Comment on “MEMS-based high speed scanning probe microscopy” [Rev. Sci. Instrum. 81, 043702 (2010)]

In a recent article, Disseldorp et al. [Rev. Sci. Instrum. 81, 043702 (2010)] present a micromachined z-scanner for scanning probe microscopy (SPM). The scanner comprises a micromachined electrostatically actuated membrane anchored to its substrate with crab-leg flexures. This structure is used as a fast actuator specifically for atomic force microscope and scanning tunneling microscope. The authors present topographic images acquired using the scanner in this paper and elsewhere [F. C. Tabak et al., Ultramicroscopy 110, 599 (2010)]. Although the work is clearly described, it does not appear to be placed in proper context. For example, the authors claim that previous work on microelectromechanical systems SPM has not been focused on high-speed imaging with feedback, which is not supported by the existing literature. In addition, similar actuator structures, albeit slightly larger scale, have been designed and used for SPM applications. Here, we would like comment briefly on the existing literature to clarify the significance of the work.