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Koala drive: Ultra-compact nanopositioner

The Koala drive: How it works

Here we present a new type of ultra-compact nanodrive which has a diameter < 2.5 mm and which can serve as an STM coarse positioning device. Alternating movements of springs move a tube which holds the STM tip or the AFM sensor. Due to its operation principle we have named it the "Koala drive". The travel range is limited only by the tube length, which can be several centimeters. The new operation principle provides a smooth travel and avoids the shaking that is intrinsically present if nanopositioners based on inertial motion with saw tooth driving signals are employed. For the Koala drive no high slew rate of the driving electronics is required. Please click on the image below to start the movie showing the operation principle.

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Two are stronger than one! Click on the image to run the movie

  • The central tube is held by springs which are attached to two piezo tubes
  • If only one spring moves, the other two springs hold the tube in place, because the static frictional force of two springs is larger than the sliding friction of one
  • If two springs move, the tube moves with them (two are stronger than one)
  • The operation is quasi-static: No large accelerations and no shaking occur

The Koala drive: What it looks like



  • Compact dimensions down to diameters < 2.5 mm
  • Combining long range stroke (cm range) with sub-nanometer positioning ability
  • Smooth travel, no saw-tooth signal, no shaking










The Koala drive: How it moves

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  • Tube diameter: ~ 1 mm
  • Speed: up to 1 mm/s
  • Ideally suited for scanning probe microscopy applications







The Koala drive: SEM movies

Low magnification SEM movie of a STM tip moved by the Koala drive (grid spacing: 100 µm)

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High magnification SEM movie of the end of a STM tip moved by the Koala drive

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  • ~5 µm travel per period
  • This real time SEM movie demonstrates the smooth travel of the Koala Drive
  • Ideally suited as coarse approach for scanning probe microscopy applications

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