TOWARDS CELLULAR LEVEL MICROSURGERY: DESIGN AND TESTING OF A HIGH PRESISION DELTA ROBOT FOR MEDICAL APLICATIONS

Abstract

The development of future surgical therapies has driven the efforts to increase the precision of robot-guided manipulators beyond sub-millimetre accuracies. Medical applications such as reconstructive microsurgery, vitreoretinal eye surgery and cellular level neurosurgery still require achieving precision comparable to the size of human cells [1]. Most commercially available systems can achieve millimetre accuracies with a few examples of higher precision instruments including ophthalmic and reconstructive microsurgery robots achieving accuracies within the range of hundreds of microns [1]. A parallel robot is a closed-loop mechanism where the end-effector is coupled to the base via multiple sequences of links. These devices are mostly used in industrial pick and place applications due their advantages including high precision, stiffness, speed, and low moving inertia [2]. However, a major disadvantage is their limited workspace and rotational capabilities. In the context of cellular level surgical applications, having a reduced workspace does not represent a disadvantage given that, as in most of the cases, the surgical procedure is to be performed within a reduced manipulation volume. This paper presents an integrated methodology outlining the design and testing of a delta robot based on linear actuators achieving micron level end effector positioning accuracy. The main application of the here presented design is to perform superficial tissue optical biopsy with future prospects of being able to conduct cellular level surgeries. The design methodology considers two parameters determining the robot geometry and dimensions these are: the end-effector workspace (~ 5 mm3) and the end-effector motion resolution (1 μm). The robot performance was evaluated using a non-contact metrology approach based on bright field microscopy (BFM) to characterize the precision and kinematic performance. Our results demonstrate that the presented methodology can be used for designing high precision robots achieving accuracies <1 μm.