Controlling thermal transport has become relevant in recent years. Traditionally, this control has been achieved by tuning the scattering of phonons by including various types of scattering centres in the material (nanoparticles, impurities, etc). Here we take another approach and demonstrate that one can also use coherent band structure effects to control phonon thermal conductance, with the help of periodically nanostructured phononic crystals. We perform the experiments at low temperatures below 1 K, which not only leads to negligible bulk phonon scattering, but also increases the wavelength of the dominant thermal phonons by more than two orders of magnitude compared to room temperature. Thus, phononic crystals with lattice constants ≥1 μm are shown to strongly reduce the thermal conduction. The observed effect is in quantitative agreement with the theoretical calculation presented, which accurately determined the ballistic thermal conductance in a phononic crystal device.

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Engineering thermal conductance using a two-dimensional phononic crystal

The feasibility of tuning the band structure of phononic crystals is demonstrated by employing magnetostrictive materials and applying an external magnetic field. Band structures are calculated with a plane wave expansion method that accounts for coupling between the elastic behavior and the magnetic field through the development of elastic, piezomagnetic, and magnetic permeability effective tensors. We show the contactless tunability of the absolute band gaps of a two-dimensional phononic crystal composed of an epoxy matrix and Terfenol-D inclusions. The tunable phononic crystal behaves like a transmission switch for elastic waves when the magnitude of an applied magnetic field crosses a threshold.

Tunable magnetoelastic phononic crystals

Gas sensors are important in many fields such as environmental monitoring, agricultural production, public safety, and medical diagnostics. Herein, Tamm plasmon resonance in a photonic bandgap is used to develop an optical gas sensor with high performance. The structure of the proposed sensor comprises a gas cavity sandwiched between a one-dimensional porous silicon photonic crystal and an Ag layer deposited on a prism. The optimised structure of the proposed sensor achieves ultra-high sensitivity (S = 1.9×105 nm/RIU) and a low detection limit (DL = 1.4×10−7 RIU) compared to the existing gas sensor. The brilliant sensing performance and simple design of the proposed structure make our device highly suitable for use as a sensor in a variety of biomedical and industrial applications.

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Refractive index gas sensor based on the Tamm state in a one-dimensional photonic crystal: Theoretical optimisation.

Porous silicon one-dimensional photonic crystals (PSi-1DPCs) are capable of sensing solutions and liquids based on the smallest variation of the refractive indices. In the present work, we present a novel metal/PSi-1DPC as a liquid sensor based on Tamm/Fano resonances. The operating wavelength range is from 6.35 to 9.85 μm in the mid-infrared (MIR) spectral region. Different metals (Al, Ag, Au, and Pt) are attached to the top surface of the PSi-1DPCs structure to show Tamm/Fano resonances more clearly. To the best of our knowledge, it is the first time that Tamm/Fano resonances exhibit simultaneously in PSi-1DPCs within the same structure. The reflection spectra were calculated for the metal/PSi-1DPC structure by using the transfer matrix method (TMM) and the Bruggeman’s effective medium approximation (BEMA). The simulations show that the Tamm/Fano resonances are red-shifted towards the higher wavelengths with increasing the refractive index of the pores. The Ag/PSi-1DPC sensor showed the highest performance. Its sensitivity can be reached to the value 5018 nm/RIU with a high-quality factor of about 2149.27. We predict the proposed sensors can be easily fabricated and we expect them to show higher performance than other reported sensors of this type. Therefore, it will be of interest in the field of optical sensing in different fields.

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Ultra-high sensitive 1D porous silicon photonic crystal sensor based on the coupling of Tamm/Fano resonances in the mid-infrared region

