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16 pages, 4440 KB

Open AccessArticle

High Stability and Low Power Nanometric Bio-Objects Trapping through Dielectric–Plasmonic Hybrid Nanobowtie

by Paola Colapietro, Giuseppe Brunetti, Annarita di Toma, Francesco Ferrara, Maria Serena Chiriacò and Caterina Ciminelli

Biosensors 2024, 14(8), 390; https://doi.org/10.3390/bios14080390 - 13 Aug 2024

Viewed by 1888

Abstract

Micro and nano-scale manipulation of living matter is crucial in biomedical applications for diagnostics and pharmaceuticals, facilitating disease study, drug assessment, and biomarker identification. Despite advancements, trapping biological nanoparticles remains challenging. Nanotweezer-based strategies, including dielectric and plasmonic configurations, show promise due to their efficiency and stability, minimizing damage without direct contact. Our study uniquely proposes an inverted hybrid dielectric–plasmonic nanobowtie designed to overcome the primary limitations of existing dielectric–plasmonic systems, such as high costs and manufacturing complexity. This novel configuration offers significant advantages for the stable and long-term trapping of biological objects, including strong energy confinement with reduced thermal effects. The metal’s efficient light reflection capability results in a significant increase in energy field confinement (EC) within the trapping site, achieving an enhancement of over 90% compared to the value obtained with the dielectric nanobowtie. Numerical simulations confirm the successful trapping of 100 nm viruses, demonstrating a trapping stability greater than 10 and a stiffness of 2.203 fN/nm. This configuration ensures optical forces of approximately 2.96 fN with an input power density of 10 mW/μm² while preserving the temperature, chemical–biological properties, and shape of the biological sample. Full article

(This article belongs to the Special Issue Nanotechnology-Based Optical Sensors for Biomedical Applications)

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25 pages, 9585 KB

Open AccessReview

Integration of Plasmonic Structures in Photonic Waveguides Enables Novel Electromagnetic Functionalities in Photonic Circuits

by Giovanni Magno, Vy Yam and Béatrice Dagens

Appl. Sci. 2023, 13(23), 12551; https://doi.org/10.3390/app132312551 - 21 Nov 2023

Cited by 6 | Viewed by 5941

Abstract

The development of integrated, compact, and multifunctional photonic circuits is crucial in increasing the capacity of all-optical signal processing for communications, data management, and microsystems. Plasmonics brings compactness to numerous photonic functions, but its integration into circuits is not straightforward due to insertion losses and poor mode matching. The purpose of this article is to detail the integration strategies of plasmonic structures on dielectric waveguides, and to show through some examples the variety and the application prospect of integrated plasmonic functions. Full article

(This article belongs to the Special Issue Advances in Photonics and Optics: Materials and Structures for Emerging Applications)

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11 pages, 1566 KB

Open AccessArticle

Multiplexed smFRET Nucleic Acid Sensing Using DNA Nanotweezers

by Anisa Kaur, Roaa Mahmoud, Anoja Megalathan, Sydney Pettit and Soma Dhakal

Biosensors 2023, 13(1), 119; https://doi.org/10.3390/bios13010119 - 10 Jan 2023

Cited by 4 | Viewed by 3666

Abstract

The multiplexed detection of disease biomarkers is part of an ongoing effort toward improving the quality of diagnostic testing, reducing the cost of analysis, and accelerating the treatment processes. Although significant efforts have been made to develop more sensitive and rapid multiplexed screening methods, such as microarrays and electrochemical sensors, their limitations include their intricate sensing designs and semi-quantitative detection capabilities. Alternatively, fluorescence resonance energy transfer (FRET)-based single-molecule counting offers great potential for both the sensitive and quantitative detection of various biomarkers. However, current FRET-based multiplexed sensing typically requires the use of multiple excitation sources and/or FRET pairs, which complicates labeling schemes and the post-analysis of data. We present a nanotweezer (NT)-based sensing strategy that employs a single FRET pair and is capable of detecting multiple targets. Using DNA mimics of miRNA biomarkers specific to triple-negative breast cancer (TNBC), we demonstrated that the developed sensors are sensitive down to the low picomolar range (≤10 pM) and can discriminate between targets with a single-base mismatch. These simple hybridization-based sensors hold great promise for the sensitive detection of a wider spectrum of nucleic acid biomarkers. Full article

(This article belongs to the Special Issue Devices and Wearable Devices toward Innovative Applications)

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13 pages, 5601 KB

Open AccessArticle

Phase Transformation in TiNi Nano-Wafers for Nanomechanical Devices with Shape Memory Effect

by Alexey Kartsev, Peter V. Lega, Andrey P. Orlov, Alexander I. Pavlov, Svetlana von Gratowski, Victor V. Koledov and Alexei S. Ilin

