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Flexible transparent electrodes, encompassing the combination of optical transparency and electrical conductivity, empower numerous optoelectronic applications. While the main efforts nowadays concentrate on developing wire meshes and conductive oxides, those technologies are still in a quest to find a balance between price, performance, and versatility. Here we propose a new platform, encompassing the advantages of nanophotonic design and roll‐to‐roll large‐scale lithography fabrication tools, granting an ultimate balance between optical, electrical, and mechanical properties. The design is based on an array of silica microspheres deposited on a patterned thin aluminum film attached to a flexible polymer matrix. Microspheres are designed to squeeze 80% light through nanoscale apertures with the aid of the photonic nanojet effect given the light impinges the structure from the top. The photonic structure blocks the transmission for the backpropagation direction thus granting the device with the high 5‐fold level of asymmetry. The patterned layer demonstrates a remarkable 2.8 Ω sq−1 sheet resistance comparable to that of a continuous metal layer. The high conductivity is shown to be maintained after a repeatable application of strain on the flexible electrode. Such remarkable optical, mechanical and electrical properties, makes the demonstrated device an essential component for applications, where such attributes are critically required. [ABSTRACT FROM AUTHOR]

Laser and molecular detection techniques that have been used to overcome the limitations of fluorescent DNA labeling have presented new challenges. To address some of these challenges, we developed a DNA laser that uses a solid-state silica microsphere as a ring resonator and a site for DNA-binding reactions, as well as a platform to detect and sequence target DNA molecules. We detected target DNA using laser emission from a DNA-labeling dye and a developed solid-state silica microsphere ring resonator. The microsphere was sensitive; a single base mismatch in the DNA resulted in the absence of an optical signal. As each individual microsphere can be utilized as a parallel DNA analysis chamber, this optical digital detection scheme allows for high-throughput and rapid analysis. More importantly, the solid-state DNA laser is free from deformation, which guarantees stable lasing characteristics, and can be manipulated freely outside the solution. Thus, this promising advanced DNA laser scheme can be implemented on platforms other than optofluidic chips. [ABSTRACT FROM AUTHOR]

Laser and molecular detection techniques that have been used to overcome the limitations of fluorescent DNA labeling have presented new challenges. To address some of these challenges, we developed a DNA laser that uses a solid-state silica microsphere as a ring resonator and a site for DNA-binding reactions, as well as a platform to detect and sequence target DNA molecules. We detected target DNA using laser emission from a DNA-labeling dye and a developed solid-state silica microsphere ring resonator. The microsphere was sensitive; a single base mismatch in the DNA resulted in the absence of an optical signal. As each individual microsphere can be utilized as a parallel DNA analysis chamber, this optical digital detection scheme allows for high-throughput and rapid analysis. More importantly, the solid-state DNA laser is free from deformation, which guarantees stable lasing characteristics, and can be manipulated freely outside the solution. Thus, this promising advanced DNA laser scheme can be implemented on platforms other than optofluidic chips.

Passive radiative cooling is a key technology to solve the global warming and energy waste caused by refrigeration. However, because of the high price and complex manufacturing process, the application of daytime radiative cooling materials in the field of building materials is hindered. Here, we studied a low-cost radiative cooling cellulose-based composite material prepared from wood powder that exhibits highly selective infrared emission and high solar reflectivity. And we use the evaporation deposition technique to form a dual-layer structure with silica microspheres in the lower layer. The radiative cooling film based on the intrinsic absorption of lignocellulose and silica microspheres exhibits not only high infrared emissivity of 98.7% in the ‘atmospheric window’ range but also exhibits high reflectivity of 98.44% in the visible light range. We have also found that the performance of the radiative cooling film is the best when the content of silica microspheres reaches 30 wt%, and the film exhibits a cooling of 9.6 °C under direct sunlight. The preparation method of low-cost and high-performance radiative cooling material provided in this article is expected to provide a reference for the application of radiative cooling materials in building materials.

