Cantilever Size Research Articles

Quantification of the dielectric constant of MoS2 and WSe2 Nanosheets by electrostatic force microscopy

The quantitative characterization of the local permittivity of transition metal dichalcogenide (TMD) materials is essential to estimate both their electrostatic properties and further achieve electronic applications. Electrostatic force microscopy (EFM) can achieve local, non-destructive, and high-resolution characterization of the dielectric properties of materials. However, in EFM, the probe geometry and long-range nature of electrostatic forces make the effective probe region that interacts with the specimen complex, posing daunting challenges to accurately measuring the dielectric property. Here, we present a systematic analysis of the impact of probe geometry on the EFM measurement and quantification of the dielectric constant. Then, a corrected methodology to partly remove such a geometric effect is developed. The proposed methodology has been validated by using finite element numerical calculations and successfully applied to quantitatively characterize the dielectric performance of MoS2 and WSe2 nanosheets. The results show that the dielectric constant determined by the corrected method is insensitive to the geometric parameters of the probe, especially the probe height and cantilever size. This work provides a more accurate and universal way to estimate the dielectric constants, and opens new opportunities in the study of the electrostatics of 2D materials that is essential for their promised applications.

Redesigned Microcantilevers for Sensitivity Improvement of Microelectromechanical System Tactile Sensors

We previously reported a microelectromechanical system tactile sensor with elastomer-embedded microcantilevers. The sensor enabled the gripping control of soft objects by a robotic hand and acquisition of the object surface texture data. However, sensitivity improvement for more precise control and better texture information acquisition is desired. Here, the cantilever size and the sensor’s strain-gauge arrangement were redesigned, resulting in a sensor with significantly improved sensitivity. In addition, we report the sensitivity dependence on the cantilever size.

Optimization of Substrate Layer Material and Its Mechanical Properties for Piezoelectric Cantilever Energy Harvesting System

AbstractA cantilever piezoelectric energy harvester (PEH) is a popular choice to harvest energy for applications with natural or unnatural vibrations. Other than the choice of piezoelectric material, the substrate layer material also plays an important role to increase the energy harvesting in PEH. Earlier researches have emphasized on selecting a few substrate materials than all available in literature. However, we argue that the choice of the substrate material and its mechanical properties depend on the design of the PEH. We establish this fact by designing 20 different PEH models by varying the size of cantilever, substrate layer thickness, and types of the piezoelectric materials. These models are simulated in COMSOL with every known substrate material to select the best substrate material. We also propose a greedy approach to further increase the energy harvesting by optimizing the mechanical properties of the best substrate material. In all models, the best substrate material harvests at least 2 × more energy. The greedy approach increases energy harvesting in almost 50% of the models. Some of the substrate materials with optimized mechanical properties are reported in literature, however, this research opens up a discussion to manufacture new substrate materials to increase energy harvesting in PEH.

Research on the selection and layout of the cantilever sensor based on photoacoustic spectroscopy gas detection technology

Gas detection has become an indispensable part of the power equipment maintenance. Because of many advantages, cantilever enhanced photoacoustic(PA) spectroscopy was studied by many researchers. In this paper, with the help of Finite Element Method (FEM) simulations with the commercial software COMSOL, we have analyzed the distribution of the sound pressure inside the gas cell, in addition, we have analyzed the relationship between the Young’s modulus and size of the cantilever beam and its deformation, the relationship between the cantilever size and its eigen-frequencies were also obtained. Besides, we have performed the experiment of the deformation measurement. The results show that: for the gas cell, when it works at the first order resonance frequency, the maximum value of the sound pressure appears at the geometric center. For the main resonance cavity, with its length and radius increase, the first order resonance frequency of the gas cell decreases. Under the condition of ideal linear sound source, as the length and radius of the main resonance cavity changes, in the frequency domain, the sound pressure response curve changes, the maximum sound pressure corresponds the PA cell with 85 mm in length and 2 mm in radius. For the cantilever beam, with the increase of the Young’s modulus, the deformation decreases. The deformation is proportional to the fourth power of the length, whereas it is inversely proportional to the width and inversely proportional to the third power of the thickness. However, the experimental results showed that there may be a deviation in the vibration measurements by the vibration meter. As for the first order eigen-frequency, it is negatively correlated with the length and positively correlated with the thickness, but independent of the width. With the increase of the distance between the sound source and the cantilever beam, the deformation decreases.

