Simulation of Micromechanical Measurement of Mass Accretion: Quantifying the Importance of Material Selection and Geometry on Performance

10.1115/1.4025842 â—˝  
2013 â—˝  
Vol 136 (2) â—˝  
Author(s):  
Michael James Martin
Keyword(s):  
Natural Frequency â—˝  
System Performance â—˝  
Elastic Moduli â—˝  
Material Selection â—˝  
Optimal Thickness â—˝  
Force Microscopy â—˝  
Atomic Force â—˝  
Functionalized Surfaces â—˝  
Silicon Cantilever â—˝  
Afm Cantilever

Micro- and nanomechanical resonators operating in liquid have been used to measure the change in the mass of either cells or functionalized surfaces attached to the resonator. As the system accretes mass, the natural frequency of the system changes, which can be measured experimentally. The current work extends methods previously developed for simulation of an atomic force microscope operating in liquid to study this phenomenon. A silicon cantilever with a 10 micron width, an 800 nm thickness, and a length of 30 microns was selected as a baseline configuration. The change in resonant frequency as the system accretes mass was determined through simulation. The results show that the change in natural frequency as mass accretes on the resonator is predictable through simulation. The geometry and material of the cantilever were varied to optimize the system. The results show that shorter cantilevers yield large gains in system performance. The width does not have a large impact on the system performance. Selecting the optimal thickness requires balancing the increase in overall system mass with the improvement in frequency response as the structure becomes thicker. Because there is no limit to the maximum system stiffness, the optimal materials will be those with higher elastic moduli. Based on these criteria, the optimum resonator for mass accretion measurements will be significantly different than an optimized atomic-force microscopy (AFM) cantilever.

scholarly journals Multiple regimes of operation in bimodal AFM: understanding the energy of cantilever eigenmodes

10.3762/bjnano.4.45 â—˝  
2013 â—˝  
Vol 4 â—˝  
pp. 385-393 â—˝  
Author(s):  
Daniel Kiracofe â—˝  
Arvind Raman â—˝  
Dalia Yablon
Keyword(s):  
Single Frequency â—˝  
Force Microscopy â—˝  
Atomic Force â—˝  
Afm Imaging â—˝  
Multiple Regimes â—˝  
Nanoscale Imaging â—˝  
Relative Kinetic â—˝  
Series Of Experiments â—˝  
Tapping Mode Afm â—˝  
Afm Cantilever

One of the key goals in atomic force microscopy (AFM) imaging is to enhance material property contrast with high resolution. Bimodal AFM, where two eigenmodes are simultaneously excited, confers significant advantages over conventional single-frequency tapping mode AFM due to its ability to provide contrast between regions with different material properties under gentle imaging conditions. Bimodal AFM traditionally uses the first two eigenmodes of the AFM cantilever. In this work, the authors explore the use of higher eigenmodes in bimodal AFM (e.g., exciting the first and fourth eigenmodes). It is found that such operation leads to interesting contrast reversals compared to traditional bimodal AFM. A series of experiments and numerical simulations shows that the primary cause of the contrast reversals is not the choice of eigenmode itself (e.g., second versus fourth), but rather the relative kinetic energy between the higher eigenmode and the first eigenmode. This leads to the identification of three distinct imaging regimes in bimodal AFM. This result, which is applicable even to traditional bimodal AFM, should allow researchers to choose cantilever and operating parameters in a more rational manner in order to optimize resolution and contrast during nanoscale imaging of materials.

scholarly journals A Novel Toolkit for Characterizing the Mechanical and Electrical Properties of Engineered Neural Tissues

Biosensors â—˝  
10.3390/bios9020051 â—˝  
2019 â—˝  
Vol 9 (2) â—˝  
pp. 51 â—˝  
Author(s):  
Meghan Robinson â—˝  
Karolina Valente â—˝  
Stephanie Willerth
Keyword(s):  
Elastic Modulus â—˝  
Electrical Properties â—˝  
Elastic Moduli â—˝  
Direct Method â—˝  
Hydrogel Scaffolds â—˝  
Force Microscopy â—˝  
Mechanical And Electrical Properties â—˝  
Atomic Force â—˝  
Neural Tissues â—˝  
Electrical Signaling

