Optical Sensor Technology Research Articles

Deep Learning for Optical Sensor Applications: A Review.

Over the past decade, deep learning (DL) has been applied in a large number of optical sensors applications. DL algorithms can improve the accuracy and reduce the noise level in optical sensors. Optical sensors are considered as a promising technology for modern intelligent sensing platforms. These sensors are widely used in process monitoring, quality prediction, pollution, defence, security, and many other applications. However, they suffer major challenges such as the large generated datasets and low processing speeds for these data, including the high cost of these sensors. These challenges can be mitigated by integrating DL systems with optical sensor technologies. This paper presents recent studies integrating DL algorithms with optical sensor applications. This paper also highlights several directions for DL algorithms that promise a considerable impact on use for optical sensor applications. Moreover, this study provides new directions for the future development of related research.

Peripheral intravenous therapy infiltration/extravasation (PIVIE) risks and the potential for earlier notification of events using a novel sensor technology in a neonatal population.

Intravenous (IV) therapy using short peripheral IV catheters (PIVC) is commonplace with neonatal patients. However, this therapy is associated with high complication rates including the leakage of infused fluids from the vasculature into the surrounding tissues; a condition referred to as, peripheral IV infiltration/extravasation (PIVIE). The quality improvement project aimed to identify the prevalence of known risk factors for PIVIE in the neonatal intensive care unit (NICU) and explore the feasibility of using novel optical sensor technology to aid in earlier detection of PIVIE events. The plan, do, study, act (PDSA) model of quality improvement (QI) was used to provide a systematic framework to identify PIVIE risks and evaluate the potential utility of continuous PIVC monitoring using the ivWatch model 400® system. The site was provided with eight monitoring systems and consumables. Hospital staff were supported with theoretical education and bedside training about the system operations and best use practices. In total 113 PIVIE's (graded II-IV) were recorded from 3476 PIVCs, representing an incidence of 3.25%. Lower birth weight and gestational age were statistically significant factors for increased risk of PIVIE (p = 0.004); all other known risk factors did not reach statistical significance. Piloting the ivWatch with 21 PIVCs using high-risk vesicant solutions over a total of 523.9 h (21.83 days) detected 11 PIVIEs (graded I-II). System sensitivity reached 100%; 11 out of 11 PIVIEs were detected by the ivWatch before clinician confirmation. Prevailing risk factors for PIVIE in the unit were comparable to those published. Continuous infusion site monitoring using the ivWatch suggests this technology offers the potential to detect PIVIE events earlier than relying on intermittent observation alone (i.e. the current standard of care). However, large-scale study with neonatal populations is required to ensure the technology is optimally configured to meet their needs.

Study the Dispersion and Losses in Fiber Optics Communication

This paper presents the dispersion of optical fiber in terms of mode of dispersion, attenuation, and losses, etc including optical fiber in terms of introduction, which gives an overview of the optical fiber, including the classifications, type, attenuation losses, etc. Some basic optical fiber sensor technologies are also reviewed .under this study the different types of sensors that introduced the principle and different types of optical sensors based on sensing location i.e. extrinsic and intrinsic sensors, based on operating principles i.e.ProcessinvolvingDemodulation, Sensor based on Intensity Modulation, SensorsbasedonPhase Modulation, Sensors based on Polarization Modulation, Sensors based on Wavelength Modulation, which are constructedonapplicationthatcanmeasure temperature, stress, pH, blood flow along with glucose content.

Saltwater intrusion ecophysiological effects on Pseudophoenix sargentii, Roystonea regia, Sabal palmetto “Lisa,” and Thrinax radiata in South Florida