Nanomaterials 2022, 12(7), 1107; https://doi.org/10.3390/nano12071107 - 28 Mar 2022

Cited by 3 | Viewed by 3049

Abstract

Recently, Ti-Ni based intermetallic alloys with shape memory effect (SME) have attracted much attention as promising functional materials for the development of record small nanomechanical tools, such as nanotweezers, for 3D manipulation of the real nano-objects. The problem of the fundamental restrictions on the minimal size of the nanomechanical device with SME for manipulation is connected with size effects which are observed in small samples of Ti-Ni based intermetallic alloys with thermoplastic structural phase transition from austenitic high symmetrical phase to low symmetrical martensitic phase. In the present work, by combining density functional theory and molecular dynamics modelling, austenite has been shown to be more stable than martensite in nanometer-sized TiNi wafers. In this case, the temperature of the martensitic transition asymptotically decreases with a decrease in the plate thickness h, and the complete suppression of the phase transition occurs for a plate with a thickness of 2 nm, which is in qualitative agreement with the experimental data. Moreover, the theoretical values obtained indicate the potential for even greater minimization of nanomechanical devices based on SME in TiNi. Full article

(This article belongs to the Special Issue Nano-Manipulation)

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10 pages, 5848 KB

Open AccessArticle

Theoretical Study on Symmetry-Broken Plasmonic Optical Tweezers for Heterogeneous Noble-Metal-Based Nano-Bowtie Antennas

by Guangqing Du, Yu Lu, Dayantha Lankanath, Xun Hou and Feng Chen

Nanomaterials 2021, 11(3), 759; https://doi.org/10.3390/nano11030759 - 17 Mar 2021

Cited by 7 | Viewed by 3746

Abstract

Plasmonic optical tweezers with a symmetry-tunable potential well were investigated based on a heterogeneous model of nano-bowtie antennas made of different noble substances. The typical noble metals Au and Ag are considered as plasmonic supporters for excitation of hybrid plasmonic modes in bowtie dimers. It is proposed that the plasmonic optical trapping force around a quantum dot exhibits symmetry-broken characteristics and becomes increasingly asymmetrical with increasing applied laser electric field. Here, it is explained by the dominant plasmon hybridization of the heterogeneous Au–Ag dimer, in which the plasmon excitations can be inconsistently modified by tuning the applied laser electric field. In the spectrum regime, the wavelength-dependent plasmonic trapping potential exhibits a two-peak structure for the heterogeneous Au–Ag bowtie dimer compared to a single-peak trapping potential of the Au–Au bowtie dimer. In addition, we comprehensively investigated the influence of structural parameter variables on the plasmonic potential well generated from the heterogeneous noble nano-bowtie antenna with respect to the bowtie edge length, edge/tip rounding, bowtie gap, and nanosphere size. This work could be helpful in improving our understanding of wavelength and laser field tunable asymmetric nano-tweezers for flexible and non-uniform nano-trapping applications of particle-sorting, plasmon coloring, SERS imaging, and quantum dot lighting. Full article

(This article belongs to the Special Issue Functional Plasmonic Nanostructures)

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13 pages, 4341 KB

Open AccessArticle

An Evaluation System for the Contact Electrification of a Single Microparticle Using Microelectromechanical-Based Actuated Tweezers

by Daichi Yamaguchi

Sensors 2018, 18(6), 1835; https://doi.org/10.3390/s18061835 - 5 Jun 2018

Cited by 1 | Viewed by 3267

Abstract

The image quality of laser and multi-function printers that make use of electrophotography depends on the amount of surface charge generated by contact electrification on the toner particles. However, because it has been impossible to experimentally evaluate such amounts under controlled contact conditions using macroscopic measurements, theoretical elucidation of the contact electrification mechanism has not progressed sufficiently. In the present study, we have developed a system to experimentally evaluate the contact electrification of a single particle using atomic force microscopy (AFM) and nanotweezers (microelectromechanical systems (MEMS)-based actuated tweezers). This system performs, in succession, (i) a contact test that makes use of the nanotweezers and three piezoelectric stages, and (ii) an image force measurement using the AFM cantilever. Using this system, contact electrification was evaluated under controlled conditions, such as the contact number and the indentation depth. In addition, differences in contact electrification due to the amount of external surface additives were investigated. The results reveal that a coating with external additives leads to a decrease in the amount of contact electrification due to a reduction in the contact area with the substrate. Full article

(This article belongs to the Special Issue Integrated MEMS Sensors for the IoT Era)

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