Nanorefractive index transducer using a ring cavity with an internal h-shaped cavity grounded on Fano resonance.

Building on the Fano resonance observation, a new refractive index transducer structure at the nanoscale is proposed in this article, which is a refractive index transducer consisting of a metal-insulator-metal (MIM) waveguide structure coupled with a ring cavity internally connected to an h-shaped structure (RCIhS). Using an analytical method based on COMSOL software and finite element method (FEM), the effect of different geometric parameters of the structure on the trans-mission characteristics of the system is simulated and analyzed, which in turn illustrates the effect of the structural parameters on the output Fano curves. As simulation results show, the internally connected h-shaped structure is an influential component in the Fano resonance. By optimizing the geometrical parameters of the structure, the system finally accomplishes a sensitivity (S) of 2400 nm/RIU and a figure of merit (FOM) of 68.57. The sensor has also been demonstrated in the realm of temperature detection, having tremendous potential for utilization in future nano-sensing and optically integrated systems.

Improved Energy Storage Performance of Composite Films Based on Linear/Ferroelectric Polarization Characteristics.

The development and integration of high-performance electronic devices are critical in advancing energy storage with dielectric capacitors. Poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (PVTC), as an energy storage polymer, exhibits high-intensity polarization in low electric strength fields. However, a hysteresis effect can result in significant residual polarization, leading to a severe energy loss, which impacts the resultant energy storage density and charge/discharge efficiency. In order to modify the polarization properties of the polymer, a biaxially oriented polypropylene (BOPP) film with linear characteristics has been selected as an insulating layer and combined with the PVTC ferroelectric polarization layer to construct PVTC/BOPP bilayer films. The hetero-structure and polarization characteristics of the bilayer film have been systematically studied. Adjusting the BOPP volume content to 67% resulted in a discharge energy density of 10.1 J/cm3 and an energy storage efficiency of 80.9%. The results of this study have established the mechanism for a composite structure regulation of macroscopic energy storage performance. These findings can provide a basis for the effective application of ferroelectric polymer-based composites in dielectric energy storage.

Identification of near-infrared characteristic bands of small bowel necrosis based on cellwise detection algorithm.

The near-infrared spectroscopy is often used to distinguish small bowel necrosis due to necrotizing enterocolitis (NEC). The characteristic bands of small bowel necrosis, as an important basis for evaluating the confidence of the differentiation results, are challenging to identify quickly. In this study, we proposed to identify characteristic bands of lesion samples based on hyperspectral imaging (HSI) and cellwise outlier detection. Rabbits were used as an animal model to simulate the clinical symptoms of NEC. The rabbits were detected at intervals of 10, 30, 60, and 90 min. The characteristic bands were identified within the same rabbit, between different rabbits and at different times. The result showed the bands near 763 nm, corresponding to the absorption peak of deoxyhemoglobin, were the characteristic bands separating samples with NEC. The identification result was plausible because hypoxia was the main cause of NEC. The method was easy to perform.

A Nano Refractive Index Sensing Structure for Monitoring Hemoglobin Concentration in Human Body.

This paper proposes a nanosensor structure consisting of a metal-insulator-metal (MIM) waveguide with a rectangular root and a double-ring (SRRDR) with a rectangular cavity. In this paper, the cause and internal mechanism of Fano resonance are investigated by the finite element method (FEM), and the transport characteristics are optimized by changing various parameters of the structure. The results show that the structure can achieve double Fano resonance. Due to the destructive disturbance between the wideband mode of the inverted rectangle on the bus waveguide and the narrowband mode of the SRRDR, the output spectrum of the system shows an obvious asymmetric Fano diagram, and the structural parameters of the sensor have a great influence on the Fano resonance. By changing the sensitive parameters, the optimal sensitivity of the refractive index nanosensor is 2280 nm/RIU, and the coefficient of excellence (FOM) is 76.7. In addition, the proposed high-sensitivity nanosensor will be used to detect hemoglobin concentration in blood, which has positive applications for biosensors and has great potential for future nanosensing and optical integration systems.

Refractive Index and Alcohol-Concentration Sensor Based on Fano Phenomenon.

A novel nano-refractive index sensor based on the Fano resonance phenomenon is proposed in this paper. The sensor consists of the metal-insulator-metal (MIM) waveguide and a V-ring cavity with a groove (VRCG). We analyzed the performance of the nanoscale sensor using the finite element method. The simulation results show that the asymmetry of the geometric structure itself is the main factor leading to Fano resonance splitting. In Fano splitting mode, the Fano bandwidth of the system can be significantly reduced when the sensor sensitivity is slightly reduced, so that the figure of merit (FOM) of the sensor can be substantially improved. Based on the above advantages, the sensor's sensitivity in this paper is as high as 2765 nm/RIU, FOM = 50.28. In addition, we further applied the sensor to alcohol concentration detection. The effect is good, and the sensitivity achieves about 150. This type of sensor has a bright future in the precision measurement of solution concentrations.