We have designed and validated a set of robust and non-toxic protocols for directly evaluating the properties of engineered neural tissue. These protocols characterize the mechanical properties of engineered neural tissues and measure their electrophysical activity. The protocols obtain elastic moduli of very soft fibrin hydrogel scaffolds and voltage readings from motor neuron cultures. Neurons require soft substrates to differentiate and mature, however measuring the elastic moduli of soft substrates remains difficult to accurately measure using standard protocols such as atomic force microscopy or shear rheology. Here we validate a direct method for acquiring elastic modulus of fibrin using a modified Hertz model for thin films. In this method, spherical indenters are positioned on top of the fibrin samples, generating an indentation depth that is then correlated with elastic modulus. Neurons function by transmitting electrical signals to one another and being able to assess the development of electrical signaling serves is an important verification step when engineering neural tissues. We then validated a protocol wherein the electrical activity of motor neural cultures is measured directly by a voltage sensitive dye and a microplate reader without causing damage to the cells. These protocols provide a non-destructive method for characterizing the mechanical and electrical properties of living spinal cord tissues using novel biosensing methods.

scholarly journals Advanced Surface Probing Using a Dual-Mode NSOM–AFM Silicon-Based Photosensor

Nanomaterials â—˝  
10.3390/nano9121792 â—˝  
2019 â—˝  
Vol 9 (12) â—˝  
pp. 1792
Author(s):  
Matityahu Karelits â—˝  
Emanuel Lozitsky â—˝  
Avraham Chelly â—˝  
Zeev Zalevsky â—˝  
Avi Karsenty
Keyword(s):  
Surface Characterization â—˝  
Near Field â—˝  
Optical Microscope â—˝  
Dual Mode â—˝  
Atomic Force â—˝  
Reflected Light â—˝  
Afm Imaging â—˝  
Silicon Cantilever â—˝  
Afm Cantilever â—˝  
Silicon Based

A feasibility analysis is performed for the development and integration of a near-field scanning optical microscope (NSOM) tip–photodetector operating in the visible wavelength domain of an atomic force microscope (AFM) cantilever, involving simulation, processing, and measurement. The new tip–photodetector consists of a platinum–silicon truncated conical photodetector sharing a subwavelength aperture, and processing uses advanced nanotechnology tools on a commercial silicon cantilever. Such a combined device enables a dual-mode usage of both AFM and NSOM measurements when collecting the reflected light directly from the scanned surface, while having a more efficient light collection process. In addition to its quite simple fabrication process, it is demonstrated that the AFM tip on which the photodetector is processed remains operational (i.e., the AFM imaging capability is not altered by the process). The AFM–NSOM capability of the processed tip is presented, and preliminary results show that AFM capability is not significantly affected and there is an improvement in surface characterization in the scanning proof of concept.

Hydrodynamic interactions for the measurement of thin film elastic properties

2011 â—˝  
Vol 674 â—˝  
pp. 389-407 â—˝  
Author(s):  
S. LEROY â—˝  
E. CHARLAIX
Keyword(s):  
Elastic Moduli â—˝  
Scaling Laws â—˝  
Surface Forces â—˝  
Force Response â—˝  
Elastic Surface â—˝  
Dynamic Surface â—˝  
Force Microscopy â—˝  
Atomic Force â—˝  
Experimental Parameters â—˝  
Simple Scaling

We study the elasto-hydrodynamic (EHD) interaction of a sphere with a flat elastic surface in the prospect of measuring the elastic moduli of soft supported thin films, with non-contact dynamic surface forces or atomic force microscopy measurements. When the sphere is oscillated at a very small amplitude close to the surface, the linear force response undergoes a dynamic transition from a viscous-dominated behaviour at large distance to an elastic-dominated behaviour at short distance. In the limit of very thin or very thick supported layers, we show that the force response obeys simple scaling laws which allow to unambiguously determine the absolute elastic modulus of the layer. In the general case, we establish the very rich phase diagram of the EHD interaction and discuss its application for optimizing experimental parameters.

