Millimeter-Wave Band Electro-Optical Imaging System Using Polarization CMOS Image Sensor and Amplified Optical Local Oscillator Source.

In this study, we developed and demonstrated a millimeter-wave electric field imaging system using an electro-optic crystal and a highly sensitive polarization measurement technique using a polarization image sensor, which was fabricated using a 0.35-µm standard CMOS process. The polarization image sensor was equipped with differential amplifiers that amplified the difference between the 0° and 90° pixels. With the amplifier, the signal-to-noise ratio at low incident light levels was improved. Also, an optical modulator and a semiconductor optical amplifier were used to generate an optical local oscillator (LO) signal with a high modulation accuracy and sufficient optical intensity. By combining the amplified LO signal and a highly sensitive polarization imaging system, we successfully performed millimeter-wave electric field imaging with a spatial resolution of 30×60 µm at a rate of 1 FPS, corresponding to 2400 pixels/s.

Presenting a Multispectral Image Sensor for Quantification of Total Polyphenols in Low-Temperature Stressed Tomato Seedlings Using Hyperspectral Imaging.

Hyperspectral imaging was used to predict the total polyphenol content in low-temperature stressed tomato seedlings for the development of a multispectral image sensor. The spectral data with a full width at half maximum (FWHM) of 5 nm were merged to obtain FWHMs of 10 nm, 25 nm, and 50 nm using a commercialized bandpass filter. Using the permutation importance method and regression coefficients, we developed the least absolute shrinkage and selection operator (Lasso) regression models by setting the band number to ≥11, ≤10, and ≤5 for each FWHM. The regression model using 56 bands with an FWHM of 5 nm resulted in an R2 of 0.71, an RMSE of 3.99 mg/g, and an RE of 9.04%, whereas the model developed using the spectral data of only 5 bands with a FWHM of 25 nm (at 519.5 nm, 620.1 nm, 660.3 nm, 719.8 nm, and 980.3 nm) provided an R2 of 0.62, an RMSE of 4.54 mg/g, and an RE of 10.3%. These results show that a multispectral image sensor can be developed to predict the total polyphenol content of tomato seedlings subjected to low-temperature stress, paving the way for energy saving and low-temperature stress damage prevention in vegetable seedling production.

Hybrid Organic-Si C-MOSFET Image Sensor Designed with Blue-, Green-, and Red-Sensitive Organic Photodiodes on Si C-MOSFET-Based Photo Signal Sensor Circuit.

The resolution of Si complementary metal-oxide-semiconductor field-effect transistor (C-MOSFET) image sensors (CISs) has been intensively enhanced to follow the technological revolution of smartphones, AI devices, autonomous cars, robots, and drones, approaching the physical and material limits of a resolution increase in conventional Si CISs because of the low quantum efficiency (i.e., ~40%) and aperture ratio (i.e., ~60%). As a novel solution, a hybrid organic-Si image sensor was developed by implementing B, G, and R organic photodiodes on four n-MOSFETs for photocurrent sensing. Photosensitive organic donor and acceptor materials were designed with cost-effective small molecules, i.e., the B, G, and R donor and acceptor small molecules were Coumarin6 and C_60, DMQA and MePTC, and ZnPc and TiOPc, respectively. The output voltage sensing margins (i.e., photocurrent signal difference) of the hybrid organic-Si B, G, and R image sensor pixels presented results 17, 11, and 37% higher than those of conventional Si CISs. In addition, the hybrid organic-Si B, G, and R image sensor pixels could achieve an ideal aperture ratio (i.e., ~100%) compared with a Si CIS pixel using the backside illumination process (i.e., ~60%). Moreover, they may display a lower fabrication cost than image sensors because of the simple image sensor structure (i.e., hybrid organic-Si photodiode with four n-MOSFETs).

Brain-implantable needle-type CMOS imaging device enables multi-layer dissection of seizure calcium dynamics in the hippocampus.

Current neuronal imaging methods use bulky lenses that either impede animal behavior or prohibit multi-depth imaging. To overcome these limitations, we developed a lightweight lensless biophotonic system for neuronal imaging, enabling compact and simultaneous visualization of multiple brain layers. Our developed "CIS-NAIST" device integrates a micro-CMOS image sensor, thin-film fluorescence filter, micro-LEDs, and a needle-shaped flexible printed circuit. With this device, we monitored neuronal calcium dynamics during seizures across the different layers of the hippocampus. The CIS-NAIST device revealed distinct calcium activity patterns across the CA1, molecular interlayer, and dentate gyrus. Our findings indicated an elevated calcium amplitude activity specifically in the dentate gyrus compared to other layers. Then, leveraging the multi-layer data obtained from the device, we employed machine learning techniques for seizure classification and prediction. Using Long-Short Term Memory and Hidden Markov Models, we successfully classified seizure calcium activity and predicted seizure behavior based on the multi-layer imaging data. Taken together, our device can enable a minimally invasive method of seizure monitoring that can help elucidate the mechanisms of temporal lobe epilepsy. .

