A thin, flexible device could help people with visual impairments ‘feel’ surroundings. The medical device delivers various sensations, including vibrations, pressure and twisting.
The device comprises a hexagonal array of 19 actuators encapsulated in soft silicone and it only uses energy when actuators change position, operating for longer periods of time on a single battery charge.
The development comes from a Northwestern University-led team of engineers and it seeks to provide more realistic and immersive sensory experiences.
The device could help people with visual impairments “feel” their surroundings or give feedback to people with prosthetic limbs. The overall system is composed of tiny devices that can deliver controlled forces across a range of frequencies, providing constant force without continuous application of power.
The new device comprises a hexagonal array of 19 small magnetic actuators encapsulated within a thin, flexible silicone-mesh material. Each actuator can deliver different sensations, including pressure, vibration and twisting.
Using Bluetooth technology in a smartphone, the device receives data about a person’s surroundings for translation into tactile feedback — substituting one sensation (like vision) for another (touch).
An alternative version allows the same actuators to provide a gentle twisting motion at the surface of the skin to complement the ability to deliver vertical force, adding realism to the sensations.
To test the device, the researchers blindfolded healthy subjects to test their abilities to avoid objects in their path, change foot placement to avoid injury and alter their posture to improve balance.
One experiment involved a subject navigating a path through obstructing objects. As the subject approached an object, the device delivered feedback in the form of light intensity in its upper right corner. As the person moved nearer to the object, the feedback became more intense, moving closer to the center of the device.
With only a short period of training, subjects using the device were able to change behavior in real time.
Although the device is powered by a small battery, it saves energy using a clever “bistable” design. This means it can stay in two stable positions without needing constant energy input. When the actuators press down, it stores energy in the skin and in the device’s internal structure.
When the actuators push back up, the device uses the small amount of energy to release the stored energy. So, the device only uses energy when the actuators change position. With this energy-efficient design, the device can operate for longer periods of time on a single battery charge.
The new study builds on earlier work based on “epidermal virtual reality”. This is a skin-interfaced system that communicates touch through an array of miniature vibrating actuators across large areas of the skin, with fast wireless control.
The research appears in the journal Nature, titled “Bioelastic state recovery for haptic sensory substitution.”
