The design of a continuously tunable optical delay line based on a compact graphene-based silicon Bragg grating is reported. High performance, in terms of electro-optical switching time (tswitch < 8 ...ns), delay range (Δτ = 200 ps), and figure of merit FOM = Δτ/A = 1.54x10
ps/mm
, has been achieved with an ultra-compact device footprint (A ~1.3 x 10
mm
), so improving the state-of-the-art of integrated optical delay lines. A continuous and complete tunability of the delay time can be achieved with a very low delay loss ( = 0.03 dB/ps) and a weak power consumption ( = 0.05 mW/ps). A flat bandwidth B = 1.19 GHz has been calculated by exploiting the slow-light effect in the device. This performance makes the proposed optical delay line suitable for several applications in Microwave Photonics (MWP), such as beamsteering/beamforming, for which large delay range, flat and wide bandwidth and small volume are required.
According to the World Health Organization (WHO) forecasts, Antimicrobial Resistance (AMR) will be the leading cause of death worldwide in the next decades. To prevent this phenomenon, rapid ...Antimicrobial Susceptibility Testing (AST) techniques are required to drive the selection of the most suitable antibiotic and its dosage. In this context, we propose an on-chip platform, based on a micromixer and a microfluidic channel, combined with a pattern of engineered electrodes to exploit the di-electrophoresis (DEP) effect. The role of the micromixer is to ensure the proper interaction of the antibiotic with the bacteria over a long time (≈1 h), and the DEP-based microfluidic channel enables the efficient sorting of live from dead bacteria. A sorting efficiency of more than 98%, with low power consumption (
= 1 V) and time response of 5 s, within a chip footprint of ≈86 mm
, has been calculated, which makes the proposed system very attractive and innovative for efficient and rapid monitoring of the antimicrobial susceptibility at the single-bacterium level in next-generation medicine.
Advances in Gyroscope Technologies Armenise, Mario N; Ciminelli, Caterina; Dell'Olio, Francesco ...
2011, 2010, 20101120, 2014-07-30
eBook
This monograph collects and critically reviews the main results obtained by the scientific community in gyroscope technologies research field. It describes architectures, design techniques and ...fabrication technology of angular rate sensors proposed in literature. MEMS, MOEMS, optical and mechanical technologies are discussed together with achievable performance. The book also consideres future research trends aimed to cover special applications. The book is intended for researchers and Ph.D. students interested in modelling, design and fabrication of gyros. The book may be a useful education support in some university courses focused on gyro technologies.
Optical trapping has revolutionized our understanding of biology by manipulating cells and single molecules using optical forces. Moving to the near-field creates intense field gradients to trap very ...smaller particles, such as DNA fragments, viruses, and vesicles. The next frontier for such optical nanotweezers in biomedical applications is to trap multiple particles and to study their heterogeneity. To this end, we have studied dielectric metasurfaces that allow the parallel trapping of multiple particles. We have explored the requirements for such metasurfaces and introduce a structure that allows the trapping of a large number of nanoscale particles (>1000) with a very low total power P < 26 mW. We experimentally demonstrate the near-field enhancement provided by the metasurface and simulate its trapping performance. We have optimized the metasurface for the trapping of 100 nm diameter particles, which will open up opportunities for new biological studies on viruses and extracellular vesicles, such as studying heterogeneity, or to massively parallelize analyses for drug discovery.
Accurate probing, monitoring, and controlling the pH level is critical in different fields. In the last two decades, optical fiber/waveguide-based pH sensors have been widely investigated with the ...aim of further enhancement of sensitivity and miniaturization. Here, we propose a novel and cost-effective pH sensor based on polymer waveguide Bragg grating, addressing main aspects like sensitivity enhancement, miniaturization, narrow band response, and stable performance. The large evanescent field due to metal under cladding and high index coating combined with excellent penetration depth match with pH-sensitive polymer coating of poly-acrylic acid/poly-allylamine hydrochloride (PAA/PAH) in an aqueous medium, ensures a sensitivity of 10.4 nm/pH for a pH range of 4 to 7, two orders higher than all reported Bragg grating pH sensors to our knowledge. A narrow band (∼1 nm) response has been ensured by low propagation loss of the TE mode. Further, the variations in sensitivity and peak reflectivity are within 3% for a ±10% inaccuracy in various structural parameters, reflecting excellent fabrication tolerances. The proposed sensor is an important development, especially for the perishable food industry in which a high sensitivity in a pH range of 4 to 7 is highly desirable to accurately determine the freshness of foods.
