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1.
Artigo em Inglês | MEDLINE | ID: mdl-38651800

RESUMO

Light-element-based fluorescent materials, colloidal graphene quantum dots, and carbon dots (CDs) have sparked an immense amount of scientific interest in the past decade. However, a significant challenge in practical applications has emerged concerning the development of solid-state fluorescence (SSF) materials. This study addresses this knowledge gap by exploring the unexplored photonic facets of C-based solid-state microphotonic emitters. The proposed synthesis approach focuses on carbonized polymer microspheres (CPMs) instead of conventional nanodots. These microspheres exhibit remarkable SSF spanning the entire visible spectrum from blue to red. The highly spherical shape of CPMs imparts built-in photonic properties in addition to its intrinsic CD-based attributes. Leveraging their excitation-dependent photoluminescence property, these microspheres exhibit amplified spontaneous emission, assisted by the whispering gallery mode resonance across the visible spectral region. Remarkably, unlike conventional semiconductor quantum dots or dye-doped microresonators, this single microstructure showcases adaptable resonant emission without structural/chemical modifications. This distinctive attribute enables a plethora of applications, including microcavity-assisted energy transfer for white light emission, highly sensitive chemical sensing, and secure encrypted anticounterfeiting measures. This interdisciplinary approach, integrating photonics and chemistry, provides a robust solution for light-element-based SSF with inherent photonic functionality and wide-ranging applications.

2.
J Bone Miner Res ; 38(12): 1800-1808, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37850817

RESUMO

The long-term bone health of young adults born extremely preterm (EP; <28 weeks' gestation) or extremely low birth weight (ELBW; <1000 g birth weight) in the post-surfactant era (since the early 1990s) is unclear. This study investigated their bone structure and estimated bone strength using peripheral quantitative computed tomography (pQCT)-based finite element modeling (pQCT-FEM). Results using this technique have been associated with bone fragility in several clinical settings. Participants comprised 161 EP/ELBW survivors (46.0% male) and 122 contemporaneous term-born (44.3% male), normal birth weight controls born in Victoria, Australia, during 1991-1992. At age 25 years, participants underwent pQCT at 4% and 66% of tibia and radius length, which was analyzed using pQCT-FEM. Groups were compared using linear regression and adjusted for height and weight. An interaction term between group and sex was added to assess group differences between sexes. Parameters measured included compressive stiffness (kcomp ), torsional stiffness (ktorsion ), and bending stiffness (kbend ). EP/ELBW survivors were shorter than the controls, but their weights were similar. Several unadjusted tibial pQCT-FEM parameters were lower in the EP/ELBW group. Height- and weight-adjusted ktorsion at 66% tibia remained lower in EP/ELBW (mean difference [95% confidence interval] -180 [-352, -8] Nm/deg). The evidence for group differences in ktorsion and kbend at 66% tibia was stronger among males than females (pinteractions <0.05). There was little evidence for group differences in adjusted radial models. Lower height- and weight-adjusted pQCT-FEM measures in EP/ELBW compared with controls suggest a clinically relevant increase in predicted long-term fracture risk in EP/ELBW survivors, particularly males. Future pQCT-FEM studies should utilize the tibial pQCT images because of the greater variability in the radius possibly related to lower measurement precision. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).


Assuntos
Recém-Nascido de Peso Extremamente Baixo ao Nascer , Lactente Extremamente Prematuro , Recém-Nascido , Feminino , Humanos , Masculino , Adulto Jovem , Adulto , Peso ao Nascer , Minerais , Vitória
3.
Intern Med J ; 53(12): 2247-2256, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36876960

