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BACKGROUND The COVID-19 pandemic has spread globally in a short period of time. It is known that antibody (nAb) level can effectively predict vaccine efficacy, which leads to the exploration of vaccine trials for efficacy assessment. Thus, the current study aimed to develop a platform to quantify nAb levels faster, at lower cost, and with better efficiency. MATERIAL AND METHODS A total of 69 sera samples were collected for the research, 28 of which were from unvaccinated participants. The other 27 samples and the remaining 14 samples were from the participants who had received the first and second dose, respectively, of AZ vaccine 1 month before. With cPass assays (Genscript cPass nAb ELISA assay) used as a criterion standard and lateral flow immunoassay kit (Healgen Scientific - LFIA test kit) coupled with a spectrometer (LFIA+S) for checking each specimen, we aimed to detect the presence of neutralizing antibodies in sera and to confirm the relationship between the inhibition rate from cPass assays and the nAb index from the LFIA+S. RESULTS Data analysis of the research were taken from the certified ELISA and LFIA+S, which indicated a high consistency (Pearson's r =0.864; ICC=0.90138) between the 2 methods. CONCLUSIONS The dataset demonstrated that LFIA+S was affordable, had a strong correlation with results of the cPass nAbs detection kit, and has potential clinical applications, with an exclusive feature that allows non-experts to use it with ease. It is believed that the proposed platform can be promoted in the near future.

Spectroscopic analysis has been widely used in medical research and healthcare testing including trace chemical, biochemical and immunoassay. We have developed a chip based spectrometer - SpectroChip based on novel MEMS technology. It has a spectral resolution of 5 nm with a spectral range of 350 1100 nm and a signal to noise ratio of 300:1. We have built a rapid test reader for COVID-19 antibody and antigen detection using our SpectroChip. Our SpectroChip technology will play a key role not only in disease control for COVID-19 pandemic but also in telemedicine and homecare health monitoring.

As coronavirus disease 2019 (COVID-19) continues to spread around the world, the establishment of decentralized severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) diagnostics and point-of-care testing is invaluable. While polymerase chain reaction (PCR) has been the gold standard for COVID-19 screening, serological assays detecting anti-SARS-CoV-2 antibodies in response to past and/or current infection remain vital tools. In particular, lateral flow immunoassay devices are easy to produce, scale, distribute, and use, however, they are unable to provide quantitative information. To enable quantitative analysis of lateral flow immunoassay device results, microgating technology was used to develop an innovative spectrochip that can be integrated into a portable, palm-sized device that was capable of capturing high-resolution reflectance spectrum data for quantitative immunoassay diagnostics. Using predefined spiked concentrations of recombinant anti-SARS-CoV-2 immunoglobulin G (IgG), this spectrochip-coupled immunoassay provided extraordinary sensitivity, with a detection limit as low as 186 pg/mL. Furthermore, this platform enabled the detection of anti-SARS-CoV-2 IgG in all PCR-confirmed patients as early as day 3 after symptom onset, including two patients whose spectrochip tests would be regarded as negative for COVID-19 using a direct visual read-out without spectral analysis. Therefore, the quantitative lateral flow immunoassay with an exceptionally low detection limit for SARS-CoV-2 is of value. An increase in the number of patients tested with this novel device may reveal its true clinical potential.

The coronavirus disease (COVID-19) is the global public health challenge currently persisting at a grand scale. A method that meets the rapid quantitative detection of antibodies to assess the body’s immune response from natural COVID-19 illness or vaccines’ effects is urgently needed. In the present study, an attempt was made to integrate a newly designed spectrometer to the COVID-19 test strip procedure; this augmentation provides the quantitative capacity to a lateral flow immunoassay (LFIA). Optical interpretation of results by quantitative α index, rather than visual qualification, can be done quickly, in 5–10 minutes. The developed product was compared with several other serological IgM/IgG antibody reagents on the market by recruiting 111 participants suspected of having COVID-19 infection from March to May 2020 in a hospital. Taking RT-PCR as the diagnostic gold standard, the quantitative spectral LIFA platform could correctly detect all 12 COVID-19 patients. Concerning RT-PCR negative patients, all three antibody testing methods found positive cases. The optical-based platform exhibited the ability of early detection of immunoglobulins of RT-PCR negative patients. There was an apparent trend that elevation of IgM levels in the acute phase of infection; then IgG levels rose later. It exhibited the risk of a false-negative diagnosis of RT-PCR in COVID-19 testing. The significant detection ability of this new optical-based platform demonstrated clinical potential.

