(6ex) Active Soft Matters and Soft Interfaces

My main research interest is in biological active soft material focusing on 1) colloidal motion near and on active biological interfaces and 2) hydrodynamic interaction of active colloids with soft surfaces. I have spent my research career advancing state of art techniques to image colloids such as bacteria in 3-d and to quantitatively determine the mechanical properties of complex and heterogeneous soft matters such as living cells. In addition to successfully developing state of art techniques, I am very interested in implementing these techniques to explain the physics of many complex active systems. Previously, implementing a robust 3-d particle tracking method using Digital Holographic Microscopy, I have shown that the hydrodynamic forces induced by the solid surfaces and ow shears strongly alters the ability of the wild-type Escherichia coli to tumble. I have also studied how the hydrodynamic and physiochemical boundary condition at interfaces alter bacterial motility. In this line of research, I have focused on the motion of Pseudomonas cells on the oil-water interfaces and their encounter phenomena with oil droplets. I am also very interested in the motion of colloids over membranes of active soft matters such as living cells. It has been well stablished that the mechanical structure of the cells and their mechanosensing ability play important roles in their biological functions. Tracking the 3-d orientation and motion of gold nanorods on the plasma membrane using state of art Dark Field Microscope, I am trying to measure its viscoelastic response, bending modulus, and stiffness. Throughout my research carrier I have planned my future research to address two main issues.

I. Physical interaction of bacteria with planktonic and sessile life style with bio-inspired interfaces:

In this research area, I aim at fundamental understanding of the relation between complex mechanical structure of the surfaces that covers the internal organs of the human body and bacterial behavior near and on these surfaces. Mucous membranes of digestive, respiratory, and urogenital tissues which establish the rst barrier to limit the invasion by bacteria, have a complex structures with diverse length scales. Furthermore, the mucosal environment in proximity of these membranes have a complex viscoelastic characteristic. These complex membrane structure and the viscoelasticity of mucus can strongly aect bacterial locomotion, surface attachment, and biolm formation. My main goal in this line of research is to study these interactions using well controlled lab on a chip platforms and advanced imaging techniques.

II. Rheological characterization of active biological interfaces:

Many biological soft materials are far from equilibrium. Many of these active materials are uids or deformable solids with complex viscoelastic responses. This complexity is partially due to their heterogeneous and convoluted structures and partially is due to their activity. Therefore, wide range of mechanisms with wide range of length scales need to be explored to explain mechanical behavior of active soft materials. Over the years, many instruments and techniques have been developed to study soft materials. For example, active and passive microrheology, atomic force measurement (AFM), rheometry, or micro pipet aspiration have been utilized to study rheology of living cells and have provided treasured knowledge in cell mechanics. My research in this eld aims to extend active and passive microrheology to nanometer length scales and microseconds time scale to explore active phenomena closer to molecular motor levels.

Teaching Interests:

I strongly believe that engineering students should learn how to encounter and internalize new concepts in their academic lives to be prepared to face dierent challenges and problems in their professional lives as researchers or engineers. My teaching philosophy therefore is while learning new course topics, students should also practice to teach themselves. While I was a M.Sc. student in Aerospace Engineering and also during my Ph.D program in Mechanical Engineering, I had to learn great deal about microbiology to perform my research on bacterial locomotion. Later on as a postdoc researcher in the Chemical Engineering Department, I had too teach myself cell biology. These experiences showed me the value of the self teaching. I intend to engage the students in the teaching process by assigning smaller projects to them. Students will need to present the way they approach the problem and teach what they learned to their classmates.

Following my teaching philosophy, I plan to engage research in my teaching. Performing experiments, analyzing data, or surveying literature can help students to get involved in advanced topics and higher education experiences. Having research experiences can form a strong learning platform for students. Exploring research environment shows students how they can employ course materials in solving research problems. Although performing specic research project in a short period of time could be challenging I have great experiences in the Research Experience for Undergraduate (REU) program. Through Summer REU Programs, I successfully trained 6 undergraduate fellows to perform experiments, analyze data, interpret the result and present the research during a short period of time.

I have established a solid background in Chemical and Mechanical Engineering and in the eld of Biophysics. At this interface between engineering and biophysics, my research leverages many disciplines including advanced imagining, cell mechanics, and advanced rheology. These experiences will allow me to teach courses like Transports, Fluid Mechanics, Biotechnology, and BioFluid. I am also very interested to develop new interdisciplinary courses to contribute to the department curriculum.