The MIDAS experiment for the Rosetta mission (original) (raw)
This paper discusses a measurement device for the determination of force displacement curves or spring constants respectively. Especially the calibration of spring constants of atomic force microscopes (short: AFM) cantilevers is an important field of investigation and concentration of this work. The spring constant can be measured with two measurement modes. One mode uses separate force and displacement measurement devices which correspond to the state of the art. The second measurement mode is more sophisticated using one sensor which measures force as well as the displacement simultaneously; a separate nanostage is not need. The measured sample is an AFM type cantilever, its determined spring constant is in both measurement modes approximately 50 Nm-1 with a very good repeatability of 0.02 %.
Applications based on cantilever sensor technology like atomic force microscopy, mass spectroscopy, magnetic resonance force microscopy, and other physical or chemical sensing techniques demand theoretical understanding of sensing and actuation mechanism. Moreover reliable calibration of any instrumentation is necessary in order to enable comparison of obtained results between various laboratories. When mass or force investigations are performed in nanoscale the reliable system calibration is even more difficult due to the lack of appropriate references and established metrological techniques. In this article we present the calibration methodology of thermally driven piezoresistive cantilevers which were used for mass and force measurements. We adapt the mass loading spring constant calibration method and compare the results obtained in this way with the method which was based on the resonance frequency detection. Additionally we will present results of the cantilever deflection sensitivity measurement and low-frequency noise properties.
Uncertainty Quantification in Calibration of AFM Probes Due to Non-uniform Cantilevers
2010
For more than two decades, the Atomic Force Microscope (AFM) has provided valuable insights in nanoscale phenomena, and it is now widely employed by scientists from various disciplines. AFMs use a cantilever beam with a sharp tip to scan the surface of a sample both to image it and to perform mechanical testing. Since the AFM measures the deection of the probe beam, one must rst nd the spring constant of the cantilever in order to estimate the force between the sample and the probe tip. Commonly applied calibration methods regard the probe as a uniform cantilever, neglecting the tip mass and any non-uniformity in the thickness along the length of the beam. This work explores these issues, recognizing that dynamic calibration boils down to nding the modal parameters of a dynamic model for a cantilever from experimental measurements and then using those parameters to estimate the static stiness of a probe; if the modes of the cantilever do not match the expectations, for example because non-uniformity was neglected, then the calibration will be in error. This work explores the inuence of variation in the thickness of a cantilever probe on its static stiness as well as its dynamics, seeking to determine when the uniform beam model that is traditionally employed is not valid and how one can make sure whether the model is valid from measurable quantities. In this study, the implications for two commonly applied dynamic calibration methods, the method of Sader and the Thermal Tune method, were explored.
Exact solutions of AFM scanning probes subjected to tip-sample forces
Journal of Mechanics of Materials and Structures, 2007
In this study, an analytical method for the static deflection of an AFM nonuniform probe subjected to tip-sample forces is presented. The effects of the Lennard-Jones and electrostatic noncontact forces and a contact force on the deflection of a cantilever are investigated. The contact force is simulated by the Derjaguin-Muller-Toporov model. In general, when an atomic force microscopy is used to measure a sample's topography and properties, a jump phenomenon of a cantilever usually exists. Unfortunately, there is a lack of a complete and precise description about this jump phenomenon. This proposed analytical method is helpful to investigate precisely the jump phenomenon. Moreover, the effects of several parameters on the jump phenomenon are studied. Finally, several simple and general relations between the deflection of beam and the tip-sample distance are presented.
An interferometric platform for studying AFM probe deflection
Precision Engineering, 2011
This paper describes an interferometric platform for measuring the full-field deflection of atomic force microscope (AFM) probes and generic cantilevers during quasi-static loading. The platform consists of a scanning white light interferometer (SWLI), holders for the cantilevers, a translation stage, a rotation (tip-tilt) stage, and an adapter plate to connect these items to the SWLI table. Visualization of cantilever bending behavior is demonstrated for snap-in against a rigid surface, cantilever-on-cantilever tests, and a damaged AFM probe. A new approach to normal force calculation using a polynomial fit to the cantilever deflection profile is also presented and verified experimentally. The method requires only the coefficient for the third order (cubic) term from the fit to the deflection profile, the elastic modulus, and the area moment of inertia for the cantilever under test.
Cantilever's behavior in the AC mode of an AFM
Materials Characterization, 2003
In this paper, a model with a small number of parameters is used to simulate the motion of a cantilever in the AC mode of an atomic force microscope (AFM). The results elucidate the transition dependence-from noncontact to tapping operating mode-on the height of the contamination layer and on the stiffness of the sample.
The limit of mass determination with an AFM cantilever-based system
IOP Conference Series: Materials Science and Engineering
The application of an atomic force microscope (AFM) based microcantilever system for the determination of mass of gold nanoparticles (AuNPs) has been demonstrated. In this system, standard AFM microcantilevers for measurements in vacuum have been employed. The limit of mass determination with our AFM-based system has been determined to be of the order of 10-10 g. The prospects of employing AFM cantilever-based sensors for highly sensitive protein detection in proteomic studies and in diagnostics have been discussed.
We present a comparative study between three different methods for the spring constant calibration of silicon beam-shaped Atomic Force Microscope (AFM) cantilevers, used in tapping AFM mode in air. The geometries of these levers can be quite different from the standard rectangular cross section. We examine a method that combines the knowledge of cantilever dimensions and eigenfrequencies (Cleveland formula), the Sader method and we build cantilever models based on Finite Element Analysis (FEA). We demonstrate that with accurate measurement of dimensions, resonance frequency and quality factor, the Cleveland formula yields a combined cantilever stiffness uncertainty of approximately ±7% and the Sader method an uncertainty of ±5%. We also use FEA to show that when trying to approximate a realistic trapezoidal 3D tipped geometry, there exists a systematic overestimation in cantilever stiffness of ±2%, compared to when considering a simple rectangular cross section. Our constructed FE models are able to account for inhomogeneities in material properties as well as the influence of the added reflective coating in the cantilever stiffness estimation.