594 research outputs found
New ultrasensitive resonant photonic platform for label-free biosensing
No full textA multi-analyte biosensing platform with ultra-high resolution (= 0.2 ng/mL),-which is appropriate for the detection in the human serum of a wide range of biomarkers, e.g. those allowing the lung cancer early diagnosis, has been designed. The platform is based on a new configuration of planar ring resonator. The very strong light-matter interaction enabled by the micro-cavity allows a record limit-of-detection of 0.06 pg/mm2, five times better than the state-of-the-art. The device with footprint = 2,200 μm2 for each ring, due to its features, has the potential to be integrated in lab-onchip microsystems for large-scale screenings of people with high risk of developing cancer
Design of a New Ultracompact Resonant Plasmonic Multi-Analyte Label-Free Biosensing Platform
No full textIn this paper, we report on the design of a bio-multisensing platform for the selective label-free detection of protein biomarkers, carried out through a 3D numerical algorithm. The platform includes a number of biosensors, each of them is based on a plasmonic nanocavity, consisting of a periodic metal structure to be deposited on a silicon oxide substrate. Light is strongly confined in a region with extremely small size (=1.57 μm2), to enhance the light-matter interaction. A surface sensitivity Ss = 1.8 nm/nm has been calculated together with a detection limit of 128 pg/mm2. Such performance, together with the extremely small footprint, allow the integration of several devices on a single chip to realize extremely compact lab-on-chip microsystems. In addition, each sensing element of the platform has a good chemical stability that is guaranteed by the selection of gold for its fabrication
Photonic and Plasmonic Nanotweezing of Nano- and Microscale Particles
No full text The ability to manipulate and sense biological molecules is important in many life science domains, such as single-molecule biophysics, the development of new drugs and cancer detection. Although the manipulation of biological matter at the nanoscale continues to be a challenge, several types of nanotweezers based on different technologies have recently been demonstrated to address this challenge. In particular, photonic and plasmonic nanotweezers are attracting a strong research effort especially because they are efficient and stable, they offer fast response time, and avoid any direct physical contact with the target object to be trapped, thus preventing its disruption or damage. In this paper, we critically review photonic and plasmonic resonant technologies for biomolecule trapping, manipulation, and sensing at the nanoscale, with a special emphasis on hybrid photonic/plasmonic nanodevices allowing a very strong light–matter interaction. The state-of-the-art of competing technologies, e.g., electronic, magnetic, acoustic and carbon nanotube-based nanotweezers, and a description of their applications are also included. </jats:p
Novel Micro-Nano Optoelectronic Biosensor for Label-Free Real-Time Biofilm Monitoring
No full textAccording 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
Effect of fabrication tolerances on the performance of two-dimensional polymer photonic crystal channel drop filters: a theoretical investigation based on the finite element method
No full textGuidelines for the design and fabrication of polymer photonic crystal channel drop filters for coarse wavelength division multiplexing are provided. A Fabry-Perot cavity consisting of a membrane-type slab photonic crystal, where a hole row perpendicular to the propagation direction is removed, is considered. We selected nanoimprinting as the manufacturing technique. The influence on the cavity performance of several key parameters, i.e., polymer core material, lattice geometry, defect length, and holes’ radius, has been investigated in a device compliant with the requirement of the ITU-T G.694.2 standard. A detailed analysis of the fabrication tolerances has been carried out at 1551 nm. The maximum acceptable drift of the geometrical parameters has been accurately
evaluated by using the finite element method to prove that the fabrication tolerances do not significantly affect the performance of polymer filters for
coarse wavelength division multiplexing, when manufactured by thermal nanoimprinting lithography
New miniaturized exhaled nitric oxide sensor based on a high Q/V mid-infrared 1D photonic crystal cavity
