Study of thermal and acoustic noise interferences in low stiffness atomic force microscope cantilevers and characterization of their dynamic properties

Abstract

The atomic force microscope (AFM) is a powerful tool for the measurement of forces at the micro/nano scale when calibrated cantilevers are used. Besides many existing calibration techniques, the thermal calibration is one of the simplest and fastest methods for the dynamic characterization of an AFM cantilever. This method is efficient provided that the Brownian motion (thermal noise) is the most important source of excitation during the calibration process. Otherwise, the value of spring constant is underestimated. This paper investigates noise interference ranges in low stiffness AFM cantilevers taking into account thermal fluctuations and acoustic pressures as two main sources of noise. As a result, a preliminary knowledge about the conditions in which thermal fluctuations and acoustic pressures have closely the same effect on the AFM cantilever (noise interference) is provided with both theoretical and experimental arguments. Consequently, beyond the noise interference range, commercial low stiffness AFM cantilevers are calibrated in two ways: using the thermal noise (in a wide temperature range) and acoustic pressures generated by a loudspeaker. We then demonstrate that acoustic noises can also be used for an efficient characterization and calibration of low stiffness AFM cantilevers. The accuracy of the acoustic characterization is evaluated by comparison with results from the thermal calibration.

Quantitative Normal Force Measurements by Means of Atomic Force Microscopy Towards the Accurate and Easy Spring Constant Determination

“…Boudaoud et al verified the impact of the ground vibrations and acoustic noise on the thermal method, as it is very sensitive technique and presence of certain noise may be a source of significant fraction of error [110]. They showed, that at the temperatures 22 o C and higher, the acoustic waves have more significant impact on the soft cantilevers (k<0.1 N/m), than the ground movement in particular, in noisy environment, where the acoustic noise exceeds 30 dB level at the 1 kHz-20 kHz bandwidth.…”

An Overview on Gripping Force Measurement at the Micro and Nano-Scales Using Two-Fingered Microrobotic Systems

“…This uncertainty is mainly due to the fabrication process and leads to uncertain quantitative force measurements. As such, the stiffness calibration of AFM cantilevers has for many years been an open research field [42][43][44][45]. One of the widely used calibration methods is the so-called thermal calibration .…”

An output feedback LPV control strategy of a nonlinear electrostatic microgripper through a singular implicit modeling

“…In (Boudaoud et al [2011]) and (Boudaoud et al [2012]), a detailed study on environmental noises and their effect on the positioning resolution of micromanipulation systems is performed. Three main sources of noise have been studied: cultural noises (ground vibrations), acoustic noises and thermal noises.…”

“…The thermal noise is often considered as the main limitation of the positioning resolution in MEMS. In (Boudaoud et al [2012]), it has been found that the positioning resolution of AFM (Atomic Force Microscopy) based microgrippers is ranging from 365 pm to 675 pm. It is shown that resolutions are limited by both thermal and acoustic noises.…”

“…As such, an affine LPV descriptor model and a finite number of linear matrix inequalities are used for the controller synthesis. In order to achieve resolution requirement, the main source of noise to be considered for the controller synthesis is defined taking into account results from previous works (Boudaoud et al [2011]; Boudaoud et al [2012]). A specific weighting function is introduced to ensure a high positioning resolution.…”