Resonance Force Research Articles

Resonant sensors for multi-axis force and torque estimation in collaborative robotics

This paper presents a complete design methodology for a multi-axis resonant force sensor. The proposed device has been designed to be useable in a context of physical interaction between robots and humans. The proposed solution allows the three force components and the three torque components to be measured simultaneously and can be inserted into an interface handle or a robot end-effector. The information on wrench can then be used to detect and control interactions for cooperative tasks between humans and robots. In the context of sensors for robotic co-manipulation, it is imperative to guarantee not only a certain level of performance (accuracy, dynamics, size) but also to guarantee certain non-functional specifications associated with safety, measurement redundancy or functional integration of the sensor into its environment. The consideration of all these design specifications, both functional and non-functional, led to the principles and technologies used to develop this sensor. Multi-axis resonant sensors have excellent performance and safety characteristics, two key elements for collaborative robotics, but the literature review did not reveal any significant previous work in this area. Thus, this paper proposes an original sensor based on a breakthrough technology in the crucial field of multi-axis force sensors. The performances obtained on our prototype are already close to the performances of the best existing 6-axis industrial sensors, which suggests very good prospects for this new technology. In addition, and compared to alternative technologies, resonance technology offers new possibilities in terms of sensor fault detection, thus improving the intrinsic safety of these devices.

Dextran-based polyelectrolyte multilayers: Effect of charge density on film build-up and morphology

We have studied the growth process of thin polyelectrolyte (PE) films fabricated by the layer-by-layer assembly (LbL) and composed of Dextran sulfate with high (DexS H) and low (DexS L) sulfation rate and poly(allylamine hydrochloride) (PAH). Film growths were monitored by combining Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), Surface Plasmon Resonance (SPR) and Atomic Force Microscopy (AFM). Even though, the two films growth up to 10 bilayers, QCM-D showed that polyelectrolyte pairs do not display similar behaviours. (PAH/DexS H) systems lead to linear growth, i.e. amounts deposited increase both for PAH and DexS H, while the PAH/DexS L pair generated zig-zag shaped asymmetric growth. Film water contents were determined by QCM-D solvent exchange and SPR experiments. DexS L contains less water than DexS H and in agreement with the QCM-D dissipation values that suggest the formation of more rigid films in the case of DexS L than DexS H. Surface morphology investigated by AFM display distinct surface patterns since DexS H form thin films with fibril-like morphology covering all the surface while heterogeneous films with “puddle-like” aggregates were imaged in the case of DexS L. Difference of charge compensation and charge neutralisation between both systems likely lead to dissimilar growth mechanisms that are tentatively proposed in this paper.

Formulation of resonant optical force based on the microscopic structure of chiral molecules.

Optical manipulation, exemplified by Ashkin's optical tweezers, is a promising technique in the fields of bioscience and chemistry, as it enables the non-destructive and non-contact selective transport or manipulation of small particles. To realize the separation of chiral molecules, several researchers have reported on the use of light and discussed feasibility of selection. Although the separation of micrometer-sized chiral molecules has been experimentally demonstrated, the separation of nanometer-sized chiral molecules, which are considerably smaller than the wavelength of light, remains challenging. Therefore, we formulated an optical force under electronic resonance to enhance the optical force and enable selective manipulation. In particular, we incorporated the microscopic structures of molecular dipoles into the nonlocal optical response theory. The analytical expression of optical force could clarify the mechanism of selection exertion of the resonant optical force on chiral molecules. Furthermore, we quantitatively evaluated the light intensity and light exposure time required to separate a single molecule in a solvent. The results can facilitate the design of future schemes for the selective optical manipulation of chiral molecules.

Gain-Assisted Optical Pulling Force on Plasmonic Graded Nano-Shell with Equivalent Medium Theory

The tunable optical pulling force on a graded plasmonic core-shell nanoparticle consisting of a gain dielectric core and graded plasmonic shell is investigated in the illumination of a plane wave. In this paper, the electrostatic polarizability and the equivalent permittivity of the core-shell sphere are derived and the plasmonic enhanced optical pulling force in the antibonding and bonding dipole modes of the graded nanoparticle are demonstrated. Additionally, the resonant pulling force occurring on the dipole mode is shown to be dependent on the aspect ratio of the core-shell particle, which is illustrated by the obtained equivalent permittivity. This shows that the gradation of the graded shell will influence the plasmonic feature of the particle, thus further shifting the resonant optical force peaks and strengthening the pulling force. The obtained results provide an additional degree of freedom to manipulate nanoparticles and give a deep insight into light–matter interaction.