RESUMO

BACKGROUND: Effective post-pandemic telehealth (TH) requires understanding patients' characteristics and perceptions, which have not been established in broader clinical services and are independent of TH appointments. AIMS: To understand medical patients' characteristics and perspectives on using TH. METHODS: General medical patients in a statewide tertiary hospital in Victoria, Australia received a de-identified survey independent of TH appointments during visits between July and November 2020. Patients' characteristics, access to devices enabling TH, knowledge of TH and willingness to use TH were analysed with descriptive statistics. RESULTS: Of 1600 patients, 754 (46.4% female, aged 72.0 years [59.0-83.0]) were able to complete the survey. The majority lived in metropolitan areas (74.4%), owned at least one TH device (98.1%) and had internet access at home (55.6%). About 52.7% of patients were comfortable with their devices, and 43.5% had successfully used TH. Although patients preferred face-to-face appointments (80.8%) and 41.4% agreed TH would be as good as in-person appointments, 63.9% were interested in future TH appointments. Patients preferring face-to-face appointments were older (P = 0.008) and had lower education levels (P = 0.010), whereas patients preferring TH had video TH devices (P < 0.05), were comfortable with their devices (P = 0.002) and were willing to use TH (P < 0.05). TH cost saving was parking AU$10.0 [0.0-15.0], driving AU$5.8 [4.5-19.9], public transport AU$8.00 [5.0-10.0], taxis AU$30.00 [15.0-50.0] and time AU$153.2 [76.6-153.2]. CONCLUSION: From predominantly middle-aged to older, metropolitan-based general medical patients completing the survey, most patienpreferred face-to-face appointments to TH. Health services should subsidise those in need of TH and target the patients' barriers to effective TH use.


Assuntos
Telemedicina , Pessoa de Meia-Idade , Humanos , Feminino , Masculino , Atenção à Saúde , Pandemias , Inquéritos e Questionários , Vitória/epidemiologia
4.
Sci Rep ; 12(1): 20160, 2022 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-36418408

RESUMO

Osteoporosis contributes significantly to health and economic burdens worldwide. However, the development of osteoporosis-related prediction tools has been limited for lower-middle-income countries, especially Vietnam. This study aims to develop prediction models for the Vietnamese population as well as evaluate the existing tools to forecast the risk of osteoporosis and evaluate the contribution of covariates that previous studies have determined to be risk factors for osteoporosis. The prediction models were developed to predict the risk of osteoporosis using machine learning algorithms. The performance of the included prediction models was evaluated based on two scenarios; in the first one, the original test parameters were directly modeled, and in the second the original test parameters were transformed into binary covariates. The area under the receiver operating characteristic curve, the Brier score, precision, recall and F1-score were calculated to evaluate the models' performance in both scenarios. The contribution of the covariates was estimated using the Permutation Feature Importance estimation. Four models, namely, Logistic Regression, Support Vector Machine, Random Forest and Neural Network, were developed through two scenarios. During the validation phase, these four models performed competitively against the reference models, with the areas under the curve above 0.81. Age, height and weight contributed the most to the risk of osteoporosis, while the correlation of the other covariates with the outcome was minor. Machine learning algorithms have a proven advantage in predicting the risk of osteoporosis among Vietnamese women over 50 years old. Additional research is required to more deeply evaluate the performance of the models on other high-risk populations.


Assuntos
Aprendizado de Máquina , Osteoporose , Humanos , Feminino , Idoso , Pessoa de Meia-Idade , Vietnã/epidemiologia , Osteoporose/diagnóstico , Osteoporose/epidemiologia , Fatores de Risco , Povo Asiático
5.
Front Public Health ; 10: 973362, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36159240

RESUMO

Background: Tuberculosis has caused significant public health and economic burdens in Vietnam over the years. The Vietnam National Tuberculosis Program is facing considerable challenges in its goal to eliminate tuberculosis by 2030, with the COVID-19 pandemic having negatively impacted routine tuberculosis services at all administrative levels. While the turnaround time of tuberculosis infection may delay disease detection, high transportation frequency could potentially mislead epidemiological studies. This study was conducted to develop an online geospatial platform to support healthcare workers in performing data visualization and promoting the active case surveillance in community as well as predicting the TB incidence in space and time. Method: This geospatial platform was developed using tuberculosis notification data managed by The Vietnam National Tuberculosis Program. The platform allows case distribution to be visualized by administrative level and time. Users can retrieve epidemiological measurements from the platform, which are calculated and visualized both temporally and spatially. The prediction model was developed to predict the TB incidence in space and time. Results: An online geospatial platform was developed, which presented the prediction model providing estimates of case detection. There were 400,370 TB cases with bacterial evidence to be included in the study. We estimated that the prevalence of TB in Vietnam was at 414.67 cases per 100.000 population. Ha Noi, Da Nang, and Ho Chi Minh City were predicted as three likely epidemiological hotspots in the near future. Conclusion: Our findings indicate that increased efforts should be undertaken to control tuberculosis transmission in these hotspots.


