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Rohan's Project Page - RISE summer 2005 |
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Intern: Rohan Patel, Electrical Engineering, University of California, Santa Barbara
Mentor: Georg Fantner
Faculty Supervisor: Paul Hansma
Department: Physics |
NANOSCALE MANIPULATION OF BIOLOGICAL MATERIALS
Atomic force microscopy (AFM) has the ability to take high resolution
topographic images. Continued development in the field has led to a demand
for an AFM system capable of both nanoscale surface modification as well as
single molecule manipulation. On this scale, with the piezoelectric
scanner alone, issues such as hysteresis arise giving us limited
positional accuracy of the cantilever tip. The addition of a strain-gauge
closed-loop controller minimizes the nonlinearity and hysteresis effects.
This advancement allows for better positioning resulting in more accurate
surface modifications and manipulations. Scan speeds of the AFM have also
been improved with the use of much smaller cantilevers corresponding to
a resonant frequency two orders of magnitude greater than larger cantilevers.
To control this faster and more accurate system, we developed a new control
environment capable of imaging at 50Hz line rate at an imaging resolution
of 512 by 512 pixels. For manipulation applications, we control the z-movement
of the cantilever tip with respect to the sample, allowing us to accurately
indent and pull on the surface. We look forward to combining these new AFM
techniques to create a new imaging and control system capable of greatly
surpassing the abilities of current commercial products.
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