Navigational and Emotional 4D Haptic Feedback Interface Based on Ultra-Low Voltage Driven Electret Actuators

Advanced haptic feedback interfaces represent an extremely important reality in the field of assistance for people with disabilities. People with visual and hearing impairments desire an emotional experience in reading or communicating with others, rather than being confronted with traditional Braille or mechanical sounds. Existing haptic interfaces usually rely on high voltage or current stimulation, causing safety concerns and discomfort in use.<br/><br/>Here, we report a thin, flexible electrostatic actuator enabling high bandwidth and programmable haptic feedback under ultra-low driving voltages. Computational studies and experimental measurements demonstrate excellent operational stability and output characteristics. By introducing multilayer variable stiffness PDMS elastomers and high-temperature charged electret films, we have achieved: 1) ultra-low voltage actuation, capable of generating perceptible haptic feedback forces at as low as 5 V actuation. 2) high gain (mN/V), with a gain of 1.06 mN/V at 200 V actuation, and 0.98 mN/V at 35 V actuation. 3) ultra-high frequency bandwidth in the range of 15-450 Hz, covering all frequency intervals of manual sensitivity. 4) electrostatic charge decay rate of less than 6% to maintain high electrostatic potential energy of the electret film for several years.<br/><br/>The haptic interface provides four-dimensional haptic feedback programming capabilities, including time, position, frequency, and amplitude. Through software signal design, the interface demonstrated the ability to convey Braille with four fundamental emotions. The test results by 15 users are 83 % (without learning mode) and 100 % (with a learning mode) accuracy. This demonstrates that the haptic interface can provide vivid sensations and information, and the haptic driving signals we designed can naturally induce human emotions. The interface also supports multi-command navigation based on haptic illusions. It can generate continuous signals between multiple points, simulating the sensation of real arrow-like directional flow, which efficiently meets the navigational needs of visually impaired people without requiring a complicated learning process. Potential applications of this technology extend to fields such as neuroscience and psychology, including personalized rehabilitation, disability education, and virtual reality experiences. The interface is expected to contribute to an accessible society.