The investigation of optical microcavity solitons is in demand both for applications and basic science. Despite the tremendous progress in the study of microresonator solitons, there is still no complete understanding of all features of their nonlinear dynamics in various regimes. Controlling soliton properties is also of great interest. We proposed and investigated experimentally and theoretically a simple and easily reproducible way to generate Raman solitons with controllable spectral width in an anomalous dispersion region in a functionalized silica microsphere with whispering gallery modes (WGMs) driven in a normal dispersion regime. To functionalize the microsphere, coating (TiO2 + graphite powder) was applied at the pole. The coating is used for effective thermalization of the radiation of an auxiliary laser diode launched through the fiber stem holding the microsphere to control detuning of the pump frequency from exact resonance due to the thermo-optical shift of the WGM frequencies. We demonstrated that the thermo-optical control by changing the power of an auxiliary diode makes it possible to switch on/off the generation of Raman solitons and control their spectral width, as well as to switch Raman generation to multimode or single-mode. We also performed a detailed theoretical analysis based on the Raman-modified Lugiato–Lefever equation and explained peculiarities of intracavity nonlinear dynamics of Raman solitons. All experimental and numerically simulated results are in excellent agreement. [ABSTRACT FROM AUTHOR]

Novel chiral microporous organic network/covalent organic framework composites functionalized silica microspheres (CMON/CCOF@SiO 2) were cleverly designed for multi-mode HPLC separation of various chiral/hydrophilic/hydrophobic analytes. [Display omitted] • MON/COF composites were first explored as ideal modifiers of silica gel. • Clever bonding of L -cysteine endowed the MON/COF@SiO 2 with chirality. • CMON/CCOF@SiO 2 exhibited superior separation ability to CCOF@SiO 2. • CMON/CCOF@SiO 2 showed good application prospects in HPLC separation. • Various chiral/hydrophilic/hydrophobic analytes were effectively separated. Nowadays, covalent organic framework (COF) has shown great potential in chromatographic separation, and enriching the design of novel COF based stationary phases and broadening their application prospects remains of great significance. Microporous organic network (MON) is a novel type of porous material with large specific surface area and excellent stability connected by covalent bonding, which is extremely similar to COF. Especially, nano-sized MON has the characteristics of easy binding with silica matrix and superior chromatographic separation performance. In this work, the combination of MON and COF as the surface modification materials of silica gel was first explored. The conjugated network structure of MON and COF can improve the permeability of silica stationary phase, and the presence of abundant functional groups in COF and MON can enhance the separation ability for a series of aromatic compounds. Moreover, hydrophilic L -cysteine containing thiol group was cleverly introduced into MON/COF@SiO 2 via thiol-ene/yne click reactions to balance the hydrophilicity and hydrophobicity of stationary phase. The L -cysteine modified chiral MON/COF@SiO 2 (CMON/CCOF@SiO 2) was used for effective separation of various chiral/hydrophilic/hydrophobic analytes, and the CMON/CCOF@SiO 2 was observed to exhibit superior separation ability to the CCOF@SiO 2. Multi-mode chromatographic separation mechanisms were explored, demonstrating that multiple interactions were involved in the separation process. Finally, the CMON/CCOF@SiO 2 was applied to detect the environmental endocrine disruptors in the water sample and pyridoxine in the tablet sample, respectively, indicating a great potential for application in actual sample detection. [ABSTRACT FROM AUTHOR]

Adsorption of silica microspheres prepared by improved Stober process on Cu2+ ion in solution was investigated. The structure and properties of silica microspheres were analyzed and characterized by XRD, SEM, particle size an alysis, and nitrogen adsorption-desorption method. Effects of temperature, time, initial concentration of Cu2+ ion, and adsorbent dosage, on adsorption were examined, adsorption kinetics and isothermal adsorption process were discussed. Experimental results showed that copperion removal rate was 98.49 % at conditions of 40°C, 240 min, 50 mL solution with Cu2+ initial concentration of 100 mg/L treated by 0.1g silica. Pseudo-second-order model fits the adsorption kinetic behavior better, the adsorption isotherm conforms to Langmuir model, and the maximum adsorption capacity is 52.524 3 mg/g at 40°C. Silica microsphere has good adsorption properties for Cu2+ ions in solution. [ABSTRACT FROM AUTHOR]

Kerr optical frequency combs (OFCs) based on silica microsphere whispering gallery mode resonator (WGMR) have various applications where they are used as a light source. For telecommunication purposes, WGMR-based Kerr-OFC comb generators can be physically realized using silica microsphere resonators and can be used to replace multiple laser arrays. In such a realization, these novel light sources have the potential to demonstrate an attractive solution for intra-datacenter interconnects (DCI). In this paper, we show an experimental demonstration of a silica microsphere WGMR-based Kerr OFC light source where newly generated 400 GHz spaced carriers together with powerful linear equalization techniques, such as a linear symbol-spaced adaptive decision-feedback equalizer (DFE) with feed-forward (FF) and feedback (FB) taps, provide an alternative to individual lasers ensuring low-cost and low-complexity IM/DD scheme for the transmission of NRZ-OOK modulated signals at data rates up to 50 Gbps/λ over 2 km SMF link. Finally, we demonstrate a record 50 Gbps per λ transmission of NRZ-OOK modulated signals with a novel silica microsphere WGMR-based Kerr-OFC as a light source operating in the optical C-band, surpassing the previously demonstrated data rate record by five times. [ABSTRACT FROM AUTHOR]