Refractive index sensor based on a ring with a disk-shaped cavity for temperature detection applications.

In this study, we proposed a novel refractive index sensor structure, comprising a metal-insulator-metal (MIM) waveguide and a circular ring containing a disk-shaped cavity (CRDC). The finite element method was used to theoretically analyze the sensor characteristics. The simulation results showed that the disk-shaped cavity is the key to the asymmetric Fano resonance, and the radius of the CRDC has a significant influence on the performance of the sensor. A maximum sensitivity and figure of merit (FOM) of 2240 nm/RIU and 62.5, respectively, were realized. Additionally, the refractive index sensor exhibits the potential of aiding in temperature detection owing to its simple structure and high sensitivity of 1.186 nm/ºC.

A Nanoscale Sensor Based on a Toroidal Cavity with a Built-In Elliptical Ring Structure for Temperature Sensing Application.

In this article, a refractive index sensor based on Fano resonance, which is generated by the coupling of a metal-insulator-metal (MIM) waveguide structure and a toroidal cavity with a built-in elliptical ring (TCER) structure, is presented. The finite element method (FEM) was employed to analyze the propagation characteristics of the integral structure. The effects of refractive index and different geometric parameters of the structure on the sensing characteristics were evaluated. The maximum sensitivity was 2220 nm/RIU with a figure of merit (FOM) of 58.7, which is the best performance level that the designed structure could achieve. Moreover, due to its high sensitivity and simple structure, the refractive index sensor can be applied in the field of temperature detection, and its sensitivity is calculated to be 1.187 nm/℃.

Multiwalled Carbon Nanotube/Graphite Powder Film for Wearable Pressure Sensors with High Sensing Performance.

With the continuous progress of artificial intelligence and other manufacturing technologies, there is promising potential for wearable piezoresistive sensors in human physiological signal detection and bionic robots. Here, we present a facile solution-mixing process to fabricate a multiwalled carbon nanotube/graphite powder (MWCNT@Gp) film, which has high sensitivity and great linearity and is more oriented to flexible piezoresistive sensors. The sensor consists of two parts: a spinosum microstructure shaped by a sandpaper template and polydimethylsiloxane (PDMS) as the top substrate and interdigital electrodes as the bottom substrate. The experiments we have conducted show that these two parts provide good protection to the MWCNTs@Gp film and improve sensor sensitivity. Additionally, the sensitivity of the optimal ratio of multiwalled carbon nanotubes and graphite powder is analyzed. The 5%MWCNT@5%Gp composites were found to have relatively good conductivity, which is convenient for the fabrication of conductive films of piezoresistive sensors. Finally, we conducted application experiments and found that the flexible piezoresistive sensor can detect minute signals of human motion and different pressure points. This indicates the feasibility of portable sensors in electronic skin and smart devices.

High-Property Refractive Index and Bio-Sensing Dual-Purpose Sensor Based on SPPs.

A high-property plasma resonance-sensor structure consisting of two metal-insulator-metal (MIM) waveguides coupled with a transverse ladder-shaped nano-cavity (TLSNC) is designed based on surface plasmon polaritons. Its transmission characteristics are analyzed using multimode interference coupling mode theory (MICMT), and are simulated using finite element analysis (FEA). Meanwhile, the influence of different structural arguments on the performance of the structure is investigated. This study shows that the system presents four high-quality formants in the transmission spectrum. The highest sensitivity is 3000 nm/RIU with a high FOM* of 9.7 × 105. In addition, the proposed structure could act as a biosensor to detect the concentrations of sodium ions (Na+), potassium ions (K+), and the glucose solution with maximum sensitivities of 0.45, 0.625 and 5.5 nm/mgdL-1, respectively. Compared with other structures, the designed system has the advantages of a simple construction, a wide working band range, high reliability and easy nano-scale integration, providing a high-performance cavity choice for refractive index sensing and biosensing devices based on surface plasmons.

Refractive Index Sensor Based on a Metal-Insulator-Metal Bus Waveguide Coupled with a U-Shaped Ring Resonator.

In this study, a novel refractive index sensor structure was designed consisting of a metal-insulator-metal (MIM) waveguide with two rectangular baffles and a U-Shaped Ring Resonator (USRR). The finite element method was used to theoretically investigate the sensor's transmission characteristics. The simulation results show that Fano resonance is a sharp asymmetric resonance generated by the interaction between the discrete narrow-band mode and the successive wide-band mode. Next, the formation of broadband and narrowband is further studied, and finally the key factors affecting the performance of the sensor are obtained. The best sensitivity of this refractive-index sensor is 2020 nm/RIU and the figure of merit (FOM) is 53.16. The presented sensor has the potential to be useful in nanophotonic sensing applications.

