applications, a set of separate existing sensor structures 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 possibility of combining the measurement results obtained from these sensor structures. However, a new trend in chemical sensing is the development of sensor arrays and the use of more than one transduction principle applied to the same selective layer (J. Janata, M. Josowicz, Chemical sensors, Anal. Chem. 70 (1998) 179R–208R). An integrated sensor structure with the highest level of integration was developed and tested. The structure with a size of 1 mm2 can be accessed by only four contacting leads. By scheduling this structure in different modes, several sensing modes are selected for determining electrolyte conductivity, temperature and hydrogen peroxide concentration, where the latter one represents one example of many species that can be determined amperometrically. In addition, two actuator functions using the same single structure were tested as well: the local environment was thermoresistively heated and a local pH gradient was created by the electrolysis of water. The two actuator operations together with the three sensor operations makes the structure an excellent starting point for many local experiments, which will lead to the determination of more environmental parameters than the number of sensors present in the array.