Faster technology lets atomic force microscope capture nano movies
February 10, 2006 | Source: KurzweilAI
Georgia Tech researchers have created a highly sensitive atomic force microscopy (AFM) technology capable of high-speed imaging 100 times faster than current AFM. This technology could prove invaluable for many types of nano-research, in particular for scanning integrated circuits for mechanical and material defects and observing fast biological interactions on the molecular scale, even translating into movies of molecular interactions in real time.
FIRAT probe
FIRAT (Force sensing Integrated Readout and Active Tip) can capture other measurements never before possible with AFM, including material property imaging and parallel molecular assays for drug screening and discovery. It could also speed up semiconductor metrology and even enable fabrication of smaller devices.
FIRAT solves two of AFM’s chief disadvantages as a tool for examining nanostructures: AFM doesn’t record movies and it can’t reveal information on the physical characteristics of a surface, said Dr. Calvin Quate, one of the inventors of AFM and a professor at Stanford University.
The current AFM scans surfaces with a thin cantilever with a sharp tip at the end. An optical beam is bounced off the cantilever tip to measure the deflection of the cantilever as the sharp tip moves over the surface and interacts with the material being analyzed.
In one version of the FIRAT probe, the membrane with a sharp tip moves toward the sample and just before it touches, it is pulled by attractive forces. Much like a microphone diaphragm picks up sound vibrations, the FIRAT membrane starts taking sensory readings well before it touches the sample. And when the tip hits the surface, the elasticity and stiffness of the surface determines how hard the material pushes back against the tip. So rather than just capturing a topography scan of the sample, FIRAT can pick up a wide variety of other material properties in one scan, including topography, adhesion, stiffness, elasticity, and viscosity.
Georgia Tech researchers have been able to use FIRAT with a commercial AFM system to produce clear scans of nanoscale features at speeds as high as 60 Hertz (or 60 lines per second). The same system was used to image the topography as well as elastic and adhesive properties of carbon nanotubes simultaneously, which is another first.