Pulsed vapor cell atomic clock with a differential Faraday rotation angle detection.

Laser intensity noise is one of the main limiting factors in pulsed vapor cell clocks. To reduce the contribution of the laser intensity noise to detection signal in the pulsed optically pumped atomic clock, a scheme based on the differential Faraday rotation angle is proposed. Theoretically, the Ramsey fringes, the sensitivity of clock frequency to laser intensity fluctuation and the signal to noise ratio for absorption, differential, and Faraday rotation angle methods are calculated and compared. Using a Wollaston prism rotated 45°relative to the incident polarization, and two photodetectors, Ramsey fringes of three detection methods are obtained simultaneously. In the proposed scheme, the long-term Faraday rotation angle fluctuation is 0.66% at 30000s, which is much smaller than fluctuation of traditional absorption signal 3.9% at 30000s. And the contribution of laser intensity noise to clock instability is also reduced. Using optimized photodetector with high common mode rejection ratio, a better performance should be expected. This proposed scheme is attractive for the development of high performance vapor clock based on pulsed optically pumped.

A Nanoscale Structure Based on an MIM Waveguide Coupled with a Q Resonator for Monitoring Trace Element Concentration in the Human Body.

In this study, a nano-refractive index sensor is designed that consists of a metal-insulator-metal (MIM) waveguide with a stub-1 and an orthogon ring resonator (ORR) with a stub-2. The finite element method (FEM) was used to analyze the transmission characteristics of the system. We studied the cause and internal mechanism of Fano resonance, and optimized the transmission characteristics by changing various parameters of the structure. In our experimental data, the suitable sensitivity could reach 2260 nm/RIU with a figure of merit of 211.42. Furthermore, we studied the detection of the concentration of trace elements (such as Na+) of the structure in the human body, and its sensitivity reached 0.505 nm/mgdL-1. The structure may have other potential applications in sensors.

Exergy Analysis of Phase-Change Heat-Storage Coupled Solar Heat Pump Heating System.

With the rapid development of industrialization, the excessive use of fossil fuels has caused problems such as increased greenhouse gas emissions and energy shortages. The development and use of renewable energy has attracted increased attention. In recent years, solar heat pump heating technology that uses clean solar energy combined with high-efficiency heat pump units is the development direction of clean heating in winter in northern regions. However, the use of solar energy is intermittent and unstable. The low-valley electricity policy is a night-time electricity price policy. Heat pump heating has problems such as frosting and low efficiencies in cold northern regions. To solve these problems, an exergy analysis model of each component of a phase-change heat-storage coupled solar heat pump heating system was established. Exergy analysis was performed on each component of the system to determine the direction of optimization and improvement of the phase-change heat-storage coupled solar heat pump heating system. The results showed that optimizing the heating-end heat exchanger of the system can reduce the exergy loss of the system. When the phase-change heat-storage tank meets the heating demand, its volume should be reduced to lower the exergy loss of the tank heat dissipation. Air-type solar collectors can increase the income exergies of solar collectors.

Double ring nanostructure with an internal cavity and a multiple Fano resonances system for refractive index sensing.

A novel nanosensor based on a metal-insulator-metal waveguide coupled to a double ring resonator is proposed. The spectral characteristics are studied by finite element method, and a Fano resonance (FR) formed by the interference of the narrowband mode and the broadband mode is discovered. After analyzing the effects of structural parameters on the transmission characteristics, the structure is further optimized by adding a rectangular cavity inside the ring cavity. The maximum sensitivity reaches 1885 nm/RIU with the figure of merit (FOM) of 77. Additionally, a tunable multiple FR system is realized through the derivative structure, which leads to the splitting of the resonance mode and produces two new narrowband modes. Their formation mechanism and performance are studied through a normalized magnetic field distribution and transmission spectrum. The designed structure with excellent performance can discover significant applications in the future nanosensing domain.

A Nanosensor Based on a Metal-Insulator-Metal Bus Waveguide with a Stub Coupled with a Racetrack Ring Resonator.

A nanostructure comprising the metal-insulator-metal (MIM) bus waveguide with a stub coupled with a racetrack ring resonator is designed. The spectral characteristics of the proposed structure are analyzed via the finite element method (FEM). The results show that there is a sharp Fano resonance profile and electromagnetically induced transparency (EIT)-like effect, which are excited by a coupling between the MIM bus waveguide with a stub and the racetrack ring resonator. The normalized HZ field is affected by the displacement of the ring from the stub x greatly. The influence of the geometric parameters of the sensor design on the sensing performance is discussed. The sensitivity of the proposed structure can reach 1774 nm/RIU with a figure of merit of 61. The proposed structure has potential in nanophotonic sensing applications.

