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Understanding the binding affinities and kinetics of protein-ligand interactions using a label-free method is crucial for identifying therapeutic candidates in clinical diagnostics and drug development. In this work, the IGZO-TFT (thin-film transistor) biosensor integrated with a tailored microfluidic chip was developed to explore binding kinetics of protein-ligand biochemical interactions in the real-time manner. The IGZO-TFT sensor extracts the binding characteristics through sensing biomolecules by their electrical charges. Using lysozyme and tri-N-acetyl-D-glucosamine (NAG3) as an example, we established a procedure to obtain the parameters, such as the dissociation constant, Kd, and association rate constant, ka, that are critical to biochemical reactions. The correlation between the lysozyme concentration and TFT drain current signal was first constructed. Next, solutions of lysozyme and NAG3 of different mixing ratios were prepared. They were pre-mixed for various periods of reaction time before applying to the TFT sensor to extract signals of lysozyme molecules and the concentration remaining. With the knowledge of drain current changes at different reaction times, ka and Kd can be obtained. The values from our experiment are comparable to other methods, which suggests the proposed approach can be employed to explore protein-ligand interaction kinetics in the massively parallel manner if the TFT array is considered.

The fundamental detection scheme of typical grating or photonic crystal (PhC) sensors relies on the correlation of the diffraction behaviors with the refractive index of target analyte. For biomaterial detection, a thin gold film is usually deposited on the sensor surface so that cross linkers can be anchored before functionalizing the device. The nanoscale metallic film suggests plasmonic resonances play a critical role in light-matter interaction. In this work, we demonstrated a compact two-dimensional (2D) hexagonal PhC biosensor with thin gold film coating. In such a device, surface plasmon polariton (SPP) on the metal structure and phase matching of optical wave with the PhC are considered when analyzing light-biomaterial interaction on the detector. Using Epstein-Barr nuclear antigen-1 (EBNA-1) antibody as an example, protein sensing along different lattice orientations of the PhC biosensor was investigated. Based on the dispersion relationship and phase matching conditions, we unravel the mechanisms involved in the wavelength shifts and sensitivities. The simulation results verify the phenomenon of tighter spatial confinement and higher local field intensity from the SPP, which helps detecting small variations of the refractive index on the sensor surface.

Recently, GaN-based light-emitting diodes (LEDs) find their applications in, other than general lighting, visible light communication (VLC) for high-speed wireless data networks. The pursuit for more bandwidth from the LED can be realized by engineering the LED material structure and device design, or by modulation techniques. In this paper, we proposed GaN-based LEDs with the photonic crystal (PhC) structure for VLC applications. Contradictory to general thought that higher small frequency response translates to better large-signal performance, our results reveal that a PhC LED may not perform well at low data rate due to its relatively poorer signal-to-noise ratio (SNR). However, at higher data rates, the performance of PhC LEDs surpasses conventional LED structure. We showed data transmission capability of PhC LEDs with a bit rate up to 400 Mb/s using on–off keying modulation. To demonstrate the chip capability for large-signal transmission, without using preemphasis or postemphasis, VLC with 16-quadrature amplitude modulation orthogonal frequency-division multiplexing transmission capacity up to 2 Gbit/s is achieved with an error vector magnitude of 17.07%, SNR of 15.35 dB, and bit error rate of $3.3 \times {10}^{-3}$ . Our LEDs embedded with PhCs pass the forward error correction criterion. The results reveal the advantages of LEDs with PhC for achieving higher data rate transmission.

We demonstrated an integrated biosensor with a thin film transistor for recording electrical charges carried by bio-molecules and a microfluidic channel for detecting diffusion properties of the target solution. Using streptavidin and biotin as examples, the sensor is able to detect the binding interaction of streptavidin-biotin complexes by monitoring the transient responses of the transistor current. Our approach can be applied to the field of detection of protein–protein interactions.

A transistor-based biosensor with high sensitivity is demonstrated in this paper. The sensor is composed of a reusable In–Ga–ZnO (IGZO)-thin-film transistor (TFT) array wire connected to an external sensing pool. The TFT acts as an electrical charge transducer as well as the signal readout device. Contrast to typical approachesofemploying parameters, such as transconductance, threshold voltage, or current change as the benchmark for sensitivity, we develop a model to extract the corresponding electrical changes after introducing analytes so as tomitigate device-to-device sensing variations. Using Epstein–Barr nuclear antigen-1 (EBNA-1) antibody as the example of target analyte, the IGZO-TFT biosensors are able to selectively detect 10 pg/mL of EBNA-1 antibody in the phosphate-buffered saline solution. The measurement results were cross verifiedwith conventional enzyme-linked immunosorbent assay (ELISA). Our approach is four orders of magnitude better than the ELISA.

The sensitivity of traditional diffraction grating sensors is limited by the spatial resolution of the measurement setup. Thus, a large space is required to improve sensor performance. Here, we demonstrate a compact hexagonal photonic crystal (PhC) optical sensor with high sensitivity. PhCs are able to diffract optical beams to various angles in azimuthal space. The critical wavelength that satisfies the phase matching or becomes evanescent was used to benchmark the refractive index of a target analyte applied on a PhC sensor. Using a glucose solution as an example, our sensor demonstrated very high sensitivity and a low limit of detection. This shows that the diffraction mechanism of hexagonal photonic crystals can be used for sensors when compact size is a concern.

