Resonant frequency skin stretch uses cyclic lateral skin stretches matching the skin’s resonant frequency to create highly noticeable stimuli, signifying a new approach for wearable haptic stimulation. In this project, three experiments were performed to explore biomechanical and perceptual aspects of resonant frequency skin stretch. In the first experiment, skin resonant frequencies were quantified at the forearm, shank, and foot. In the second experiment, perceived haptic stimuli were characterized for skin stretch actuations across a spectrum of frequencies. In the third experiment, haptic classification ability was determined as subjects differentiated haptic stimulation cues while sitting, walking, and jogging. Results showed that subjects perceived stimulations at, above, and below the skin’s resonant frequency differently: stimulations lower than the skin resonant frequency felt like distinct impacts, stimulations at the skin resonant frequency felt like cyclic skin stretches, and stimulations higher than the skin resonant frequency felt like standard vibrations. Subjects successfully classified stimulations while sitting, walking, and jogging, and classification accuracy decreased with increasing speed, especially for stimulations at the shank. This work could facilitate more widespread use of wearable skin stretch. Potential applications include gaming, medical simulation, and surgical augmentation, and for training to reduce injury risk or improve sports performance.

For details see: Shull PB, Tan T, Culbertson HM, Zhu X, Okamura A, “Resonant frequency skin stretch for wearable haptics,” IEEE Transactions on Haptics, 12(3): 247-256, 2019.