Flexible ferroelasticity in monolayer PdS2: a DFT study.

As an unusual mechanical response, the ferroelastic phenomenon in two-dimensional materials has been reported both experimentally and theoretically in recent years. Here, we present the theoretical findings of ferroelastic switching in monolayer PdS2. We demonstrate four types of PdS2 allotropes, showing excellent ferroelasticity with low ferroelastic barriers and strong switching signals. The ferroelastic transitions in monolayer PdS2 include the lattice rotation in penta-α PdS2, the transformation between penta-α PdS2 and penta-ß PdS2, the transformation between penta-α PdS2 and penta-γ PdS2, the transformation between penta-ß PdS2 and penta-γ PdS2, the transformation between penta-α PdS2 and δ PdS2, and the lattice rotation in δ PdS2. The ferroelastic transitions between these four allotropes have revealed the flexible ferroelasticity in monolayer PdS2. Specifically, the flexible switching in PdS2 allotropes may efficiently control the anisotropic transport of electrons. Thus, the presence of these outstanding mechanical properties endows PdS2 with great potential for applications in next-generation shape memory devices.

Recent Progress of Black Silicon: From Fabrications to Applications.

Since black silicon was discovered by coincidence, the special material was explored for many amazing material characteristics in optical, surface topography, and so on. Because of the material property, black silicon is applied in many spheres of a photodetector, photovoltaic cell, photo-electrocatalysis, antibacterial surfaces, and sensors. With the development of fabrication technology, black silicon has expanded in more and more applications and has become a research hotspot. Herein, this review systematically summarizes the fabricating method of black silicon, including nanosecond or femtosecond laser irradiation, metal-assisted chemical etching (MACE), reactive ion etching (RIE), wet chemical etching, electrochemical method, and plasma immersion ion implantation (PIII) methods. In addition, this review focuses on the progress in multiple black silicon applications in the past 10 years. Finally, the prospect of black silicon fabricating and various applications are outlined.

A Nanostructure with Defect Based on Fano Resonance for Application on Refractive-Index and Temperature Sensing.

Herein, a nanosensor structure is proposed, which comprises metal-insulator-metal (MIM) waveguide with stub and circular ring cavity with a stub (CRCS). The phenomenon of Fano resonance appears in the transmission spectrum, which is formed by interaction between the narrowband mode of CRCS and broadband mode of stub on bus waveguide. The influence of geometric asymmetry on mode splitting of Fano resonance was discussed. The mode splitting of Fano resonance can vastly improve figure of merit (FOM) with a sight decrease of sensitivity. The best performance of the refractive-index nanosensor is attained, which is 1420 nm/RIU with a high FOM of 76.76. Additionally, the application of designed structure on temperature sensing was investigated, which has sensitivity of 0.8 nm/°C. The proposed structure also possesses potential applications on other on-chip nanosensors.

Fano Resonance in a MIM Waveguide with Two Triangle Stubs Coupled with a Split-Ring Nanocavity for Sensing Application.

Herein, a compact refractive index nanosensor comprising a metal- insulator- metal (MIM) waveguide with symmetric two triangle stubs coupled with a circular split-ring resonance cavity (CSRRC) is theoretically presented. An analysis of the propagation characteristics of the designed structure is discussed employing the finite element method (FEM). The calculation results revealed that a Fano resonance outline emerged, which results from an interaction between the continuous broadband state of the waveguide with two symmetric triangle stubs and the discrete narrowband state of the CSRRC. The influence of geometric parameters on sensing properties was studied in detail. The maximum sensitivity reached 1500 nm/RIU with a high figure of merit of 65.2. The presented structure has great applications for on-chip plasmonic nanosensors.

Fano Resonance in an Asymmetric MIM Waveguide Structure and Its Application in a Refractive Index Nanosensor.

Herein, the design for a tunable plasmonic refractive index nanosensor is presented. The sensor is composed of a metal⁻insulator⁻metal waveguide with a baffle and a circular split-ring resonator cavity. Analysis of transmission characteristics of the sensor structures was performed using the finite element method, and the influence of the structure parameters on the sensing characteristics of the sensor is studied in detail. The calculation results show that the structure can realize dual Fano resonance, and the structural parameters of the sensor have different effects on Fano resonance. The peak position and the line shape of the resonance can be adjusted by altering the sensitive parameters. The maximum value of structural sensitivity was found to be 1114.3 nm/RIU, with a figure of merit of 55.71. The results indicate that the proposed structure can be applied to optical integrated circuits, particularly in high sensitivity nanosensors.