Mechanical Oscillator Model Research Articles

Mapping the Optomechanical Coupling Mediated by Light among Mechanical Resonators Including Multilayer Cavity and Molecules

For a wide range of health applications, label-free sensing is essential, and microphotonics offers innovative technical solutions for pursuing important objectives. It has been shown that the strong light/matter coupling formed between a cavity and molecules through light excitation enhances biological and clinical applications by providing deep insights into molecular analysis. The multilayer cavity’s proposed architecture is meant to promote a robust interaction between light and matter. The top layer was made of silver Ag multishape features that, after being synthesized and characterized, were immobilized on the surface of a multilayer system. A layer of indium tin oxide (ITO) was flipped to produce two distinct layouts. An investigation of the mode behavior was conducted to describe the two layouts; experimental and numerical results point to a strong light/matter interaction by the ITO/SiO2/spacer/Ag design. For the characterization of light/matter coupling, a fluorophore was adsorbed on the surface; the anticrossing energy was then examined by integrating the experimental data with a three mechanical oscillator model. To show the system’s sensitivity, the analysis was carried out again using bovine serum albumin (BSA). The protein is water-soluble and exhibits an infrared absorption band (amide I), while also being active in the Raman region. In addition, it may consistently bind to Ag multishape features. The excellent sensitivity was demonstrated, enabling the use of image analysis to capture the surface-enhanced Raman scattering of BSA. In conclusion, the suggested sensing approach raises fresh possibilities for highly sensitive biomolecule detection method and encourages results when used as a fundamental sensing technique to investigate molecular patterns.

Programmable Multiple Plasmonic Resonances of Nanoparticle Superlattice for Enhancing Photoelectrochemical Activity

AbstractBuilding nanoparticle (NP) superlattices formed in a complex fashion by subsets that can be explored separately presents a promising approach to realize the next generation of superlattices for different applications. Here, by incorporating self‐aligned and geometrically different subsets of Au NPs into one matrix with the assistance of multi‐pore anodic alumina oxide templates, scaled‐up NP superlattices are constructed with programmable multiple plasmonic resonances. The inter‐peak spectral distance is tailored in a broad wavelength range from less than 50 nm up to about 1000 nm through altering not only the size and height of each subset, but also the number and nature of the NP subset. Importantly, a mechanical oscillator model is developed to elucidate the microscopic origin of the spectral programmability and to reproduce the parameter dependence of the multiple plasmonic resonances. A photoelectrochemical cell using Au NP superlattice embedded photoanodes is investigated as a proof‐of‐concept, demonstrating a high photoresponse improvement of about 260% compared to that of bare film reference. In light of the compatibility of this technique with other plasmonic materials and the geometrical tunability, these findings enable systematic optical controlling toward optical devices with multimodal plasmonics.

Symmetric mechanical plate resonators for fluid sensing

In this contribution, we present a symmetric arrangement of electromagnetically actuated, resonating plates for viscosity and density measurement. Regarding the oscillation mode, the design resembles a tuning fork and is based on previously introduced resonating plate designs. It exhibits similar sensitivity to viscosity as previously characterized single plate resonators, while having two shear modes at different frequencies, that can be both actuated with the same setup allowing a multi-frequency analysis of viscoelastic liquids. We introduce the new design and present the results of FE simulations in order to determine the associated eigenmodes. We investigate the effects of the actuation method on the sensors performance by actuating with two different magnetic field configurations and by trying different configurations of the actuation and readout circuit, from which we show that with a particular configuration, Q-factors of up to 5000 can be reached for the symmetric shear mode. From these results we then proceed to suggesting a simplified lumped mechanical oscillator model explaining the dependence of the resonator’s Q-factor while operated in air on induced eddy currents damping. Measurement results are presented which show the general dependence of the new design’s actuated modes, the anti-symmetric and symmetric mode, on viscosity and density. We apply two different models to our data: a newly developed generalized model and a simplified version of that model which better describes the observed relation of our measurements to the square root of the product viscosity density. We then proceed to perform an estimated error analysis on viscosity, density, and the square root of their products based on the above mentioned applied models. From this error analysis several conclusions are drawn, mainly that the symmetric mode is more accurate than the anti-symmetric one, the sensor is generally more accurate for lower viscosity liquids, and lastly that the square root of the viscosity density product is a more suited value for the description of the sensor's behavior than the viscosity or the density alone.

Noninvasive Methods for Determining Pulmonary Vascular Function in Children with Pulmonary Arterial Hypertension: Application of a Mechanical Oscillator Model

Noninvasive diagnostics for pulmonary arterial hypertension (PAH) have traditionally sought to predict main pulmonary artery pressure from qualitative or direct quantitative measures of the flow velocity pattern obtained from spectral Doppler ultrasound examination of the main pulmonary artery. A more detailed quantification of flow velocity patterns in the systemic circuit has been obtained by parameterizing the flow trace with a simple dynamic system model. Here, we investigate such a model's utility as a noninvasive predictor of total right heart afterload and right heart function. Flow velocity and pressure was measured within the main pulmonary artery during right heart catheterization of patients with normal hemodynamics (19 subjects, 20 conditions) and those with PAH undergoing reactivity evaluation (34 patients, 69 conditions). Our model parameters were obtained by least-squares fitting the model velocity to the measured flow velocity. Five parameter means displayed significant (P < .05) differences between normotensive and hypertensive groups. The model stiffness parameter correlated to actual pulmonary vascular resistance (r = 0.4924), pulmonary vascular stiffness (r = 0.6811), pulmonary flow (r = 0.6963), and stroke work (r = 0.7017), while the model initial displacement parameter had good correlation to stiffness (r = 0.6943) and flow (r = 0.6958). As predictors of total right heart afterload (resistance and stiffness) and right ventricle work, the model parameters of stiffness and initial displacement offer more comprehensive measures of the disease state than previous noninvasive methods and may be useful in routine diagnostic monitoring of patients with PAH.

New bifurcations of basin boundaries involving Wada and a smooth Wada basin boundary

This paper demonstrates and analyses double heteroclinic tangency in a three-well potential model, which can produce three new types of bifurcations of basin boundaries including from smooth to Wada basin boundaries, from fractal to Wada basin boundaries in which no changes of accessible periodic orbits happen, and from Wada to Wada basin boundaries. In a model of mechanical oscillator, it shows that a Wada basin boundary can be smooth.

Generalized solutions for quantum mechanical oscillator on Kähler conifold

We study the possible generalized boundary conditions and the corresponding solutions for the quantum mechanical oscillator model on Kahler conifold. We perform it by self-adjoint extension of the initial domain of the effective radial Hamiltonian. Remarkable effect of this generalized boundary condition is that at certain boundary condition the orbital angular momentum degeneracy is restored! We also recover the known spectrum in our formulation, which of course corresponds to some other boundary condition.

From metaphors to equations: How can we find the good ones?

Among the metaphors used in the target article are “musical instruments,” “water waves,” and other types of mechanical oscillators. The corresponding equations have inertial properties and lead to standing waves that depend on boundary conditions. Other, physiologically relevant quantities like refractory times are not contained in the mechanical oscillator model but occur naturally, for instance, in biological forest fire metaphors.