Paraquat is a highly toxic herbicide. Paraquat poisoning is often fatal and is an important public health threat in many places. The quick identification and timely initiation of treatment based on timely analysis of the paraquat concentration in urine/serum could improve the prognosis for patients. However, current paraquat concentration measurements are time-consuming and difficult to implement due to the expensive and bulky equipment required. To address these practical challenges, paper-based devices have emerged as alternative diagnostic tools for improving point-of-care testing. In this study, we demonstrate the successful use of a paper-based analytical device for the accurate detection of urine paraquat concentration. The developed paper-based analytical device employs colorimetric paraquat concentration measurements. The R2 value for the urine paraquat standard curve was 0.9989, with a dynamic range of 0&ndash, 100 ppm. The limit of detection was 3.01 ppm. Two other optical-based approaches, Spectrochip and NanoDrop, were used for comparison. The results suggest that the developed paper-based analytical device is comparable to other colorimetric measurements, as determined by Bland&ndash, Altman analysis. The device was clinically validated using urine from six paraquat-poisoned patients. The results prove that the developed paper-based analytical device is accurate, easy-to-use, and efficient for urine paraquat concentration measurement, and may enable physicians to improve clinical management.

To design a concave grating for a hyperspectral imaging (HSI) system, it is critical to achieve flat field focusing in both the horizontal and vertical directions on the image sensor. We have developed a generalized automation aberration reduction procedure (ARP) that can be applied in any cases of a concave grating spectrometer. The concave grating, which has a free-form profile with blaze grating pitch and variable line spacing [3], is fabricated using five-axis CNC machine with nanometer machining precision for hyperspectral imaging. In order to evaluate the performance, an optical system is designed and setup to measure the focused spot size, spectral resolution and diffraction efficiency.

We have proposed an analytical 2D model [1] of a thickness gradient function for thin film deposition of a LVF for order sorting of a diffraction grating using an evaporation chamber. The LVF was fabricated and its thickness profile was measured using a probe-type surface analyzer. This study proposes an innovative method for overcoming the low production rates currently associated with LVF fabrication. Within the 25% - 75% thickness range, the profile distribution exhibits a high degree of linearity, with R2 are greater than or equal to 0.9914 for both the cases. The LVF zone width appears to be a linear function of the mask height h, with R2 are greater than or equal to 0.9982 for all the cases. This indicates that the thickness gradient function is a more accurate model for obtaining the thickness profile of an LVF than any other modeling mentioned in previous published results. This study demonstrates that the developed theoretical 2D model can be used to predict accurately the thin film profile of an LVF. The effective zone width of the LVF is defined as a thickness range of 25% - 75%, which appears to have high degree of linearity as a function of the mask height, h (mask-to-substrate gap). Thus, these results also confirms that the linear variable area increases as the mask-to-substrate gap increases. Thin film layer structures are constructed to demonstrate the efficacy of the proposed LVF design concept. Transmission spectrum result (wavebands 400nm to 1000nm) for varying mask heights at different positions shows maximum number of wavebands with transmittance (>99.9%). Comparison of both the theoretical and the evaporating results matches satisfactorily.

