Northwestern Engineers develop First ‘Human Resolution’ Haptic Device
Northwestern University engineers have developed the first haptic device that achieves “human resolution,” meaning it accurately matches the sensing abilities of the human fingertip.
Called VoxeLite, the ultra-thin, lightweight, flexible, wearable device recreates touch sensations with the same clarity, detail and speed that skin naturally detects. Similar to a bandage, the device gently wraps around a fingertip to give digital touch the same realism people now expect from today’s screens and speakers.
By combining high spatial resolution with a pleasant, wearable form factor, VoxeLite could transform how people interact with digital environments, including more immersive virtual reality systems, assistive technologies for people with vision impairments, human-robot interfaces and enhanced touchscreens.
The study was published in the journal Science Advances.
“Touch is the last major sense without a true digital interface,” said Northwestern’s Researchers at Northwestern University have developed a new device, voxelite, that creates realistic touch sensations without any moving parts. The technology builds upon previous work with electroadhesion, the same principle that causes a balloon to stick to a wall after being rubbed. In their previously developed TanvasTouch technology, Colgate and Peshkin used electroadhesion to control friction between a fingertip and a smooth touchscreen surface. Those devices used an electric field to alter friction and create the illusion of texture, but did not involve any moving parts.
VoxeLite advances this concept. The new technology applies electrostatic forces in a precise, controlled way to make each tiny node “grip” a surface and tilt to press into skin. This generates a highly localized mechanical force, so each “pixel” of touch pushes the skin on a fingertip. Higher voltages increase friction during movement, producing more pronounced tactile cues to simulate the feeling of a rough surface. Conversely, lower voltages create less friction and, therefore, the sensation of a slipperier surface.
“When swiped across an electrically grounded surface, the device controls the friction on each node, leading to controllable indentation on the skin,” Colgate said. “Past attempts to generate haptic effects have been large, unwieldy, and complex devices. VoxeLite weighs less than a gram.”
reaching human resolution
To create the human-resolution sensations, Tan packed the nodes closely together. In the densest version of the device, nodes are spaced about 1 millimeter apart. In user testing, Tan used a version with 1.6 millimeters of spacing among the nodes.
“The density of the nodes really matters for matching human acuity,” Tan said. “The nodes need to be far enough apart that your body can tell them apart. If two nodes are less than one millimeter apart, your fingertips only sense one node instead of two. But if nodes are too far apart, they cannot recreate fine details. To make sensations that feel real,we wanted to match that human acuity.”
VoxeLite operates in two modes: active and passive. In active mode, the device generates virtual tactile sensations by rapidly tilting and indenting individual nodes as a user moves across a surface.