February 23, 2011 Wednesday 15:30
Hamdi Torun, Boğaziçi University
Microsystem Development for Single-Molecule Measurements

Abstract: Atomic force microscope (AFM) is widely used to measure single-molecular interactions with sub-nano sensitivity. In this technique, a single biological bond between a specimen on the sharp tip of an AFM cantilever and another specimen on a substrate can be loaded and its basic characteristics such as the strength and life-time can be measured. In this talk, I will describe our research efforts on the development of micro-probes using MEMS technology for improved AFM applications. We introduced and demonstrated membrane-based active probe structures with electrostatic actuation and integrated diffraction-based optical interferometric force detection for single-molecular force measurements. The actuation range of the membrane is adequate for a wide range of biomolecular experiments and within this range it is possible to actuate the membrane fast, with negligible hydrodynamic drag. Actuating these membrane probes and using a cantilever coupled to the membrane, we demonstrated fast pulling experiments with an order of magnitude faster than achieved by regular AFM systems. The displacement noise spectral density for the probe was measured to be below 10 fm/√Hz for frequencies as low as 3 Hz. This noise floor provides a force sensitivity of 0.3 – 3 pN with 1 kHz bandwidth using membranes with spring constants of 1 – 10 N/m. This low inherent noise has a potential to probe wide range of biomolecules and to investigate interesting phenomena such as catch bonds. I will also present our efforts for the development of a novel thermomechanical IR detector. We successfully acquired thermal images using the IR detector arrays with diffraction grating interferometer based readout. Thermal design and array readout techniques developed in this project have implications for the development of including but not limited to biological microsensors.

Biography: Dr. Hamdi Torun is an assistant professor at The Department of Electrical and Electronics Engineering, Boğaziçi University, Istanbul, Turkey. His research interests include microsystems development for biological applications, atomic force microscopy, and infrared imagers. He received the B.S. degree in electrical and electronics engineering from Middle East Technical University, Ankara, Turkey, in 2003, the M.S. degree in electrical and computer engineering from Koc University, Istanbul, Turkey, in 2005, and the Ph.D. degree in electrical and computer engineering from the Georgia Institute of Technology, Atlanta, in 2009. He worked as a postdoctoral fellow in the Woodruff School of Mechanical Engineering, Georgia Institute of Technology from 1/2010 to 9/2010. He has actively involved with industrial projects. Currently, he is a consultant for Arcelik R&D, Istanbul. Previously he was a consultant for Aselsan Inc., Ankara, Turkey (2006-2008). From 2002 to 2003, he was an Intern and then a R&D Engineer at Aselsan Inc., Ankara, Turkey.