Utility of measuring anterior-posterior spread to determine distal cantilever length off a fixed implant-supported full-arch prosthesis: A review of the literature

BackgroundHistorically, anterior-posterior (AP) spread assessments were often used to determine the length that a distal cantilever could be extended off an implant-supported fixed full-arch prosthesis. Types of Studies ReviewedThe authors searched the literature for articles that used AP spread to calculate cantilever size to be constructed off implants bearing a fixed implant-supported full-arch rehabilitation. ResultsThe data indicate that the relationship between AP spread and cantilever length is not linear and many influences (such as beam theory, cantilever size differences in the mandible versus maxilla, number and distribution of placed implants, prosthetic materials, and framework design) need to be considered when computing cantilever length with respect to fixed implant-supported prostheses. Practical ImplicationsRecommendations using AP spread assessments to compute cantilever lengths have not been validated by means of prospective scientific evaluations. Therefore, AP spread evaluation is just one of many issues that need to be considered when determining distal cantilever length associated with a fixed full-arch implant-bearing prosthesis.

Limit of Thermal-Vibration Noise in Magnetic Field Detection with Magnetoelectric-Composite Cantilevers

The fundamental thermal limit of magnetic field sensing using the resonance-enhanced magnetoelectric (ME) effect in strain-coupled ferroic composite cantilevers is investigated theoretically with results applied to $({\mathrm{Fe}}_{90}{\mathrm{Co}}_{10}{)}_{78}{\mathrm{Si}}_{12}{\mathrm{B}}_{10}/\mathrm{Si}/\mathrm{Al}\mathrm{N}$ using experimental material parameters. An analytic theory of the ME response and noise from thermal vibrations, Johnson-Nyquist noise from dielectric losses in $\mathrm{Al}\mathrm{N}$, and amplifier electronics is given to yield the magnetic field detection limit for the first bending mode. A systematic investigation of scaling behavior of ME response, sensitivity, noise components, and detection limit with cantilever size, layer thicknesses, quality factor ${Q}_{f}$, and resonance frequency $f$ is presented emphasizing the low-frequency small-size regime essential for biomagnetic sensing applications. Thermal vibrations are found to dominate all investigated noise sources for practical composite sizes except at low quality factors. Detection limit scaling inversely with functional layer thickness, as $1{/\mathrm{size}}^{2}$ for constant $f$ and ${Q}_{f}$, and as ${Q}_{f}^{\ensuremath{-}1/2}$ (constant size and $f$) is found. Achievable detection limits below $100\phantom{\rule{0.2em}{0ex}}\mathrm{fT}/\mathrm{H}{\mathrm{z}}^{1/2}$ are predicted for $({\mathrm{Fe}}_{90}{\mathrm{Co}}_{10}{)}_{78}{\mathrm{Si}}_{12}{\mathrm{B}}_{10}/\mathrm{Si}/\mathrm{Al}\mathrm{N}$ composite cantilevers at sizes below $10\phantom{\rule{0.2em}{0ex}}\mathrm{mm}$ (and even lower without size constraint) with $f=1\phantom{\rule{0.2em}{0ex}}\mathrm{kHz}$, ${Q}_{f}=1000$, and $({\mathrm{Fe}}_{90}{\mathrm{Co}}_{10}{)}_{78}{\mathrm{Si}}_{12}{\mathrm{B}}_{10}$ layers of $50\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$. The scaling behavior implies the absence of an absolute detection limit for thick ferroic layers within the range of validity of the experimental material parameters observed at $\ensuremath{\sim}2\dots{}4\phantom{\rule{0.1em}{0ex}}\ensuremath{\mu}\mathrm{m}$.

Effect of excitation mode on the magnetic field detection limit of magnetoelectric composite cantilevers

Magnetic field excitation of strain-coupled magnetoelectric composite cantilevers in different bending modes is investigated for magnetic field sensing, yielding the sensitivity, noise, and magnetic field detection limit. An analytic theory covering the resonant magnetoelectric response and thermal vibration noise of arbitrary bending modes and the Johnson–Nyquist noise from the composite and electronics is presented, and detection limit results of thin film FeCoBSi–Si–AlN composite cantilevers are calculated for the first three bound–free and free–free bending modes over a wide range of dimensions. We use size-scaling to yield the same 1 kHz resonance frequency for all modes and dimensions, constant quality factors Qf = 1000, and thickness-independent experimental material parameters. Magnetic field detection limits in the 1 pT/Hz1/2 to 100 fT/Hz1/2 range are predicted for practical cantilever dimensions, whereby higher modes are found to yield lower detection limits at similar functional layer thicknesses but a greater cantilever size. All detection limits are found to be thermal vibration noise limited and for different modes to display the same 1/size2 scaling behavior but require different FeCoBSi–Si–AlN layer thickness ratios.