Calibration of Carbon Nanotube Probes for Pico-Newton Order Force Measurement Inside a Scanning Electron Microscope

2004 â—˝  
Vol 16 (2) â—˝  
pp. 155-162 â—˝  
Author(s):  
Masahiro Nakajima â—˝  
â—˝  
Fumihito Arai â—˝  
Lixin Dong â—˝  
Toshio Fukuda
Keyword(s):  
Electron Microscope â—˝  
Carbon Nanotube â—˝  
Scanning Electron Microscope â—˝  
Elastic Moduli â—˝  
Force Measurement â—˝  
Ultrasonic Waves â—˝  
Copper Electrodes â—˝  
Atomic Force â—˝  
Afm Cantilever â—˝  
Scanning Electron

A method is presented for pico-Newton (pN) order force measurement using a carbon nanotube (CNT) probe, which is calibrated by electromechanical resonance. A CNT probe is constructed by attaching a CNT to the end of a tungsten needle or an atomic force microscope (AFM) cantilever using nanorobotic manipulators inside a field-emission scanning electron microscope (FE-SEM). Conductive electron-beam-induced deposition (EBID) is used for the fixation of CNTs with an internal vaporized precursor W(CO)6. For manipulating them easily and quickly, CNTs are dispersed in ethanol by ultrasonic waves and oriented on copper electrodes by electrophoresis. The elastic moduli of CNT probes are calibrated for use as a force measurement probe by electrically exciting at fundamental frequency. We analyzed the resolution of force measurement using a CNT probe. This force measurement can be used to characterize the mechanical properties of nanostructures and to measure friction or exfoliation forces in nanometer order.

Measurement of Interactions between Abrasive Silica Particles and Copper, Titanium, Tungsten and Tantalum

MRS Proceedings â—˝  
2007 â—˝  
Vol 991 â—˝  
Author(s):  
Ruslan Burtovyy â—˝  
Alex Tregub â—˝  
Mansour Moinpour â—˝  
Mark Buehler â—˝  
Igor Luzinov
Keyword(s):  
Ph Value â—˝  
High Sensitivity â—˝  
Model Systems â—˝  
Thin Polymer Film â—˝  
Colloidal Probe â—˝  
Force Microscopy â—˝  
Atomic Force â—˝  
Afm Cantilever â—˝  
The Moment â—˝  
Silica Slurry

ABSTRACTColloidal probe technique has been widely employed to measure the adhesion between micro- and nanosize objects using atomic force microscopy (AFM). However, majority of studies concerns model systems, which do not incorporate real abrasive particles. The approach applied allows measuring adhesion between real CMP nanoparticles and different surfaces. Thin polymer film with high affinity to the particles was used to anchor the particles to a surface. Hollow glass bead (20-30 ÎĽm) representing flat surface was attached to soft AFM cantilever. Application of large hollow bead and the cantilever with small spring constant allows measuring the interactions with high sensitivity. Titanium, tungsten and tantalum metals were sputtered on the bead surface. The effect of different factors such as pH value, concentration and type of a surfactant on adhesion between surfaces of metals and silica slurry has been studied. Character and intensity of interactions at the moment of contact have been evaluated from experimental force-distance curves.

Nanomechanical Probing of Layered Nanoscale Polymer Films With Atomic Force Microscopy

2004 â—˝  
Vol 19 (3) â—˝  
pp. 716-728 â—˝  
Author(s):  
A. Kovalev â—˝  
H. Shulha â—˝  
M. Lemieux â—˝  
N. Myshkin â—˝  
V.V. Tsukruk
Keyword(s):  
Atomic Force Microscopy â—˝  
Polymer Films â—˝  
Elastic Moduli â—˝  
Solid Substrate â—˝  
Elastic Solids â—˝  
Polymer Layers â—˝  
Transition Zones â—˝  
Force Microscopy â—˝  
Microstructural Parameters â—˝  
Atomic Force