Magnetic Resonance Force Microscopy With Vacuum-Packaged Magnetic Cantilever Towards Free Radical Detection

Magnetic resonance force microscopy is becoming increasingly important for three-dimensional image reconstruction inside a sample with non-invasive measurements. In this study, a magnetic resonance force sensor with a vacuum-packaged magnetic cantilever was developed for the detection of free radicals in an atmospheric environment. A 1.5- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> -thick silicon-based cantilever, which was mounted with a 25- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> -diameter Nd-Fe-B magnet at the end of the cantilever, was hermetically packaged in a vacuum cavity using an anodic-bonding technique. The evaluation of the pressure dependence on the quality factor of the mechanical magnet-based cantilever revealed that the packaged-cavity pressure was approximately in the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.3\,\,\times10$ </tex-math></inline-formula> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.0\,\,\times10$ </tex-math></inline-formula> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> Pa after vacuum packaging. The corresponding detection sensitivity of the magnet-based cantilever sensor was calculated to be <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.1\,\,\times10$ </tex-math></inline-formula> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-13</sup> N/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sqrt {Hz} $ </tex-math></inline-formula> . Based on the magnetic force interaction, the magnetic field gradients were detected by mapping the variations in the resonant frequency and resonant amplitude of the magnetic cantilever. Finally, the magnetic resonance force, caused by the electron spin resonance in a standard radical of 1, 1-Diphenyl-2-picrylhydrazyl, was detected with a spin density of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 1.5\,\,\times10$ </tex-math></inline-formula> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> spins/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> in an atmospheric environment. The proposed vacuum-packaged magnet-based cantilever confirmed the high feasibility of magnetic resonance force detection within a non-hermetic environment.

In-situ Mo doped ZnIn2S4 wrapped MoO3 S-scheme heterojunction via Mo-S bonds to enhance photocatalytic HER

The construction of ZnIn2S4 based heterogeneous structure combined with in-situ relatively metal doping remains a great challenge. A direct Step-scheme (S-scheme) of in-situ Mo doped ZnIn2S4 wrapped MoO3 (MoO3@Mo-ZIS) was prepared in this work based on the thermal solubility properties of MoO3. The optimized photocatalyst of MoO3@Mo-ZIS exhibits superior H2 evolution rate of 5.5 mmol/g/h without co-catalysts, which is the 6.5 and 1.3 times of ZIS and 40 Mo doped ZIS (40 Mo-ZIS), respectively. The excellent photocatalytic activity was attributed to the Mo doping and formation of Mo-S species. The density functional theory (DFT) calculations demonstrate that the Mo-S species would form a new hybridized state near the Fermi level, reducing the ΔGH* to enhance photocatalytic hydrogen evolution reaction (HER). Furthermore, the direct S-scheme heterojunction of MoO3@Mo-ZIS confirmed by Electron paramagnetic resonance (EPR) and Kelvin probe force microscopy (KPFM) promotes photogenerated carrier separation, thus enhancing the performance of photocatalytic HER.

Broadband dichromatic variational measurement

Standard Quantum Limit (SQL) of a classical mechanical force detection results from quantum back action impinged by the meter on a probe mechanical transducer perturbed by the force of interest. In this paper we introduce a technique of continuous \vy{broadband} back action avoiding measurements for the case of a resonant signal force acting on a linear mechanical oscillator supporting one of mirrors of an optical Michelson-Sagnac Interferometer (MSI). The interferometer with the movable mirror is an opto-mechanical transducer able to support polychromatic probe field. The method involves a dichromatic optical probe resonant with the MSI modes and having frequency separation equal to the mechanical frequency. We show that analyzing each of the harmonics of the probe reflected from the mechanical system separately and postprocessing the measurement results allows excluding the back action in a broad frequency band and measuring the force with sensitivity better than SQL.

