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Abstract: Silicon Photonics technology is rapidly maturing as a platform for larger‐scale photonic circuits. As a result, the associated design methodologies are also evolving from component‐oriented design to a more circuit‐oriented design flow, that makes abstraction from the very detailed geometry and enables design on a larger scale. In this paper, the state of this emerging photonic circuit design flow and its synergies with electronic design automation (EDA) are reviewed. The design flow from schematic capture, circuit simulation, layout and verification is covered. The similarities and the differences between photonic and electronic design, and the challenges and opportunities that present themselves in the new photonic design landscape, such as variability analysis, photonic‐electronic co‐simulation and compact model definition are discussed. [ABSTRACT FROM AUTHOR]

In the maturing field of silicon photonics, advances continue in both design and process improvements. Waveguide propagation loss is strongly affected by sidewall roughness, and so for fabrication using e-beam lithography, loss is influenced by e-beam writing parameters. Here, the authors look specifically at fracturing strategies in data preparation for e-beam lithography, and find significant reduction in waveguide loss by utilizing advanced fracturing options. For our evaluation, the authors fabricate optical waveguides using a well-characterized, highly stable baseline fabrication process with hydrogen silsesquioxane resist exposed by a 100 kV electron beam, a high-contrast tetramethyl-ammonium hydroxide develop, and a Cl2 inductively coupled plasma etch. Using surface grating couplers for input and output, automated optical measurements are made by scanning input light in the region of the design wavelength of 1550 nm and measuring optical output power. The authors use a design cell containing grating couplers and both straight and curved waveguides with a range of lengths. The authors find a significant reduction in grating coupler insertion loss and waveguide loss along with increased uniformity by leveraging a new fracturing strategy implemented in the beamer pattern data processing software from GenISys, GmbH. Single line edge smoothing is an exposure strategy in which all feature edges are traced using a single-line shape (sometimes referred to as a single-pass line) while the bulk of the shape is then exposed with trapezoidal beam filling. The insertion loss for grating couplers written using single line edge smoothing shows a significant loss reduction of 1.2 dB as well as greatly improved uniformity. Both straight and curved waveguide losses were also reduced by use of single line edge smoothing, by 0.7 and 1.1 dB/cm, respectively. Here, the authors will discuss the likely mechanisms of this improvement as well as present additional device data using these new fracturing methods which represent a significant, incremental improvement in performance of optical waveguides written by e-beam lithography. [ABSTRACT FROM AUTHOR]

In recent years, wearable contact lenses for medical applications have attracted significant attention, as they enable continuous real-time recording of physiological information via active and noninvasive measurements. These devices play a vital role in continuous monitoring of intraocular pressure (IOP), noninvasive glucose monitoring in diabetes patients, drug delivery for the treatment of ocular illnesses, and colorblindness treatment. In specific, this class of medical devices is rapidly advancing in the area of drug loading and ocular drug release through incorporation of electrospun fibers. The electrospun fiber matrices offer a high surface area, controlled morphology, wettability, biocompatibility, and tunable porosity, which are highly desirable for controlled drug release. This article provides an overview of the advances of contact lens devices in medical applications with a focus on four main applications of these soft wearable devices: (i) IOP measurement and monitoring, (ii) glucose detection, (iii) ocular drug delivery, and (iv) colorblindness treatment. For each category and application, significant challenges and shortcomings of the current devices are thoroughly discussed, and new areas of opportunity are suggested. We also emphasize the role of electrospun fibers, their fabrication methods along with their characteristics, and the integration of diverse fiber types within the structure of the wearable contact lenses for efficient drug loading, in addition to controlled and sustained drug release. This review article also presents relevant statistics on the evolution of medical contact lenses over the last two decades, their strengths, and the future avenues for making the essential transition from clinical trials to real-world applications. [ABSTRACT FROM AUTHOR]