Photonic sensing is a new technology and accurate measurement for biosensing applications. The present work has been proposed blood sugar biosensor in the visible region by using a defective one-dimensional photonic crystal (1D-PC). The structure adopted is Air/(SiO2/Si)^5/SiO2/D/SiO2/(SiO2/Si)^5/ SiO_2substrate. The defect layer (D) is filled with blood sugar solution with different concentrations. The transmission spectrum was calculated numerically by using the transfer matrix method (TMM). The thickness of the defect layer and incident angle has been optimized to achieve the best performance of the sensor. The localization of defect mode shifts to a longer wavelength with increasing the defect layer thickness. In addition to increase the incident angle from θ_0=0 to θ_0=90 degree, the defect peak was shifted towards the short wavelength region. The optimized value of our structure demonstrates high sensitivity for the blood sugar (S = 1100 nm/RIU) in range of concentration C=0 to C=500 mg/dl, more enhancement of the quality factor (about 3.755*106) and very low detection limit (DL=10^(-8) RIU) are achieved. These results indicate that the proposed structure has higher performance as a blood sugar sensor than many previously reported data.

https://iopscience.iop.org/article/10.1088/1402-4896/ab53f5/pdf

Theoretical study of hybrid multifunctional one-dimensional photonic crystal as a flexible blood sugar sensor

In this work, the evolution of dispersion relations of 2D asymmetric phononic crystals in the low-frequency range is introduced and discussed. Two phononic crystal structures are proposed and calculated using Finite Element method. The first one is a thin plate from PDMS with a circular one-side stubbed from tungsten and the other is a thin plate in the X-shape from rubber and tungsten. The effects of some parameters such as stub height and diameter on the phononic band gap value are studied. Low-frequency band gaps can be found in both structures with frequencies corresponding to the audible sound frequency range. The symmetry and shape of the stub has a remarkable influence on the band structures. Where, the proposed one-side stubbed exhibits a phononic band gap in a lower frequency range compared with the published studies about the double side stubbed. Furthermore, with the same thickness value the band gap value was reduced in the X-shape phononic stub compared with the one-side stubbed. These results may be useful for the low-frequency and noise suppression devices.

Evolution of Low-Frequency Band Gaps Using X-Shapes and Single-Sided Stubbed Phononic Crystals

Detection of dangerous metallic oxides nano-powders by a one-dimensional resonant phononic crystal sensor

https://www.mdpi.com/2079-6374/13/7/683/pdf?version=1687859063

Enhanced Sensitivity of Binary/Ternary Locally Resonant Porous Phononic Crystal Sensors for Sulfuric Acid Detection: A New Class of Fluidic-Based Biosensors

In this study, the biosensing capabilities of conventional and hybrid multilayer structures were theoretically examined based on surface plasmon resonance (SPR). The transfer matrix method is adopted to obtain the reflectance spectra of the hybrid multilayer structure in the visible region. In this regard, the considered SPR sensor is configured as, [prism (CaF2)/Al2O3/Ag/Al2O3/2D material/Al2O3/Sensing medium]. Interestingly, many optimization steps were conducted to obtain the highest sensitivity of the new SPR biosensor from the hybrid structure. Firstly, the thickness of an Al2O3 layer with a 2D material (Blue P/WS2) is optimized to obtain an upgraded sensitivity of 360° RIU−1. Secondly, the method to find the most appropriate 2D material for the proposed design is investigated to obtain an ultra-high sensitivity. Meanwhile, the inclusion of black phosphorus (BP) increases the sensor's sensitivity to 466° RIU−1. Thus, black phosphorus (BP) was obtained as the most suitable 2D material for the proposed design. In this regard, the proposed hybrid SPR biosensing design may pave the way for further opportunities for the development of various SPR sensors to be utilized in chemical and biomedical engineering fields.

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A theoretical approach for a new design of an ultrasensitive angular plasmonic chemical sensor using black phosphorus and aluminum oxide architecture

/pdf/correction-to-simple-efficient-and-accurate-method-toward-eizloebc.pdf

Ahmed Mehaney

Papers

Evolution of Low-Frequency Band Gaps Using X-Shapes and Single-Sided Stubbed Phononic Crystals

Detection of dangerous metallic oxides nano-powders by a one-dimensional resonant phononic crystal sensor

Enhanced Sensitivity of Binary/Ternary Locally Resonant Porous Phononic Crystal Sensors for Sulfuric Acid Detection: A New Class of Fluidic-Based Biosensors

A theoretical approach for a new design of an ultrasensitive angular plasmonic chemical sensor using black phosphorus and aluminum oxide architecture

Correction to: Simple, efficient and accurate method toward the monitoring of ethyl butanoate traces