Organic Actuators Are New Bioengineering Tools

Researchers have developed a new class of all-organic field-type (controlled by an external electrical field) electroactive polymer (EAP) composites that can exhibit high elastic energy densities induced by an electric field of only 13 V µm-1. The composites are fabricated from an organic filler material possessing very high dielectric constant dispersed in the electrostrictive polymer matrix. The research was published in the September 19, 2002, issue of Nature.

EAPs can behave as actuators, changing their shape in response to electrical stimulation. Field-type EAPs can exhibit fast response speeds, low hysteresis and strain levels far above those of traditional piezoelectric materials, with elastic energy densities even higher than those of piezoceramics. However, these polymers also require a high field (>70 V µm-1) to generate such high elastic energy densities.

The researchers, from Pennsylvania State University (University Park, USA; www.psu.edu), revealed a new composite that reduced the voltage to one tenth of that previously needed. "Potential applications for this material include a variety of tiny pumps, because the material can be made to pump periodically or in a wave fashion,” said Feng Xia, a graduate student and member of the research team. "Small insulin or other pharmaceutical pumps could be powered by a low voltage battery and an electroactive composite.”



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