High-speed force mapping based on an astigmatic atomic force microscope

Abstract

The force mapping function in an atomic force microscope (AFM) can be used to measure mechanical properties at the nanoscale. Currently, the temporal and spatial resolutions of force mapping are mainly limited by the bandwidths of the scanner and the cantilever tip. The measurement speed can be improved by using an ultra-small cantilever tip. However, a customized read-out system is essential for detecting the cantilever deflection. In this study, a high-speed force mapping mode was built on an astigmatic high-speed AFM. The experimental results demonstrated that this homemade system achieved a high-speed force-curve rate of 6.1 kHz and scan rate of 12 line s−1 (21 s/frame) with an image resolution of 256 × 256 pixels. The sample stiffness mapping qualitatively distinguished the polystyrene and polyolefin elastomer materials.

Characterization of higher-order resonant cantilevers for density determination in different flowing liquids

“…On the other hand, the resonator with a higher working frequency directly induces a reduction in vibration amplitude, thus bringing difficulties for electrical characterization. A common approach for resonator output detection in in-liquid applications still relies on optical measurement [2][3][4][5]45], which is largely limited by its bulky and alignment-dependent. In comparison, a low frequency of the resonator is desirable not only for the flexibility of the electrical readout, but also for reducing the viscoelastic effect [46] when sensing the widespread non-Newtonian liquid.…”

“…The resonant device based on micro-electromechanical systems (MEMS) technology has been employed in widespread applications for determining chemical and physical properties in liquid media. For decades, the dynamic-mode cantilevers have received extensive attention for decades, such as in density and viscosity monitoring [1][2][3][4], the material imaging by AFM (atomic force microscope) [5], and the biochemical active molecule and particle detection [6][7][8]. In order to make the most beneficially use of their capabilities of simplicity, reliability, high sensitivity, and mature fabrication process, diverse cantilevers were designed with different structural shapes [9,10], actuation and sensing methods [11][12][13], and vibration modes [14,15].…”

Low-cost, open-source XYZ nanopositioner for high-precision analytical applications

“…The nanopositioner provides long-range stepping and high-resolution scanning modes, which are convenient for X – Y axes coarse adjustment/ Z -axis tip motion and atomic-resolution imaging, respectively. Crucially, the DVD OPU monitors the AFM probe at atomic resolution [54] , [55] , [56] , [57] , [58] , [59] , [60] . To characterize the performance of the ‘Espresso AFM’ system, a highly oriented pyrolytic graphite (HOPG) sample was used.…”

PeakForce AFM Analysis Enhanced with Model Reduction Techniques

“…In this particular AFM mode, the tip is intermittently brought into contact with the sample by monitoring the cantilever deflection, thus avoiding any potential surface damage and greatly reducing the lateral force during tip–sample interaction. More importantly, the force–indentation data are generated separately for each tip oscillation (pixel per pixel) inside the region of interest (ROI), whereby the applied maximum force of the nano-indentation (the so-called PeakForce) can be held constant, allowing for quantitative, robust and detailed mapping of various mechanical properties as well as on-the-fly topography comparison [ 9 , 10 , 11 , 12 ]. This AFM mode is a major step forward in characterizing heterogeneous multi-phase materials at the nanometre scale.…”