10 research outputs found
Towards Stirling engine using an optically confined particle subjected to asymmetric temperature profile
The realization of microscopic heat engines has gained a surge of research
interest in statistical physics, soft matter, and biological physics. A typical
microscopic heat engine employs a colloidal particle trapped in a confining
potential, which is modulated in time to mimic the cycle operations. Here, we
use a lanthanide-doped upconverting particle (UCP) suspended in a passive
aqueous bath, which is highly absorptive at 975 nm and converts NIR photons to
visible, as the working substance of the engine. When a single UCP is optically
trapped with a 975 nm laser, it behaves like an active particle by executing
motion subjected to an asymmetric temperature profile along the direction of
propagation of the laser. The strong absorption of 975 nm light by the particle
introduces a temperature gradient and results in significant thermophoretic
diffusion along the temperature gradient. However, the activity of the particle
vanishes when the trapping wavelength is switched to 1064 nm. We carefully
regulate the wavelength-dependent activity of the particle to engineer all four
cycles of a Stirling engine by using a combination of 1064 nm and 975 nm
wavelengths. Since the motion of the particle is stochastic, the work done on
the particle due to the stiffness modulation per cycle is random. We provide
statistical estimation for this work averaged over 5 cycles which can be
extended towards several cycles to make a Stirling engine. Our experiment
proposes a robust set-up to systematically harness temperature which is a
crucial factor behind building microscopic engines.Comment: For published version, see
https://iopscience.iop.org/article/10.1088/1367-2630/acd94e/met
Roadmap for Optical Tweezers 2023
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 life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nanoparticle 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
Facets of optically and magnetically induced heating in ferromagnetically doped-NaYF4 particles
Upconverting particles like Yb and Er-doped NaYF _4 are known to heat up after illumination with light at pump wavelength due to inefficient upconversion processes. Here we show that NaYF _4 particles which have been co-doped not only with Yb and Er but also Fe improves the photothermal conversion efficiency. In addition, we show for the first time that alternating magnetic fields also heat up the ferromagnetic particles. Thereafter we show that a combination of optical and magnetic stimuli significantly increases the heat generated by the particles
Comparison of optical trapping wavelengths for nanoscopic diamonds containing nitrogen-vacancy centers
In this article, we explore the effect of two different infrared (IR) laser wavelengths on the optical properties of trapped nano-diamonds containing high-density ensembles of nitrogen vacancy (NV) centers. We investigate 975 nm and 1064nm wavelengths for trapping lasers and find that NV photoluminescence quenching is more prominent for 1064nm illumination than for 975 nm illumination when simultaneously excited with a 532 nm laser. In order to understand the underlying mechanism, we develop a rate-equation-based model that takes into account various transition probabilities. The model suggests that the findings cannot be explained only by imposing modification of the NV charge-state ratio under varied illumination wavelengths, and, thus, we speculate that the effective ionization and recombination rates associated with NV charge states for the studied samples are highly wavelength-dependent in the probed regime. Importantly, the results demonstrate that 975 nm laser is desirable for optical trapping of NV-diamonds, especially for NV-based sensing applications
Formation of Two-Dimensional Magnetically Responsive Clusters Using Hematite Particles Self-Assembled via Particle-Induced Heating at an Interface
Hematite particles, which exhibit
a high magnetic moment, are used
to apply large forces on physical and biological systems under magnetic
fields to investigate various phenomena, such as those of rheology
and micromanipulation. However, the magnetic confinement of these
particles requires complicated field configurations. On the other
hand, laser-assisted optical confinement of single hematite particles
results in thermophoresis and subsequent ejection of the particle
from the laser spot. Herein, we explore an alternative strategy to
induce the self-assembly of hematite. In this strategy, with indirect
influence from an optically confined and heated upconverting particle
(UCP) at an air–water interface, there is the generation of
convection currents that facilitate assembly. We also show that the
assembly remains at the interface even after removal of the laser
light. The hematite particle assemblies can then be moved using magnetic
fields and employed to perform interfacial rheology
Roadmap for optical tweezers
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
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Roadmap for optical tweezers
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
Roadmap for optical tweezers
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
Roadmap for optical tweezers
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 life sciences, physics, and engineering. These include
accurate force and torque measurement at the femtonewton level, microrheology
of complex fluids, single micro- and nanoparticle 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