**3. Conclusion**

The sensorized surgical blade, with its large force range and high resolution, is perfectly suitable for minimal invasive surgery and has the potential to lead to a new generation of endoscopic tools for robotic aided surgery capable also of providing precise and accurate haptic force feedback. The tool can withstand a normal load of 20N and a tangential load of 3N without damage to the structure. At the same time, it is possible to perform sensitive touching and probing movements with high force sensitivity down to the mN range.

In applications where the crucial point of the surgical intervention is not accessible with rigid manipulators, a steerable catheter can be helpful. A novel device was developed that is equipped with a steerable tip, but also with an electrical and an optical sensor system for tissue characterisation. The catheter tip is steered by a joystick. First insertion and navigation tests in phantoms were successfully carried out. The current catheter diameter is 3.5mm, but for applications in severe cases like pulmonary atresia, a further miniaturisation to an outer diameter of 0.8mm is necessary and still feasible. Forces on the bowden wires are detected with strain gauges and used to generate haptic force feedback.

Commercial available force feedback joysticks turned out not to be precise enough for haptic sensing, thus a prototype device was developed to satisfy these additional requirements. Differently from existing force feedback input devices, where the position is sensed and then a torque is applied by a motor, in this device the force is first sensed and then the position of the joystick is set according to the programmed force/angle model within a closed loop control. A design for a second prototype joystick with reduced dimensions and improved electronics was also presented. Based on the same force sensing/control approach a further development of an haptic input device with 3 or more DOF is possible, which can be a low cost alternative to devices like the Phantom.

Force sensorized tool and haptic force feedback input devices for surgical interventions are still in early development stages and only few devices are already used in surgical interventions, but latest developments are promising. These novel devices have the potential to revolutionize robotic aided surgery, as the can be considered as key elements to regain the sensation of feeling tissues in a robot dominated surgical scenario.
