A new haptic sensor-actuator system for virtual reality applications in medicine

The pathological state of soft tissues is often correlated with changes in stiffness. Malignant tumors are significantly stiffer and more immobile than surrounding healthy tissue, (hard lesions, "nodes" in organs: tumors; calcifications in vessels: arteriosclerosis). The main problem is, that such information is usually not available or can only be obtained by manual palpation, which is subjective and limited in sensitivity. It requires intuitive assessment and does not allow quantitative documentation. On the one hand a suitable sensor is required for quantitative measurement of mechanical tissue properties. On the other hand, there is also a need for a realistic mechanical display of such tissue properties. Suitable actuator arrays with high spatial resolution acting in real time are required. A haptic sensor actuator system is presented in this paper including a sensitive sensor part and an actuator array for different applications. The mechanical consistency of an o bject is to be locally specified using a sensor system and represented perceptibly in a remote position on a tactile display (actuator system) for the user. The sensor system uses ultrasound (US) elastography, whereas the actuator array is based on electrorheological (ER) fluids.