New design of actuator using shear piezoelectricity of a chiral polymer, and prototype device

Chiral polymers have been known to exhibit small shear piezoelectricity for about fifty years. However, recently, we reported that poly( L ‐lactic acid) treated with supercritical carbon dioxide (sc‐PLLA), which is a type of chiral polymer, exhibits much higher shear piezoelectricity than other chiral polymers. On the other hand, we found an important difference between motion due to shear piezoelectricity and that due to tensile piezoelectricity in piezoelectric materials through computer simulations. On the basis of these results, we fabricated a new type of electrically controlled tweezers constructed from a pair of sc‐PLLA sheets with shear piezoelectricity. In general, when conventional tweezers open to the left and right, the trajectory of their motion becomes fanlike at the center of the connection (one end of the tweezers). In the new tweezers, the two small sheets making up the tweezers open parallel to each other, without the motion of parts near the connection. Moreover, a prototype ‘finger’ system using sc‐PLLA sheets to realize complex motion in which the finger curled upon stretching of the sc‐PLLA sheets was manufactured as a trial device. Using the prototype finger system, we demonstrated the firm grasping of a sample, but the sample could not be removed from a vessel. Thus, sc‐PLLA increases the likelihood of realizing a device with highly operational pick‐up in a very small region by using the shear piezoelectricity of a chiral polymer. Copyright © 2010 Society of Chemical Industry