According to the World Health Organization forecasts, AntiMicrobial Resistance (AMR) is expected to become one of the leading causes of death worldwide in the following decades. The rising danger of ...AMR is caused by the overuse of antibiotics, which are becoming ineffective against many pathogens, particularly in the presence of bacterial biofilms. In this context, non-destructive label-free techniques for the real-time study of the biofilm generation and maturation, together with the analysis of the efficiency of antibiotics, are in high demand. Here, we propose the design of a novel optoelectronic device based on a dual array of interdigitated micro- and nanoelectrodes in parallel, aiming at monitoring the bacterial biofilm evolution by using optical and electrical measurements. The optical response given by the nanostructure, based on the Guided Mode Resonance effect with a Q-factor of about 400 and normalized resonance amplitude of about 0.8, allows high spatial resolution for the analysis of the interaction between planktonic bacteria distributed in small colonies and their role in the biofilm generation, calculating a resonance wavelength shift variation of 0.9 nm in the presence of bacteria on the surface, while the electrical response with both micro- and nanoelectrodes is necessary for the study of the metabolic state of the bacteria to reveal the efficacy of antibiotics for the destruction of the biofilm, measuring a current change of 330 nA when a 15 µm thick biofilm is destroyed with respect to the absence of biofilm.
Synthetic aperture radar (SAR) systems employ a Linearly Chirped Microwave Waveform Generator (LCMWG) with large time–bandwidth product (TBWP), to provide a wide range resolution. Photonics has now ...been recognized as a disruptive approach to achieve high performance at bandwidth of few tens of gigahertz, with light and compact architectures, due to the typical photonics benefits, such as electromagnetic interference immunity, small power consumption, small footprint, and high immunity to vibration/shock and radiation. In this article, we report on the photonic generation of a high-frequency LCMW, with a large TBWP (10
2
–10
3
), using a chip-scaled architecture, based on a frequency-tunable optoelectronic oscillator (OEO) and a recirculating phase modulation loop (RPML). A new configuration of the OEO employing an ultrahigh
Q
-factor resonator has been conceived to allow the oscillator working in
Ka
band at 40 GHz or even more, with very low phase noise. Key building block of the RPML is a phase modulator driven by an engineered parabolic split waveform. The ultra-large pulse compression rate (PCR) >> 10
2
, together with large signal purity, was also obtained, making the proposed architecture particularly suitable for SAR systems with large range resolution demand, such as Earth surveillance and monitoring.
The measurement of small changes in the refractive index (RI) leads to a comprehensive analysis of different biochemical substances, paving the way to non-invasive and cost-effective medical ...diagnosis. In recent times, the liquid biopsy for cancer detection via extracellular vesicles (EV) in the bodily fluid is becoming very popular thanks to less invasiveness and stability. In this context, here we propose a highly sensitive RI sensor based on a compact high-index-coated polymer waveguide Bragg grating with a metal under cladding. Owing to the combined effect of a metal under cladding and a high-index coating, a significant enhancement in the RI sensitivity as well as the dynamic range has been observed. The proposed sensor has been analyzed by combining finite element method (FEM) and coupled-mode theory (CMT) approaches, demonstrating a sensitivity of 408–861 nm/RIU over a broad dynamic range of 1.32–1.44, and a strong evanescent field within a 150 nm proximity to the waveguide surface compliant with EV size. The aforementioned performance makes the proposed device suitable for performing real-time and on-chip diagnoses of cancer in the early stage.
In the framework of the NewSpace revolution, time-to-market and budget constraints drive the development of small and medium-sized satellites in Low Earth Orbit (LEO) orbit. The adoption of ...Commercial Off-the-Shelf (COTS) components represents the current trend to fulfill the NewSpace goals, given their low cost, wide product availability, small time-to-market, and the ability to integrate the most recent advancements in space applications. However, migrating from radiation-hardened (rad-hard) devices to COTS ones requires ensuring comparable reliability levels. To this end, an "up-screening" of the COTS devices and systems should be performed in compliance with widely adopted standard regulations, such as those used by ESA or NASA. In this paper, we review COTS components and systems, such as diodes, Bipolar Junction Transistors (BJTs), Field Effect Transistors (FETs), Operational Amplifiers (OPAMPs), memories, and Field Programmable Gate Arrays (FPGAs), proven-flight or ad-hoc tested for compliance with standard regulations. In conclusion, the most promising devices in terms of cost and radiation tolerances are identified, providing useful benchmarks for space engineers developing COTS-based innovative systems.
Plasmonic and dielectric tweezers represent a common paradigm for an innovative and efficient optical trapping at the micro/nanoscale. Plasmonic configurations provide subwavelength mode confinement, ...resulting in very high optical forces, at the expense of a higher thermal effect, that could undermine the biological sample under test. On the contrary, dielectric configurations show limited optical forces values but overcome the thermal challenge. Achieving efficient optical trapping without affecting the sample temperature is still demanding. Here, we propose the design of a silicon (Si)-based dielectric nanobowtie dimer, made by two tip-to-tip triangle semiconductor elements. The combination of the conservation of the normal component of the electric displacement and the tangential component of the electric field, with a consequent large energy field confinement in the trapping site, ensures optical forces of about 27 fN with a power of 6 mW/µm2. The trapping of a virus with a diameter of 100 nm is demonstrated with numerical simulations, calculating a stability S = 1, and a stiffness k = 0.33 fN/nm, within a footprint of 0.96 µm2, preserving the temperature of the sample (temperature variation of 0.3 K).
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