Mechanical Strain Generation in a Polydiacetylene Crystal due to Photoinduced Phase Transition

Abstract

The mechanical strain generation in a polydiacetylene crystal caused by light irradiation was directly measured. Using a thin cantilever made of this material, the transient deflection response of the cantilever subjected to pulse laser irradiation was precisely detected on the millisecond scale. The cantilever exhibited a long-term sustained deflection strongly dependent on temperature. This was consistent with the bimorph formation due to the phase transition of the thin surface layer induced by the light irradiation. The response time was less than 2 ms. The conversion efficiency from light energy to elastic energy was estimated to be 2×10-8. This new actuator principle can be used to achieve a large power density relating to the phase transition of solid materials with a rapid response time by excluding slow heat cycles.