Learn about the 8 most common types of optical trapping techniques used in physics and biology. Manipulate and study microscopic objects with laser tweezers.

8 Most Common Types of Optical Trapping Techniques

Optical trapping techniques, also known as laser tweezers, are experimental methods used in physics and biology to manipulate and study microscopic objects such as cells, bacteria, and particles. In optical trapping, a focused laser beam is used to create a gradient force that can hold, move, and deform the target object. Optical trapping has been widely used in various research fields, including biophysics, microbiology, and nanotechnology. In this article, we will introduce the eight most common types of optical trapping techniques.

1. Single-beam gradient force trap

The single-beam gradient force trap, also known as the optical tweezers, was first demonstrated by Arthur Ashkin in 1970. In this technique, a focused laser beam creates a gradient force that can trap and manipulate a single particle or cell. The trap is created by the difference in the refractive index of the particle and the surrounding medium, which causes a force towards the region of higher intensity of the laser beam. The single-beam gradient force trap has been widely used in biophysics and microbiology, such as to study the mechanics and dynamics of single cells and the properties of molecular motors.

2. Dual-beam gradient force trap

The dual-beam gradient force trap, also known as the optical stretcher, uses two counter-propagating laser beams to stretch and deform a cell or particle. The two beams create a gradient force that pulls the object in opposite directions, resulting in elongation and deformation. The dual-beam gradient force trap has been used to study the mechanical properties of cells, such as the elasticity and viscosity, and to measure the forces involved in cell adhesion and migration.