The overall chip size is less than half of a SD card. The spectral resolution is 3~5 nm for the whole spectral range of 350~1100 nm. The first order diffraction efficiency reaches over 70% at the blaze wavelength, which is at 550 nm. The signal-to-noise ratio of the SpectroChip system is 1000:1 with 50 ms integration time. The stray light is about 0.04%. A total solution is ready to be incorporated into any smart phone, wearable devices, and handheld device systems. With the incorporation of our SpectroChip sensors, hundreds to thousands items related to personal healthcare can be added to the worldwide health analysis cloud platform.

An analytical thin film thickness model based on the geometry of a commercial vacuum coating system is proposed. This model can calculate the profiles of linear variable filters (LVFs), which are used to eliminate overlapping orders of spectra due to the use of a diffraction grating and which are fabricated using a local mask, producing a linearly variable thickness. While the filter transmits the first-order wavelength and blocks the second-order wavelength. The 75% and 25% relative thicknesses deviation between the evaporated film and the theoretical model is less than 5%, indicating good suitability for LVF design and fabrication.

2D analytical model (Ko et al. (2016)) based on the geometry of the commercial coater system can calculate more effectively the profiles of LVFs. The model and experimental results (within 25%–75% thickness range) for LVF zone width, transmission spectrum and a thin film profile measurement of LVF shows good agreement with high degree of accuracy and the profile distribution exhibits a high degree of linearity.

A flat-field aberration corrected concave blaze grating for 400-1100nm is designed and fabricated. The concave grating, which has a free-form profile with blaze grating pitch and variable line spacing, is fabricated using five-axis CNC machine with nanometer machining precision. An optical system is setup to measure the focused spot size, spectral resolution and diffraction efficiency to evaluate the performance of aberration-corrected concave grating. The blaze grating reaches a diffraction efficiency of 70%. The focused vertical spot size is 50µm, which indicates a 50µm spatial resolution at the image plane. The focused horizontal spot size is 300µm, which converts to a spectral resolution of 6nm. The design methodology can be applied to an Offner type hyperspectral imager with a free-form convex grating and variable line spacing to achieve high efficiency and high spatial and high spectral resolving power.

A two-dimensional thin film thickness model based on the geometry of a commercial coater which can calculate more effectively the profiles of linear variable filters (LVFs) has been developed. This is done by isolating the substrate plane as an independent coordinate (local coordinate), while the rotation and translation matrices are used to establish the coordinate transformation and combine the characteristic vector with the step function to build a borderline which can conclude whether the local mask will block the deposition or not. The height of the local mask has been increased up to 40 mm in the proposed model, and two-dimensional simulations are developed to obtain a thin film profile deposition on the substrate inside the evaporation chamber to achieve the specific request of producing a LVF zone width in a more economical way than previously reported.

A flat-field aberration corrected concave blaze grating for 400–1100nm is designed and fabricated. An optical system is setup to measure the focused spot size, spectral resolution and grating efficiency to evaluate the performance of grating.

In this paper, a bending machine for tuning optical design of LED module is proposed. The tuning is done by changing the bending angles of each package on a given module with the help of automatic control program. Luminous intensity distribution can be controlled by adjusting the light emission path, which in turn can be implemented as changing the bending angles of individual LED packages on the module. The proposed machine is capable of bending packages to specified angles with errors less than 0.1°. Three-dimensional light distribution for bent package LED modules is also studied based on various application scenarios so that each scenario can have diversified luminous intensity distribution resulting in higher uniformity and better luminance quality. The machine has several advantages, including quick bending, high accuracy, and great customizability. These advantages make the machine meet the requirements of automatic mold forming.

In this paper, a bending machine for tuning the optical design of an LED module is proposed. The tuning is done by changing, with the help of an automatic control program, the angle at which each package on a given module is bent. The distribution of luminous intensity can be controlled by adjusting the light emission path, which in turn can be implemented by changing the angles of individual LED packages on the module. The proposed machine is capable of bending packages to specified angles with less than 0.1° of error. Three-dimensional light distribution for bent package LED modules is also studied, based on various application scenarios, so that each scenario can have a diversified luminous intensity distribution, resulting in higher uniformity and better quality luminance. The machine has several advantages, including quick bending, high accuracy, and great customizability. With these advantages, the machine meets the requirements of automatic mold forming.