Cavity optomechanical sensing

Abstract Cavity optomechanical systems enable interactions between light and mechanical resonators, providing a platform both for fundamental physics of macroscopic quantum systems and for practical applications of precision sensing. The resonant enhancement of both mechanical and optical response in the cavity optomechanical systems has enabled precision sensing of multiple physical quantities, including displacements, masses, forces, accelerations, magnetic fields, and ultrasounds. In this article, we review the progress of precision sensing applications using cavity optomechanical systems. The review is organized in the following way: first we will introduce the physical principles of optomechanical sensing, including a discussion of the noises and sensitivity of the systems, and then review the progress in displacement sensing, mass sensing, force sensing, atomic force microscope (AFM) and magnetic resonance force microscope (MRFM), accelerometry, magnetometry, and ultrasound sensing, and introduce the progress of using quantum techniques especially squeezed light to enhance the performance of the optomechanical sensors. Finally, we give a summary and outlook.

Three-dimensional imaging of electron spin resonance-magnetic resonance force microscopy at room temperature

In this study, we demonstrated the three-dimensional (3D) imaging by magnetic resonance force microscopy (MRFM) based on electron spin resonance (ESR) measurements at room temperature. For a microsample containing radicals, the 3D force distribution was obtained using a custom-made Si nanowire and a permanent magnetic particle. Calculation using precise values of the magnetic field distribution is required to define an accurate response function for the 3D deconvolution processing of the spin density distribution. A symmetric resonance magnetic field produces good periodic force maps using a spherical micromagnet, which simplifies the deconvolution processing with resonant slice systems. In addition, the 3D imaging method was processed in the wavenumber space by a Fourier transform that used a simple convolution with noise parameters in the response function. After the reconstruction of the distribution of electron spins (radicals), the shape of the sample agreed with that of the optical image; thus, the accuracy of the internal density structure was verified. We believe that the combination of a Si nanowire and a spherical magnetic particle used for magnetic resonance detection is a good candidate for Fourier transform 3D deconvolution in multiple MRFM applications.

A probe-type high-precision micro-force sensor based on quartz DETF resonator

Force measurement is widely applied in many applications. Resonant force sensors are featured with high accuracies, high resolutions, and long-term stabilities. In this paper, we report a probe-type high-precision force sensor based on a quartz resonator. The scale factor of our sensor is 161.5 mHz μN−1 and the bias stability of the sensor is 20 ppb (parts per billion) for an averaging time of 0.2 s. A comprehensive test showed that the nominal theoretical resolution of our sensor was 5 nN, and the repeated stability of our sensor has been proven by several controlled tests. With its large measurement range of 50 mN, the dynamic range of the sensor is up to 140 dB.

Resonant binding of dielectric particles to a metal surface without plasmonics

High index dielectric spherical particle supports the high-$Q$ resonant Mie modes that results in a regular series of sharp resonances in the radiation pressure. A presence of perfectly conducting metal surface transforms the Mie modes into the extremely high-$Q$ magnetic bonding or electric anti-bonding modes for close approaching of the sphere to the surface. We show that the electromagnetic plane wave with normal incidence results in repulsive or attractive resonant optical forces relative to metal for excitation of the electric bonding or magnetic anti-bonding resonant modes respectively. A magnitude of resonant optical forces reaches order of one nano Newton of magnitude for micron size of silicon particles and power of light $1mW/\mu m^2$ that exceeds the gravitational force by four orders. However what is the most remarkable there are steady positions for the sphere between pulling and pushing forces that gives rise to resonant binding of the sphere by metal surface. A frequency of mechanical oscillations of particle around the equilibrium positions reaches a magnitude of order MHz.

Multifunctional cantilevers for simultaneous enhancement of contact resonance and harmonic atomic force microscopy

To enhance contact resonance atomic force microscopy (CR-AFM) and harmonic AFM imaging simultaneously, we design a multifunctional cantilever. Precise tailoring of the cantilever’s dynamic properties is realized by either mass-removing or mass-adding. As prototypes, focused ion beam drilling or depositing is used to fabricate the optimized structures. CR-AFM subsurface imaging on circular cavities covered by a piece of highly oriented pyrolytic graphite validates the improved CR frequency to contact stiffness sensitivity. The detectable subsurface depth and cavity radius increase accordingly by using the multifunctional cantilever. At the same time, the free resonance frequency of the second mode is tuned to an integer multiple of the fundamental one. Harmonic AFM imaging on polystyrene and low-density polystyrene mixture shows the improved harmonic amplitude contrast and signal strength on the two material phases. The multifunctional cantilever can be extended to enhance other similar AFM operation modes and it has potential applications in relevant fields such as mechanical characterization and subsurface imaging.

