摘要
We have successfully demonstrated a diaphragm-type pneumatic valve capable of amplifying electrostatic actuation and attenuating air pressure applied onto the diaphragm. When a high voltage is applied between the flexible electrode coated on top of the diaphragm and an underneath ground electrode, the electrostatic attraction induces a zipping motion of the diaphragm. The actuation of the pneumatic valve can seal an air chamber and maintain its internal pressure at a high level, which drives a circular elastomer membrane to form a bump and stimulate the skin. If the applied voltage falls below a certain threshold, air bypasses the diaphragm to the atmosphere and causes a sharp drop of the inter pressure, whose magnitude is controlled by a dedicated fluidic resistor located upstream. By manipulating pressure, the electrically-driven valve can control the movement of the membrane and the stimulation to the skin. In the prototype demonstration, structures are 3D manufactured, selectively coated with silver electrodes, and integrated to realize the proposed actuator with 1 cm(3) in volume. The fabricated circular elastomer membrane of 3 mm in diameter and 0.1 mm in thickness forms a bump of 0.5 mm in height under an air pressure of 10 kPa, which requires a voltage of >472 V for the valve to maintain. While the voltage is lower than 472 V, the pressure drops and the membrane moves down. Once a voltage of >814 V is applied, it seals the chamber and forms the bump again. Therefore, haptic actuation can be generated as desired.