Assuntos
COVID-19 , Tuberculose , COVID-19/epidemiologia , Cidades , Humanos , Incidência , Pandemias , Tuberculose/diagnóstico , Tuberculose/epidemiologia
6.
Sensors (Basel) ; 22(8)2022 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-35458953

RESUMO

In this work, we present and analyze a design of an absorber-waveguide system combining a highly sensitive waveguide array concept with a resonant selective absorber. The waveguide part is composed of an array of coupled strip waveguides and is therefore called a coupled strip array (CSA). The CSA is then coupled to the end of a slab Tamm plasmon (STP-) resonator, which is composed of a quasicrystal-like reflector formed by the patterning of a silicon slab and an interfacing tungsten slab. The concept describes an emitter-waveguide or waveguide-detector system featuring selective plasmon-enhanced resonant absorption or emission. These are crucial properties for corresponding optical on-chip integrated devices in context with evanescent field absorption sensing in fluids or gases, for example. Thus, the concept comprises a valuable and more cost-effective alternative to quantum cascade lasers. We designed the lateral dimensions of the STP resonator via a simple quasi-crystal approach and achieved strong narrowband resonances (emittance and Q-factors up to 85% and 88, respectively) for different silicon thicknesses and substrate materials (air and silicon oxide). Moreover, we analyze and discuss the sensitivity of the complete emitter-waveguide system in dependence on the slab thickness. This reveals the crucial correlation between the expected sensitivity assigned to the absorber-waveguide system and field confinement within the silicon.

7.
Front Public Health ; 10: 988107, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36711402

RESUMO

On April 27, 2021, the fourth wave of the coronavirus disease 2019 (COVID-19) pandemic originating from the Delta variant of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began in Vietnam. The adoption of travel restrictions, coupled with rapid vaccination and mask-wearing, is a global strategy to prevent the spread of COVID-19. Although trade-off between health and economic development are unavoidable in this situation, little evidence that is specific to Vietnam in terms of movement restrictions, vaccine coverage, and real-time COVID-19 cases is available. Our research question is whether travel restrictions and vaccine coverage are related to changes in the incidence of COVID-19 in each province in Vietnam. We used Google's Global Mobility Data Source, which reports different mobility types, along with reports of vaccine coverage and COVID-19 cases retrieved from publicly and freely available datasets, for this research. Starting from the 50th case per province and incorporating a 14-day period to account for exposure and illness, we examined the association between changes in mobility (from day 27 to 04-03/11/2021) and the ratio of the number of new confirmed cases on a given day to the total number of cases in the past 14 days of indexing (the potentially contagious group in the population) per million population by making use of LOESS regression and logit regression. In two-thirds of the surveyed provinces, a reduction of up to 40% in commuting movement (to the workplace, transit stations, grocery stores, and entertainment venues) was related to a reduction in the number of cases, especially in the early stages of the pandemic. Once both movement and disease prevalence had been mitigated, further restrictions offered little additional benefit. These results indicate the importance of early and decisive actions during the pandemic.


