Single molecule force spectroscopy is an important technique to determine the
interaction forces between biomolecules. Atomic force microscopy (AFM) is one of
the tools used for this purpose. So far, AFMs usually use cantilevers as the force
sensors and piezoelectrics as the actuators which may have some drawbacks in terms
of speed and noise.
In this research, a micromachined membrane actuator was used in two important
types of experiments, namely the single molecule pulling and force-clamp based force
spectroscopy. These two methods permit a more direct way of probing the forces
of biomolecules, giving a detailed insight into binding potentials, and allowing the
detection of discrete unbinding forces. To improve the quality of the experiments
there is a need for high force resolution, high time resolution and increase in the
throughput.
This research focuses on using the combination of AFM and membrane based
probe structures that have electrostatic actuation capability. The membrane actuators
are characterized for range, dynamics, and noise to illustrate their adequacy for
these experiments and to show that the complexity they introduce does not affect the
noise level in the system.
The control system described in this thesis utilizes the novel membrane actuator
structures and integrates it into the current AFM setup. This is a very useful tool
which can be implemented on any AFM without changing its mechanical architecture.
To perform an experiment, all that is needed is to place the membrane actuator on
the AFM stage, under the imagining head, and run the control system, which was
implemented using LabVIEW.
The system allows the user to maintain a precise and continuous control of the
force. This was demonstrated by performing a life time experiment using biomolecules.
Moreover, by slightly modifying the control scheme, the system allows us to linearize
the membrane motion, which is inherently non-linear. The feasibility of using this
control system for a variety of loading rate experiments are also demonstrated.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/31669 |
| Date | 17 November 2009 |
| Creators | Finkler, Ofer |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Detected Language | English |
| Type | Thesis |
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