With conventional heating process, ultraviolet (UV) illumination, and microwave irradiation, we have successfully synthesized UV curable encapsulating adhesives with excellent gas barrier capabilities, good adhesive strength, moderate hardness, and high refractive indices. The experimental results manifest that the physical properties of lab-made encapsulating adhesives are highly dependent on their chemical structures and synthetic procedure. We also discover that the encapsulating adhesive prepared by microwave irradiation (i.e. encapsulating adhesive VI-MW) exhibits better adhesive strength and higher gas resistance than those prepared by conventional heating process and UV illumination. Furthermore, encapsulating adhesive VI-MW has also been applied for the package of organic light emitting diodes (OLEDs), flexible OLEDs, and organic solar cells. With encapsulating adhesive VI-MW, the entry of oxygen and moisture in the air into these organic optoelectronic devices has been blocked, therefore enhancing the lifetimes.

By ultraviolet (UV) irradiation, brightness enhancement films (BEFs) have been successfully manufactured with UV-curable polymers and applied for organic light emitting diodes (OLEDs). With BEFs, either green OLEDs (BEF/ITO glass/NPB (30 nm)/Alq3 (65 nm)/LiF (0.5 nm)/Al (100 nm)) or white OLEDs (BEF/ITO glass/TAPC (40 nm)/mCP:Os:Firpic mixture (weight ratio = 82:17:1; 25 nm)/BCP (15 nm)/Alq3 (30 nm)/LiF (0.5 nm)/Al(150 nm)) exhibit better electroluminescent performances than those without BEFs. In case of green OLEDs, the luminance and electroluminescent yield with 45° compound BEFs are, respectively, 1.51-fold and 1.42-fold (at 9 V, 60 mA/cm2) larger than those without BEFs. In case of white OLEDs, moreover, the luminance and electroluminescent yield with 45° compound BEFs are, respectively, 1.28-fold and 1.21-fold (at 9 V, 16 mA/cm2) larger than those without BEFs.

A two-dimensional sub-wavelength grating (SWG) is fabricated on light-emitting diodes (LEDs). The SWG is simulated by finite-difference time-domain (FDTD) method. The SWG surface has silver-coated dielectric materials with sinusoidal structures, 175 nm period and 125 m depth of groove. When the incident wave is in the red light region of 600–700nm, the transmission efficiency of TM propagated light will reach 0.82. If this SWG structure is applied in LCD direct backlight module, the lower polarization piece can be replaced and fluorescence efficiency of LED can be improved.

The energy relaxation of electrons in InN epilayers is investigated by excitation- and electric field-dependent photoluminescence (PL). From the high-energy tail of PL, we determine the electron temperature of the hot carriers. It was found that the electron temperature variation can be explained by a model in which the longitudinal optical (LO)-phonon emission is the dominant energy relaxation process. The LO-phonon lifetime is fitted to be 0.89 ps, which is higher than the theoretical phonon lifetime. This deviation is attributed to the presence of the non-equilibrium hot-phonon effects.

A generalized optimization process to reduce the aberration of a concave grating is developed. The approach has a dramatic improvement in aberration reduction and spectral resolution. Calculated result is in good agreement with measurement.

An analytical thin film thickness model calculates the profiles of linear variable filters, which perform spectral filtering. Coupled with an image sensor and using a computational algorithm, this device becomes a LVF-hyperspectral imager.

An optimization process to control the aberration of a concave grating is developed. The approach has a dramatic improvement in aberration reduction and spectral resolution. Calculated result is in good agreement with measurement.

The temperature dependence of the time-resolved photoluminescence (PL) of self-assembled InAs quantum dots (QDs) with InGaAs covering layers was investigated. The PL decay time increases with temperature from 50 to 170 K, and then decreases as the temperature increases further above 170 K. A model based on the phonon-assisted transition between the QD ground state and the continuum state is used to explain the temperature dependence of the PL decay time. This result suggests that the continuum states are important in the carrier capture in self-assembled InAs QDs.

