Trilayer AFM cantilever beam with piezoelectric actuation and sensing
Atomic Force Microscopes (AFMs) have revolutionized nanoscale imaging and measurement, with self-sensing cantilevers offering a more compact solution when compared to the traditionally used Optical Beam Deflection (OBD) method. The LBNI group has developed soft, high-force sensitivity self-actuating and self-sensing cantilevers, featuring piezoresistive strain sensing. In this context, piezoelectric sensing specifically offers the advantage of low heat emission when compared to piezoresistive strain sensors, which is critical for applications requiring low or stable temperatures. In piezoelectric sensing, the main challenge relies on charge generation for high deflection sensitivity. This project aims at integrating piezoelectric actuation and sensing into the group’s AFM cantilevers. Finite Element Method (FEM) simulations were conducted to optimize charge generation on the sensing electrodes while reducing actuation-sensing coupling. Additionally, FEM was used to simulate the mechanical properties. Based on these insights, three cantilever designs were fabricated in the cleanroom. A complete tipless wafer was successfully released, with tip formation completed on a second wafer. Preliminary resonance frequency and Q-factor measurements confirm expected device behavior, with displacement curves and phase shifts aligning with expected behavior. Further testing is required to fully characterize actuation performance, and a dedicated sensing circuit must be developed for readout.
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