Climate change will alter natural areas on a global scale within the next century, especially in low-lying coastal areas where sea-level rise is predicted to severely degrade or destroy many ecosystems. As sea-level rise continues, it is expected that salinity due to saltwater intrusion will impact soil health and agricultural production, this is of even greater importance in areas such as South Florida where the surface and groundwater resources are hydrologically connected due to the shallow and highly permeable limestone soils. The chlorophyll concentrations in leaf tissue were chosen as the primary health indicator to assess whether this is a valuable factor to consider for plant health risk assessment and whether optical sensor technology such as the SPAD and NDVI, are valuable tools when understanding the impact seawater encroachment has on plant nitrogen uptake. Therefore, the aim of this study was to evaluate the effects of salt concentrations on plant growth and health of four palm species. The treatments were from pure reverse osmosis water, Fresh water, brackish water, seawater and hypersaline water (0, 0.5, 5, 10, 15, 25, and 50 ppt). Control treatment that received reverse osmosis filtrated water with a salinity concentration of 0 ppt had the highest health-indicator averages compared to treatment 50 ppt. As the salinity increased, all health indicators gradually declined or remained rather constant and declined as they approached the greater salinity concentrations. The growth parameters and chlorophyll content were reduced over time, particularly at higher salt concentrations for all palm species studied. The chlorophyll content by SPAD and the normalized difference vegetation index (NDVI) can be used as health indicators of the palm species studied, as it was observed in this study a decline in the chlorophyll content as there was an increase in salt concentrations. It is important to emphasize that leaf chlorosis and subsequent decline of palm species were observed in the treatment with higher salt concentration, thus highlighting the importance of chlorophyll content as an indicator of plant health. The species Roystonea regia was very susceptible to salinity, and the palm Sabal palmetto is more susceptible to salinity than the Thrinax radiata and Pseudophoenix sargentii palms.

Optical fiber sensors in infrastructure monitoring: a comprehensive review

Abstract The purpose of this article is to review and further promote the application of optical fiber sensor technology in infrastructure monitoring. Compared with traditional sensors, optical fiber sensors have low maintenance costs and are small in size; consequently, they have gradually become a future development direction of sensors. This paper introduces the basic principles of several commonly used optical fiber sensors and the progress of optical fiber sensors in the monitoring of physical, mechanical, and chemical parameters and demonstrates the applications of optical fiber sensors in infrastructure.

Investigation and performance improvement of optical fiber acoustic sensor based on diaphragm prestress tunable technology

In this paper, sensitivity and response frequency tunable optical fiber acoustic sensor technology is proposed for the first time, in which a C-shape pedestal mounted diaphragm sensor structure is employed for prestress tuning and consequently for the rigidity adjustment of the diaphragm to investigate and improve the performance of single mode-multimode-single mode (SMS) fiber acoustic sensor. By employing the proposed sensor structure, the influence of prestress on the resonance frequency and the sensitivity of optical fiber acoustic sensor can be investigated theoretically and experimentally. The results also confirm that the proposed method provide a simple but effective solution for the performance improvement of acoustic sensor, by which the response range can be extended from 800 Hz to 1500 Hz with a sensitivity fluctuation of 0.7 dB and a value of 0.998 by adjusting the prestress of diaphragm, meanwhile the background noise can be significantly suppressed from −57 dB to −67 dB.

Best Nitrogen Management Practices Using Sensor-Based Smart Agriculture in Nursery Production of Cacao

Reducing fertilizer costs and ensuring environmental sustainability are critical issues given the challenges posed by nutrient run-off. The use of smart technologies such as optical sensors is essential in achieving these goals. This study was conducted to determine the most efficient fertilizer regime based on chlorophyll content monitoring using optical sensor technology in cacao samplings in the nursery setting. The 8N-3P-9K (slow-released fertilizer) was used at 15 g (control), 15 g (supplemented with +15 g applied 2 times), 15 g (+15 g), 30 g (+15 g applied 2 times), 30 g (+15 g), and 45 g (+15 g applied two times). Chlorophyll content (measured using optical sensors such as soil plant analysis development (SPAD), atLEAF, normalized difference vegetation index (NDVI)), plant height, number of leaves, total nitrogen of leachate samples, and the total nitrogen and total carbon contents of the leaf and soil samples were evaluated over six months. The results show that the lower application of nitrogen fertilizer can provide the necessary required nutrients of cocoa plants and cause less contamination via run-off. Using 45 g (+15 g applied 2 times) causes more pollution through nutrient run-off. This study demonstrates the importance of handheld sensor technology in determining the best nitrogen management practices in fruit nurseries to reduce excessive fertilization while decreasing the extra costs and mitigating environmental pollution.

