Abstract: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.

Abstract-Laser induced convection flows is a new and promising method to achieve better manipulation of mesoscale objects (above 1 µm and below 500 µm) in a liquid medium. The temperature gradient created by laser absorption generates natural and thermocapillary (or Marangoni) convection flows. These flows are used to perform the manipulation itself. In this paper, we demonstrate for the first time that large and heavy particles can be dragged using the Marangoni convection flows. Experiments based on these phenomena show that fast and accurate underwater micromanipulation of particles up to 280 µm is possible using only a convergent 1 480 nm laser beam.

Piezo actuators are widely used for precision positioning purposes where a submicron resolution is needed. Among the possible means to increase the working range of those actuators whose stroke is, depending on the material, usually limited to a small fraction of the actuator length, is a stepping motion of the actuator. We use a steppingmotion based on the stick and slip effect in order to achieve a long range while maintaining the advantage of a virtually unlimited resolution. In this paper we introduce miniature x-y-stages dedicated to the manipulation of samples under a microscope. As previous setups and experiments have shown, a parallel kinematic structure for positioning purposes in microscopy or micro assembly is not well suited because x and y motion of the actuators have an influence on each other. A system with a serial kinematic structure has therefore been developed. The proposed device will provide the same capabilities as existing motorized stages, but at a lower cost than manual positioning stages and at a very compact size.

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