Developing of low cost capacitive sensors for laboratory classes

This work presents an approach to the education in sensors, targeted to future engineers that relies on using educational sensors. An analysis of major issues on sensor education is carried out and two types of didactic, capacitive and low cost sensors are presented, which allow the student to easily under-stand the physical principle of the measurement, as well as to evaluate other sensor features like repeatability, sensitivity and measurement uncertainty. To this aim, some capacitive sensors have been developed to measure levels of oil and water in the laboratories. In the academic year 2006-07, the Laboratory of Sensors and Signal Conditioning of the Electronic Technology Department of the University of Vigo started using those sensors experimentally. During 2007-08 and 2008-09, a methodology based on these didactic sensors, combined with signal conditioning circuits and simulations in Pspice, has been launched. Then, a signal conditioning circuit is assembled and the information displayed on a PC monitor, connected by a data acquisition system. Furthermore, this paper includes the efficiency evaluation results of the proposed methodology, obtained from student surveys.