The approach developed for the microindentation of layered elastic solids was adapted to analyze atomic force microscopy probing of ultrathin (1–100 nm-thick) polymer films on a solid substrate. The model for analyzing microindentation of layered solids was extended to construct two- and tri-step graded functions with the transition zones accounting for a variable gradient between layers. This “graded” approach offered a transparent consideration of the gradient of the mechanical properties between layers. Several examples of recent applications of this model to nanoscale polymer layers were presented. We considered polymer layers with elastic moduli ranging from 0.05 to 3000 MPa with different architecture in a dry state and in a solvated state. The most sophisticated case of a tri-layered polymer film with thickness of 20–50 nm was also successfully treated within this approach. In all cases, a complex shape of corresponding loading curves and elastic modulus depth profiles obtained from experimental data were fitted by the graded functions with nanomechanical parameters (elastic moduli and transition zone widths) close to independently determined microstructural parameters (thickness and composition of layers) of the layered materials.

Force Measurement by AFM Cantilever with Different Coating Layers

2006 â—˝  
Vol 326-328 â—˝  
pp. 377-380 â—˝  
Author(s):  
Meng Kao Yeh â—˝  
Bo Yi Chen â—˝  
Nyan Hwa Tai â—˝  
Chien Chao Chiu
Keyword(s):  
Force Measurement â—˝  
Force Measurements â—˝  
The Finite Element Method â—˝  
Force Microscopy â—˝  
Atomic Force â—˝  
Nonlinear Force â—˝  
Coating Layers â—˝  
Afm Cantilever â—˝  
Force Displacement â—˝  
Spring Constants

Atomic force microscopy (AFM) is widely used in many fields, because of its outstanding force measurement ability in nano scale. Some coating layers are used to enhance the signal intensity, but these coating layers affect the spring constant of AFM cantilever and the accuracy of force measurement. In this paper, the spring constants of rectangular cantilever with different coating thickness were quantitatively measured and discussed. The finite element method was used to analyze the nonlinear force-displacement behavior from which the cantilever’s normal and torsional spring constants could be determined. The experimental data and the numerical results were also compared with the results from other methods. By considering the influence of coating layers and real cantilever geometries, the more accurate force measurements by AFM cantilever can be obtained.

Elastic moduli of faceted aluminum nitride nanotubes measured by contact resonance atomic force microscopy

Nanotechnology â—˝  
2008 â—˝  
Vol 20 (3) â—˝  
pp. 035706 â—˝  
Author(s):  
G Stan â—˝  
C V Ciobanu â—˝  
T P Thayer â—˝  
G T Wang â—˝  
J R Creighton â—˝  
...  
Keyword(s):  
Atomic Force Microscopy â—˝  
Aluminum Nitride â—˝  
Elastic Moduli â—˝  
Force Microscopy â—˝  
Atomic Force â—˝  
Aluminum Nitride Nanotubes â—˝  
Contact Resonance

scholarly journals PROBING ATOMIC LEVEL INTERACTIONS IN NI NANORODS AND AFM CANTILEVER USING ATOMIC FORCE MICROSCOPY BASED F–D SPECTROSCOPY

2017 â—˝  
Author(s):  
Sudipta Dutta â—˝  
Mahesh Kumar Singh â—˝  
M. S. Bobji
Keyword(s):  
Atomic Force Microscopy â—˝  
Magnetic Interaction â—˝  
Interaction Force â—˝  
Small Scale â—˝  
Magnetic Composite â—˝  
Force Microscopy â—˝  
Atomic Force â—˝  
Lift Height â—˝  
Afm Cantilever â—˝  
Force Displacement

Atomic force microscopy based force-displacement spectroscopy is used to quantify magnetic interaction force between sample and magnetic cantilever. AFM based F–D spectroscopy is used widely to understand various surface-surface interaction at small scale. Here we have studied the interaction between a magnetic nanocomposite and AFM cantilevers. Two different AFM cantilever with same stiffness but with and without magnetic coating is used to obtain F–D spectra in AFM. The composite used has magnetic Ni nanophase distributed uniformly in an Alumina matrix. Retrace curves obtained using both the cantilevers on magnetic composite and sapphire substrate are compared. It is found for magnetic sample cantilever comes out of contact after traveling 100 nm distance from the actual point of contact. We have also used MFM imaging at various lift height and found that beyond 100nm lift height magnetic contrast is lost for our composite sample, which further confirms our F–D observation.

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