Etching Tungsten Tips for our AFM

This is a picture inside the SEM.  You can see the electron gun, the two detectors, and the samples at the bottom.  

I'm doing research for Dr. Cross.  I'm attempting to create cheep and effective tungsten tips for our Atomic Force Microscope (AFM)

The tips are etched using electrolysis.  I dip a thin tungsten wire into 7.5 molar KOH solution.  The wire is hooked up to direct current at about 3 volts and the KOH solution is hooked to the other end of the circuit.

These pictures were taken with he biology department's SEM.  I am checking the tips for blemishes and to see if they are sharp enough to use in the AFM.

You can see some defects in the surface and shape of this tip.  I think they may have formed because the etching was too violent and the wire entered the KOH solution at an angle.  

Again you can see odd shape this tip takes.  

Overall I'm really happy with my research.  The tips are forming at about a 50% success rate, with 2/3 of the tips looking fairly usable.  I'll be working with Dr. Cross to test them sometime next week.