Enhancing the multiple harmonics by step-like cantilever

In atomic force microscopy (AFM), the higher modes are highly sensitive to the tip-sample interactions which generate many harmonics. When a higher harmonic is close to the natural frequency of a mode, the harmonic signal is enhanced by a resonance. The step-like cantilever is proposed as an effective design to enhance the higher harmonic signals. The natural frequencies are changed with the variations of the step-like cantilever sizes. By carefully designing the step-like cantilever, the first three modes can be simultaneously excited. A comprehensive map is provided as a guidance of selecting the appropriate geometric parameters.

Modelling and analysis of diaphragm integrated SU8/CB nanocomposite piezoresistive polymer microcantilever biosensor

This study investigates the effect of cantilever size and diaphragm size on deflection, frequency, stress and sensitivity characteristics of a diaphragm integrated SU8/CB piezoresistive polymer microcantilever biosensor. It consists SU8 square diaphragm anchored by four SU8 cantilevers with SU8/CB piezoresistor inside. Analytical model for biosensor deflection is presented and validated against numerical obtained using ANSYS Multiphysics. Diaphragm size was changed as 305, 505 and 705 µm. Cantilever length and width were first changed independently and then jointly to characterise performance of biosensor. Results show good conformity between analytical and numerical results and the sensitivity results are increasing linearly with diaphragm size, and short and narrow cantilevers show higher sensitivity.

Detection of atomic force microscopy cantilever displacement with a transmitted electron beam.

The response time of an atomic force microscopy (AFM) cantilever can be decreased by reducing cantilever size; however, the fastest AFM cantilevers are currently nearing the smallest size that can be detected with the conventional optical lever approach. Here, we demonstrate an electron beam detection scheme for measuring AFM cantilever oscillations. The oscillating AFM tip is positioned perpendicular to and in the path of a stationary focused nanometer sized electron beam. As the tip oscillates, the thickness of the material under the electron beam changes, causing a fluctuation in the number of scattered transmitted electrons that are detected. We demonstrate detection of sub-nanometer vibration amplitudes with an electron beam, providing a pathway for dynamic AFM with cantilevers that are orders of magnitude smaller and faster than the current state of the art.

Performance of pre-deformed flexible piezoelectric cantilever in energy harvesting

This paper proposes a novel structure for pre-rolled flexible piezoelectric cantilevers that use wind energy to power a submunition electrical device. Owing to the particular installation position and working environment, the submunition piezoelectric cantilever should be rolled when not working, but this pre-rolled state can alter the energy harvesting performance. Herein, a working principle and installation method for piezoelectric cantilevers used in submunitions are introduced. To study the influence of the pre-rolled state, pre-rolled piezoelectric cantilevers of different sizes were fabricated and their performances were studied using finite element analysis simulations and experiments. The simulation results show that the resonance frequency and stiffness of the pre-rolled structure is higher than that of a flat structure. Results show that, (1) for both the pre-rolled and flat cantilever, the peak voltage will increase with the wind speed. (2) The pre-rolled cantilever has a higher critical wind speed than the flat cantilever. (3) For identical wind speeds and cantilever sizes, the peak voltage of the flat cantilever (45 V) is less than that of the pre-rolled cantilever (56 V). (4) Using a full-bridge rectifier, the output of the pre-rolled cantilever can sufficiently supply a 10 μF capacitor, whose output voltage may be up to 23 V after 10 s. These results demonstrate that the pre-rolled piezoelectric cantilever and its installation position used in this work are more suitable for submunition, and its output sufficiently meets submunition requirements.

