3D force-feedback optical tweezers for experimental biology
Résumé
The manipulation and characterization of single biological objects has become of major scientific interest. Different techniques have been explored, both by traditional contact approaches (microclamps, tips, AFM, etc.) as well as by so-called “noncontact” approaches such as optical and magnetic forces, electric force fields, etc., that allow working at the scale of a single cell. Optical manipulation is one of the most widespread techniques in the biology field. We describe here a 3D force sensing method for optical tweezers with high bandwidth (up to 10 kHz) and low latency. The proposed technique uses high-speed image tracking in an event-based camera with nanometric resolution in three directions. This real-time force sensing allows the implementation of robotic control techniques for optical manipulation. An optical tweezer platform coupled to a haptic device providing transparent force feedback is then presented to demonstrate the possibilities of such a system. The apparatus can sense forces in the piconewton range, and upscale these to the users’ hands to let them operate with dexterity, and mechanically probe bio-samples’ mechanical characteristics.