To:   the MEMS community
From: Darin Platte at the University of Colorado, Boulder
      Dept. of Mechanical Engineering

This is a call for suggestions/help with difficulties that we are having
in running the salient-pole micromotors we have. They are manufactured by
MCNC in North Carolina.  This is what we have tried so far.

- To ensure that the etching was done properly we did a "push test" which
  is simply to lightly nudge the motor to see if it is free to spin.
  They are. Although this nudging damaged some motors, we are confident
  that many were left unharmed.

_ Using seven probes (one being a ground) a square wave excitation
  voltage (variable up to 120
  volts dc) was applied to pads on opposite sides of the motor. Three
  pairs of such probes were synchronized to continue around the motor to
  make it spin. Different speeds between 20 and 120 Hz were tried. This
  was unsuccessful.

- An attempt was made to "rock" the motor back and forth by exciting
  adjacent pairs back and forth. This was also unsuccessful at getting the
  motor to move.

_ Suspecting that the roughness of the bearing surfaces is what was
  precluding the electrical operation of the motors, we thought
  that if we could spin the motor by pushing it with a fine stream of
  nitrogen any rough spots on the bearing might be worn down.
  MCNC agrees with this approach but says that a nozzle or micropipette
  with a hole size of a FEW MICRONS in diameter is necessary.  They used
  to have such a small holed device but no longer do.  We tried this
  approach with an orifice of 35 microns in diameter unsuccessfully.

We have not been able to get the motors to spin using this "nitrogen jet"
approach or electrically. We would very much appreciate any suggestions
for what might be done differently - OR where we could find a micropipette
or similar device with a hole of only a few microns in diameter.

Thank you,

Darin Platte
Research Assistant
University of Colorado, Boulder