Silicon microparticles as handles for optical tweezers experiments

Abstract

We study the behavior of silicon microparticles in a 1064 nm Gaussian-beam optical tweezers, showing that this semiconductor can be used to perform different types of optical manipulation experiments. Depending on the focal position and the laser power used, the particles can present an oscillatory dynamics in the tweezers or can be stably 3D-trapped with a trap stiffness that allows the application of femtoNewton forces with accuracy. A new, to the best of our knowledge, interpretation based on the photoexcitation of electrons in the valence band is proposed to explain the oscillations, and the quantities associated with such dynamics (e.g., amplitude, period, etc.) were characterized as a function of relevant parameters to optical tweezers setups.

Use of Organic Semiconductors as Handles for Optical Tweezers Experiments: Trapping and Manipulating Polyaniline (PANI) Microparticles

“…Furthermore, it is also expected that such coefficient depends on the pH solution, and on the rate of PANI/stabilizer used to produce the beads . These characteristics suggest the optical manipulation of PANI particles can be strongly modulated, and the possibility to obtain an oscillatory behavior similar to that observed with inorganic semiconductors , cannot be discarded. In addition, due to the fact that those particles are made of an organic semiconductor, they can be functionalized with other polymers and/or molecules more easily than inorganic semiconductors for specific applications in microrheology and other fields.…”

“…In addition, due to the fact that those particles are made of an organic semiconductor, they can be functionalized with other polymers and/or molecules more easily than inorganic semiconductors for specific applications in microrheology and other fields. Finally, as a relevant perspective of this work it is worth it to say that, as a consequence of the semiconductor behavior of the PANI particles, the optical forces on them can be modulated 15 through the charge carriers generation, optimizing for example the construction of photophoretic traps. Moreover, the possibility of modulating the absorption coefficient allows the building of these types of traps at higher wavelengths (around infrared), opening the door for improvements in technological applications, e.g., to increase the efficiency of volumetric displays, whose construction is based on photophoretic traps.…”

“…Such dynamics can be modulated by changing simple setup parameters such as the laser power or the distance between the particle and the coverslip used to construct the sample chamber . After that work, a similar behavior was also observed for semiconductor particles (germanium and silicon) with an additional feature: the oscillations in this case depend on the polarization direction of the laser beam. This oscillatory dynamics observed for semiconductor and topological insulator beads opened the door for promising applications of optical tweezers, e.g.…”

Optothermal Microparticle Oscillator Induced by Marangoni and Thermal Convection

“…4 The oscillation of microparticles is driven by the explosive vaporization of the surrounding liquid and by the optical force of optical tweezers. Since then, optical tweezers have been used to control the oscillation of microparticles with different materials, such as silicon particles, 5 topological insulator particles, 6 germanium particles, 7 and magnetic particles. 8,9 However, for these oscillators, the microparticles are attracted to the laser focus, which may lead to a sharp increase in surface temperature, resulting in thermal damage.…”

Micromanipulação de partículas superparamagnéticas utilizando feixes de Bessel e estudo das interações DNA-líquidos iônicos

“…A técnica de pinça óptica já é amplamente utilizada no Laboratório de Física Biológica da UFV, principalmente no estudo da interação DNA-Ligantes. A partir de 2018, o grupo também tem se dedicado a estudar o pinçamento óptico de novos materiais [6,7,46]. Novos efeitos têm sido observados, demonstrando ser uma área de enorme potencial para novos estudos e novas aplicações.…”