Semiconductor nanocomposites provide advantages beyond the capability of typical fluorescent materials for cancer detection. In this work, nanowire-based probes with dual color channels are employed to demonstrate the capacity of cancer cell detection. Purple emitting ZnO/antibody probes are applied to detect cancer cells and meanwhile TiO2 /antibody probes with green light emission are applied to identify normal fibroblast cells. A series of quantitative analyses are conducted to verify the correlation between the concentrations of ZnO and TiO2 probes, cell numbers, and peak intensities of the PL spectra. The results provide a quantitative reference for developing nanowire-based cancel cell probes.

Recently, GaN based light-emitting diodes (LEDs) have become a promising candidate for visible light communication (VLC). In this work, we demonstrated 2-Gbit/s data rate transmission using GaN-based LEDs with photonic crystal (PhC) structure.

As internet of things (IOT) has become a popular topic in current consumer electronics, there is a demand for cost-effective sensors to monitor bio-signals. Traditional optical sensors employ low-dimensional gratings and high-resolution spectrometers to detect the refractive index changes of the solutions. In this work, we develop an alternative approach to correlate the concentration of molecules to the band diagrams of the photonic crystals. A relatively low-resolution spectrum analyzer can be employed, yet achieves higher sensitivity than traditional approaches.

Semiconductor nanocomposites provide advantages beyond the capability of typical fluorescent materials for cancer detection. In this work, nanowire-based probes with dual color channels are employed to demonstrate the capacity of cancer cell detection. Purple emitting ZnO/antibody probes are applied to detect cancer cells and meanwhile TiO

Optoelectronic properties of undoped ZnSe/ZnMgSSe multiple quantum wells (MQWs) grown by molecular beam epitaxy on (001) GaAs substrates have been investigated by photoluminescence, photoconductivity, and persistent photoconductivity (PPC) measurements. The features related to the band-to-band excitonic and impurity-related transitions of ZnSe/ZnMgSSe MQWs are observed and discussed. In addition, the parameters that describe the temperature dependence of the interband transition energy and broadening function of the excitonic feature are evaluated. PPC has been observed in undoped ZnSe/ZnMgSSe MQWs. The decay kinetics of the PPC effect can be described by a stretched-exponential function, Ippc(t)=Ippc(0)exp[−(t/τ)β], (0

Tumor detection is a significant health issue, but it is still a limit to identify cancer cells during tumor resection by using traditional methods such as fluorescence. In this study, zinc oxide (ZnO) nanorods bonded to antibodies was investigated as nanoprobes for sensing cancer cells. The result shows that antibodies toward epidermal growth factor receptor (EGFR) can be connected to ZnO nanorods and EGFR receptors of squamous cell carcinoma (SCC). The cancer cells can be recognized via the observation of purple light emission from these probes by using naked eye or an optical microscope. By contrast, the HS68 cells with less EGFR expression had no purple light emission as the probes were washed off. Besides, from the photoluminescent spectra, the intensity ratio between the purple light (from ZnO nanorods) and green band (from the autofluorescence of cells) is much higher in SCC than in HS68 cells, which suggest that the cancer cells can be detected by comparing the peak intensity ratio. The probes have the potential clinical application for real-time tumor detection, and the cancer cells can be excised more precisely with the help of purple light emission.

In this paper the optimal lighting for oral cavity detection is proposed. The illuminants consist of several LEDs with different intensity ratios and peak wavelengths, which can enhance the color difference between normal and abnormal regions in the oral cavity. An algorithm combined with multi-spectral imaging (MSI) and color reproduction technique is applied to find the best enhancement of this difference. The colored LEDs of the optimal lighting, the Color Rendering Index (CRI) of the illuminants, and comparison with traditional illuminants are discussed. The calculations show that color enhancement ability in the oral cavity is not entirely a function of the higher CRI of some illuminants, as the narrowband illuminants (LEDs) produce an image with greater contrast than the broadband spectra and higher CRI of traditional illuminants in the reddish oral environment. Accordingly, an illuminant with specific intensity ratio of red, green, and blue LEDs is proposed, which has optimal color enhancement for oral cavity detection. Compared with the fluorescent lighting commonly in the use now, the color difference between normal and inflamed tissues can be improved from 21.5732 to 30.5532, a 42% increase, thus making medical diagnosis more efficient, so helping patients receive early treatment.

We describe a color image reconstruction method that enables both direct visualization and direct digital image acquisition from one oral tissue by using various light sources and color compensating filters. In this method, the image of the oral tissue with white light emitting diodes (LEDs) with blue color compensating filter has a larger color difference between the normal and inflamed tissues. The enhanced visualization comes from the white light color mixing between the red normal tissue and bluish white light from the LEDs. With our method, we evaluate the perceived tissue reflectance in each pixel of the image and color reproduction with different illuminated spectra. Our approach to enhancement of visually perceived color difference between normal and inflamed oral tissue involves optimization of illumination and observation conditions by allowing a significant optical contrast of illuminated spectrum to reach the observer's eyes. In comparison with a conventional daylight LED flashlight, a LED with blue filter as the illuminant for oral cavity detection enhances the color difference between normal and inflamed tissues by 32%.

We have performed electrical transport measurements on metal-organic vapor phase epitaxy grown In-rich InxGa1−xN (x=1, 0.98, and 0.92) films. Within the experimental error, the electron density in InGaN films is temperature independent over a wide temperature range (4K⩽T⩽285K). Therefore, InxGa1−xN (0.92⩽x⩽1) films can be regarded as degenerate semiconductor systems. The experimental results demonstrate that electron transport in In-rich InxGa1−xN (x=1, 0.98, and 0.92) films is metalliclike. This is supported by the temperature dependence of the density, resistivity, and mobility which is similar to that of a metal. We suggest that over the whole measuring temperature range residue imperfection scattering limits the electron mobility in In-rich InxGa1−xN (x=1, 0.98, and 0.92) films.