Remapping Wetness Perception in Upper Limb Amputees

Recent research has made remarkable strides in restoring sensory feedback for prosthetic users, including tactile, proprioceptive, and thermal feedback. Herein, a sensory modality that has been largely neglected is explored: the ability to perceive wetness. Providing moisture-related information to prosthesis users can increase their overall sensory palette toward a more natural sensory experience. A rapid decrease in skin temperature is found to trigger the illusion of contact with something wet. Two body parts were tested, the upper arm and the lateral abdomen, in a group of non amputated participants, and it was found that a wetness sensation can be elicited and maintained for at least 10 s in 86% and 93% of participants, respectively. It is then demonstrated how to mediate the wetness sensation in real-time using a thermal wearable device that mimics the thermal properties of the skin. Finally, two upper limb amputee individuals used their prosthetic arm, sensorized with the device, to discriminate between three levels of moisture; their detection accuracy was similar to one they had with their intact hands. The current study is a stepping stone for future prostheses aimed at restoring the richness of sensory experience in upper limb amputees. A new generation of prostheses aims to restore the rich sensory feedback of amputated people, but one modality is often neglected: wetness perception. Ploumitsakou and colleagues present an approach to detect and mediate moisture information: a cold, dry skin stimulation created the vivid sensation of touching something wet. Blindfolded amputees could scan objects and discriminate three levels of moisture.image (c) 2024 WILEY-VCH GmbH