We proposed a novel method of constructing a chip polarization beam splitter (PBS) based on two-dimensional metallic photonic crystal (2D-MPC) structures that can be realized using the industrial-based semiconductor IC Cu-interconnect technology. The performance of such a PBS at wavelengths for optical telecommunications is evaluated by the finite-difference-time-domain (FDTD) simulation method. This 2D-MPC PBS device uses three rows of one-dimensional (1D) arrays (3×N-MPC-2D-MPC) as a basic building block to construct the PBS. Using this architecture, the incoming transverse magnetic (TM) and transverse electric (TE) waves can be splitted with very high splitting efficiency (polarization ratio over 1000 for both the TM and TE modes). The implication of our scheme is that the fabrication of such a 2D-MPC PBS is totally compatible with current commercial complementary metal oxide semiconductor (CMOS) fabrication technology. This makes it a ready-to-use technology for the fabrication of a chip-base 2D-MPC PBS.

Time-resolved photoluminescence (PL) was performed to investigate the decay of blue–green luminescence in MCM-41 nanotubes. The PL decay exhibits a clear nonexponential profile, which can be fitted by a stretched exponential function. In the temperature range from 50 to 300 K the photogenerated carriers become thermally activated with a characteristic energy of 29 meV, which is an indication of the phonon-assisted nonradiative process. The temperature dependence of the lifetime of PL decay has been explained using a model based on the radiative recombination of localized carriers and the phonon-assisted nonradiative recombination.

Deep x-ray lithography (DXL) was used to fabricate two-dimensional photonic crystals (PCs) for a terahertz high-pass filter. Instead of the conventional poly(methyl methacrylate) resist, high-sensitivity SU-8 resist was used to pattern the ultra-deep (1 mm), and high aspect ratio (>30) PC structures. In this study, an x-ray mask with thick Si membrane was used in the DXL process owing to the high-sensitivity nature of SU-8. The robust mask structure can significantly improve the fabrication yield of the conventional x-ray mask with a very thin (< 2 µm) membrane. Preliminary results demonstrate that SU-8 has poor pattern definition after DXL process, probably due to its high sensitivity. This phenomenon can be eliminated by dissolving oxygen into the resist to 'quench' the excessive photochemical reaction. Thanks to the high adhesion property of SU-8, the sticking problem of the high aspect ratio crystals is easily solved with natural drying by reducing the unbalanced capillary force. After optimizing all the processes, the proposed DXL SU-8 technique successively fabricated the terahertz crystals with high efficiency, high precision (< 1 µm) and high surface quality (Ra ~12 nm). The resist pillars were then deposited with a 300 nm thick gold layer for subsequent terahertz measurement. The measurement results show that the PC structure acts as a high-pass filter in the terahertz range, agreeing with the simulation results.

Various photoluminescence (PL) methods were used to investigate the blue–green luminescence from mesoporous MCM-48 molecular sieves. The blue–green luminescence intensity is enhanced after rapid thermal annealing. The surface properties of the mesoporous MCM-48 molecular sieves reveal that the generation of twofold coordinated Si centers and non-bridging oxygen hole centers is responsible for this enhancement. Studies of PL following rapid thermal annealing, polarized PL and PL excitation strongly suggest that a triplet-to-singlet transition of twofold-coordinated silicon centers is responsible for the blue–green luminescence in mesoporous MCM-48 molecular sieves.

An optimization process to reduce the aberration of a concave grating is developed. The result shows that the new approach has a dramatic reduction in aberration and great improvement in spectral resolution.

