Electrokinetic Trapping for Sub-Micron Object Control

The patent replaces optical trapping mechanisms (laser tweezers) with electrokinetic trapping mechanisms. Electrophoretic traps use electric fields to apply forces on charged particles, while electroosmotic traps use electric fields to induce fluid flow that carries particles. This substitution eliminates the harmful heating and photochemical effects of optical trapping while maintaining the ability to trap and manipulate sub-micron objects.

The patent employs electrokinetic trapping mechanisms that can capture a broad spectrum of particles including charged particles, colloids, viruses, and molecules in solution. The electrophoretic trap captures charged particles through electric field interactions, while the electroosmotic trap captures particles through fluid flow induced by electric fields. These mechanisms are universally applicable to diverse particle types without requiring magnetic properties, thereby eliminating material specificity limitations.

The patent changes the trapping mechanism from AC dielectrophoresis to electrokinetic methods (electrophoresis and electroosmosis). These electrokinetic methods generate forces that are not limited by the scaling relationships of dielectrophoretic forces. The electric field-based mechanisms can apply sufficient forces to sub-micron objects by directly interacting with charged particles or inducing fluid flow, thereby overcoming the volume-scaling limitation that plagues dielectrophoretic approaches.

The patent implements feedback control in the electrokinetic trapping system. The system continuously monitors the position of sub-micron objects and dynamically adjusts the electric field parameters to counteract Brownian motion. This feedback mechanism allows the system to maintain precise control over object positioning while preserving the natural mobility of particles in fluid solution, thereby resolving the contradiction between ease of operation and measurement precision.