MEMS Nanopositioner for On-Chip Atomic Force Microscopy: A Serial Kinematic Design

The design and characterization of a two-degree-of-freedom serial kinematic microelectromechanical systems (MEMS) nanopositioner for on-chip atomic force microscopy (AFM) is reported. A novel design is introduced to achieve a serial kinematic mechanism based on a standard silicon-on-insulator MEMS fabrication process. The nanopositioner comprises a slow axis with a resonance frequency of 2.4 kHz and a fast axis with a resonance frequency of above 4.4 kHz, making it ideal for rastering, as required in the AFM. Strokes of 14 and 9 μm are experimentally achieved for the fast and slow axes, respectively. The serial kinematic design of the stage enables the cross-coupling between the two axes of motion to be as low as -60 dB. Electrothermal displacement sensors are incorporated in the device, which may be used to enable feedback control as required in high-speed AFM.