An Improvement Method for Improving the Surface Defect Detection of Industrial Products Based on Contour Matching Algorithms.

Aiming at the problems of the poor robustness and universality of traditional contour matching algorithms in engineering applications, a method for improving the surface defect detection of industrial products based on contour matching algorithms is detailed in this paper. Based on the image pyramid optimization method, a three-level matching method is designed, which can quickly obtain the candidate pose of the target contour at the top of the image pyramid, combining the integral graph and the integration graph acceleration strategy based on weak classification. It can quickly obtain the rough positioning and rough angle of the target contour, which greatly improves the performance of the algorithm. In addition, to solve the problem that a large number of duplicate candidate points will be generated when the target candidate points are expanded, a method to obtain the optimal candidate points in the neighborhood of the target candidate points is designed, which can guarantee the matching accuracy and greatly reduce the calculation amount. In order to verify the effectiveness of the algorithm, functional test experiments were designed for template building function and contour matching function, including uniform illumination condition, nonlinear condition and contour matching detection under different conditions. The results show that: (1) Under uniform illumination conditions, the detection accuracy can be maintained at about 93%. (2) Under nonlinear illumination conditions, the detection accuracy can be maintained at about 91.84%. (3) When there is an external interference source, there will be a false detection or no detection, and the overall defect detection rate remains above 94%. It is verified that the proposed method can meet the application requirements of common defect detection, and has good robustness and meets the expected functional requirements of the algorithm, providing a strong technical guarantee and data support for the design of embedded image sensors in the later stage.

High-Spike Barrier Photodiodes Based on 2D Te/WS2 Heterostructures.

Two-dimensional (2D) van der Waals (vdWs) heterojunctions have been actively investigated in low-power-consumption and fast-response photodiodes owing to their atomically smooth interfaces and ultrafast interfacial charge transfer. However, achieving ultralow dark current and ultrafast photoresponse in the reported photovoltaic devices remains a challenge as the large built-in electric field in a heterojunction can not only speed up photocarrier transport but also increase the minority-carrier dark current. Here, we propose a high-spike barrier photodiode that can achieve both an ultralow dark current and an ultrafast response. The device is fabricated by the Te/WS2 heterojunction, while the band alignment can transition from type-II to type-I with a high electron barrier and a large hole built-in electronic field. The high electron barrier can greatly reduce the drift current of minority carriers and the generation current of the thermal carriers, while the large built-in electronic field can still speed up the photocarrier transport. The designed Te/WS2 vdWs photodiode yields an ultralow dark current of 8 × 10-14 A and an ultrafast photoresponse of 10/13 µs. Furthermore, a high-performance visible-light imager with a pixel resolution of 100 × 40 is demonstrated using the Te/WS2 vdWs photodiode. This work provides a comprehensive understanding of designing 2D-material-based photovoltaics with excellent overall performance.

Advancing Fab-Compatible Color-Selective Organic Photodiodes: Tailored Molecular Design and Nanointerlayers.

High-performance organic photodiodes (OPDs) and OPD-based image sensors are primarily realized using solution processes based on various additives and coating methods. However, vacuum-processed OPDs, which are more compatible with large-scale production, have received little attention, thereby hindering their integration into advanced systems. This study introduces innovations in the material and device structures to prepare superior vacuum-processed OPDs for commercial applications. A series of vacuum-processable, low-cost p-type semiconductors is developed by introducing an electron-rich cyclopentadithiophene core containing various electron-accepting moieties to fine-tune the energy levels without any significant structural or molecular weight changes. An additional nanointerlayer strategy is used to control the crystalline orientation of the upper-deposited photoactive layer, compensating for device performance reduction in inverted, top-illuminated OPDs. These approaches yielded an external quantum efficiency of 70% and a specific detectivity of 2.0 × 1012 Jones in the inverted structures, which are vital for commercial applications. These OPDs enabled visible-light communications with extremely low bit error rates and successful X-ray image capture.

Three-Stage Interpolation Method for Demosaicking Monochrome Polarization DoFP Images.

