Bringing real-time traceability to high-speed atomic force microscopy

Abstract

In recent years, there has been growth in the development of high-speed AFMs, which offer the possibility of video rate scanning and long-range scanning over several hundred micrometres. However, until recently these instruments have been lacking full traceable metrology. In this paper traceable metrology, using optical interferometry, has been added to an open-loop contact-mode high-speed AFM to provide traceability both for short-range video rate images and large-area scans made using a combination of a high-speed dual-axis scanner and long-range positioning system. Using optical interferometry to determine stages’ positions and cantilever displacement enables the direct formation of images, obviating the need for complex post-processing corrections to compensate for lateral stage error. The application of metrology increases the spatial accuracy and linearisation of the high-speed AFM measurements, enabling the generation of very large traceable composite images.

Digital Polymerase Chain Reaction Paired with High-Speed Atomic Force Microscopy for Quantitation and Length Analysis of DNA Length Polymorphisms

“…Single-molecule imaging requires less material, which minimizes invasive biopsies and allows for additional testing per sample, and there are statistical advantages to single-molecule resolution over bulk methods: for example, individual species can be identified and quantified after multiplexing with low-cycle-number PCR, and the Bayesian approach we applied here can be extended to sophisticated hierarchical models . In addition, unlike a narrow-range CE like that employed in the Leukostrat assay, HSAFM can image DNA of virtually any length by stitching together multiple overlapping HSAFM images, , and HSAFM images can convey more than length: as we previously showed, labeling a target motif with programmable Cas9 and imaging to reveal the Cas9 molecules bound to strands allows on-target DNA to be distinguished from off-target, improving specificity.…”

Characteristics and Functionality of Cantilevers and Scanners in Atomic Force Microscopy

“…Using the flexural stage and interferometric position measurement system, the natural frequency of the scanner x-and y-axes can be increased to 4.37 kHz and 3.75 kHz, respectively. As a result, this design achieved a scanning speed of 8 mm/s [104].…”

Multiple-fibre interferometry setup for probe sample interaction measurements in atomic force microscopy

“…In this family of techniques the probe is used as a height sensor, travelling very fast over the surface, surpassing the speed limitations of all conventional approaches [11]. The cantilever surfs above the surface and deflects by an amount corresponding to the surface topography since there is no closed loop correction [12]. From a metrology point of view, this approach is limited by the presence of different ringing artefacts related to cantilever vibration excitation when scanning across topographical features [13].…”