Optical frequency combs generated in whispering gallery mode microresonators are in high demand for basic science and a large number of applications including telecommunication systems and quantum optics. Here, we study experimentally and theoretically optical frequency comb generation in a silica microsphere with a zero dispersion wavelength near $1.55 μm pumped by a continuous wave laser widely tunable in the C-band. We considered the optical frequency comb generation for a pump wavelength in a normal dispersion region, in a low anomalous dispersion region, and very close to the zero dispersion wavelength. Kerr-assisted and Raman-assisted (Stokes) combs as well as anti-Stokes combs emerging due to the four-wave mixing between the Kerr and Raman combs are attained in experiments. The mechanisms of producing individual peaks of optical frequency combs are verified in numerical simulations. A 270-nm optical frequency comb covering the telecommunication E-, S-, C-, L-, U-bands and further up to $1.7 μm is also demonstrated.

This article reports an implementation of a microsphere-based optical frequency comb (OFC) generator for substitution of individual laser arrays and simulates wavelength division multiplexed passive optical network (WDM-PON) based on this OFC generator. Our proposed generator is built based on silica microsphere, barely studied for fiber optical communication systems, and is a promising solution with photonic integration capability. Kerr OFC as a multiple light source containing more than 20 spectral carriers in the fundamental mode family in the C-band and beyond is demonstrated experimentally. Four of these OFC generator carriers with the highest peak power are studied in simulated 4-channel 393 GHz spaced WDM-PON. Additionally, we show this OFC as a source of optical carriers capable of providing data transmission over most utilized fiber types in modern optical communication systems, namely, single-mode fiber (SMF), non-zero dispersion-shifted fiber (NZ-DSF), and cut-off shifted fiber (CSF). We show through the simulations that error-free data transmission is possible, providing a total transmission capacity of 40 Gbit/s by using four OFC generated carriers.

This study presents a robust and scalable method for synthesizing continuously the silica microspheres via the Stöber method. Owing to the superb mixing accessible with gas-liquid segmented flow in coiled microtube, satisfactory morphology and mono-dispersity of silica spheres was obtained. The continuous method was firstly optimized through investigating the effects of various operation parameters on the morphology, particle size, size distribution and chemical structure of silica spheres. Without the surfactant, the size of silica spheres was limited < 850 nm due to the partial blockage of microchannel when synthesizing larger silica spheres. The addition of surfactant migrated the clogging issue, enabling the reliable synthesis of microspheres with diameters over 1 μm within a four times shorter residence time (30 min). Moreover, the mono-dispersity of silica microspheres could be further improved by increasing the gas/liquid ratio in segmented flow due to the more intensified mixing in liquid segments, as verified in visual flow field investigation. [ABSTRACT FROM AUTHOR]

In order to study the band gap performance of structural color films under different conditions, Monodisperse submicron silica microspheres with different particle sizes were prepared by the modified Stöber method, and a photonic crystal structure color film with silica as a structural element was prepared on the surface of the glass by vertical deposition self-assembly. The morphology and optical properties of microspheres and films were analyzed by scanning electron microscope, infrared spectrometer and UV-vis spectrophotometer. The results show that during the synthesis process, with the increase of the reaction temperature, the particle size of silica microspheres gradually reduces; with the increase of the diameter of SiO2 microspheres, the corresponding photonic band gap of photonic crystals occurs red shifting. It is found through further study that as the angle between the incident light and the normal line of color film increases, the center wavelength corresponding to the photonic band gap becomes shorter, then blue shifting occurs.