Electrochemically driven adsorptive separation techniques: From ions to proteins and cells in liquid streams

• Electrochemical separation processes have a great potential beyond ion separation. • Both, faradaic and capacitive current, can be used to separate macromolecules. • The change in surface wetting upon applying electric stimuli is essential for the separation of macromolecules. • Surface plasmon resonance and atomic force spectroscopy techniques will be essential techniques to further investigate electrochemical separation approaches for macromolecules. Separation processes are of utmost importance for most industrial processes in the chemical, food, and pharma sectors. Electrochemical separation technologies gain more and more attention especially for the desalination of water, as they potentially lead to a reduction in the environmental footprint of the process. For salt, many different electrochemical desalination architectures and electrode designs have been proposed. Also other target molecules have been investigated, such as carboxylates, amino acids, proteins and whole cells. We note that the efforts are still scattered; therefore in this review we bundle and summarize the technological state of the art, and the application possibilities for capacitive as well as faradaic separation technologies for various targets. From this it is clear that there are still a lot of options that have been underused so far, and that electrochemical separation processes are key for the separation processes needed for a sustainable future.

On Weakly Coupled Resonant MEMS Transducers Operating in the Modal Overlap Regime.

Miniaturized physical transducers based on weakly coupled resonators have previously demonstrated the twin benefits of high parametric sensitivity and the first-order common-mode rejection of environmental effects. Current approaches to sensing based on coupled resonator transducers employ strong coupling where the modal overlap of the responses is avoided. This strong coupling limits the sensitivity for such mode-localized sensors that utilize an amplitude ratio (AR) output metric as opposed to tracking resonant frequency shifts. In this article, this limitation is broken through by theoretically and experimentally demonstrating the operation of the weakly coupled resonators in the weak-coupling (modal overlap) regime. Especially, a prototype microelectromechanical systems (MEMS) sensor based on this principle is employed to detect shifts in stiffness, with a stiffness bias instability of [Formula: see text]/m (9.5 ppb) and a corresponding noise floor of [Formula: see text]/m/ √ Hz (6.8 ppb/ √ Hz). The linear dynamic range of such AR readout sensors is first explored and found to be defined by the dynamic range of the secondary resonator. The proposed method provides a promising approach for high-performance resonant force and inertial sensors.

Resonance-based approach for section flexural rigidity identification of simply supported beams

Deteriorated sections decide the bearing capacity of beams. Because reinforced concrete beams are nonhomogeneous materials and often have variable sections along the beam, it is a challenge to precisely measure flexural rigidity of damage or repaired sections. This paper proposes a resonance-based non-destructive approach to identify section flexural rigidity for non-uniform simply supported beams. In the method, the resonant force is applied to the beam at the mid-span to measure the accelerations of evenly spaced segments and the strains of sections. The amplitude of the mid-span displacement is limited to approximately 1/104 of the span to avoid new damage. The proposed method can transform the calculation of dynamic bending moment and curvature into an equivalent static calculation to formulate a straightforward algorithm and easy-to-use equation on section flexural rigidity. It is applicable to non-uniform simply supported beams with arbitrary stiffness distribution. Theoretical and test results of a reinforced concrete and a non-uniform steel beam show that the identified section flexural rigidity would converge the exact result with the increased numbers of evenly spaced segments, and no less than five evenly spaced segments are sufficient in engineering applications.

