Nanoscale microscope on a chip
New Scientist recently reported that a UK company is developing a microscope on a chip four times more powerful than the best scanning electron microscopes (SEMs) available today. The best SEMs have a resolution of 0.05 nanometer. This new one, which will be small enough to fit onto a fingertip, should achieve a resolution of 0.01 nanometer. The prototype should be ready by the end of the year. If successful, it could be used for a variety of applications, such as making holograms of large single molecules. But read more...
You can see above a diagram of NFAB's prototype microscope. (Credit: NFAB), a company whose motto is "Generating a Revolution in Electron Microscopy."
This project has been led by Derek Eastham of NFAB, a condensed matter physicist who was previously the technical coordinator of the EU-funded Monarch project, whose aim was to develop a "ultra-bright nanoscale SEM-on-a-chip."
Now, let's read the New Scientist article to discover how Eastham plans to build such a small microscope with a resolution much better than other SEMs. "His design uses a much lower energy beam in a device with just a few millimetres between the electron generator and the object being studied. That distance is more usually a few feet. Instead of firing electrons from a tungsten filament, it will shoot them from a single atom at the peak of a tiny gold pyramid with a height of around 100 nanometres. The beam will be focused as it passes through a 2 micrometer hole in a silicon chip before it hits the target below. The electron beam itself is just 10 micrometers long in Eastham's new microscope -- the beam of a standard SEM is around 60 centimetres long."
The NFAB home page gives additional details. "NFAB's sub-miniature scanning electron microscope is a completely new concept in electron microscopy. The microscope is 5 µm long and has atomic resolution (2 Å) at 500 eV energy and 10 nA of current. The low energy means it can identify single atoms on a surface as well as being able to make holograms of large molecules. All of the component parts can be manufactured by existing commercial technology. For example, the electron source is a gold nanopyramid. These can be routinely manufactured in nanotechnology laboratories. The microscope body is manufactured by standard MEMS techniques."
And here is the company's description of this future tool. "The final packaged instrument will be a microtip with the microscope on the end rather like an STM with an electron beam focussed to atomic sizes. Because the depth of field is large and the beam current is high, it will scan much more quickly than an STM, can study practical surfaces and can identify atoms directly from the elastic scattering."
According to New Scientist, a prototype of this nano-SEM should be completed within 3 to 6 months. In this very short note, Sky News adds that this microscope is expected to be available for trials within two years for a cost of approximatively £100K ($195 K or €127K). Current SEMs with a resolution of 0.05 nanometers can cost around £4m ($7.8m or €5m).
Sources: Colin Barras, New Scientist, June 13, 2008; and various websites
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