Microprobe-Capture In-Emitter Elution: An Affinity Capture Technique to Directly Couple a Label-Free Optical Sensing Technology with Mass Spectrometry for Protein Analysis.

Affinity capture of an analyte by a capture agent is one of the most effective sample preparation approaches in mass spectrometry (MS), especially top-down MS. We describe a new affinity capture technique for protein targets, called microprobe-capture in-emitter elution (MPIE), which can directly couple a label-free optical sensing technology (next-generation biolayer interferometry, BLI) with MS. To implement MPIE, an analyte is first captured on the surface of a microprobe and subsequently eluted from the microprobe inside an electrospray emitter. The capture process is monitored in real-time via BLI. When electrospray is established from the emitter to a mass spectrometer, the analyte is immediately ionized via electrospray ionization (ESI) for MS analysis. By this means, BLI and MS are directly coupled in the form of MPIE-ESI-MS. The performance of MPIE-ESI-MS was demonstrated by the analysis of β-amyloid 1-40 and transferrin using both standard samples and human specimens. In comparison to conventional affinity capture techniques such as bead-based immunoprecipitation, MPIE innovates the affinity capture methodology by introducing real-time process monitoring and providing binding characteristics of analytes, offering more information-rich experiment results. Thus, MPIE is a valuable addition to the top-down MS sample preparation toolbox, and MPIE-ESI-MS can be useful for identification and characterization of targets of interest.

Single microhole per pixel for thin Ge-on-Si complementary metal-oxide semiconductor image sensor with enhanced sensitivity up to 1700 nm

We present a germanium “Ge-on-Si” CMOS image sensor with backside illumination for the near-infrared (NIR) electromagnetic waves (wavelength range 300 to 1700 nm) detection essential for optical sensor technology. The microholes help to enhance the optical efficiency and extend the range to the 1.7-μm wavelength. We demonstrate an optimization for the width and depth of the microholes for maximal absorption in the NIR. We show a reduction in the crosstalk by employing thin SiO2 deep trench isolation in between the pixels. Finally, we show a 26 to 50% reduction in the device capacitance with the introduction of a microhole. Such CMOS-compatible Ge-on-Si sensors will enable high-density, ultrafast, and efficient NIR imaging.

Precision Horticulture: Application of Optical Sensor Technology for Nitrogen Monitoring Status in Cocoplum, a Native Landscaping Plant.

Cocoplum (Chrysobalanus icaco) is an ecologically significant native species to Southern Florida. Application of precision agriculture technologies such as optical sensors reduces the cost of over-fertilization and nutrient runoff. The aim of this work was to establish a base line sensor value for fertilizer treatment in cocoplum by monitoring chlorophyll content using the Soil Plant Analytical Development (SPAD), atLEAF, and Normalized Difference Vegetation Index (NDVI) sensors. Initial slow-released fertilizer treatment 8N-3P-9K was used at 15 g (control), 15 g (supplemented with +15 g × 2; T1), 15 g (+15 g; T2), 30 g (+15 g × 2; T3), 30 g (+15 g; T4), and 45 g (+15 g × 2; T5). Evaluations were conducted at 0 (base reading), 30, 60, 90, 120, 150, and 180 days after treatment. Growth parameters, optical non-destructive chlorophyll meters, leaf and soil total nitrogen and total carbon, and total nitrogen of leachate were analyzed. The results demonstrated that the treatment using 30 g slow-released fertilizer (8N-3P-9K) supplemented twice with 15 g in November and March after the first fertilization in October provided the least contamination through runoff while still providing adequate nutrients for plant growth compared to higher fertilizer concentrations. These results demonstrate that the highest treatment of nitrogen can cause considerable losses of N, causing extra costs to producers and environmental damage due to the flow of nutrients. Thus, techniques that help in N monitoring to avoid the excessive use of nitrogen fertilization are necessary. This study can serve as a basis for future research and for nurseries and farms, since it demonstrated from the monitoring of the chlorophyll content by optical sensors and by foliar and substrate analysis that lower treatments of nitrogen fertilization are sufficient to provide nutrients suitable for the growth of cocoplum plants.

