Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Electrical and Computer Engineering


Dr. Mehrdad Moallem

Second Advisor

Dr. Rajni V. Patel


The Interfacial Force Microscope (IFM) is a modification of the Atomic Force Micro­ scope (AFM) which works on the basis of a force-balancing capacitive sensor. It was originally developed for measuring force-displacement curves in studying surface prop­ erties of materials. Furthermore, IFM can be used in topography measurements and nanomanipulation. IFM has superior capabilities over other members of the Scanning Probe Microscope (SPM) family for biomedical applications. This is mainly because of its longer and more rigid tip, which makes it easy to use inside live cells without significant changes in its characteristics.

Performance of the current IFM system is limited by the sensor’s dynamic be­ haviour and its controller. In this thesis, a new control scheme and actuation mech­ anism is developed in order to achieve higher performance for existing microscopes. This is done by replacing the conventional analog controller with an advanced digital controller and a novel actuation scheme. To improve the sensitivity of the sensor, an optical interferometer is introduced to measure the deflection of the common plate of the IFM sensor.

The proposed controller and actuation scheme improve the dynamic range of the force measurement device and reduce the time to setup and fine tune the IFM, hence simplifying its operation. Using the interferometry technique increases the accuracy of force measurement and also reduces the complexity of the system. Experimental results are presented that confirm analytical developments.



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