Bizarre navigation aid that guides by shocking walker’s feet

A quirky navigation aid directs walkers by shocking their feet. The so-called FeetThrough system uses electrotactile stimulation to the bottom of the foot.

A proof-of-concept is being developed by the University of Chicago with the hope it could help people such as those with poor sight.

The current prototype is 0.1 mm thick and can be applied directly to soles, insoles or socks. It is designed to enable applications such as barefoot interactive experiences, such as yoga posture correction, or negate the need for special shoes in applications such as guidance for low-vision users.

The thinness of the electrode application allows users to also feel the ground while experiencing what is described as “a nice touch sensation” that may point them directionally.

Assoc. Prof. Pedro Lopes and electro-communications PhD student Keigo Ushiyama are leading the study. They explain that most haptic interfaces for the feet use mechanical actuators, or vibration motors, which they argue are not the ideal actuators for the job.

The researchers believe that electrotactile stimulation is a more powerful feet-haptic interface, as users feel not only the stimulation but also the terrain under their feet which could be critical to safely balance on uneven terrains.

The study suggests another advantage electrotactile sensations can feels more localised, while a single vibrotactile actuator will also vibrate surrounding skin areas.

They write: “We argue that foot haptic interfaces should optimise for what users feel during output and prioritise letting users feel the terrain under their feet.

“Feeling ground features with our soles is critical for balance on uneven terrains and stairs. We demonstrate that electrotactile stimulation not only achieves an improved “feel-through” of terrains compared to traditional vibrotactile foot interfaces but also lets users feel the output more clearly (lower two-point discrimination threshold).”

The researchers say the current prototype requires manual attachment and individual calibration, but future everyday usage of FeetThrough could see them integrated via conductive threads into socks.