Three-Axis Acceleration Sensor Using Polyurea Films

Focusing on the possibilities of polyurea as an acceleration sensor with characteristics such as flexibility, durability against large deformation, good linearity, and capability of deposition in dryprocess and insolubility in organic solvent, we first fabricated a cantilever acceleration sensor and a three-axis acceleration sensor. The output voltage in the large-strain region is measured using a polyurea cantilever sensor attached to a beryllium copper substrate. The results show that output voltages have good linearity for large strains up to 1%. This value is much larger than the breakdown limit of lead zirconate titanate. Second, we fabricated a polyurea three-axis acceleration sensor. The sensor consists of an insulation layer of polyurea on the cross beam substrate of phosphor bronze, a bottom aluminum electrode, a polyurea active layer, and four top aluminum electrodes. The experimental results for harmonic acceleration show that the sensor works as expected. The cross-axis sensitivity of the polyurea sensor was less than 8%, which is close to that of conventional microelectromechanical system sensors. [DOI: 10.1143/JJAP.47.4044]