Multiphysics in the Human-Machine Interface—Impact on Friction and Haptic Perception

Haptics is the field that deals with technology that stimulates the sense of touch and motion. Haptic researchers are working to create the same level of fidelity in touch-based recording and display that we currently have in audio and video. Why is this so complicated? One of the many reasons is the complexity of the finger-device interaction and the role that this plays in the generation of touch perception in humans. The finger-device interface is complex and variations with environment and person-to-person can cause finger material property changes that impact device performance and human perception of it. Multiphysics modeling of interfacial phenomena such as capillary forces and surface tension, electrowetting, electrophoresis, multiphase flow, and soft tissue contact mechanics can help predict friction under various conditions and enable purposeful design for consistent or enhanced performance. Examples of design for consistent performance with humidity, design for consumer preference, and consideration and use of temperature will be explored. Additionally, we will consider how human finger property changes can be used as bioinspiration for material design for active friction modulation in clutches and robotic grasping.