Review on optical visual sensor technology

视觉传感是人类感知外界、认知世界的主要途径，研究表明人类获取的外界信息大约有80%来自于视觉。作为感知外界信息的“电子眼球”，视觉传感器是消费电子、机器视觉、安防监控、科学探测和军事侦察等领域的核心器件。近年来视觉传感器技术发展迅速，不同类型的传感器从不同维度提供丰富的视觉数据，不断增强人类感知与认知能力，视觉传感器研究工作具有重要的理论与应用需求。本报告以典型光学视觉传感器技术为主线，通过综合国内外文献和相关报道，从CCD图像传感器、CMOS图像传感器、智能视觉传感器以及红外图像传感器等研究方向，梳理论述近年来光学视觉传感器技术的发展现状、前沿动态、热点问题和趋势。;Visual sensing technique is essential for human to perceive and understand the world around them. An electronic eyeball can be melted into outdoor-related visual information, and visual sensors are equipped with such domains like consumer electronics, machine vision, surveillance, and academic researches. Visual sensor technology-based multiple sensors can be used to richer multi-dimension visual data, which can enhance human-related perceptive and cognitive ability. This literature review is focused on the growth of optical visual sensor technology, including such image sensors in relevance to CCD, CMOS, intelligent-visual, and infrared-context. The CMOS image sensor chip is produced in terms of CMOS technology, in which image acquisition unit and signal processing unit can be integrated into the same chip. It can be massproduced to a certain extent. Cost-effective applications can be oriented to such aspects in related to small size, light weight, low cost and low power consumption. With the rapid development of autonomous driving, intelligent transportation, machine vision and other fields, multi-functional and intelligent CMOS image sensors with small size will become the focus of research. The emerging CCD sensor technology and its applications have been facilitating as well. The potentials of CCD image sensor can be applied for such domains in related to remote sensing, astronomy, low light detection. In the future, the multi-spectral TDI CCD architecture based on CCD and CMOS fusion technology will be widely used. Infrared image sensor is configured and set that infrared radiation detection can be converted into physical quantity. The high-performance digital signal processing function can be integrated on the infrared focal plane. The newly infrared image sensor can be focused on larger array, higher resolution, wider spectrums, more flexible sensitivity, multi-band, and system-level chip further.

Detection of road vehicles at a railway level crossing by means of optical fiber distributed sensor

The exploit of distributed optical fiber sensor technology for vibration source detection in a railway environment using standard telecommunication cables is a new area of research with great potential. In this work, the detection of vehicles passing at a railway level crossing in the south of France is investigated by analyzing optical signals from an optical fiber sensor system. The results show high reliability and accuracy in detecting vehicles along with their direction at the level crossing. There is a correlation indicating a possible linearity between the vehicle's weight and the signal, we even were able to visually classify vehicles into three different categories according to their weight. These results are promising and opening the way for further work on automation and real-time analysis.

Innovative Method of Embedding Optical Fiber inside Titanium Alloy Utilizing Friction Stir Forming

The development of FBG (Fiber Bragg Grating) sensors is essential for intelligent parts of airplanes to achieve ultra-lightweight structures and intelligent aviation control. Awaiting solution is embedding technology of optical fiber sensors into the base material of the parts; however, it has been challenging to embed fibers into high melting temperature point alloys like titanium-based materials without having any defects. Present research fulfills the mentioned demands effectively by utilizing Friction Stir Forming (FSF). Precisely, optical fiber has been placed into a guide slit inside the titanium sheet. Then, FSF was applied to the surface of the titanium. As a result, titanium plasticizes and flows into the guide slit. This mechanically interlocks the optical fiber inside the titanium alloy. This solid-state stirring process can bury sensors inside the titanium to protect the sensor from harsh environments. Embedded sensors will detect the strain and temperature of the host titanium in real-time. Moreover, this research can have further considerable effects on the areas like aerospace and artificial intelligence systems that demand real-time condition monitoring systems.

