A New Electroadhesive Clutch To Improve Haptics in Virtual Reality Gloves and Beyond

When engaging in virtual reality (VR) and manipulating an object, users want to be able to feel what they’re touching in virtual space. A hard object needs to feel hard and a soft object needs to feel soft; mechanisms that can accurately deliver these touch sensations are called haptic systems. Haptic systems achieve their goals through a number of approaches. One method involves the use of components called electroadhesive clutches. An electroadhesive clutch uses electrical voltage to create adhesion between two electrodes. The mechanism is typically made up of two overlapping, metallized electrodes separated by a non-metal, insulating material called a dielectric. The sheets can slide past one another when there is no electric field present, but when a voltage is applied, an electric field creates a strong attraction across the sheets, causing them to stick together in the same way your hair sticks to a balloon when you create an electric charge through rubbing, only much stronger. Gloves used in VR haptic systems can be embedded with these electroadhesive clutches to simulate touch sensations by changing from stiff to flexible and vice versa. However, electroadhesion through the traditional dielectric setup requires anywhere from 100 to 10,000 volts of electricity to operate, levels that can be unsafe for direct human use. Additionally, their ability to switch back and forth from stiff to flexible is limited. Improving these clutches would not only improve a user’s experience in virtual reality, but could improve other applications such as robotic exoskeletons and prosthetics, finger-gripping systems, and shape-shifting robots. A new design may now offer the best of all worlds: an electroadhesive material that is strong, operates at low voltages and quickly switches states. This system, which utilizes ionoelastomers instead of dielectrics, is explained in a paper published in Advanced Materials. This work is the result of a collaboration between Kevin Turner, Professor and Chair of Mechanical Engineering and Applied Mechanics (MEAM) in Penn Engineering, James Pikul, Associate Professor of Mechanical Engineering at the University of Wisconsin-Madison, and Ryan Hayward, Professor of Chemical and Biological Engineering at the University of Colorado Boulder. Kevin Turner (left), James Pikul (center) and Ryan Hayward (right) “Ionoelastomers are flexible, elastic ion conductors that can stretch and bend while still allowing electricity to pass through them,” says Pikul. “The material itself feels like gummy rubber and was inspired by electroadhesive materials found in nature. Organisms like mussels and sandcastle worms use proteins with opposite charges to create a bioadhesive to secure their shells to the reef. The bond works due to the laws of electrostatics, where opposite charges attract and create a very strong adhesion on the molecular level. Biology activates this adhesion with chemicals, whereas we activate electrostatic adhesion in our materials by applying a voltage, i.e. electroadhesion.” Read the full article in Penn Engineering Today.