Light-driven polymer auto-oscillators

New light-driven actuators based on films of polymer polyvinylidene fluoride are described. The actuators use the photomechanical bending of the polymer film caused by low power laser radiation. The photomechanical effect combines physical mechanisms, such as anisotropic thermal expansion, converse piezoelectric mechanism, photovoltaic and pyroelectric, while thermal expansion is dominant for slow motion. Mechanical vibrations of the strips of the photomechanical polymer were observed with periodic pulsed laser excitation. The resonance frequency is inversely proportional to the square of the length of the strip, in agreement with the theory. Resonance frequency measurements were used to determine the modulus of elasticity of the films, which was close to 3.0x109 Pa. Three possible applications are a photonic switch, an adaptive mirror, and an auto-oscillator. The proposed actuators have a potential of being used as the components of future light-driven micro/nano systems.