Fingers made of laser light: Controlled grabbing and rotation of biological micro-objects

Science Daily  December 23, 2021 Although optical trapping forces are strong enough and related photodamage is acceptable, the precise (re-) orientation of large specimen with multiple optical traps is difficult, since they grab blindly at the object and often slip off. Researchers in Germany have developed an approach to localize and track regions with increased refractive index using several holographic optical traps with a single camera in an off-focus position. They estimated the 3D grabbing positions around several trapping foci in parallel through analysis of the beam deformations, which are continuously measured by defocused camera images of cellular structures inside […]

Optical tweezer technology tweaked to overcome dangers of heat

Phys.org  June 26, 2021 The requirement of a strongly focused and high-intensity laser beam results in potential photon-induced thermal damages to target objects, including nanoparticles, cells, and biomolecules. Researchers at UT Austin have developed a new version of optical tweezers which exploit solid-state optical refrigeration and thermophoresis to trap particles and molecules at the laser-generated cold region. While laser refrigeration can avoid photothermal heating, the use of a weakly focused laser beam can further reduce the photodamages to the target object. The noninvasive optical tweezing technique will bring new possibilities in the optical control of nanomaterials and biomolecules for essential […]

Research paves the way for next generation of optical tweezers

Phys.org  March 14, 2019 Optical tweezers are used to study proteins, biological molecular motors, DNA and the inner life of cells – to hold objects as small as a single nanoparticle in one place. However, the high intensities of light required by optical tweezers can damage live biological specimens and restrict the types of objects that can be held. Researchers in the UK have developed optically trapped micro-rotors, which are placed in the liquid surrounding the particle, and used to manipulate its movement using fluid flow. As the micro-rotors are rotated, they create a wave in the liquid that exerts […]

Shedding a new light on optical trapping and tweezing

Eurekalert  November 27, 2018 While holographic optical trapping and tweezing is not new, an international team of researchers (South Africa, USA – MIT) found a way to optimally use the full force of light – including vector light to control and manipulate minute objects such as single cells in a human body, tiny particles in small volume chemistry, or working on future on-chip devices. They showed how to create and control any pattern of light holographically, and then used this to form a new optical trapping and tweezing device…read more. Open Access TECHNICAL ARTICLE

Feynman’s ratchet is built at last using 19 optical tweezers

Physics World  October 26, 2018 “Feynman’s ratchet” is a microscopic heat engine that converts thermal fluctuations into work when connected to two heat sources at different temperatures. It is a way of showing how the second law of thermodynamics cannot be violated. Until now no-one has built such a tiny ratchet because of significant technical challenges that include how to prevent convection from washing out thermal fluctuations. An international team of researchers (USA – Purdue University, University of Maryland, China) has built a ratchet using a 780 nm-diameter ball of silicon dioxide confined to a 1D optical trap set up […]