Capacitance transducer using a thin dielectric and variable-area electrode

A miniature capacitance transducer, having a high capacitance and displacement sensitivity, is described. It uses a thin dielectric film on a fixed plate electrode (anodised tantalum), and a variable-area electrode (a gold-coated flexible elastomer dome). An experimental transducer of diameter 7 mm and depth 1 mm has a full-scale capacitance of about 300 pF and a sensitivity of over 2 000 pF/mm.