Influence of Different Heat Loads and Durations on the Field Thermal Response Test

Geothermal energy exhibits considerable development potential in space heating. Shallow geothermal energy stored in the soil in the form of low-grade energy is mainly extracted via the ground source heat pump (GSHP) system. GSHP systems use the subsoil as a heat source, typically involving a vertical borehole heat exchanger (BHE) to extract heat from the formation. Accurate measurement of the thermal properties of the formation is very important for the design of BHEs. At present, the most common and effective method to measure the thermal conductivity of the formation in the field is the thermal response test (TRT). However, the test conditions (heat load, test time) during the thermal response test can impact the test results. Therefore, in this study, a borehole with a depth of 130 m was evaluated in the field. The TRT module and the distributed thermal response test (DTRT) module based on distributed optical fiber temperature sensor (DOFTS) technology were used to monitor the test with different working conditions in real-time. In the field tests, geothermal conditions and the evolution of the formation temperature with time and depth were determined. Based on the test results under different heat loads and test times, the influence of the test conditions on the thermal conductivity results was analyzed and described. A constant temperature zone was located at a depth from 25 m to 50 m, and an increasing temperature zone was located at a depth from 50 m to 130 m, with a geothermal gradient of 3 °C/100 m. The results showed that the heat load slightly influenced the thermal conductivity test results. At the initial stage of the test, the temperature significantly increased from 0 to 12 h. After reaching the quasi-stable state, the test time slightly influenced the thermal conductivity test results. The characteristics of the formation thermal recovery stage after the test stage were studied. The heat load decreased, which could shorten the time for the formation to recover the initial temperature. The results could provide a basis for the optimization of thermal response test conditions.

Recent Advances in Gas Sensing Technology Using Non-Oxide II-VI Semiconductors CdS, CdSe, and CdTe

In recent years, there has been an increasing need and demand for gas sensors to detect hazardous gases in the atmosphere, as they are indispensable for environmental monitoring. Typical hazardous gas sensors that have been widely put to practical use include conductometric gas sensors, such as semiconductor gas sensors that use the change in electrical resistance of metal oxide semiconductors, catalytic combustion gas sensors, and electrochemical gas sensors. However, there is a growing demand for gas sensors that perform better and more safely, while also being smaller, lighter, less energy-demanding, and less costly. Therefore, new gas sensor materials are being explored, as well as optical gas sensor technology that expresses gas detection not electrically but optically. Cadmium sulfide (CdS), cadmium selenide (CdSe), and cadmium telluride (CdTe) are typical group II-VI non-oxide semiconductors that have been used as, for example, electronic materials. Recently, they have attracted attention as new gas sensor materials. In this article, recent advances in conductometric and optical gas sensing technologies using CdS, CdSe, and CdTe are reviewed.

Development of a Digital Twin of a Local Road Network: A Case Study

Abstract Virtual replicas of infrastructure can be used to run simulations and optimize the construction, management, and maintenance of such assets throughout their entire lifecycle. These digital twins (defined as integrated multi-physics, multiscale, and probabilistic simulations of a complex product) mirror the behavior and environmental responses of its corresponding twin. Digital reconstruction techniques using optical sensor technologies and mobile sensor platforms are providing viable, low-cost alternatives to develop digital twins of physical infrastructure. In previous work, the digital twinning of asphalt pavement surfacings using visual simultaneous localization and mapping and the initiation of a digital twin of a local road network were investigated and successfully demonstrated. In this article, the further development of the concept, incorporating road surface temperatures collected over a 1-month period, as well as potential inferences based on these data, in the micro- and macro-twinning of a local road, are discussed. Light detection and ranging, unmanned aerial vehicles, and traffic counting artificial intelligence allows for quantification of the road geometry and infrastructure utilization over large areas (macro-twinning), whereas the photogrammetric reconstruction technique based on a neural network, a proprietary environmental condition sensor (SNOET, or SNiffing Omgewing / Environmental Tester) and commercial temperature sensors were used to acquire the surface texture and environmental conditions respectively (micro-twinning), as well as surface temperatures at four locations and different surfacing materials. The combination of advanced environmental monitoring data, physical data, and surface temperature data provide management data that can assist in the maintenance of such roads. This article expands (with the permission of the conference organizers) on a GeoChina 2021 article through the addition of further temperature data collected on the discussed digital twin, with substantial additional data analysis and discussion.