Nanoscale imaging of Gilbert damping using signal amplitude mapping

Ferromagnetic resonance force microscopy (FMRFM) is a powerful scanned probe technique that uses sub-micrometer-scale, spatially localized standing spin wave modes (LMs) to perform local ferromagnetic resonance (FMR) measurements. Here, we show the spatially resolved imaging of Gilbert damping in a ferromagnetic material (FM) using FMRFM. Typically damping is measured from the FMR linewidth. We demonstrate an approach to image the spatial variation of Gilbert damping utilizing the LM resonance peak height to measure the LM resonance cone angle. This approach enables determination of damping through field-swept FMRFM at a single excitation frequency. The extreme force sensitivity of ∼2 fN at room temperature can resolve changes of Gilbert damping as small as ∼2×10−4 at 2 GHz, corresponding to ∼0.16 Oe in FMR linewidth resolution. This high sensitivity, high spatial resolution, and single frequency imaging of Gilbert damping creates the opportunity to study spin interactions at the interface between an insulating FM and a small volume of nonmagnetic material such as atomically thin two-dimensional materials.

Optical selection and sorting of nanoparticles according to quantum mechanical properties.

Optical trapping and manipulation have been widely applied to biological systems, and their cutting-edge techniques are creating current trends in nanomaterial sciences. The resonant absorption of materials induces not only the energy transfer from photons to quantum mechanical motion of electrons but also the momentum transfer between them, resulting in dissipative optical forces that drive the macroscopic mechanical motion of the particles. However, optical manipulation, according to the quantum mechanical properties of individual nanoparticles, is still challenging. Here, we demonstrate selective transportation of nanodiamonds with and without nitrogen-vacancy centers by balancing resonant absorption and scattering forces induced by two different-colored lasers counterpropagating along a nanofiber. Furthermore, we propose a methodology for precisely determining the absorption cross sections for single nanoparticles by monitoring the optically driven motion, which is called as "optical force spectroscopy." This method provides a novel direction in optical manipulation technology toward development of functional nanomaterials and quantum devices.

Measurements of the magnetic properties of conduction electrons

We consider various methods and techniques that are used in experimental condensed matter physics for measuring electron magnetization and susceptibility. The list of considered methods for macroscopic measurements includes magnetomechanical, electromagnetic, modulation-type, and thermodynamic methods based on chemical potential variation measurements. We also consider local methods of magnetic measurements based on the spin Hall effect and nitrogen-substituted vacancies (NV centers). Scanning probe magnetometers–microscopes are considered, such as the magnetic resonance force microscope, SQUID microscope, and Hall microscope. The review focuses on the electron spin magnetization measurements in nonmagnetic materials and systems, particularly in low-dimensional electron systems in semiconductors and in nanosystems that have come to the forefront in recent years.

Edge mode engineering for optimal ultracoherent silicon nitride membranes

Due to their high force sensitivity, mechanical resonators combining low mechanical dissipation with a small motional mass are highly demanded in fields as diverse as resonant force microscopy, mass sensing, or cavity optomechanics. “Soft-clamping” is a phononic engineering technique by which mechanical modes of highly stressed membranes or strings are localized away from lossy regions, thereby enabling ultrahigh-Q for ng-scale devices. Here, we report on parasitic modes arising from the finite size of the structure, which can significantly degrade the performance of these membranes. Through interferometric measurements and finite-element simulations, we show that these parasitic modes can hybridize with the localized modes of our structures, reducing the quality factors by up to one order of magnitude. To circumvent this problem, we engineer the spectral profile of the parasitic modes in order to avoid their overlap with the high-Q defect mode. We verify via a statistical analysis that the quality factors of devices fabricated with this modal engineering technique are consistently closer to the value predicted by dissipation dilution theory. We expect this method to find applications in a broad range of contexts such as optomechanical cooling, resonant force microscopy, swept-frequency sensing, or hybrid quantum networks.

Prediction of minimum fluidization velocity in pulsed gas–solid fluidized bed

Fluidized bed technology plays a vital role in petrochemistry and coal separation. To enhance fluidization stability, the flow is periodically introduced into the gas–solid fluidized bed to form a pulsed gas–solid fluidized bed (PGFD). As the main fluidization parameter, the minimum fluidization velocity (umf) can reflect the change of the critical state of particles in the PGFD, directly affecting the study of two-phase distribution in the bed. Due to lack of theoretical study on umf in PGFD, the work proposed a novel method to predict umf combined with soft sphere model. Meanwhile, the spring-damping model (SDM) and the resonance force model (RFM) were developed under the action of pulsating airflow. A theoretical model of umf was then derived for PGFD based on experimental stress analysis of particles. The error of the new model is small, which is in good agreement with the data in the existing literature and present work.