Shear shock waves mediate haptic holography via focused ultrasound

Abstract

Emerging holographic haptic interfaces focus ultrasound in air to enable their users to touch, feel, and manipulate three-dimensional virtual objects. However, current holographic haptic systems furnish tactile sensations that are diffuse and faint, with apparent spatial resolutions that are far coarser than would be theoretically predicted from acoustic focusing. Here, we show how the effective spatial resolution and dynamic range of holographic haptic displays are determined by ultrasound-driven elastic wave transport in soft tissues. Using time-resolved optical imaging and numerical simulations, we show that ultrasound-based holographic displays excite shear shock wave patterns in the skin. The spatial dimensions of these wave patterns can exceed nominal focal dimensions by more than an order of magnitude. Analyses of data from behavioral and vibrometry experiments indicate that shock formation diminishes perceptual acuity. For holographic haptic displays to attain their potential, techniques for circumventing shock wave artifacts, or for exploiting these phenomena, are needed.

Technology-Mediated Hindustani Dhrupad Music Education: An Ethnographic Contribution to the 4E Cognition Perspective

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“…In addition to mentioned approaches, other novel feedbacks have been investigated for expanding applications of haptic feedback in VR systems, such as thermal feedback [ 159 , 160 ], ultrasound feedback [ 161 , 162 ], and piezoelectric actuator [ 163 ]. Temperature sensing is also considered as the main function of human tactile receptor, and temperature sensation originates from heat flux occurring when contacting with object of different thermal conductivities.…”