Raman scattering-based distributed temperature sensors: A comprehensive literature review over the past 37 years and towards new avenues

Over the last 37 years, particular interest has been directed towards exploring the characteristics of the optical environment for sensing, giving rise to what would now be one of the largest applications of well-known optical fibers, typically employed to transmit data at high rates. Sensing temperature, pressure, liquid level, deformation, and other physical parameters utilizing optical fibers has become a growing branch of research and a business competing with well-established electrical sensors in the industry. Optical fiber sensors have all the inherent characteristics of a fiber optic cable, such as electromagnetic immunity, small size and weight, multiplexing, and so on. These exclusive features have made fiber sensors so versatile as to become a transformative technology by enabling several industrial processes to be carried out with higher reliability. Nowadays, there are several optical sensors, including fiber Bragg grating, interferometric, polarimetric, polymer fiber, distributed, and several others. Specifically, Raman-based distributed temperature sensor (RDTS) is a class of fiber optic sensors broadly employed in temperature measurement of large structures such as oil and gas wells, tunnels, and pipelines. Since 1985, many techniques have been proposed to break through the barriers of exploring Raman scattering as a distributed temperature measurement method. Range, spatial and temperature resolutions have been the most investigated parameters. In this perspective, this paper presents a comprehensive review focused on the progress of the RDTS technology over the past 37 years (1985–2022), covering an analysis of over 500 journal papers. First, a brief introduction to fiber optic sensor technology is presented as a theoretical basis, discussing the emergence of distributed sensors. Subsequently, Raman scattering in optical fibers is introduced, as well as how this nonlinear effect can be used to build temperature sensors. Next, RDTS technology is detailed, followed by a discussion of its applications and evolution over nearly four decades of development. Lastly, future perspectives are addressed in this review for the advancements in distributed temperature sensor technologies.

Integration Aspects of Plasmonic TiN-based Nano-Hole-Arrays on Ge Photodetectorsin a 200mm Wafer CMOS Compatible Silicon Technology

