Flexible Force Sensor Based on C-axis Oriented Aluminum Nitride

Force sensors are key components in a wide range of high-controlled environments and operations. Force sensors based on piezoelectric transduction mechanism are particular attractive since they are able to provide electrical signals even without power supply. Among the most investigated materials for force sensing, aluminum nitride (AlN) has the peculiar properties of high isolation and the highest thermal conductivity. Despite the piezoelectric coefficient d33 is moderate, AlN thin films integrated on polymeric substrates improve the piezoelectric response of the sensor as a whole. This work presents a promising technology based on piezoelectric highly c-axis oriented aluminum nitride integrated on Kapton substrate, which provides a self-induced three-dimensional structure dome shaped. The flexible piezoelectric transducers realized by this technology detect normal contact forces in the load range of interest for robotics application, with an improvement of the output voltages with respect to similar sensors based on silicon.