The scanning tunneling microscope (STM) is a powerful tool for visualizing specimens on the nanoscale. But why spend thousands of dollars for “low cost” systems (starting at $8000-$9500, http://www.nanotech-now.com/James-Logajan/stm.htm) and up to $150,000 for more sophisticated ones when you can build a STM right in your home for under $100? This would be a great complement for all the other DIY entries in this blog, as it provides a means for seeing the end-products of those projects!
Materials & Methods (adapted from John D. Alexander’s project, http://www.geocities.com/spm_stm/Project.html)
Disc Scanner (http://www.geocities.com/spm_stm/Disk_Scanner_Exp.html)
- Unimorph disk (from piezo buzzer from Panasonic electronics)
- Box-cutter or any sharp blade
- Tape
- Scrap metal
- Pencil eraser
- Ohm meter
- Heat source
- Conductive silver paint
- Scanner wires
- Super glue
- 9/16″ steel washers
- “Plastruct” plastic tubing
- Pin from IC socket
- Remove case of the buzzer by cutting the edges, leaving only the Unimorph disk.
- Tape disk to scrap metal.
- Divide electrode into quadrants (scratch with knife).
- Clean electrode with pencil eraser.
- Test electrode with Ohm meter.
- Coat with conductive silver paint and heat.
- Attach wires.
- Make mount by using blade to make grooves in steel washers for wires and STM tip.
- Use tape to insulate electrode (piezo disk) in mount (washers); glue.
- Add “Plastruct” tubing and tip holder (pin from IC socket) in center tube.
Completed disk scanner with wires
Scanner Holder
- 1/8″ x 1-1/2″ x 3-3/8″ aluminum stock piece
- Drill
- UNCF #1-72 screws (4) and nuts (8)
- Drill 4 holes in aluminum stock piece.
- Super glue two 1-72 nuts on each hole (on on each side).
- Insert screws.
From left to right: Scanner holder, sample stage, and disk scanner.
Sample Stage
- 1/8″ x 1-1/2″ x 3-3/8″ aluminum stock piece
- Drill
- Ceramic magnets
- Glue
- Screws
- Brass shim stock
- Steel washer
- Wire
- Pre-amplifier circuit board
- Mark where screws from mount touch when pieces are lined up.
- Drill a cone-shaped hole and file a V-shaped groove in two separate landing points.
- Use magnet to hold steel washer and brass shim stock with wire.
- Glue disk scanner and sample holder to mountings.
- Put edge of pre-amplifier circuit board in between two magnets.
Finished product of mechanical portion of STM.
Electronic Design and Operation
Far from an expert in physics and engineering, I have only superficial knowledge of the electrical side of this DIY project. For details on the operational procedure for this STM, consult http://www.geocities.com/spm_stm/STM_operation.html.