We studied the photoluminescence (PL) in CuInSe2 thin films grown by metal organic chemical vapor deposition (MOCVD) using a Cu precursor and two gases. By X-ray diffraction (XRD) and PL analysis, we found that the best quality of CuInSe2 thin films can be obtained when the deposition time of the trimethylindium (TMI) gas is 30 min. The improvement of the quality of CuInSe2 thin films after rapid thermal annealing (RTA) is evident from the full width at half maximum (FWHM) of PL. The FWHM of the PL peak is minimum when the RTA temperature is 500 ?C. It is found the binding energy of the impurity level in CuInSe2 thin films increases after RTA, revealing that the thermal stability of CuInSe2 thin films is improved after RTA.

A two-dimensional thin film thickness model based on the geometry of a commercial coater which can calculate more effectively the profiles of linear variable filters (LVFs) has been developed. This is done by isolating the substrate plane as an independent coordinate (local coordinate), while the rotation and translation matrices are used to establish the coordinate transformation and combine the characteristic vector with the step function to build a borderline which can conclude whether the local mask will block the deposition or not. The height of the local mask has been increased up to 40 mm in the proposed model, and two-dimensional simulations are developed to obtain a thin film profile deposition on the substrate inside the evaporation chamber to achieve the specific request of producing a LVF zone width in a more economical way than previously reported [Opt. Express23, 5102 (2015)OPEXFF1094-408710.1364/OE.23.005102].

Inner shell processes in the light elements provide the contrast mechanisms for soft X-ray microscopy. Bright X-ray sources and precision focusing elements have led to the development of high resolution instruments. Our efforts in scanning microscopy, holography and diffraction at the National Synchrotron Light Source are aimed at the development of microimaging techniques mostly for biological specimens.

We present recent developments with the scanning photoelectron microscope at beam line X1A (X1-SPEM) at the National Synchroton Light Source. It was the first to demonstrate elemental and chemical imaging with primary photoelectrons and achieve submicron resolution [Appl. Phys. Lett. 56, 1841-1843 (1990)]. Subsequent improvements allow us now to acquire XPS images with lateral resolution approaching 0.1 μm. We have utilized the instrument to examine artificial structures such as microelectronic devices and describe here our preliminary work in the study of photon-beam-mediated chemistry on aluminium surfaces.

The Soft X‐ray Undulator beamline at the NSLS supports a soft x‐ray imaging program including scanning transmission microscopy, scanning photoemission microscopy, Gabor and Fourier transform holography, and large angle diffraction. Zone plates from an LBL Center for X‐ray Optics/IBM collaboration are used as optical elements. The current instrumentation of the beamline and the experimental stations is discussed, along with plans for the future at the NSLS and prospects for imaging programs at third generation sources.

The miniature spectrometer has many applications in integrated optics and photonics. The blazed grating with the Rowland circle structure has the advantage of self-focusing and is chosen as the major component in the spectrometer chip. In the simulations for the blaze angle design in the visible spectrum, we discover the phenomenon of the double reflection diffraction. Its cause and parameter space are discussed. The spectrometer utilizing the phenomenon has similar performance to the standard blazed grating and is easier to manufacture in microelectromechanical systems (MEMS) technology. The discovery will greatly ease the design of the spectrometer chip.

We propose and demonstrate a tunable and stable single-longitudinal-mode (SLM) erbium fiber laser with a passive triple-ring cavity structure in S-band operation. The proposed laser is fundamentally structured by using three different lengths of ring cavities, which serve as the mode filters. When a mode-restricting intracavity fiber Fabry-Perot tunable filter (FFP-TF) is combined, the proposed resonator can guarantee a tunable and stable SLM laser oscillation. Moreover, the performances of the output power, wavelength stability, tuning range, and side-mode suppression ratio (SMSR) are studied.

An S-band gain-clamped erbium-doped fiber amplifier module, employing a fiber Bragg grating to serve as a reflected element for lasing a saturated tone injected into the module by forward optical feedback method, is proposed and investigated experimentally. Moreover, the performance and behavior of the gain and noise figure in the proposed gain-clamped S-band fiber amplifier have also been discussed in the effectively wavelength range of 1478 to 1520 nm.