A super-twisting observer for atomic-force reconstruction in a probe microscope. (January 2020)

• Record Type: Journal Article
• Authors: Zhang, Kaiqiang; Hatano, Toshiaki; Nguyen, Thang Tien; Edwards, Christopher; Herrmann, Guido; Burgess, Stuart; Antognozzi, Massimo; Khan, Said; Harniman, Robert; Miles, Mervyn
• Is Part Of: Control engineering practice. Volume 94(2020)
• Publication Date: 2020-01
• Subjects: Probe microscope -- Shear force -- Elastic and dissipative force -- Sliding mode control -- Super-twisting observer; Automatic control -- Periodicals; 629.89
• DOI: 10.1016/j.conengprac.2019.104191
• Languages: English
• ISSNs: 0967-0661

Abstract

Abstract: This paper presents a new methodology, employing a super-twisting sliding mode observer, to reconstruct un-measureable atomic-forces at nano-Newton precision in a Vertically Oriented Probe Microscope (VOPM). The VOPM senses the deflection of a vertically oriented cantilever, caused by shear-force interaction with a confined water layer above the sample-substrate. The paper describes the development of a model and the subsequent experimental process for computing its parameters. This forms the basis for the design of a super-twisting observer to estimate the unknown shear-forces. The reconstructed force can be decomposed into elastic and viscous components, which are important in biological research.