Assuntos
COVID-19 , Vacinas , Humanos , COVID-19/epidemiologia , COVID-19/prevenção & controle , SARS-CoV-2 , Incidência , Pandemias/prevenção & controle , Vietnã/epidemiologia
8.
Sci Rep ; 11(1): 23895, 2021 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-34903808

RESUMO

There have been few independent evaluations of computer-aided detection (CAD) software for tuberculosis (TB) screening, despite the rapidly expanding array of available CAD solutions. We developed a test library of chest X-ray (CXR) images which was blindly re-read by two TB clinicians with different levels of experience and then processed by 12 CAD software solutions. Using Xpert MTB/RIF results as the reference standard, we compared the performance characteristics of each CAD software against both an Expert and Intermediate Reader, using cut-off thresholds which were selected to match the sensitivity of each human reader. Six CAD systems performed on par with the Expert Reader (Qure.ai, DeepTek, Delft Imaging, JF Healthcare, OXIPIT, and Lunit) and one additional software (Infervision) performed on par with the Intermediate Reader only. Qure.ai, Delft Imaging and Lunit were the only software to perform significantly better than the Intermediate Reader. The majority of these CAD software showed significantly lower performance among participants with a past history of TB. The radiography equipment used to capture the CXR image was also shown to affect performance for some CAD software. TB program implementers now have a wide selection of quality CAD software solutions to utilize in their CXR screening initiatives.


Assuntos
Aprendizado de Máquina/normas , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Tuberculose Pulmonar/diagnóstico por imagem , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Interpretação de Imagem Radiográfica Assistida por Computador/normas , Radiografia Torácica/métodos , Software/normas , Tuberculose Pulmonar/diagnóstico
9.
Sensors (Basel) ; 21(21)2021 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-34770299

RESUMO

In this study, we investigate the potential of one-dimensional plasmonic grating structures to serve as a platform for, e.g., sensitive refractive index sensing. This is achieved by comparing numerical simulations to experimental results with respect to the excitation of surface plasmon polaritons (SPPs) in the mid-infrared region. The samples, silver-coated poly-silicon gratings, cover different grating depths in the range of 50 nm-375 nm. This variation of the depth, at a fixed grating geometry, allows the active tuning of the bandwidth of the SPP resonance according to the requirements of particular applications. The experimental setup employs a tunable quantum cascade laser (QCL) and allows the retrieval of angle-resolved experimental wavelength spectra to characterize the wavelength and angle dependence of the SPP resonance of the specular reflectance. The experimental results are in good agreement with the simulations. As a tendency, shallower gratings reveal narrower SPP resonances in reflection. In particular, we report on 2.9 nm full width at half maximum (FWHM) at a wavelength of 4.12 µm and a signal attenuation of 21%. According to a numerical investigation with respect to a change of the refractive index of the dielectric above the grating structure, a spectral shift of 4122nmRIU can be expected, which translates to a figure of merit (FOM) of about 1421 RIU-1. The fabrication of the suggested structures is performed on eight-inch silicon substrates, entirely accomplished within an industrial fabrication environment using standard microfabrication processes. This in turn represents a decisive step towards plasmonic sensor technologies suitable for semiconductor mass-production.

10.
Trop Med Infect Dis ; 6(3)2021 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-34564547

RESUMO

X-ray screening is an important tool in tuberculosis (TB) prevention and care, but access has historically been restricted by its immobile nature. As recent advancements have improved the portability of modern X-ray systems, this study represents an early evaluation of the safety, image quality and yield of using an ultra-portable X-ray system for active case finding (ACF). We reported operational and radiological performance characteristics and compared image quality between the ultra-portable and two reference systems. Image quality was rated by three human readers and by an artificial intelligence (AI) software. We deployed the ultra-portable X-ray alongside the reference system for community-based ACF and described TB care cascades for each system. The ultra-portable system operated within advertised specifications and radiologic tolerances, except on X-ray capture capacity, which was 58% lower than the reported maximum of 100 exposures per charge. The mean image quality rating from radiologists for the ultra-portable system was significantly lower than the reference (3.71 vs. 3.99, p < 0.001). However, we detected no significant differences in TB abnormality scores using the AI software (p = 0.571), nor in any of the steps along the TB care cascade during our ACF campaign. Despite some shortcomings, ultra-portable X-ray systems have significant potential to improve case detection and equitable access to high-quality TB care.

