Particle Tracking of a Complex Microsystem in Three Dimensions and Six Degrees of Freedom

We make use of the intrinsic aberrations of an optical microscope to track single particles in three dimensions, and we combine information from multiple particles on a rigid body of a microelectromechanical system to measure its motion in six degrees of freedom. Our tracking method provides an extraordinary amount of information from an ordinary imaging system, revealing unintentional motion of the microsystem due to fabrication tolerance and nanoscale clearance between parts in sliding contact. Our work facilitates quantification and study of the actuation performance and reliability of complex microsystems.