The investigation of optical microcavity solitons is in demand both for applications and basic science. Despite the tremendous progress in the study of microresonator solitons, there is still no complete understanding of all features of their nonlinear dynamics in various regimes. Controlling soliton properties is also of great interest. We proposed and investigated experimentally and theoretically a simple and easily reproducible way to generate Raman solitons with controllable spectral width in an anomalous dispersion region in a functionalized silica microsphere with whispering gallery modes (WGMs) driven in a normal dispersion regime. To functionalize the microsphere, coating (TiO2 + graphite powder) was applied at the pole. The coating is used for effective thermalization of the radiation of an auxiliary laser diode launched through the fiber stem holding the microsphere to control detuning of the pump frequency from exact resonance due to the thermo-optical shift of the WGM frequencies. We demonstrated that the thermo-optical control by changing the power of an auxiliary diode makes it possible to switch on/off the generation of Raman solitons and control their spectral width, as well as to switch Raman generation to multimode or single-mode. We also performed a detailed theoretical analysis based on the Raman-modified Lugiato–Lefever equation and explained peculiarities of intracavity nonlinear dynamics of Raman solitons. All experimental and numerically simulated results are in excellent agreement.

Kerr optical frequency combs (OFCs) based on silica microsphere whispering gallery mode resonator (WGMR) have various applications where they are used as a light source. For telecommunication purposes, WGMR-based Kerr-OFC comb generators can be physically realized using silica microsphere resonators and can be used to replace multiple laser arrays. In such a realization, these novel light sources have the potential to demonstrate an attractive solution for intra-datacenter interconnects (DCI). In this paper, we show an experimental demonstration of a silica microsphere WGMR-based Kerr OFC light source where newly generated 400 GHz spaced carriers together with powerful linear equalization techniques, such as a linear symbol-spaced adaptive decision-feedback equalizer (DFE) with feed-forward (FF) and feedback (FB) taps, provide an alternative to individual lasers ensuring low-cost and low-complexity IM/DD scheme for the transmission of NRZ-OOK modulated signals at data rates up to 50 Gbps/λ over 2 km SMF link. Finally, we demonstrate a record 50 Gbps per λ transmission of NRZ-OOK modulated signals with a novel silica microsphere WGMR-based Kerr-OFC as a light source operating in the optical C-band, surpassing the previously demonstrated data rate record by five times.

We demonstrate experimentally a silica microresonator-based single-mode Raman laser tunable in the U-band and beyond. The Stokes wavelength is tuned in the 1631–1685 nm range when tuning a C-band pump laser in the 1520–1570 nm range. We also demonstrate switching between Raman lasing modes which corresponds to “jumps” by 2 or 3 whispering gallery modes (WGMs) while sweeping the pump laser near a certain WGM (without pump “jumps” between WGMs). In addition, four-wave mixing (FWM) leading to single mode anti-Stokes wave generation in the E-band near 1450 nm is obtained when the pump wavelength is near the microresonator zero dispersion wavelength (ZDW) and the phase matching condition for the pump, Stokes, and anti-Stokes waves is satisfied.

An optical sensor based on silica micromaterial doped with Ni(II) ion has been developed for quantitation of ammonia (NH3) concentration using reflectometric transduction in an aqueous environment. The as-synthesized silica nanospheres were immobilized with Ni(II) ion via electrostatic interaction between positively charged divalent transition metal ion and negatively charged terminal silanol groups at silica microspheres surface. The optical microsensor demonstrated a colour change from green to blue upon introduced with NH3 solution, as a result of the formation of blue-hued hexamminenickelate(II) ([Ni(NH3)6] 2+) complex on the silica microspheres surface, and a maximum reflectance response was attained at the wavelength of 615 nm. The response time of the silica microspheres-based sensor is rapid towards the reflectance determination of NH3, i.e. <1 min at optimum pH 6. The linear response range of the developed reflectometric NH3 microsensor was acquired from 0.0003 M to 0.008 M (R²=0.9826) with a limit of detection (LOD) of 0.0012 M. The ammonia optical sensor response is good reproducibility with a relative standard deviation (RSD) obtained at 0.25% (n=7). The recovery test exhibited satisfactory results of 101.5% when the fabricated sensor was applied for the determination of NH3 in a polluted water sample collected from landfill wastewater. [ABSTRACT FROM AUTHOR]