The emergence of polarization image sensors presents both opportunities and challenges for real-time full-polarization reconstruction in scene imaging. This paper presents an innovative three-stage interpolation method specifically tailored for monochrome polarization image demosaicking, emphasizing both precision and processing speed. The method introduces a novel linear interpolation model based on polarization channel difference priors in the initial two stages. To enhance results through bidirectional interpolation, a continuous adaptive edge detection method based on variance differences is employed for weighted averaging. In the third stage, a total intensity map, derived from the previous two stages, is integrated into a residual interpolation process, thereby further elevating estimation precision. The proposed method undergoes validation using publicly available advanced datasets, showcasing superior performance in both global parameter evaluations and local visual details when compared with existing state-of-the-art techniques.

Investigating a Machine Learning Approach to Predicting White Pixel Defects in Wafers-A Case Study of Wafer Fabrication Plant F.

CMOS image sensor (CIS) semiconductor products are integral to mobile phones and photographic devices, necessitating ongoing enhancements in efficiency and quality for superior photographic outcomes. The presence of white pixels serves as a crucial metric for assessing CIS product performance, primarily arising from metal impurity contamination during the wafer production process or from defects introduced by the grinding blade process. While immediately addressing metal impurity contamination during production presents challenges, refining the handling of defects attributed to grinding blade processing can notably mitigate white pixel issues in CIS products. This study zeroes in on silicon wafer manufacturers in Taiwan, analyzing white pixel defects reported by customers and leveraging machine learning to pinpoint and predict key factors leading to white pixel defects from grinding blade operations. Such pioneering practical studies are rare. The findings reveal that the classification and regression tree (CART) and random forest (RF) models deliver the most accurate predictions (95.18%) of white pixel defects caused by grinding blade operations in a default parameter setting. The analysis further elucidates critical factors like grinding load and torque, vital for the genesis of white pixel defects. The insights garnered from this study aim to arm operators with proactive measures to diminish the potential for customer complaints.

A Reconfigurable Bipolar Image Sensor for High-Efficiency Dynamic Vision Recognition.

Dynamic vision perception and processing (DVPP) is in high demand by booming edge artificial intelligence. However, existing imaging systems suffer from low efficiency or low compatibility with advanced machine vision techniques. Here, we propose a reconfigurable bipolar image sensor (RBIS) for in-sensor DVPP based on a two-dimensional WSe2/GeSe heterostructure device. Owing to the gate-tunable and reversible built-in electric field, its photoresponse shows bipolarity as being positive or negative. High-efficiency DVPP incorporating front-end RBIS and back-end CNN is then demonstrated. It shows a high recognition accuracy of over 94.9% on the derived DVS128 data set and requires much fewer neural network parameters than that without RBIS. Moreover, we demonstrate an optimized device with a vertically stacked structure and a stable nonvolatile bipolarity, which enables more efficient DVPP hardware. Our work demonstrates the potential of fabricating DVPP devices with a simple structure, high efficiency, and outputs compatible with advanced algorithms.

Efficacy of an Electric Toothbrush With Monitor in Dental Plaque Removal: A Crossover Randomized Controlled Trial.

BACKGROUND AND PURPOSE: Plaque control is very important in the treatment of periodontitis. However, plaque is difficult to remove because one cannot see one's own oral cavity. The purpose of this study was to verify the plaque removal effect of a prototype device that has a built-in image sensor in the head of an electric toothbrush, enabling the user to brush while checking the condition of the tooth surface on a monitor in real time and to assess their sense of use. MATERIALS AND METHODS: The subjects were 10 fifth-year students from the Graduate School of Dental Science, Fukuoka Dental College, Fukuoka, Japan. The subjects were divided into those who used electric toothbrushes while having the condition of the tooth surface checked with a monitor (monitor group) and those without a monitor (non-monitor group). O'Leary plaque control records before and after brushing and the brushing time were measured, and questionnaires were given to the subjects after brushing. Scaling and professional tooth cleaning were performed after completing the questionnaire. One week later, subjects were switched to the opposite group and had the same measurements and questionnaires. The Wilcoxon signed-rank test was used to compare both groups before and after the examination at a 5% significance level. RESULTS: The monitor group had significantly better plaque removal than the non-monitor group. In addition, the monitor group spent significantly more time brushing than the control group. CONCLUSION: Brushing while monitoring oral conditions in real time using an electric toothbrush with a built-in image sensor showed that significantly better plaque removal can be achieved with a longer brushing time.

Ultrasensitive Near-Infrared Polarization Photodetectors with Violet Phosphorus/InSe van der Waals Heterostructures.

