IFAs are MEMS actuators which are powered by the electrostatic forces between the plates of many microscopic deformable capacitors arranged in monolithic arrays. IFAs are fabricated using standard techniques of VLSI electronics. The IFAs reported here resemble thin, flexible plastic membranes 10 mm long and either 1 or 3 mm wide, which contain from 75,000 to 200,000 cells. They are low-weight, high-efficiency actuators with low power consumption, silent operation, and absence of sliding friction. Testing methods applicable to these free- standing MEMS structures are discussed, along with experimental observations and measurements of forces and displacements. We have measured forces in excess of 6 dynes and displacements of over 700 micrometers . The force/cross-sectional area of this MEMS structure is 2800 dynes/mm2, and the work done by the IFA divided by its volume is in excess of 7 ergs/mm3. A rate over 20,000 contractions/second has been observed, as well as lifetimes of greater than 108 contractions. The metalization of the IFA strongly affects the performance. Experimental results are presented demonstrating the improvements in the performance with a Cr/Au metal system compared to the Cr/Pd metal system originally used.