Characterization of tactile display for stiffness distribution using Magneto-rheological fluid

This paper demonstrates a tactile display to reproduce stiffness distribution using a Magneto-rheological (MR) fluid. Computed tomography (CT) scan and endoscope are widely used to diagnosis intravital condition and contribute the quality of life. However, CT scan cannot detect tumors smaller than 5 mm and endoscope can only diagnosis only surface of the tissue surface. Since tumors is stiffer than normal tissue, intravital palpation may be effective to detect tumors smaller than 5 mm. To perform intravital palpation, tactile displays to reproduce stiffness information from micro tactile sensors is needed. In present study, we propose tactile display using MR fluid to change its stiffness in an external magnetic field. MR fluid was encapsulated in an acrylic chamber covered by a thin PDMS membrane. Compression tests were conducted to evaluate mechanical properties of the display. Two types of probes were used. A narrow probe was used to perform detailed measurement and a wider probe was used to simulate how subjects felt. The experimental results indicated that the display could successfully create the stiffness of tumor under an external magnetic field of 200 mT. Then, the display was evaluated using five subjects. The results indicated all of the subjects perceived stiffer spot smaller than 5 mm under an external magnetic field of 100 mT.