| 1. |
- Volpe, Giovanni, 1979, et al.
(författare)
-
Roadmap for optical tweezers
- 2023
-
Ingår i: Journal of Physics-Photonics. - : IOP Publishing. - 2515-7647. ; 5:2
-
Tidskriftsartikel (refereegranskat)abstract
- Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration.
|
|
| 2. |
- Gillibert, R., et al.
(författare)
-
Raman Tweezers for Small Microplastics and Nanoplastics Identification in Seawater
- 2019
-
Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 53:15, s. 9003-9013
-
Tidskriftsartikel (refereegranskat)abstract
- Our understanding of the fate and distribution of micro- and nano- plastics in the marine environment is limited by the intrinsic difficulties of the techniques currently used for the detection, quantification, and chemical identification of small particles in liquid (light scattering, vibrational spectroscopies, and optical and electron microscopies). Here we introduce Raman Tweezers (RTs), namely optical tweezers combined with Raman spectroscopy, as an analytical tool for the study of micro- and nanoplastics in seawater. We show optical trapping and chemical identification of sub-20 mu m plastics, down to the 50 nm range. Analysis at the single particle level allows us to unambiguously discriminate plastics from organic matter and mineral sediments, overcoming the capacities of standard Raman spectroscopy in liquid, intrinsically limited to ensemble measurements. Being a microscopy technique, RTs also permits one to assess the size and shapes of particles (beads, fragments, and fibers), with spatial resolution only limited by diffraction. Applications are shown on both model particles and naturally aged environmental samples, made of common plastic pollutants, including polyethylene, polypropylene, nylon, and polystyrene, also in the presence of a thin ecocorona. Coupled to suitable extraction and concentration protocols, RTs have the potential to strongly impact future research on micro and nanoplastics environmental pollution, and enable the understanding of the fragmentation processes on a multiscale level of aged polymers.
|
|
| 3. |
- Gillibert, R., et al.
(författare)
-
Raman tweezers for tire and road wear micro- and nanoparticles analysis
- 2022
-
Ingår i: Environmental Science-Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; 9:1, s. 145-161
-
Tidskriftsartikel (refereegranskat)abstract
- Tire and road wear particles (TRWP) are non-exhaust particulate matter generated by road transport means during the mechanical abrasion of tires, brakes and roads. TRWP accumulate on the roadsides and are transported into the aquatic ecosystem during stormwater runoffs. Due to their size (sub-millimetric) and rubber content (elastomers), TRWP are considered microplastics (MPs). While the amount of the MPs polluting the water ecosystem with sizes from similar to 5 mu m to more than 100 mu m is known, the fraction of smaller particles is unknown due to the technological gap in the detection and analysis of <5 mu m MPs. Here we show that Raman tweezers, a combination of optical tweezers and Raman spectroscopy, can be used to trap and chemically analyze individual TRWPs in a liquid environment, down to the sub-micrometric scale. Using tire particles mechanically grinded from aged car tires in water solutions, we show that it is possible to optically trap individual sub-micron particles, in a so-called 2D trapping configuration, and acquire their Raman spectrum in few tens of seconds. The analysis is then extended to samples collected from a brake test platform, where we highlight the presence of sub-micrometric agglomerates of rubber and brake debris, thanks to the presence of additional spectral features other than carbon. Our results show the potential of Raman tweezers in environmental pollution analysis and highlight the formation of nanosized TRWP during wear.
|
|
| 4. |
- Polimeno, P., et al.
(författare)
-
Gain-Assisted Optomechanical Position Locking of Metal/Dielectric Nanoshells in Optical Potentials
- 2020
-
Ingår i: Acs Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 7:5, s. 1262-1270
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate gain-assisted optical forces on dye-enriched silver nanoshell in the quasi-static limit by means of a theoretical/numerical approach. We demonstrate the onset of nonlinear optical trapping of these resonant nanostructures in a counter-propagating Gaussian beam configuration. We study the optical forces and trapping behavior as a function of wavelength, particle gain level, and laser power. We support the theoretical analysis with Brownian dynamics simulations that show how particle position locking is achieved at high gains in extended optical trapping potentials. Finally, for wavelengths blue-detuned with respect to the plasmon-enhanced resonance, we observe particle channeling by the standing wave antinodes due to gradient force reversal. This work opens perspectives for gain-assisted optomechanics where nonlinear optical forces are finely tuned to efficiently trap, manipulate, channel, and deliver an externally controlled nanophotonic system.
|
|
| 5. |
- Polimeno, P., et al.
