On-Chip Feedthrough Cancellation Methods for Microfabricated AFM Cantilevers With Integrated Piezoelectric Transducers

Active microcantilevers with on-chip sensing and actuation capabilities provide significant advantages in tapping-mode atomic force microscopy. The collocated transduction in active cantilevers enables effective control of their dynamics, allowing for the modification of the quality (Q) factor and operation at higher flexural modes to obtain higher scan rates. However, having closely spaced transducers in dynamic applications often results in electrical crosstalk from the actuation signal to the sensor output. As a result, the dynamic response of the cantilever becomes heavily dominated by this feedthrough, making the use of on-chip transduction impractical for atomic force microscope (AFM) imaging without cancelling this undesired effect. In this paper, we propose two on-chip feedthrough cancellation methods based on pseudo-differential actuation and differential sensing concepts. The implementation of the methods is demonstrated by the use of two microfabricated cantilevers with separate piezoelectric sensors and actuators. Following the cancellation of the feedthrough, both cantilevers are successfully employed for AFM imaging using the on-chip transducers for actuation and deflection sensing. [2017-0101].