Design and control of a novel thermo-tactile multimodal display

This paper describes the design and control of a water-based multimodal haptic display. The system is able to provide temperature and pressure (pulse) cues through a finger-sized display. Temperature feedback is obtained by mixing hot and cold water stored in two water tanks. The heating and cooling of the water is performed with a Peltier whose two surfaces are used, thus increasing the energetic efficiency of the system. Mixing the hot and cold water allows for very rapid temperature changes essential in applications such as object discrimination. The device can provide cooling rates sufficient to mimic the contact with any object found in our daily lives. Tactile (pulse) feedback is achieved by closing the circuit with a valve while building up the pressure with the pump. Results show that temperature is controlled with a precision of ±1°C in the range of 20°C to 40°C while simultaneously generating sensible pulses. In addition, this display is MRI-compatible as it is remotely actuated using water. These characteristics make the system suitable for psychophysics experiments, which are considered to be one of the goals and the next logic step of this work.