Tongue Display Unit

A sensory substitution device that presents visual or spatial information through an array of electrodes placed on the tongue. The tongue is ideal for electrotactile stimulation because it has a very high density of nerve endings, low and consistent electrical impedance due to saliva, and is protected inside the mouth. The BrainPort, developed from Paul Bach-y-Rita's research, translates camera images into a grid of electrical pulses felt on the tongue, allowing blind users to perceive shapes, movement, and spatial relationships. After training (typically 20-40 hours), users report perceiving the information as external spatial awareness rather than tongue sensation. Tongue displays are approved as assistive devices in some countries for balance rehabilitation and vision substitution.