The advances in the miniaturisation of electronic devices and the deployment of cheaper and faster data networks have propelled environments augmented with contextual and real-time information, such as smart homes and smart cities. These context-aware environments have opened the door to numerous opportunities for providing added-value, accurate and personalised services to citizens. In particular, smart healthcare, regarded as the natural evolution of electronic health and mobile health, contributes to enhance medical services and people's welfare, while shortening waiting times and decreasing healthcare expenditure. However, the large number, variety and complexity of devices and systems involved in smart health systems involve a number of challenging considerations to be considered, particularly from security and privacy perspectives. To this aim, this article provides a thorough technical review on the deployment of secure smart health services, ranging from the very collection of sensors data (either related to the medical conditions of individuals or to their immediate context), the transmission of these data through wireless communication networks, to the final storage and analysis of such information in the appropriate health information systems. As a result, we provide practitioners with a comprehensive overview of the existing vulnerabilities and solutions in the technical side of smart healthcare. [ABSTRACT FROM AUTHOR]

The prevalence of diabetes is increasing globally. More than 690 million cases of diabetes are expected worldwide by 2045. Continuous blood glucose monitoring is essential to control the disease and avoid long-term complications. Diabetics suffer on a daily basis with the traditional glucose monitors currently in use, which are invasive, painful, and cost-intensive. Therefore, the demand for non-invasive, painless, economical, and reliable approaches to monitor glucose levels is increasing. Since the last decades, many glucose sensing technologies have been developed. Researchers and scientists have been working on the enhancement of these technologies to achieve better results. This paper provides an updated review of some of the pioneering non-invasive optical techniques for monitoring blood glucose levels that have been proposed in the last six years, including a summary of state-of-the-art error analysis and validation techniques. [ABSTRACT FROM AUTHOR]

Digital and information technologies are heavily pervading several aspects of human activities, improving our life quality. Health systems are undergoing a real technological revolution, radically changing how medical services are provided, thanks to the wide employment of the Internet of Things (IoT) platforms supporting advanced monitoring services and intelligent inferring systems. This paper reports, at first, a comprehensive overview of innovative sensing systems for monitoring biophysical and psychophysical parameters, all suitable for integration with wearable or portable accessories. Wearable devices represent a headstone on which the IoT-based healthcare platforms are based, providing capillary and real-time monitoring of patient's conditions. Besides, a survey of modern architectures and supported services by IoT platforms for health monitoring is presented, providing useful insights for developing future healthcare systems. All considered architectures employ wearable devices to gather patient parameters and share them with a cloud platform where they are processed to provide real-time feedback. The reported discussion highlights the structural differences between the discussed frameworks, from the point of view of network configuration, data management strategy, feedback modality, etc. [ABSTRACT FROM AUTHOR]

In this article, a biosensor composed of a single metamaterial asymmetric resonator is specifically designed for sensing the glucose level of 1 µL of solution. The resonator has two gaps, and one of them ends with a semicircle shape on which the glucose solution is placed. This design helps in confining the drops of glucose solutions in a specific area where the field is maximally confined in order to enhance the electromagnetic wave-matter interaction. Six samples of glucose solutions with concentrations that cover hypoglycemia, normal and hyperglycemia conditions that vary from around 41 to 312 mg/dL were prepared and examined by this biosensor. The resonance frequency redshift was used as a measure of the changes in the glucose level of the solutions. Without glucose solution, an excellent agreement between the measured and simulated transmission amplitude was observed. The increase in glucose concentrations exhibited clear and noticeable redshifts in the resonance frequency. This biosensor revealed a 0.9997 coefficient of determination, which implies an excellent prediction fitting model. More importantly, a sensitivity of 438 kHz/(mg/dL) was observed over the range of concentrations of the aqueous solution. [ABSTRACT FROM AUTHOR]

Driving signal reflection on traveling wave electrodes (TWEs) is a critical issue in Mach–Zehnder modulators. Fabrication variation often causes a random variation in the electrode impedance and the signal reflection, which induces modulation characteristics variation. The variation of reflection could be intertwined with the variation of other electrode characteristics, such as microwave signal attenuation, resulting in complexity. Here, we characterize the (partial) correlation coefficients between the reflection and modulation characteristics at different bit rates. Decreasing correlation at higher bit rates is observed. Device physics analysis shows how the observed variation can be related to nanoscale variation of material properties, particularly in the embedded diode responsible for electro-optic modulation. We develop a detailed theory to analyze two variation modes of the diode (P-i-N diode or overlapping P/N regions), which reveal insight beyond simplistic diode models. Microwave signal attenuation tends to reduce the correlation with on-electrode reflection, particularly at high bit rates. The theory shows the relative importance of conductor-induced attenuation and "dielectric"-induced attenuation, with different dependence on the frequency and fabrication variation. Strategies on how to mitigate the effect of variation for better fabrication tolerance are discussed by considering three key factors: pre-shift in structural design, bias condition, and fabrication control accuracy. [ABSTRACT FROM AUTHOR]