Static/dynamic trade-off performance of PZT thick film micro-actuators

Piezoelectric actuators are widespread in the design of micro/nanorobotic tools and microsystems. Studies toward the integration of such actuators in complex micromechatronic systems require the size reduction of these actuators while retaining a wide range of performance. Two main fabrication processes are currently used for the fabrication of piezoelectric actuators, providing very different behaviors: (i) the use of a bulk lead zirconate titanate (PZT) layer and (ii) the use of thin film growth. In this paper, we propose a trade-off between these two extreme processes and technologies in order to explore the performance of new actuators. This resulted in the design and fabrication of thick film PZT unimorph cantilevers. They allowed a high level of performance, both in the static (displacement) and dynamic (first resonance frequency) regimes, in addition to being small in size. Such cantilever sizes are obtained through the wafer scale bonding and thinning of a PZT plate onto a silicon on insulator wafer. The piezoelectric cantilevers have a 26 μm thick PZT layer with a 5 μm thick silicon layer, over a length of 4 mm and a width of 150 μm. Experimental characterization has shown that the static displacements obtained are in excess of 4.8 μm V−1 and the resonance frequencies are up to 1103 Hz, which are useful for large displacements and low voltage actuators.

Size dependence of fatigue damage in sub-micrometer single crystal gold

Abstract In fatigue, micrometer and sub-micrometer metal components do not have sufficient space to form persistent slip band (PSB) structures, which bring about the extrusions/intrusions with the size of a few micrometers in bulk metal. The characteristic feature of fatigue behavior at this scale is investigated using resonance vibration fatigue experiments on single crystal gold cantilevers of various sizes. Fatigue damage of extrusion/intrusion is formed on the cantilever surface in all specimens. The width of the extrusion/intrusion decreases with the size of cantilever, from hundreds to tens nanometers, which is much smaller than that in bulk components. And the slip traces formation is spatially periodic. The resolved shear stress to form an extrusion/intrusion is strongly dependent on the specimen size and is much higher than that in the bulk.

Tip radius preservation for high resolution imaging in amplitude modulation atomic force microscopy

The acquisition of high resolution images in atomic force microscopy (AFM) is correlated to the cantilever's tip shape, size, and imaging conditions. In this work, relative tip wear is quantified based on the evolution of a direct experimental observable in amplitude modulation atomic force microscopy, i.e., the critical amplitude. We further show that the scanning parameters required to guarantee a maximum compressive stress that is lower than the yield/fracture stress of the tip can be estimated via experimental observables. In both counts, the optimized parameters to acquire AFM images while preserving the tip are discussed. The results are validated experimentally by employing IgG antibodies as a model system.

Thrust Force Characterization of Oscillating Cantilevers Operating Near Resonance

Harmonic oscillations from cantileverlike structures have found use in applications ranging from thermal management to atomic force microscopy and propulsion, due to their simplicity in design and ease of implementation. In addition, making use of resonance conditions, a very energy efficient solution is achievable. This paper focuses on the application of providing thrust through cantilever oscillations at or near the first mode of resonance. This method of actuation provides a balance between full biomimicry and ease of fabrication. Previous studies have shown promise in predicting the propulsion performance based on the operating parameters, however, they have only considered a single cantilever geometry. Here, additional cantilever sizes and materials are included, yielding a much larger design space to characterize the thrust trends. The thrust data is experimentally captured and is assembled into two sets of predictive correlations. The first is based on Reynolds and Strouhal numbers, while the second only employs the Keulegan–Carpenter number. Both correlations are proven to predict the experimental data and can be shown to yield nearly identical proportional relationships after accounting for the cantilever frequency response. The findings presented in this research will aid in further understanding and assessing the capabilities of thrust generation for oscillating cantilevers, but also provides a foundation for other applications such as convection heat transfer and fluid transport.

Characterization of a silicon nanowire-based cantilever air-flow sensor

Silicon nanowire (SiNW)-based cantilever flow sensors with three different cantilever sizes (10 × 50, 20 × 90 and 40 × 100 µm2) and various SiNW lengths (2, 5 and 10 µm) have been designed for air velocity sensing. The total device thickness is around 3 µm, which consists of the bottom SiO2 layer (0.5 µm) and the top SiNx layer (2.5 µm). In addition, the SiNx layer is used to compensate the initial stress and also enhance the device immunity to air-flow-induced vibrations significantly. To experience the maximum strain induced by the air flow, SiNWs are embedded at the clamp point where the cantilever is anchored to the substrate. Taking advantage of the superior properties of SiNWs, the reported flow sensor shows outstanding air-flow-sensing capability in terms of sensitivity, linearity and hysteresis. With only a supply voltage of 0.1 V and the high initial resistance of the piezoresistive SiNWs, significant energy saving is reached in contrast to the thermal-based flow sensors as well as other recently reported piezoresistive designs. Last but not least, the significant size reduction of our device demonstrates the great scalability of SiNW-based flow sensors.

