A THICK-FILM CAPACITIVE PRESSURE SENSOR WITH IMPROVED LINEARITY DUE TO ELECTRODE-SHAPING AND FREQUENCY-CONVERSION

Various methodologies are applied to the measurement of pressure. Amon g them, the capacitive pressure sensor is one of the most useful devic es due to its high performance-to-price ratio, reliability and low pow er consumption. However, the early versions of capacitive pressure tra nsducers had a general reputation of being highly nonlinear. This pape r discusses a design approach to overcome this problem by choosing a n ew electrode shaping and coupling the sensor with an electronic circui t based on a relaxation oscillator. Moreover, the output signal in the form of a frequency makes the distance transmission and the interfaci ng with digital systems easier. The theory of operation is presented w ith a description of the sensor's implementation in thick-film technol ogy on ceramic substrates and with experimental results on its charact erization.