In recent years, with the rise of global diabetes, a growing number of subjects are suffering from pain and infections caused by the invasive nature of mainstream commercial glucose meters. Non-invasive blood glucose monitoring technology has become an international research topic and a new method which could bring relief to a vast number of patients. This paper reviews the research progress and major challenges of non-invasive blood glucose detection technology in recent years, and divides it into three categories: optics, microwave and electrochemistry, based on the detection principle. The technology covers medical, materials, optics, electromagnetic wave, chemistry, biology, computational science and other related fields. The advantages and limitations of non-invasive and invasive technologies as well as electrochemistry and optics in non-invasives are compared horizontally in this paper. In addition, the current research achievements and limitations of non-invasive electrochemical glucose sensing systems in continuous monitoring, point-of-care and clinical settings are highlighted, so as to discuss the development tendency in future research. With the rapid development of wearable technology and transdermal biosensors, non-invasive blood glucose monitoring will become more efficient, affordable, robust, and more competitive on the market. [ABSTRACT FROM AUTHOR]

Selective optical filters with high rejection levels are of fundamental importance for a wide range of advanced photonic circuits. However, the implementation of high‐rejection on‐chip optical filters is seriously hampered by phase errors arising from fabrication imperfections. Due to coherent interactions, unwanted phase‐shifts result in detrimental destructive interferences that distort the filter response, whatever the chosen strategy (resonators, interferometers, Bragg filters, etc.). State‐of‐the‐art high‐rejection filters partially circumvent the sensitivity to phase errors by means of active tuning, complicating device fabrication and operation. Here, a new approach based on coherency‐broken Bragg filters is proposed to overcome this fundamental limitation. Non‐coherent interaction among modal‐engineered waveguide Bragg gratings separated by single‐mode waveguides is exploited to yield effective cascading, even in the presence of phase errors. This technologically independent approach allows seamless combination of filter stages with moderate performance free of active control, providing a dramatic increase of on‐chip rejection. Based on this concept, on‐chip non‐coherent cascading of Si Bragg filters is experimentally demonstrated, achieving a light rejection exceeding 80 dB, the largest value reported for an all‐passive silicon filter. [ABSTRACT FROM AUTHOR]

The calibration of a NIR photometer for analysis of liquid substances aims to find a curve that relates the concentration of some analyte with spectral data collected from the samples. However, the measured optical signals depend not only on the concentration of the analyte of interest, so that the quality of the calibration also depends on the natural variability of samples and on the way the optical data are processed and modeled. This paper presents a study on the influence of these two factors on the calibration of a LED-NIR photometer, which was applied to the quantification of ethanol in gasoline, and compares the results obtained by the prototype with those obtained by a commercial spectrophotometer. We used two distinct procedures for selecting the calibration samples, in order to evaluate the influence of the sample matrix, considering two different methods of determining the absorbances from the optical data. Experimental results showed that the calibration samples must be prepared and selected with uniform distribution in relation to the different sources of variance, in order to make the equipment able to accurately predict future samples. The performance of the prototype was very close to the one of the commercial equipment, with a difference in root mean square errors of less than 0.8% in the concentration (v/v) of ethanol. [ABSTRACT FROM AUTHOR]

Diabetes is one of the prominent diseases around the world. Presently, invasive techniques need a finger prick blood sample. A repetitively painful procedure that produces the chance of infection. To resolve this issue, non-invasive measurement approach is proposed. In this paper, an efficient NIR wave based optical detection system is proposed with optimized post-processing regression model. After real-time data analysis, it has been found that the coefficient of determination (R2) is improved with the value of 0.9084 using proposed regression model. Mean absolute derivative is also increased with 3.87 mg/dl corresponding to predicted blood glucose concentration. Mean absolute relative difference has exceeded to 3.25%, and average error is improved with 3.77% using proposed regression model. Average accuaracy has been analyzed 94-95% for predicted blood glucose concentration. [ABSTRACT FROM AUTHOR]