August 01, 2007

Make your own plastic-AFM heads and save tens of thousands of dollars

From nanowerk, the successful rapid prototyping of an atomic force microscope hear (AFM), something which normally costs hundreds of thousands of dollars

Go to this site for a tutorial on how to build a plastic-AFM head

The heads perform as well as traditional heads but are not as durable.

The computational chemistry simulation software and hardware is getting supercheap with Nvidia tesla boards and computers (multiple teraflops for a workstation). Now you can build AFMs for cheap.

Instead of $10 million to setup for serious nanotech work the price is dropping to about $250,000-500,000.

The most versatile implementation of the scanned probe principle is the atomic force microscope (AFM). It has become one of the foremost tools for imaging, measuring and manipulating matter at the nanoscale. The essential part of an AFM is a microscale cantilever with a sharp tip (probe) at its end that is used to scan the specimen surface. The cantilever is typically silicon or silicon nitride with a tip radius of curvature on the order of nanometers. When the tip is brought into proximity of a sample surface, forces between the tip and the sample lead to a deflection of the cantilever according to Hooke's law. A multi-segment photodiode measures the deflection via a laser beam, which is reflected on the cantilever surface. Because there are so many promising areas in nanotechnology and biophysics which can be examined by AFM (force spectroscopy on DNA, muscle protein titin, polymers or more complex structures like bacteria flagella, 3-D imaging, etc. ) the availability of instruments is crucial, especially for new groups and young scientists with limited funds. The price tag of AFMs runs in the hundreds of thousand s of dollars, though.

Selective Laser Sintering (SLS - a registered trademark of 3D Systems, Inc.) is an additive rapid manufacturing technique that uses a high powered laser to fuse small particles of plastic, metal, or ceramic powders into a mass representing a desired 3-dimensional object. The laser selectively fuses powdered material by scanning cross-sections generated from a 3-D digital description of the part (e.g. from a CAD file or scan data) on the surface of a powder bed. After each cross-section is scanned, the powder bed is lowered by one layer thickness, a new layer of material is applied on top, and the process is repeated until the part is completed.
"To evaluate the performance of a rapid prototyped AFM, we reprinted one of our aluminum AFM heads with the SLS method in plastic" Robert Lugmaier, a co-author of the paper, explains. "To compare the noise and drift values of these AFM heads under equal conditions, the same optical and electrical components were used. The laser diode, the piezoactuator, and the photodetector were identical for the plastic printed as well as the aluminum milled AFM."