During the last decade optical sensor technologies have attracted increased attention for various applications. Plasmon-based optical sensor concepts for the detection of refractive index changes that rely on propagating surface-plasmon polaritons at metal-dielectric interfaces or on localized plasmons in metallic nanostructures prove their potential for these application due to their fast detection speed, high specificity and sensitivities [1, 2]. Combining plasmonic structures directly with optoelectronic devices could enable a high level of integration, however, it represents a significant technological challenge to develop an on-chip solution for these concepts including the integration of sensor and detector components. Previous works demonstrated first approaches mainly for the integration of refractive index sensor components on wafer level [3, 4]. In [5] and [6] a proof-of-concept of a fully integrated on-chip solution with high sensitivities was presented, which can be easily combined with microfluidics [7] for potential applications in biosensing. In this concept, a nanohole array (NHA) was structured in a 100 nm thick aluminum layer on top of a vertical PIN germanium photodetector (GePD) with an intrinsic germanium sheet of 480 nm. This sensor concept relies on extraordinary optical transmission through the NHA [8]: Light transmission is only possible for narrow wavelength ranges determined by the NHA geometry which determine the transmission peaks at the resonance wavelength of the NHA. Thus, the NHA acts as a high quality wavelength filter. Due to the change in the refractive index, a material under test (MUT) contacting directly the surface of the NHA, provokes a shift of the wavelength maximum, which can be detected by measuring the photocurrent spectra of the GePD. While responsivities and sensitivities of (0 V) = 0.075 A/W and = 1200 nm/RIU could be attained in this proof-of-concept device [6, 7], the semiconductor device layers were deposited using molecular beam epitaxy (MBE). Furthermore the vertical PIN GePD was realized by a mesa procedure to enable large areas for top illuminated operations. These techniques are unsuitable for an industrial CMOS fabrication process with high throughput. Therefore, the development of a CMOS compatible technology process with low costs and high yields is an important step towards large-scale fabrication of this sensor concept.In this work we present the progress for the realization of a surface plasmon resonance (SPR) refractive index sensor in a 200 mm wafer Silicon based technology. One main challenge is the fabrication of a large area photodetector for top illuminated sensor devices. We developed a process, which is mainly based on the IHP electronic photonic integrated circuits (ePIC) technology [9]. This ePIC technology enables the production of waveguide coupled lateral PIN GePDs with high bandwidth and high responsivities [10]. However, these PDs are unsuitable for top illuminated applications because of their small germanium areas. Due to certain process conditions with respect to chemical mechanical polishing procedures there are limits for feasible large detector areas. Furthermore, large detector areas for lateral PIN GePDs would result in very low electric fields in the intrinsic zone where carriers are generated by photon absorption. Thus, very high voltages for reversed bias are necessary for sufficient carrier drifts.For the first time we have developed a modern detector design concept which is compatible to the IHP ePIC technology. This concept allows the realization of large area detectors of 1600µm² (40µm x 40µm) with optimized optical responsivities for top illuminated applications. The detector consists of several parallel connected lateral PIN GePDs. We designed different variations and varied Ge width and distance between neighboring GePDs in order to investigate process limits. The p- and n-doped regions were defined by dopant implantation using a photo resist mask. We used a finger-like design as implantation masks to enable one contact area for each p-doped and each n-doped region (Fig. 1). This contacting approach differs from the standard GePD offered in the IHP ePIC technology. We analyzed I-V characteristics in dependence of detector design and contacting scheme (Fig. 2). In addition, process adjustments for the optimization of the germanium quality were investigated to reduce dark currents and to improve optical responsivities (Fig.3).Titanium nitride (TiN) is very promising metallic alloy with respect to thickness homogeneity and low surface roughness. Therefore we used titanium nitride which was deposited by a sputtering process to develop plasmonic active NHA layers. Various process development runs were done to evaluate the NHA performance. Ellipsometry and atomic force microscope measurements were performed to characterize the quality of the TiN layer (Fig.4). Figure 1

Advances in application of sensors for determination of phthalate esters

Phthalates esters (PAEs) are extensively used as additives for polymers in plastic, particularly in polyvinyl chloride (PVC) and polyethylene terephthalate (PET). These compounds are not part of the polymer chains and can be released easily from products and migrate into beverages and foods that come into direct contact, causing environmental and human health impacts. Simple and rapid detection of such substances is of great significance for ensuring environmental food safety and consumer health. At present, optical sensor and electrochemical sensor detection technologies have been applied to PAEs detection due to their advantages, such as simple, rapid, low cost, high sensitivity, simple operation, portability and high specificity. They can make up for the shortcomings of chromatographic detection technology, such as expensive equipment, cumbersome operation, the need for professional and technical personnel, and difficulty in achieving a large number of sample screening objectives. In this paper, research progress on optical sensors and electrochemical sensors for the detection of phthalates in recent ten years is reviewed and discussed. This is helpful to better understand preparation methods for sensors and their detection mechanisms for phthalates. The review will also be used in developing a more effective trace detection sensor for phthalates.

Simultaneous interrogation of multiple cores in a shape sensor fiber with a graded index fiber micro-turnaround.

A critical limitation for optical fiber sensor technology is the complexity of the interrogators used in such measurements, which has driven continued interest in enhanced optical fibers and fiber assemblies that will simplify interrogator design. In this work, we report on a novel multicore fiber shape sensor utilizing a distal graded index (GRIN) fiber micro-turnaround. We show that four offset cores of this fiber can be interrogated simultaneously with a single high performance optical frequency domain reflectometry measurement. The GRIN turnaround is 498 µm in length and reflects signal from one offset core to an opposite core with a 2 dB roundtrip attenuation. We show that the bend sensing accuracy of our single measurement system is similar to the accuracy of sequential measurements of four individual cores. We also demonstrate fiber shape reconstruction with a single measurement over 0.55 m with 80 µm spatial resolution when the fiber is wrapped around two posts.