Printed Actuators
December 1,2011, Printed Electronics USA 2011, Santa Clara, CA—Mykyong Yoo from Artificial Muscle discussed electro active polymer (EAP) technology. This technology converts an applied voltage to displacement.
Contacts on opposite sides of a polymer use Maxwellian pressure to thin and expand the polymer. Stroke distance is proportional to the dielectric constant, voltage squared, and Young’s modulus. Force is proportional to the dielectric constant, voltage squared, and the thickness. The result is an efficient electrical to mechanical, or mechanical to electrical energy conversion device.
The EAP can be used for actuators, generators, and sensors in a compact, low profile form factor. The EAP offers quiet, low power operation in any application that requires electrical to mechanical or mechanical to electrical transformation. The technology is compatible with printed electronics technology and is easily customizable.
Some implementations are for planar in-plane motion, or for planar or diaphragm out of plane motion. Actuators are between 0.2 and 0.5 mm thick and can be on flexible and clear substrates. Due to the low mass, the actuators can offer high frequency motion and use less than half of the battery power for a motorized actuator. The lack of moving parts allows for millions of actuations. The actuator can operate from DC to 300 Hz with a response time of under 5 ms.
Now, the fast response and relatively high frequency response can be used to provide customized vibration feedback rather than the single mode of vibration available from a motorized shaker. Vibration effects are not limited to a single frequency and amplitude, but can vary across both dimensions. Motion is coupled from the actuator to the system through coupler bars to provide haptics feedback. Connecting the actuator to an inertial mass produces a device shaker. One prototype phone used the battery as the mass.
The range of potential applications is very large, due to the form factor and low power operation. Since the technology is a bidirectional force-electrical transducer, it can offer greater differentiation to the application or detection of force.
