Touching the microworld with force-feedback optical tweezers.

Optical tweezers are a powerful tool for micromanipulation and measurement of picoNewton sized forces. However, conventional interfaces present difficulties as the user cannot feel the forces involved. We present an interface to optical tweezers, based around a low-cost commercial force feedback device. The different dynamics of the micro-world make intuitive force feedback a challenge. We propose a coupling method using an existing optical tweezers system and discuss stability and transparency. Our system allows the user to perceive real Brownian motion and viscosity, as well as forces exerted during manipulation of objects by a trapped bead.