11.
Calcif Tissue Int ; 109(5): 475-489, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34132852

RESUMO

To examine the prevalence of sarcopenia and its association with antirheumatic drugs in adults with rheumatoid arthritis (RA). This review was registered on PROSPERO and followed PRISMA guidelines. Electronic databases were searched for studies reporting on the prevalence of sarcopenia in adults with RA using any muscle index (muscle mass, strength and/or physical performance) and cutpoints as recommended by established criteria (EWGSOP1/2, AWGS, FNIH, SDOC). The secondary objective was to investigate the relationship between RA, antirheumatic drugs, and sarcopenia. Among 2240 middle-aged and older adults with RA (mean age: 47.7 ± 5.5 to 75.0 ± 6.2 years, 83.8% women), the pooled prevalence of low muscle mass/sarcopenia was 30.2% [95% confidence interval (CI) 24.2-36.2%; 16 studies; I2: 89.2%]. Sub-group analysis showed a non-significant higher prevalence of low muscle mass alone (32.6%, 95% CI 25.0-40.3%; I2: 87.9%) versus consensus definitions of sarcopenia (25.4%, 95% CI 15.4-35.3%; I2: 91.2%, p = 0.255). In adults with RA, corticosteroid use was positively associated with sarcopenia [odds ratio (OR) 1.46, 95% CI 0.94-2.29, 7 studies; I2: 47.5%] while conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) was inversely associated (OR 0.70, 95% CI 0.52-0.94; 6 studies: I2: 0.00%) with this muscle disease. No association was found for biological/targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) (OR 0.83, 95% CI 0.54-1.30; 6 studies: I2: 47.6%). Sarcopenia is a common comorbidity of RA, and as such, clinicians should screen for this muscle disease in adults with RA. Further longitudinal studies are needed to understand the role of antirheumatic drugs (particularly type, dosing, and duration) in the development of sarcopenia.


Assuntos
Antirreumáticos , Artrite Reumatoide , Sarcopenia , Adulto , Idoso , Antirreumáticos/uso terapêutico , Artrite Reumatoide/complicações , Artrite Reumatoide/tratamento farmacológico , Artrite Reumatoide/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Razão de Chances , Prevalência , Sarcopenia/tratamento farmacológico , Sarcopenia/epidemiologia
12.
J Electron Mater ; 50(4): 1942-1948, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33519044

RESUMO

Ni-doped TiO2 nanoparticles have been synthesized by a modified sol-gel method. The crystal phase composition, particle size, and magnetic and optical properties of the samples were comprehensively examined using x-ray diffraction analysis, transmission electron microscopy, Brunauer-Emmett-Teller surface area analysis, Raman spectroscopy, magnetization measurements, and ultraviolet-visible (UV-Vis) absorption techniques. The results showed that the prepared Ni-doped TiO2 samples sintered at 400°C crystallized completely in anatase phase with average particle size in the range from 8 nm to 10 nm and presented broad visible absorption. The bactericidal efficiency of TiO2 was effectively enhanced by Ni doping, with an optimum Ni doping concentration of 6% (x = 0.06), at which 95% of Escherichia coli were killed after just 90 min of irradiation. Density functional theory (DFT) calculations revealed good agreement with the experimental data. Moreover, the Ni dopant induced magnetic properties in TiO2, facilitating its retrieval using a magnetic field after use, which is an important feature for photocatalytic applications.

13.
Trop Med Infect Dis ; 5(4)2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-33321696

RESUMO

Across Asia, a large proportion of people with tuberculosis (TB) do not report symptoms, have mild symptoms or only experience symptoms for a short duration. These individuals may not seek care at health facilities or may be missed by symptom screening, resulting in sustained TB transmission in the community. We evaluated the yields of TB from 114 days of community-based, mobile chest X-ray (CXR) screening. The yields at each step of the TB screening cascade were tabulated and we compared cohorts of participants who reported having a prolonged cough and those reporting no cough or one of short duration. We estimated the marginal yields of TB using different diagnostic algorithms and calculated the relative diagnostic costs and cost per case for each algorithm. A total of 34,529 participants were screened by CXR, detecting 256 people with Xpert-positive TB. Only 50% of those diagnosed with TB were detected among participants reporting a prolonged cough. The study's screening algorithm detected almost 4 times as much TB as the National TB Program's standard diagnostic algorithm. Community-based, mobile chest X-ray screening can be a high yielding strategy which is able to identify people with TB who would likely otherwise have been missed by existing health services.