In view of the importance of convenient and rapid H2O2 detection for biological analysis, we herein propose Ag nanoparticle (NP)-decorated silica microspheres as a probe for instant and non-enzymatic on-site colorimetric detection of H2O2. The surface hydroxyl groups of silica microspheres were reacted with (3-mercaptopropyl)trimethoxysilane to afford thiolated microspheres that subsequently bind Ag NPs. The oxidation of residual –SH groups on the silica surface to –S–S– moieties in the presence of H2O2 induces the aggregation of decorated microspheres and is accompanied by a color change. Sensor response is found to be proportional to H2O2 concentration in the range from 100 nM to 1 mM, with UV–Vis and colorimetric detection limits determined as 10 − 8 M and 10 − 5 M, respectively. The developed platform is successfully used to detect H2O2 in simulated human urine and is, therefore, concluded to be sufficiently stable and selective for practical applications. Ag nanoparticle-decorated silica microspheres were designed as a probe for colorimetric detection of H2O2. The oxidation of residual –SH groups on the silica surface to –S–S– moieties in the presence of H2O2 induces the aggregation of probe for a color change. The system exhibits a wide liner range from 100 nM to 1 mM, with UV-vis and colorimetric detection limits determined as 10–8 and 10–5 M, respectively. It is successfully used to detect H2O2 in simulated human urine. [ABSTRACT FROM AUTHOR]

[Display omitted] • The copper-modified catalyst could effectively avoid the metal leaching, and the residual metal content in the final product well bellowed the FDA-imposed limit for metal impurities. • The catalyst was designed to be easily synthesized and capable of repeated use in continuous reactions without significant loss of activity. • The catalyst was stable under various challenging conditions, including high temperatures, exposure to strong reductant or oxidant. • The catalyst was still suitable in a broader range of reactions, including indoles, anilines, and thiophenols. • The dispersion of copper species in silica microspheres reduced the intensity of reaction and improved the specificity of insertion reaction. Carbenes are key precursors for various transformations and are applied broadly in the synthesis of complex molecules and drug. Typically, such transformations require expensive metal and complex ligands, leading to a vigorous reaction system and trace metal residues. Herein, we report copper-modified silica microspheres (SM-b) as heterogeneous catalyst in the insertion reaction of diazo compounds with carbazole and silanes. Under this strategy, the optimal SM-b catalyst can prevent the reaction from being too vigorous and can be reused in continuous reactions. Furthermore, gram-scale and catalyst recycling reactions have been proven as the potential industrial applications of the SM-b catalysts. Inductively coupled plasma analysis revealed a residual copper content of only 6.25 ppm in the reaction solution and no detectable copper in the final product, indicating that the residual metal content of the product is far below the FDA-imposed limit of metal impurities. [ABSTRACT FROM AUTHOR]

Optical whispering gallery mode microresonators with controllable parameters in the telecommunication range are demanded for diverse applications. Controlling group velocity dispersion (GVD) in microresonators is an important problem, as near-zero GVD in a broad wavelength range could contribute to the development of new microresonator-based light sources. We demonstrated theoretically near-zero dispersion tailoring in the SCL-band in combination with free-spectral range (FSR) optimization for FSR = 200 GHz and 300 GHz in silica glass microspheres with micron-scale germanosilicate coating. As an illustration of a possible application of such a GVD, we also performed a theoretical study of degenerate four-wave mixing (FWM) processes in the proposed microresonators for pumping in the SCL-band. We found that in some cases the generation of two or even three pairs of waves–satellites in a FWM process is possible in principle due to the specific GVD features. We also determined optimal microresonator configurations for achieving gradual change in the satellite frequency shift for the pump wavelengths in the SCL-, S-, CL-, C-, and L-bands. The maximum obtained FWM satellite tunability span was ~78 THz for a pump wavelength change of ~30 nm, which greatly exceeds the results for a regular silica microsphere without coating.

Among the different types of photonic sensor devices, optical whispering gallery mode resonators (WGMRs) have attracted interest due to their high level of sensitivity, small size, and ability to perform real-time temperature measurements. Here we demonstrate the applicability of temperature measurements using WGMR in both air and liquid environments. We also show that WGMR allowed measurements of the refractive index variations in an evaporating glucose–water solution droplet. The thermal tuning of WGMR can be reduced by coating WGMRs with a thin layer of polymethyl methacrylate (PMMA). Dip-coating the silica microsphere multiple times significantly reduced the resonance shift, partially compensating for the positive thermo-optical coefficient of silica. The shift direction changed the sign eventually.

