Cantilever experimental methods

Various experimental methods have been developed for investigating the magnetoelastic properties of thin films and nanoscale magnetic systems. In the following subsections, we discuss the most important ones (i) the magnetoelastic cantilever, (ii) strain induced anisotropy, (iii) magnetostriction in spin valves, (iv) strain modulated ferromagnetic resonance, (v) secondary-electron spin-polarisation, and (vi) strain-induced anisotropy due to the spontaneous strains. 

The three major new atomic-scale experimental methods developed in the last decade are the quartz crystal microbalance (QCM) [2 4], atomic and friction force microscopes (AFM/FFM) [5,6], and the surface force apparatus (SEA) [7,7a,8]. These new tools reveal complementary information about tribology at the nanometer scale. The QCM measures dissipation as an adsorbed him of submonolayer to several monolayer thickness slides over a substrate. AFM and FFM explore the interactions between a surface and a tip whose radius of curvature is 10 100 nm [9]. The number of atoms in the contact ranges from a few to a few thousand. Larger radii of curvature and contacts have been examined by gluing spheres to an AFM cantilever [10,11]. SEA experiments measure shear forces in even larger-diameter ( 10 pm) contacts, but with angstrom-scale control of the thickness of lubricating hlms. 

Several methods have been described for measuring the bending modulus of hbers. The balanced hber method of Scott and Robbins [73,74] appears to be the easiest to handle experimentally (except for very curly hair) and provides less scatter than the other methods [74], The vibrating-reed method (oscillating hber cantilever) has also been used with human hair [10], The cantilever beam method [75], the loop deformation method [76], and the center load beam method [76] have been described for textile hbers. 

A NanoScope IV (Veeco Instraments, Inc., United States) was used. The cantilever was OMCL-TR800PSA (Olympus, Co., Japan) with 0.15N/m (nominal) or R150FM-10 (Nanosensors Inc., United States) with k= 2.5N/m (nominal). It is possible to measure the spring constant directly using some experimental methods... 

Hurst, K., Roberts, C. and Ashurst, W. (2009) A new method to determine adhesion of cantilever beams using beam height experimental data. Tribol. Lett.,... 

Quantitative evaluation of a force-distance curve in the non-contact range represents a serious experimental problem, since most of the SFM systems give deflection of the cantilever versus the displacement of the sample, while the experimentalists wants to obtain the surface stress (force per unit contact area) versus tip-sample separation. A few prerequisites have to be met in order to convert deflection into stress and displacement into tip-sample separation. First, the point of primary tip-sample contact has to be determined to derive the separation from the measured deflection of the cantilever tip and the displacement of the cantilever base [382]. Second, the deflection can be converted into the force under assumption that the cantilever is a harmonic oscillator with a certain spring constant. Several methods have been developed for calibration of the spring constant [383,384]. Third, the shape of the probe apex as well as its chemical structure has to be characterised. Spherical colloidal particles of known radius (ca. 10 pm) and composition can be used as force probes because they provide more reliable and reproducible data compared to poorly defined SFM tips [385]. 

The cantilevers can be fabricated of any shape and from substantially any material utilized in microelectronics industry, i.e. crystalline or poly-silicon, silicon nitride, silicon oxide, polymer materials (see Note 2). The rectangular shape beams are the most frequently used in biological research. In biological sensors based on the bending method, it is important to have the cantilevers flat and in plane with the base surface. Initial offset or curvature of the beams complicates adjustment of the experimental setup, especially, if working with arrays of cantilever. For this reason, the most common material for cantilevers fabrication nowadays is single crystalline silicon. A large variety of biomolecular interactions have been detected with silicon microcantilevers. 

After substituting the values of p and ei obtained experimentally by deflection of the cantilever-fixed specimen, we find SoexP = 6.303 X 10 cm, Ey = 40.562 x 10 MPa. The value obtained for the modulus of elasticity of the polymer in the adhesive layer exceeds that of steel, which clearly indicates the inadequacy of the method. 

A novel hybrid molecular simulation technique was developed to simulate AFM over experimental timescales. This method combines a dynamic element model for the tip-cantilever system in AFM and an MD relaxation approach for the sample. The hybrid simulation technique was applied to investigate the atomic scale friction and adhesion properties of SAMs as a function of chain length [81], The Ryckaert-Bellmans potential, harmonic potential, and Lennard-Jones potential were used. The Ryckaert-Bellmans potential, which is for torsion, has the form... 

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