14.
Micromachines (Basel) ; 11(1)2019 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-31878232

RESUMO

Among conductive oxide materials, niobium doped titanium dioxide has recently emerged as a stimulating and promising contestant for numerous applications. With carrier concentration tunability, high thermal stability, mechanical and environmental robustness, this is a material-of-choice for infrared plasmonics, which can substitute indium tin oxide (ITO). In this report, to illustrate great advantages of this material, we describe successful fabrication and characterization of niobium doped titanium oxide nanoantenna arrays aiming at surface-enhanced infrared absorption spectroscopy. The niobium doped titanium oxide film was deposited with co-sputtering method. Then the nanopatterned arrays were prepared by electron beam lithography combined with plasma etching and oxygen plasma ashing processes. The relative transmittance of the nanostrip and nanodisk antenna arrays was evaluated with Fourier transform infrared spectroscopy. Polarization dependence of surface plasmon resonances on incident light was examined confirming good agreements with calculations. Simulated spectra also present red-shift as length, width or diameter of the nanostructures increase, as predicted by classical antenna theory.

15.
Adv Sci (Weinh) ; 6(20): 1900579, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31637158

RESUMO

Merging photonic structures and optoelectronic sensors into a single chip may yield a sensor-on-chip spectroscopic device that can measure the spectrum of matter. In this work, an on-chip concurrent multiwavelength infrared (IR) sensor, which consists of a set of narrowband wavelength-selective plasmonic perfect absorbers combined with pyroelectric sensors, where the response of each pyroelectric sensor is boosted only at the resonance of the nanostructured absorber, is proposed and realized. The proposed absorber, which is based on Wood's anomaly absorption from a 2D plasmonic square lattice, shows a narrowband polarization-independent resonance (quality factor - Q of 73) with a nearly perfect absorptivity as high as 0.99 at normal incidence. The fabricated quad-wavelength IR sensors exhibit four different narrowband spectral responses at normal incidence following the predesigned resonances in the mid-wavelength infrared region that corresponds to the atmospheric window. The device can be applied for practical spectroscopic applications such as nondispersive IR sensors, IR chemical imaging devices, pyrometers, and spectroscopic thermography imaging.

16.
Micromachines (Basel) ; 10(7)2019 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-31337078

RESUMO

On the search for the practical plasmonic materials beyond noble metals, aluminum has been emerging as a favorable candidate as it is abundant and offers the possibility of tailoring the plasmonic resonance spanning from ultra-violet to the infrared range. In this letter, in combination with the numerical electromagnetic simulations, we experimentally study the dark-field scattering spectral mapping of plasmonic resonance from the free-standing Al bowtie antenna arrays and correlate their strong nearfield enhancement with the sensing capability by means of surface-enhanced Raman spectroscopy. The spatial matching of plasmonic and Raman mapping puts another step to realize a very promising application of free-standing Al bowtie antennas for plasmonic sensing.

17.
Micromachines (Basel) ; 10(6)2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31234373

RESUMO

We propose and experimentally demonstrate a compact design for membrane-supported wavelength-selective infrared (IR) bolometers. The proposed bolometer device is composed of wavelength-selective absorbers functioning as the efficient spectroscopic IR light-to-heat transducers that make the amorphous silicon (a-Si) bolometers respond at the desired resonance wavelengths. The proposed devices with specific resonances are first numerically simulated to obtain the optimal geometrical parameters and then experimentally realized. The fabricated devices exhibit a wide resonance tunability in the mid-wavelength IR atmospheric window by changing the size of the resonator of the devices. The measured spectral response of the fabricated device wholly follows the pre-designed resonance, which obviously evidences that the concept of the proposed wavelength-selective IR bolometers is realizable. The results obtained in this work provide a new solution for on-chip MEMS-based wavelength-selective a-Si bolometers for practical applications in IR spectroscopic devices.