Near-infrared (NIR) polarization photodetectors with two-dimensional (2D) semiconductors and their van der Waals (vdW) heterostructures have presented great impact for the development of a wide range of technologies, such as in the optoelectronics and communication fields. Nevertheless, the lack of a photogenerated charge carrier at the device's interface leads to a poor charge carrier collection efficiency and a low linear dichroism ratio, hindering the achievement of high-performance optoelectronic devices with multifunctionalities. Herein, we present a type-II violet phosphorus (VP)/InSe vdW heterostructure that is predicted via density functional theory calculation and confirmed by Kelvin probe force microscopy. Benefiting from the type-II band alignment, the VP/InSe vdW heterostructure-based photodetector achieves excellent photodetection performance such as a responsivity (R) of 182.8 A/W, a detectivity (D*) of 7.86 × 1012 Jones, and an external quantum efficiency (EQE) of 11,939% under a 1064 nm photon excitation. Furthermore, the photodetection performance can be enhanced by manipulating the device geometry by inserting a few layers of graphene between the VP and InSe (VP/Gr/InSe). Remarkably, the VP/Gr/InSe vdW heterostructure shows a competitive polarization sensitivity of 2.59 at 1064 nm and can be integrated as an image sensor. This work demonstrates that VP/InSe and VP/Gr/InSe vdW heterostructures will be effective for promising integrated NIR optoelectronics.

Using a Slit to Suppress Optical Aberrations in Laser Triangulation Sensors.

In this paper, we present a laser triangulation sensor to measure the distance between the sensor and an object without contact using a diffraction slit rather than a traditional lens. We show that by replacing the lens with a slit, we can exploit the resulting diffraction pattern to have finer and yet simpler image analysis, yielding better estimation of the distance to the object. To test our hypothesis, we build a precision position table and a laser triangulation sensor, generate large data sets to test different estimation algorithms on various materials, and compare data acquisition using a traditional lens versus using a slit. We show that position estimation when using a slit is both more precise and more accurate than comparable methods using a lens.

Optimization and miniaturization of SE-ECL for potential-resolved, multi-color, multi-analyte detection.

Electrochemiluminescence (ECL) is a bioanalytical technique with numerous advantages, including the potential for high temporal and spatial resolution, a high signal-to-noise ratio, a broad dynamic range, and rapid measurement capabilities. To reduce the complexity of a multi-electrode approach, we use a single-electrode electrochemiluminescence (SE-ECL) configuration to achieve the simultaneous emission and detection of multiple colors for applications that require multiplexed detection of several analytes. This method exploits intrinsic differences in the electric potential applied along single electrodes built into electrochemical cells, enabling the achievement of distinct colors through selective excitation of ECL luminophores. We present results on the optimization of SE-ECL intensity for different channel lengths and widths, with sum intensities being 5 times larger for 6 cm vs. 2 cm channels and linearly increasing with the width of the channels. Furthermore, we demonstrated for the first time that applying Alternating Current (AC) voltage within the single electrode setup for driving the ECL reactions has a dramatic effect on the emitted light intensity, with square waveforms resulting in higher intensities vs sine waveforms. Additionally, multiplexed multicolor SE-ECL on a 6.5 mm × 3.6 mm CMOS semiconductor image sensor was demonstrated for the first time, with the ability to simultaneously distinguish four different colors, leading to the ability to measure multiple analytes.

Synchronous Driving Method for Stitching Pixel Arrays Based on an Adaptive Correction Technique.

With the application of stitching technology in large-pixel-array CMOS image sensors, the problem of non-synchronized output signals from pixel array bilateral driver circuits has become progressively more serious and has led to the DC perforation of bilateral driver circuits, while conventional clock tree synchronization design methodology does not apply to stitching technology. Therefore, this paper analyses reasons for the inconsistency in the output signals of bilateral driving circuits and proposes a synchronous driving method applicable to stitching pixel arrays based on the idea of on-chip output signal delay detection and calibration. This method detects and corrects the non-synchrony of the row driver output signals on both sides according to changes in the operating environment of the chip. This method is characterized by a simple structure and high reliability. Finally, based on the 55 nm stitching process, simulations are carried out in a CMOS image sensor with a chip area of 77 mm × 84 mm to verify that this method is feasible. This large image sensor with a 150 M pixel array has a frame rate of over 10 FPS.

Enhancement of Optical and Chemical Resistance Properties with a Novel Yellow Quinophthalone Derivative for Image Sensor Colorants.

