R.H. Taylor and G.-Z. Yang (Eds.): IPCAI 2011, LNCS 6689, pp. 90–100, 2011. © Springer-Verlag Berlin Heidelberg 2011 Hand-Held Force Magnifier for Surgical Instruments George Stetten 1,3,4 , Bing Wu 2 , Roberta Klatzky 2 , John Galeotti 3 , Mel Siegel 3 , Randy Lee 4 , Francis Mah 5 , Andrew Eller 5 , Joel Schuman 5 , and Ralph Hollis 3 1 Department of Bioengineering, University of Pittsburgh 2 Department of Psychology, Carnegie Mellon University 3 Robotics Institute, Carnegie Mellon University 4 Department of Biomedical Engineering, Carnegie Mellon University 5 Department of Ophthalmology, University of Pittsburgh School of Medicine http://www.vialab.org Abstract. We present a novel and relatively simple method for magnifying forces perceived by an operator using a tool. A sensor measures the force be- tween the tip of a tool and its handle held by the operator’s fingers. These measurements are used to create a proportionally greater force between the handle and a brace attached to the operator’s hand, providing an enhanced perception of forces between the tip of the tool and a target. We have designed and tested a prototype that is completely hand-held and thus can be easily manipulated to a wide variety of locations and orientations. Preliminary psy- chophysical evaluation demonstrates that the device improves the ability to detect and differentiate between small forces at the tip of the tool. Magnifying forces in this manner may provide an improved ability to perform delicate sur- gical procedures, while preserving the flexibility of a hand-held instrument. Keywords: haptics, touch, robotic surgery, microsurgery, force magnifier, force-reflecting, steady hand. 1 Introduction A need exists for improvement in the perception of forces by the sense of touch when using tools to perform delicate procedures. This is especially crucial in microsurgery. For example, surgeons routinely repair tiny blood vessels under a microscope that are far too delicate to be felt by the hand of the surgeon. Another key area for potential applications is ophthalmological surgery, in which we have recently been exploring techniques for image-guided intervention using optical coherence tomography [1]. Providing a useful sense of touch for such applications would improve outcome and increase safety. Purely telerobotic systems such as the da Vinci ® Surgical System (Intuitive Surgical, Inc., Sunnyvale, CA) can provide motion-scaling, so that fine motion of the tool can be controlled by coarser motion of the operator’s hand on the controls. Although force at the tool tip cannot be sensed by the operator in the current commercial da Vinci ® device, experimental systems have been tested that translate these forces into visual cues [2] as well as into vibrotactile feedback to the operators fingers [3].