No full textA high Q/V mid-infrared 1D photonic crystal cavity in chalcogenide glass AMTIR-1 (Ge33As12Se55) resonating at λR=5.26 μm has been proposed as a key element of a sensor able to evaluate the nitric oxide (NO) concentration in the exhaled breath, namely fraction exhaled NO. The cavity design has been carried out through 3D finite-element method simulations. A Q-factor of 1.1 × 104 and a mode volume V=0.8 (λ/n)3, corresponding to a Q/V ratio of 1.4 × 104(λ/n)-3, have been obtained with a resonance transmission coefficient T=15%. A sensitivity of 10 ppb has been calculated with reference to the photothermal physical property of the material. Such a result is lower than the state-of-the-art of NO sensors proposed in literature, where hundreds of parts per trillion-level detection seem to have been achieved, but comparable with the performance obtained by commercial devices. The main advantages of the new device are in terms of footprint (=150 μm2), smaller at least 1 order of magnitude than those in literature, fast response time (only few seconds), and potential low cost. Such properties make possible in a handheld device the sensor integration in a multi-analysis system for detecting the presence of several trace gases, improving prevention, and reducing the duration of drug treatment for asthma and viral infection
Integrated Photonic and Plasmonic Resonant Devices for Label-Free Biosensing and Trapping at the Nanoscale
No full textIn the last few years, integrated photonic and plasmonic devices based on resonant cavities have become key building blocks in new microsystems, instruments, and diagnostic tools for a wide range of biomedical applications including point-of-care (POC) diagnostics, new drug development, and proteomics. Several resonant label-free photonic and plasmonic biosensors for early diagnosis and monitoring of a wide range of pathologies have attracted a remarkable research interest due to their characteristic features such as high resolution, small size, immunity to electromagnetic interferences, compatibility with the CMOS technology, and strong light–matter interaction. Moreover, recently, photonic, plasmonic, and hybrid photonic/plasmonic micro and nano-cavities have experimentally demonstrated a great potential also for trapping at the nanoscale and the interest toward these devices in the field of healthcare is quickly rising. Here, the recent advances in the field of integrated photonic and plasmonic devices based on resonant cavities for label-free biosensing and trapping at the nanoscale are critically reviewed, with a special emphasis on the specific applications of these devices such as diseases diagnostics and new drugs development
Silicon photonic biosensors
No full textThe study critically reviews the silicon-based microphotonic biosensors for biomedical applications. In particular, integrated optical devices and their advantages, in terms of high performance and compactness, and also high reliability and long life term, are reported. These features, together with the complementary metal oxide semiconductor compatibility of the silicon technology, since the last few years, have been allowing to realise high-efficiency biosensing platforms with on-chip integration of several biosensors for a multi-analyte detection. Many lab-on-chip systems integrated into portable medical instruments have been proposed in the literature and some of them already commercialised in the worldwide market, so attaining extraordinary improvements in the early detection and monitoring of several diseases. Therefore, fast and accurate self-tests achievable with silicon photonic biosensors are remarkably opening new possibilities and applications in the healthcare industry
Resonant graphene-based tunable optical delay line
No full textThe design of a new graphene-based continuously tunable optical delay line formed by two vertically stacked microring resonators coupled to a straight waveguide is proposed. High values of delay time ðg 1⁄4 360 psÞ and a wide tuning range ðg 1⁄4 230 psÞ have been calculated, due to the graphene sandwiched between the stacked ring resonators, which also provides an electrooptical tuning of the delay with low energy consumption ðEswitch 1⁄4 3:4 pJÞ and fast switching time ðtswitch G 2 nsÞ. The ratio g=A represents an important figure of merit (FOM) for optical delay lines. A value FOM 1⁄4 1:4 101 ps=m2 has been calculated, which corresponds to an enhancement of about a factor 4 compared with the state-of-the-art of the integrated optical delay lines, also providing a switching time several times faster. Such performance, together with a small device footprint ðG 1:6 103 m2Þ, gives a significant contribution to the state-of-the-art of optical delay lines, confirming the suitability of the graphene-based resonant cavity as a high-efficient optical delay line for applications in which fast tuning and wide range of tunability are required, e.g., phased array antennas
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