Human-Centered Design of a Vibrotactile Sensory Substitution Belt for Feet Somatosensation in a Patient with Multiple Sclerosis

Patients without sensation in their feet due to peripheral neuropathy or spinal cord injury have difficulty with balancing and walking. For patients with sensory loss in other modalities such as vision or hearing, sensory substitution devices have shown to be effective assistive technologies. To support the ethical design and user acceptance of novel assistive systems, the inclusion of patients from the start of the development process is an important factor. In this paper, we present the human-centered design of a sensory substitution device together with a patient lacking somatosensation in the feet. Force distribution during balancing and walking was measured with robotic skin soles and mapped to vibrotactile stimulation through motors integrated into a wearable belt. We discuss how the values and priorities of the patient were included in the system design and present her feedback obtained during a user evaluation session. Using our sensory substitution device, 5 healthy participants were able to distinguish the feedback patterns based on force distributions from 6 different phases of the gait cycle and 3 balancing conditions with 93.2% accuracy.