A unique reliability data point: the start-stop operation of a polysilicon micromotor at the eight year mark

This paper is our first report of a fully-packaged, surface-micromachined, polysilicon, harmonic side-drive (also known as "wobble") micromotor which has been operating in the field without maintenance for eight years. This micromotor was installed by us in early 1997 as part of the Micromachine Exhibit at the Great Lakes Science Center (Cleveland, Ohio). Visitors view the micromotor under a microscope and can actuate the rotor by pressing the "on" button. The rotor, which is normally at rest, spins at ∼7 rpm while the "on" button is depressed. Over this eight year period, the museum estimates a total of ∼4.7 million visitors. A conservative estimate of the number of times the "on" button has been pressed by visitors to watch the rotor spin is ∼2.5 million. The continued operation of the micromotor provides an insight into a unique reliability data point of particular importance to microsystems, i.e., routine start-stop operation at random intervals over extended periods of time in the field.