Electrical and mechanical field interactions of piezoelectric systems: foundation of smart structures-based piezoelectric sensors and actuators, and free-fall sensors

Based on an idea to fully integrate the advantages of both distributed and point sensors, we adopted mathematical tools such as method of image, linear superposition, and window functions to develop a fundamental approach towards creating no-phase delay filters for finite sensor structures. Through an expanded design freedom for piezoelectric sensors and actuators as a result of adding in situ, we can obtain a no-phase delay signal filtering capability by properly designing an effective surface electrode onto the piezoelectric layer. An inertia-based free-fall sensor that can measure the start of free-fall motion in addition to creating a piezoelectric sensor and actuator pair that possesses a spatial dependent transfer function and demonstrates the wide range applicability of the new concepts are disclosed. The fundamental perspective of pursuing signal processing through an electromechanical interaction of wave modes and of piezoelectric materials is examined in detail. It can be shown that the fundamental design criteria of electromechanical-coupled systems are highly related to the temporal and spatial characteristics of the mechanical structure and its electrical interaction between interface circuits. After pursuing the physical characteristics of these systems, the possibilities of extending the no-phase delay signal processing capabilities to other physical fields are discussed as well.