Investigating Osseoperception in Distal Regions of the Upper Limb for Augmented Sensory Feedback

The somatosensory function is crucial for motor control, but is often deemed secondary in the design of assistive technologies for individuals with neuromotor impairments. This study investigates osseoperception-auditory and vibrotactile sensations evoked through bone stimulation-at the wrist pisiform bone (PB) and metacarpal head (MCH) of the index finger in 12 participants. Vibratory stimuli (100-6000 Hz) were applied during four psychophysical experiments: sensation discrimination, perception thresholds, sensory mapping, and loudness evaluation. Tactile sensations occurred below 940 Hz at the PB and 1000 Hz at the MCH, while auditory sensations predominated above these thresholds. Stimulation at 400 Hz expanded tactile zones, with PB sensations extending to the forearm and MCH sensations to carpal and interphalangeal joints. MCH stimulation had lower perception thresholds (0.14 N), while PB stimulation exhibited frequency-dependent loudness variations. These findings suggest the MCH and wrist as promising sites to elicit osseoperception, paving the way for the development of sensory feedback strategies to complement the effect of assistive technologies, especially those interfaced through osseointegration.