Optical frequency combs (OFCs) generated in microresonators with whispering gallery modes are demanded for different applications including telecommunications. Extending operating spectral ranges is an important problem for wavelength-division multiplexing systems based on microresonators. We demonstrate experimentally three spectrally separated OFCs in the C-, U-, and E-bands in silica microspheres which, in principle, can be used for telecommunication applications. For qualitative explanation of the OFC generation in the sidebands, we calculated gain coefficients and gain bandwidths for degenerate four-wave mixing (FWM) processes. We also attained a regime when the pump frequency was in the normal dispersion range and only two OFCs were generated. The first OFC was near the pump frequency and the second Raman-assisted OFC with a soliton-like spectrum was in the U-band. Numerical simulation based on the Lugiato–Lefever equation was performed to support this result and demonstrate that the Raman-assisted OFC may be a soliton.

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Silica microspheres (SMs) were in situ synthesized in silicon-modified porous carbon foams (SCFs) by an economic and efficient technique - high temperature oxyacetylene torch ablation. The microstructure and formation mechanism of SMs were analyzed in detail. Results showed that the resultant SMs generally were several microns in diameter, and mainly distributed in the ablation center zone. The formation mechanism was governed by the vapor-liquid-solid principle during the process of ablation and cooling. The influence of the ablative flame on the physicochemical property of SCFs was the leading cause of the bizarre SMs. [ABSTRACT FROM AUTHOR]

Optical frequency comb (OFC) generators based on whispering gallery mode (WGM) microresonators have a massive potential to ensure spectral and energy efficiency in wavelength-division multiplexing (WDM) telecommunication systems. The use of silica microspheres for telecommunication applications has hardly been studied but could be promising. We propose, investigate, and optimize numerically a simple design of a silica microsphere-based OFC generator in the C-band with a free spectral range of 200 GHz and simulate its implementation to provide 4-channel 200 GHz spaced WDM data transmission system. We calculate microsphere characteristics such as WGM eigenfrequencies, dispersion, nonlinear Kerr coefficient with allowance for thermo-optical effects, and simulate OFC generation in the regime of a stable dissipative Kerr soliton. We show that by employing generated OFC lines as optical carriers for WDM data transmission, it is possible to ensure error-free data transmission with a bit error rate (BER) of 4.5 × 10−30, providing a total of 40 Gbit/s of transmission speed on four channels.

Whispering gallery mode (WGM) microresonators are widely exploited for highly sensitive sensing applications due to their ultrahigh quality (Q) factor enabling single-particle detection. The WGM surface-confined resonant light recirculates around the resonator, allowing the light to interact with analytes over several round trips, which enhances the sensitivity of detection. However, the stability of efficient coupling of WGMs to ingress-egress waveguides for lab-on-chip has been problematic. The typical way to achieve WGM coupling is to use a tapered optical fiber or a prism, which makes the device either fragile or bulky, and is not conducive to sensor integration that can lead to robust lab-on-chip devices. In this letter, we demonstrate three-dimensional (3D) fabricated polymer waveguides that can be integrated and provide evanescent coupling to silica WGM microspheres without sacrificing Q factor. By mechanically connecting the waveguides to the microcavity, we can control the coupling to the resonator and the mechanical stability of the 3D lab-on-chip sensor is greatly improved. This provides a pathway to enhance the stability of WGM coupling for sensor integration. [ABSTRACT FROM AUTHOR]

In this paper, silica microspheres were used as template to prepare porous fluorinated polyimide (FPI) thin films from polyamic acid (PAA, precursor of FPI) and silica colloid solution. The strong hydrogen-bonding interaction between silica microspheres and PAA chains have improved the dispersion of silica microspheres in N,N-Dimethylformamide (DMF) solution, resulting in the high weight content of silica template in PAA/silica colloid solution, and thus giving rise to the formation of porous FPI films with maximum porosity of 35%. The interior microstructures of the resultant porous FPI thin films were investigated. It is found that the porous FPI thin films have interconnected “ink-bottle-type” porous structure, and the pore size, porosity could be precisely controlled by the diameter and weight content of silica microspheres, respectively. Although both the tensile strength and young modules declined with the increasing porosity, the high level void of the porous FPI films endowed the FPI ultralow dielectric constant of 1.84 when the porosity increased to 35%. Furthermore, the mechanical and dielectric properties of the porous FPI films were closely related to the microstructures and porosity, indicating the desired properties could be controlled to meet the application in the microelectronics. [ABSTRACT FROM AUTHOR]

