-Abstract--Piezoelectricmaterialsoperatedathighfrequencyandlargeelectricfieldcanproduceveryhighpowerdensities.Thedifficultywithutilizingthispowerdensityinmotorapplicationsistheverysmallstrokeproducedbypiezoelectrics.Strokerectificationisimplementedtoobtainahighpowerdensitydevice.Thishasbeenaccomplishedusingapistondrivenhydraulicpump.Rectificationoffluidpowerisobtainedusingcheckvalves.Detailsofthedesignandcharacterizationoftheresultingpumparepresented.Thethermodynamiccycleofapiezoelectricstackactuatorinapiezo-pumpapplicationisalsoillustrated.INTRODUCTIONManysmartmaterialsapplicationsrequirelargeforceandlargedisplacement.Singlestrokeactuatorsproducealargeforcebutoverasmalldistance.UltrasonicmotorsusearesonantwavetorotateashaftTheresultisasolidstatemotorthatcanbemadeverysmallbutwithlowtorqueoutput[].Stepandrepeatdevicesoperatebelowresonantfrequenciesandrelyonthedirectactuationcapability