Fabrication and characterisation of piezoelectric microcantilever probe

This Letter focuses on the piezoelectric microcantilever probe fabrication processes. The sensing layer was lead zirconate titanate (PZT) thin films, prepared by sol-gel process, and formed on the Pt/Ti/SiO 2 /Si (100) substrate. The silicon-based microcantilever probe fabrication process is based on the microelectromechanical system technology. The compatible processes make the PZT thin films successfully fabricated on the silicon-based microcantilever. The size of piezoelectric cantilever is 450 m in length, 70 m in width and 12 m in thickness. The spring constant of the cantilever probe is 41.28 N/m measured by the micro-force testing system. The first resonance frequency of the cantilever probe is 43.78 KHz. The low leakage current of the PZT thin films is 0.265 nA with the applied voltage of 1 V. The results reveal that the piezoelectric cantilever probe can be substituted for the traditional atomic force microscopy probe.

Optomechanical Transduction of an Integrated Silicon Cantilever Probe Using a Microdisk Resonator

Sensitive transduction of the motion of a microscale cantilever is central to many applications in mass, force, magnetic resonance, and displacement sensing. Reducing cantilever size to nanoscale dimensions can improve the bandwidth and sensitivity of techniques like atomic force microscopy, but current optical transduction methods suffer when the cantilever is small compared to the achievable spot size. Here, we demonstrate sensitive optical transduction in a monolithic cavity-optomechanical system in which a subpicogram silicon cantilever with a sharp probe tip is separated from a microdisk optical resonator by a nanoscale gap. High quality factor (Q ≈ 10(5)) microdisk optical modes transduce the cantilever's megahertz frequency thermally driven vibrations with a displacement sensitivity of ≈4.4 × 10(-16) m/(Hz)(1/2) and bandwidth >1 GHz, and a dynamic range >10(6) is estimated for a 1 s measurement. Optically induced stiffening due to the strong optomechanical interaction is observed, and engineering of probe dynamics through cantilever design and electrostatic actuation is illustrated.

Investigation of Miniature Cantilever-Type Ultrasonic Motor Using Lead-free Array-Type Multilayer Piezoelectric Ceramics

We studied the following to clarify the design rule of the miniature cantilever-type ultrasonic motor using lead-free array-type multilayer piezoelectric ceramics, which is (Sr,Ca)2NaNb5O15. The relationship between the motor properties and stator vibrator dimensions was investigated by the finite element method and vibration analysis. The motor properties mainly depended on the cantilever sizes. The motor properties can be especially controlled from the revolution-speed-oriented type to the torque-oriented type by adjusting the vamplate radius of the cantilever. As a result, the design rule was clarified. In accordance with the design rule, the lead-free torque-oriented motor was fabricated and its properties were evaluated. The driving properties of this motor changed to the torque-oriented characteristics, such as the ratio of the maximum torque to the maximum speed was over 1200-fold of that of the motor fabricated in a previous study. It appeared that the driving properties of the lead-free cantilever-type motor can be controlled by using the design rule.

In-Situ Atomic Force Microscopy (AFM) Imaging: Influence of AFM Probe Geometry on Diffusion to Microscopic Surfaces

The effect of AFM probe geometry on diffusion to micrometer-scale reactive (electrode) interfaces is considered. A disk-shaped substrate electrode was held at a potential to reduce a species of interest (aqueous Ru(NH 3) 6 (3+)) at a diffusion-controlled rate and the current response during AFM imaging provided information on local mass transport to the interface. This approach reveals how the AFM probe influences diffusion to a reactive surface, which is of importance in more clearly delineating the conditions under which in-situ AFM can be treated as a noninvasive probe of surface processes involving mass transport (e.g., electrode reactions and crystal dissolution and growth). An assessment has been made of three types of probes: V-shaped silicon nitride contact mode probes; single beam silicon probes; and batch-fabricated scanning electrochemical-atomic force microscopy (SECM-AFM) probes. Two disk electrodes, (6.1 microm and 1.6 microm diameter) have been considered as substrates. The results indicate that conventional V-shaped contact mode probes are the most invasive and that the batch-fabricated SECM-AFM probes are the least invasive to diffusion at both of the substrates used herein. The experimental data are complemented by the development of simulations based on a simple 2D model of the AFM probe and active surface site. The importance of probe parameters such as the cantilever size, tip cone height, and cone angle is discussed, and the implications of the results for studies in other areas, such as growth and dissolution processes, are considered briefly.