(författare)
-
Optical tweezers and their applications
- 2018
-
Ingår i: Journal of Quantitative Spectroscopy & Radiative Transfer. - : Elsevier BV. - 0022-4073. ; 218, s. 131-150
-
Tidskriftsartikel (refereegranskat)abstract
- Optical tweezers, tools based on strongly focused light, enable optical trapping, manipulation, and characterisation of a wide range of microscopic and nanoscopic materials. In the limiting cases of spherical particles either much smaller or much larger than the trapping wavelength, the force in optical tweezers separates into a conservative gradient force, which is proportional to the light intensity gradient and responsible for trapping, and a non-conservative scattering force, which is proportional to the light intensity and is generally detrimental for trapping, but fundamental for optical manipulation and laser cooling. For non-spherical particles or at intermediate (meso)scales, the situation is more complex and this traditional identification of gradient and scattering force is more elusive. Moreover, shape and composition can have dramatic consequences for optically trapped particle dynamics. Here, after an introduction to the theory and practice of optical forces with a focus on the role of shape and composition, we give an overview of some recent applications to biology, nanotechnology, spectroscopy, stochastic thermodynamics, critical Casimir forces, and active matter. (C) 2018 Elsevier Ltd. All rights reserved.
|
|
| 6. |
- Polimeno, P., et al.
(författare)
-
Position locking of a resonant gain-assisted metallic/dielectric nano-shell in Optical Tweezers
- 2021
-
Ingår i: Nuovo Cimento C-Colloquia and Communications in Physics. - 2037-4909. ; 44:4-5
-
Tidskriftsartikel (refereegranskat)abstract
- We calculate optical forces on dye-enriched resonant nano-shells in dual-beam Optical Tweezers. We investigate the non-linear gain-assisted enhancement of their optomechanics and study their behaviour through Brownian dynamics simulations. When the wavelength is red detuned with respect to the plasmon resonance, we observe that the particles are efficiently trapped at the laser beam intensity maxima of the dual beam standing wave. Conversely, for blue-detuned wavelengths the nano-shells are channelled through the standing wave antinodes due to the sign reversal of the optical force. This open perspectives for gain-assisted optomechanics where non-linear optical forces are finely tuned to manipulate controlled nano-photonic systems.
|
|
| 7. |
- Kalantarifard, F., et al.
(författare)
-
Intracavity optical trapping of microscopic particles in a ring-cavity fiber laser
- 2019
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Standard optical tweezers rely on optical forces arising when a focused laser beam interacts with a microscopic particle: scattering forces, pushing the particle along the beam direction, and gradient forces, attracting it towards the high-intensity focal spot. Importantly, the incoming laser beam is not affected by the particle position because the particle is outside the laser cavity. Here, we demonstrate that intracavity nonlinear feedback forces emerge when the particle is placed inside the optical cavity, resulting in orders-of-magnitude higher confinement along the three axes per unit laser intensity on the sample. This scheme allows trapping at very low numerical apertures and reduces the laser intensity to which the particle is exposed by two orders of magnitude compared to a standard 3D optical tweezers. These results are highly relevant for many applications requiring manipulation of samples that are subject to photodamage, such as in biophysics and nanosciences.
|
|
| 8. |
- Natali, Laura, et al.
(författare)
-
Improving epidemic testing and containment strategies using machine learning
- 2021
-
Ingår i: Machine Learning-Science and Technology. - : IOP Publishing. - 2632-2153. ; 2:3
-
Tidskriftsartikel (refereegranskat)abstract
- Containment of epidemic outbreaks entails great societal and economic costs. Cost-effective containment strategies rely on efficiently identifying infected individuals, making the best possible use of the available testing resources. Therefore, quickly identifying the optimal testing strategy is of critical importance. Here, we demonstrate that machine learning can be used to identify which individuals are most beneficial to test, automatically and dynamically adapting the testing strategy to the characteristics of the disease outbreak. Specifically, we simulate an outbreak using the archetypal susceptible-infectious-recovered (SIR) model and we use data about the first confirmed cases to train a neural network that learns to make predictions about the rest of the population. Using these predictions, we manage to contain the outbreak more effectively and more quickly than with standard approaches. Furthermore, we demonstrate how this method can be used also when there is a possibility of reinfection (SIRS model) to efficiently eradicate an endemic disease.
|
|
| 9. |
- Pesce, G., et al.
(författare)
-
Optical tweezers: theory and practice
- 2020
-
Ingår i: European Physical Journal Plus. - : Springer Science and Business Media LLC. - 2190-5444. ; 135:12
-
Tidskriftsartikel (refereegranskat)abstract
- The possibility for the manipulation of many different samples using only the light from a laser beam opened the way to a variety of experiments. The technique, known as Optical Tweezers, is nowadays employed in a multitude of applications demonstrating its relevance. Since the pioneering work of Arthur Ashkin, where he used a single strongly focused laser beam, ever more complex experimental set-ups are required in order to perform novel and challenging experiments. Here we provide a comprehensive review of the theoretical background and experimental techniques. We start by giving an overview of the theory of optical forces: first, we consider optical forces in approximated regimes when the particles are much larger (ray optics) or much smaller (dipole approximation) than the light wavelength; then, we discuss the full electromagnetic theory of optical forces with a focus on T-matrix methods. Then, we describe the important aspect of Brownian motion in optical traps and its implementation in optical tweezers simulations. Finally, we provide a general description of typical experimental setups of optical tweezers and calibration techniques with particular emphasis on holographic optical tweezers.
|
|
