Search results for "cantilever"
showing 10 items of 60 documents
Activation process of reversible Pd thin film hydrogen sensors
2013
Abstract Microcantilever-based thin film palladium hydrogen sensors have high selectivity and sensitivity. Reproducibility and accuracy of the sensor performance depend on the activation process of the polycrystalline palladium film deposited on the cantilever. When the hydrogen is in solid solution ( α -phase), the cantilever bending is mostly governed by the residual film stress induced by the swelling at the grain boundaries in the film. When the palladium hydride ( β -phase) starts to be formed, the cantilever undergoes a large deflection due to hydrogen absorption-induced film swelling (10% change in volume). Differences in the phase diagrams of the palladium hydride for two film thick…
Achieving high effectiveQ-factors in ultra-high vacuum dynamic force microscopy
2010
The effective Q-factor of the cantilever is one of the most important figures-of-merit for a non-contact atomic force microscope (NC-AFM) operated in ultra-high vacuum (UHV). We provide a comprehensive discussion of all effects influencing the Q-factor and compare measured Q-factors to results from simulations based on the dimensions of the cantilevers. We introduce a methodology to investigate in detail how the effective Q-factor depends on the fixation technique of the cantilever. Fixation loss is identified as a most important contribution in addition to the hitherto discussed effects and we describe a strategy for avoiding fixation loss and obtaining high effective Q-factors in the forc…
Photothermal excitation setup for a modified commercial atomic force microscope
2014
High-resolution imaging in liquids using frequency modulation atomic force microscopy is known to suffer from additional peaks in the resonance spectrum that are unrelated to the cantilever resonance. These unwanted peaks are caused by acoustic modes of the liquid and the setup arising from the indirect oscillation excitation by a piezoelectric transducer. Photothermal excitation has been identified as a suitable method for exciting the cantilever in a direct manner. Here, we present a simple design for implementing photothermal excitation in a modified Multimode scan head from Bruker. Our approach is based on adding a few components only to keep the modifications as simple as possible and …
Experimental evidence of high spatial confinement of elastic energy in a phononic cantilever
2021
We report on experimental high spatial confinement of elastic energy in a silicon phononic cantilever for which the quality factor of a higher-order flexural resonance is increased by a factor of 27 (from Q ∼ 80 to Q ∼ 2130) with the use of a three-row phononic crystal (PnC) strip. As shown by numerical simulations performed with the finite element method, the PnC both reduces anchor loss and confines elastic energy inside the cantilever. The PnC and the cantilever are fabricated with standard clean room techniques on a silicon on insulator substrate. Optical measurements of the out-of-plane displacements are performed with a laser scanning interferometer in a frequency range around 2 MHz.
Effect of cobalt doping on the mechanical properties of ZnO nanowires
2016
Abstract In this work, we investigate the influence of doping on the mechanical properties of ZnO nanowires (NWs) by comparing the mechanical properties of pure and Co-doped ZnO NWs grown in similar conditions and having the same crystallographic orientation [0001]. The mechanical characterization included three-point bending tests made with atomic force microscopy and cantilever beam bending tests performed inside scanning electron microscopy. It was found that the Young's modulus of ZnO NWs containing 5% of Co was approximately a third lower than that of the pure ZnO NWs. Bending strength values were comparable for both materials and in both cases were close to theoretical strength indica…
Mechanical properties of sol–gel derived SiO2 nanotubes
2014
The mechanical properties of thick-walled SiO2 nanotubes (NTs) prepared by a sol–gel method while using Ag nanowires (NWs) as templates were measured by using different methods. In situ scanning electron microscopy (SEM) cantilever beam bending tests were carried out by using a nanomanipulator equipped with a force sensor in order to investigate plasticity and flexural response of NTs. Nanoindentation and three point bending tests of NTs were performed by atomic force microscopy (AFM) under ambient conditions. Half-suspended and three-point bending tests were processed in the framework of linear elasticity theory. Finite element method simulations were used to extract Young’s modulus values…
Sensing of the Molecular Spin in Spin-Crossover Nanoparticles with Micromechanical Resonators
2019
In the past years, the use of highly sensitive silicon microelectromechanical cantilevers has been proposed as a tool to characterize the spin-crossover phenomenon by employing fast optical readout of the motion. In this work, Fe II -based spin-crossover nanoparticles of the well-known [Fe(Htrz) 2 (trz)](BF 4 ) complex wrapped with thin silica shells of different sizes will be studied by means of silicon microresonators. The silica shell will enhance its chemical stability, whereas the low thickness will allow a proper mechanical coupling between the cantilever and the spin-crossover core. To maximize the sensing of the spin-crossover phenomena, different cantilever geometries and flexural…
Stress distribution of complete-arch implant-supported prostheses reinforced with silica-nylon mesh
2019
Made available in DSpace on 2020-12-12T01:20:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Background: This study evaluated the presence of a silica-nylon mesh and two cantilever lengths on the biomechanical behavior of complete-arch implant-supported prostheses. Material and Methods: Twenty-four (24) complete mandibular arch implant-supported prostheses were divided into 4 groups according to the presence of reinforcing mesh (with or without) and the cantilever length (molar-15 mm or premolar-5 mm). The specimens were submitted to strain gauge analysis (30-kgf, 10 s) at different points (molar and premolar). Three-dimensional models were created based on the in vitro spec…
Optimal Design of Piezoelectric Cantilevered Actuators for Charge-Based Self-Sensing Applications
2019
Charge-based Self-Sensing Actuation (SSA) is a cost and space-saving method for accurate piezoelectric based-actuator positioning. However, the performance of its implementation resides in the choice of its geometry and the properties of the constituent materials. This paper intends to analyze the charge-based SSA&rsquo
Does muscular activity related to vertical facial divergence influence the time needed for orthodontic extrusion of palatally impacted maxillary cani…
2018
Background The aim of the present study was to evaluate if the different muscular activity correlated to different degrees of facial divergence has an effect on the time needed to extrude a palatally impacted maxillary canine. Material and methods Twenty-six patients were retrospectively selected, all treated with a specific cantilever appliance that allows extrusion of the impacted canine applying a physiologic amount of force below 0.6 N in a predictable way. For all the patients, pre-treatment cephalometric tracings were used to evaluate facial divergence through the FMA angle, the angle between the maxillary and mandibular plane, and the angles between the occlusal plane and either the …