Optical tweezers are scientific tools that use highly focused laser beams to trap and manipulate tiny particles, such as cells, organelles, or nanoparticles, without physical contact.
How They Work:
- A laser beam is tightly focused through a microscope objective to create a small, intense light spot.
- When a dielectric particle (like a bead or cell) is placed near the focus, light exerts forces on the particle due to its electromagnetic field.
- These forces — a balance of scattering and gradient forces — pull the object toward the region of highest intensity, effectively trapping it at the beam’s focal point.
Key Features:
- The technique allows precise control in 3D, enabling movement, rotation, or stretching of tiny particles.
- It’s non-invasive, so it can be used with delicate biological samples without damage.
Applications:
- Cell biology: Measuring forces inside cells, manipulating DNA or organelles.
- Physics: Studying Brownian motion or colloidal interactions.
- Nanotechnology: Arranging and assembling nanoscale components.
Optical tweezers revolutionized how scientists interact with microscopic systems, and the technique earned Arthur Ashkin the 2018 Nobel Prize in Physics for its groundbreaking impact on biology and physics.