MultiTip: A multimodal mechano-thermal soft fingertip

In this paper we present MultiTip, a novel multimodal mechano-thermal soft tactile fingertip. In comparison to previous multimodal sensing techniques, our device uses a single optical sensor to detect both mechanical deformation and temperature change simultaneously. Our fingertip is an improved version of the TacTip, a tactile fingertip that combines compliant materials and optical tracking to perform a variety of tasks such as object manipulation, contact and pressure sensing. However, temperature sensing, which is one of the last remaining challenges to mimic the full sensory capabilities of the human finger, has been neglected as a modality in optical tactile sensors. In this work we present a novel design and fabrication method for the skin of the TacTip that enables the device to simultaneously sense local temperature change while concurrently transducing the mechanical aspects of touch. This is achieved by creating a smart skin that changes its colour due to temperature change. MultiTip achieves multimodality without adding another sensing element and is therefore ideally suited to miniaturizing the sensor. We present the characteristics of the proposed sensor in sensing mechanical deformation and temperature at the same time. Finally, we demonstrate two possible real-world applications. MultiTip thus makes an important step towards full biomimicry of the human tactile fingertip.