Trapping Characterization of Semi Metallic Magnetic Beads in Optical Tweezers

Iyengar, Shruthi S.; Praveen, P. Lakshmi; Selvan, Rekha; Ananthamurthy, Sharath; Bhattacharya, Sarbari

doi:10.1364/photonics.2014.t3a.40

Cited by 2 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, the excellent agreement achieved between the experiments and theory indicates that light absorption by the superparamagnetic beads is small under our experimental conditions, using the annular laser beam with the parameters presented in Section 3.1. In fact, Iyengar et al have previously demonstrated that the trap stiffness decreases with the laser power when there is a considerable absorption of light by the superparamagnetic particles, due to heating effects [14]. This is an intuitive result, since heating in fact tends to generate radiometric forces on the bead, which tends to push the particle away from the focal region, resulting in a more unstable trap [15,22].…”

Section: Resultsmentioning

confidence: 99%

“…The idea is to trap the superparamagnetic particles optically, which can be naturally manipulated with permanent or electromagnets. These particles usually are more difficult to trap stably by single Gaussian beam optical tweezers because they considerably absorb light, which generates relevant radiation pressure and radiometric forces on the particles, pushing them away from the focal region [13,14]. We have circumvented this problem here by changing the laser intensity profile, using a phase contrast mask to produce an annular-shaped beam.…”

Section: Introductionmentioning

confidence: 99%

“…Some instruments and/or approaches that take advantage of applying both optical and magnetic forces simultaneously on particles have been previously reported in the literature [13,14,15,16,17,18,19,20,21]. Nevertheless, most approaches use Gaussian beam optical tweezers to manipulate the magnetic beads, which can result in non-negligible heating of these beads (and consequently, of the surrounding medium) due to laser absorption, resulting in an unstable optical trap depending on the laser power and/or bead size [14]. Differently, our approach strongly reduces the laser absorption by cutting off the middle of the original Gaussian beam, which is the beam portion that mostly contributes to the radiation pressure and radiometric forces on the particles, i.e., the forces that disturb the stable trapping of such particles [22,23].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Optical Trapping and Manipulation of Superparamagnetic Beads Using Annular-Shaped Beams

Oliveira

Campos

Rocha

2018

MPs

View full text Add to dashboard Cite

We propose an optical tweezers setup based on an annular-shaped laser beam that is efficient to trap 2.8 μ m-diameter superparamagnetic particles. The optical trapping of such particles was fully characterized, and a direct absolute comparison with a geometrical optics model was performed. With this comparison, we were able to show that light absorption by the superparamagnetic particles is negligible for our annular beam tweezers, differing from the case of conventional Gaussian beam tweezers, in which laser absorption by the beads makes stable trapping difficult. In addition, the trap stiffness of the annular beam tweezers increases with the laser power and with the bead distance from the coverslip surface. While this first result is expected and similar to that achieved for conventional Gaussian tweezers, which use ordinary dielectric beads, the second result is quite surprising and different from the ordinary case, suggesting that spherical aberration is much less important in our annular beam geometry. The results obtained here provide new insights into the development of hybrid optomagnetic tweezers, which can apply simultaneously optical and magnetic forces on the same particles.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optical Trapping and Manipulation of Superparamagnetic Beads Using Annular-Shaped Beams

Oliveira

Campos

Rocha

2018

MPs

View full text Add to dashboard Cite

show abstract

Bessel beam optical tweezers for manipulating superparamagnetic beads

2021

View full text Add to dashboard Cite

We propose a Bessel beam optical tweezers setup that can stably trap superparamagnetic beads. The trap stiffness measured is practically independent of the radius of the Bessel beam and of the bead height (distance from the coverlip of the sample chamber), indicating that the beads can be trapped with high accuracy within a wide range of such parameters. On the other hand, the trap stiffness exhibits the expected linear increase with the laser power, despite the non-negligible absorption coefficient of the superparamagnetic beads. A geometrical optics model that considers spherical aberration and light absorption by the beads was used to predict the optical forces and trap stiffness, showing excellent agreement with the experimental data. We believe the results presented here advance the field of optical trapping manipulation of absorbing magnetic particles, and future applications will involve, for example, the design of new hybrid optomagnetic tweezers.

show abstract

Trapping Characterization of Semi Metallic Magnetic Beads in Optical Tweezers

Cited by 2 publications

References 0 publications

Optical Trapping and Manipulation of Superparamagnetic Beads Using Annular-Shaped Beams

Optical Trapping and Manipulation of Superparamagnetic Beads Using Annular-Shaped Beams

Bessel beam optical tweezers for manipulating superparamagnetic beads

Contact Info

Product

Resources

About