Monodispersed silica spheres were prepared by an effective method, which an ethanolic solution of tetraethyl orthosilicate (TEOS) was continuously supplied to the reaction mixture containing KCl electrolyte, water, TEOS, ethanol and ammonia. The particle size of the silica spheres ranged from 2.0 to 4.5 µm. In addition, the effects of reaction conditions such as temperature and amount of ammonia on microsphere morphology were studied. [ABSTRACT FROM AUTHOR]

We propose a scheme to achieve ultrahigh-quality (Q) silica microsphere electrical thermo-optic fully tunable tuning, which can keep its Q factor of around 1 0 8 during the tuning process. In this work, the rod of the silica microsphere is fixed on laser-induced graphene (LIG). The large amount of Joule heating generated by LIG energization can be effectively transferred to the microsphere, thus can achieve a wide range of electrical thermo-optic tuning. Experiment results show that such a simple and low-cost device owns an ultrahigh-Q factor of around 1 0 8 , an extensive tuning range of 3.03 nm, a sensitivity of 15.37 pm/°C. Its tunable range is 2.5 times greater than its azimuthal FSR. This practical scheme keeps ultrahigh-Q factors and achieves fully tunable tuning without introducing complex processes and additional instrumentations, which has great potential for tunable filters and optical switches. [ABSTRACT FROM AUTHOR]

Terpyridyl covalently grafted silica microspheres were prepared and characterized by UV–vis absorption spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. Highly selective and sensitive colorimetric sensing capacity of this hybrid material in fully aqueous solutions towards Fe 2+ among 13 metal cations tested, was verified. [ABSTRACT FROM AUTHOR]

[Display omitted] • Increased luminescence is achieved by irradiating the perovskite film with low-power laser light. • Large red shift of luminescence peak wavelength is realized by high-power laser irradiation. • Different luminescent materials are obtained by the decomposition of the perovskite. • Efficient excitation and emission is realized by exploiting particle-on-film systems. • Femtosecond laser light is more effective in modifying the optical emission of perovskite. Two-dimensional (2D) organic–inorganic hybrid perovskites, especially Ruddlesden-Popper (RP) perovskites, have attracted great interest in recent years due to their potential applications in the fields of optoelectronics and photovoltaics. In this work, the effects of laser irradiation on the optical emission of a PEA 2 MA 2 Pb 3 I 10 thin film (PTF) were systematically investigated by using 488-nm continuous wave laser light and 400-nm femtosecond laser light as the excitation sources. It was found that the photoluminescence (PL) intensity of a PTF increases rapidly with irradiation time and becomes saturated after some time, which is ascribed to the passivation of the defects near the surface of the PTF through the interaction with oxygen. A large redshift of the PL wavelength from ∼ 625 to ∼ 750 nm was realized by simply increasing the laser power. It was suggested that the decomposition of PEA 2 MA 2 Pb 3 I 10 into MAPbI 3 is responsible for this behavior. The excitation efficiency was improved while the threshold laser power for the decomposition was lowered by constructing a particle-on-film system with a silica microsphere. In this way, the blueshift of the PL wavelength from ∼ 750 to ∼ 520 nm, which is attributed to the further decomposition of MAPbI 3 into PbI 2 , was achieved. Our findings provide a simple and effective way for modifying the optical emission of 2D perovskites and pave the way for realizing photonic devices based on 2D perovskites. [ABSTRACT FROM AUTHOR]

Uranium (U) and thorium (Th) are known to cause acute toxicological effects in human, and their compounds are potential occupational carcinogens. During this work, silica microspheres were used to decontaminate the traces of U and Th in different water sources originated from groundwater and lake water. Ultra-filtration technique was used to isolate the microsphere from the water samples. Silica microspheres were synthesized based on a polyvinylpyrrolidone involved emulsion polymerization and subsequent sol-gel process. The microspheres were characterized for their size by using dynamic light scattering, and presence of silicate structure is verified by recording their attenuated total reflectance-Fourier transform infrared spectrum. The surface morphologies of the prepared silica microspheres were studied by using scanning electron microscope. Water samples collected from the groundwater and lake water were spiked with U and Th in the concentration range of 100-1,000 ng mL. The results of batch sorption experiments suggest that silica microsphere is very effective at pH 3, and sorption is more than 99.9 %. Equilibrium sorption follows Langmuir isotherms and the maximum U, and Th uptake is 30 and 36 mg g, respectively. Major physicochemical characteristics of the water were monitored before and after the decontamination process. Experimental results show no significant variations in any of the measured parameters. [ABSTRACT FROM AUTHOR]