A novel quinophthalone derivative, 4,5,6,7-tetrachloro-2-(2-(3-hydroxy-1-oxo-1H-cyclopenta[b]naphthalen-2-yl)quinolin-4-yl)isoindoline-1,3-dione (TCHCQ), was designed and synthesized as a yellow colorant additive for green color filters in image sensors. The characteristics of the new material were evaluated in terms of optical, thermal, and chemical properties under solution and color filter film conditions. TCHCQ exhibited a significantly enhanced molar extinction coefficient in solution, being 1.21 times higher than that of the commercially used yellow colorant Y138. It also demonstrated excellent thermal stability, with a decomposition temperature (Td) exceeding 450 °C. Utilizing the nano-pigmentation process, TCHCQ was used to prepare nano-sized particles with an excellent average size of 35 nm. This enabled the fabrication of a color filter film with outstanding properties. The optical properties of the produced film revealed outstanding yellow colorant transmittance of 0.97% at 435 nm and 91.2% at 530 nm. The color filter film exhibited similar optical and thermal stability to Y138, with an improved chemical stability, as evidenced by a ΔEab value of 0.52. The newly synthesized TCHCQ is considered a promising candidate for use as a yellow colorant additive in image sensor color filters, demonstrating superior optical, thermal, and chemical stability.

Synergistic Radiation Effects in PPD CMOS Image Sensors Induced by Neutron Displacement Damage and Gamma Ionization Damage.

The synergistic effects on the 0.18 µm PPD CISs induced by neutron displacement damage and gamma ionization damage are investigated. The typical characterizations of the CISs induced by the neutron displacement damage and gamma ionization damage are presented separately. The CISs are irradiated by reactor neutron beams up to 1 × 1011 n/cm2 (1 MeV neutron equivalent fluence) and 60Co γ-rays up to the total ionizing dose level of 200 krad(Si) with different sequential order. The experimental results show that the mean dark signal increase in the CISs induced by reactor neutron radiation has not been influenced by previous 60Co γ-ray radiation. However, the mean dark signal increase in the CISs induced by 60Co γ-ray radiation has been remarkably influenced by previous reactor neutron radiation. The synergistic effects on the PPD CISs are discussed by combining the experimental results and the TCAD simulation results of radiation damage.

Comparison of needle and conventional arthroscopy for visualisation of predefined anatomical structures of the knee joint: a feasibility study in human cadavers and patients.

BACKGROUND: In terms of the optics used for Knee arthroscopy, a large number of different endoscopes are currently available. However, the use of the 30° optics in knee arthroscopy has been established as the standard procedure for many years. As early as the 1990s, needle arthroscopy was occasionally used as a diagnostic tool. In addition to the development of conventional optics technology in terms of camera and resolution, needle arthroscopes are now available with chip-on-tip image sensor technology. To date, no study has compared the performance of this kind of needle arthroscopy versus standard arthroscopy in the clinical setting in terms of the visibility of anatomical landmarks. In this monocentric prospective feasibility study, our aim was to evaluate predefined anatomical landmarks of the knee joint using needle arthroscopy (0° optics) and conventional knee arthroscopy (30° optics) and compare their performance during knee surgery. METHODS: Examinations were performed on eight cadavers and seven patients who required elective knee arthroscopy. Two surgeons independently performed the examinations on these 15 knee joints, so that we were able to compare a total of 30 examinations. The focus was on the anatomical landmarks that could be visualized during a conventional diagnostic knee arthroscopy procedure. The quality of visibility was evaluated using a questionnaire. RESULTS: In summary, the average visibility for all the anatomic landmarks was rated 4.98/ 5 for the arthroscopy using 30° optics. For needle arthroscopy, an average score of 4.89/ 5 was obtained. Comparatively, the needle arthroscope showed slightly limited visibility of the retropatellar gliding surface in eight (4.5/ 5 vs. 5/ 5), medial rim of the patella in four (4.85/ 5 vs. 5/ 5), and suprapatellar recess in four (4.83/ 5 vs. 5/ 5) cases. Needle arthroscopy was slightly better at visualizing the posterior horn of the medial meniscus in four knee joints (4.9/ 5 vs. 4.85/ 5). CONCLUSION: Needle arthroscopy is a promising technology with advantages in terms of minimally invasive access and good visibility of anatomical landmarks. However, it also highlights some limitations, particularly in cases with challenging anatomy or the need for a wide field of view.

Limitations and Drawbacks of DQE Estimation Methods Applied to Electron Detectors.

The DQE is generally accepted as the main figure of merit for the comparison between electron detectors, and most of the time given as a unique number at the Nyquist frequency while it is known to vary with electron dose. It is usually estimated thanks to a method improved by McMullan in 2009. The purpose of this work is to analyse and to criticize this DQE extraction method on the basis of measurement and model results, and to give recommendations for fair comparison between detectors, wondering if the DQE is the right figure of merit for electron detectors.