18.
Opt Express ; 27(12): A725-A737, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31252849

RESUMO

Ultra-narrowband perfect absorbers and emitters are proposed and realized by engineering multiple-beam interference in Gires-Tournois etalon with the presence of low metallic loss. The absorption mechanism and spectral characteristics of the Gires-Tournois resonators are numerically and experimentally investigated for three configurations: dielectric cavity on metal, metal-dielectric-metal resonator, and distributed Bragg reflector (DBR)-dielectric-metal resonator. Narrowband thermal emitters based on the metal-dielectric-metal cavity and (DBR)-dielectric-metal cavity are experimentally demonstrated with an emissivity of 0.8 and 0.82, and a quality factor of 21 and 85, respectively. A DBR-dielectric-metal resonator-based absorber is directly loaded onto a LiTaO 3 film for the first time to constitute an on-chip ultra-narrowband pyroelectric detector with an excellent quality factor of 151 at the absorption band of methane.

19.
Micromachines (Basel) ; 10(6)2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31234295

RESUMO

Spectrally selective detection is of crucial importance for diverse modern spectroscopic applications such as multi-wavelength pyrometry, non-dispersive infrared gas sensing, biomedical analysis, flame detection, and thermal imaging. This paper reports a quad-wavelength hybrid plasmonic-pyroelectric detector that exhibited spectrally selective infrared detection at four wavelengths-3.3, 3.7, 4.1, and 4.5 µm. The narrowband detection was achieved by coupling the incident infrared light to the resonant modes of the four different plasmonic perfect absorbers based on Al-disk-array placed on a Al2O3-Al bilayer. These absorbers were directly integrated on top of a zinc oxide thin film functioning as a pyroelectric transducer. The device was fabricated using micro-electromechanical system (MEMS) technology to optimize the spectral responsivity. The proposed detector operated at room temperature and exhibited a responsivity of approximately 100-140 mV/W with a full width at half maximum of about 0.9-1.2 µm. The wavelength tunability, high spectral resolution, compactness and robust MEMS-based platform of the hybrid device demonstrated a great advantage over conventional photodetectors with bandpass filters, and exhibited impressive possibilities for miniature multi-wavelength spectroscopic devices.

20.
Nanoscale ; 11(19): 9508-9517, 2019 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-31049510

RESUMO

We propose antenna-enhanced infrared vibrational spectroscopy by adopting single-sized Al disks on Al2O3-Al films fabricated by colloidal-mask lithography. The precisely designed plasmonic resonator with dual-band perfect absorption (DPA) shows strongly-enhanced nearfield intensity and polarization independence, at both resonances, providing a powerful antenna platform for the multi-band vibrational sensing. As a proof of concept, we experimentally apply the plasmonic DPAs in bond-selective dual-band infrared sensing of an ultrathin polydimethylsiloxane (PDMS) film, simultaneously amplifying two representative vibrational bands (asymmetric C-H stretching of CH3 at 2962 cm-1 and CH3 deformation of Si-CH3 at 1263 cm-1) by surface-enhanced infrared absorption spectroscopy (SEIRA). The plasmonic DPA was successfully adopted for the in situ monitoring of reaction kinetics, by recording the spectral changes in C-H stretching and Si-CH3 deformation modes of a 10 nm PDMS elastomer, which are selectively enhanced by the two antenna resonances, during its gelation process. Our systematic study of the SEIRA spectra has demonstrated mode splitting and a clear avoided-crossing in the dispersion curve as a function of resonance frequency of DPA, manifesting itself as a promising basis for future polaritonic devices utilizing the hybridization between the molecular vibrational states and the enhanced light field.

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