Ebru Demir

Assistant Professor, Lehigh University Department of Mechanical Engineering and Mechanics

About me:

Interdisciplinary researcher enjoying collaborations to solve a variety of engineering problems

Experienced in experimental fluid dynamics, CFD simulations, 3D printing, and micromanufacturing techniques

Lifelong learner with an unlimited supply of curiosity

Latest news:

09/21 - Our paper "Wall-induced translation of a rotating particle in a shear-thinning fluid" is published in Journal of Fluid Mechanics!

Link

05/26 - Our paper "A 3D printed self-learning three-linked sphere robot for autonomous confined space navigation" is on the cover of Advanced Intelligent Systems!

Link

05/20 - I have joined the Society of Women Engineers Mentor Network! If you'd like to chat with a fellow woman engineer, come find me :)

Link
Please contact me if you are interested in full texts of my published works.

Thank you! (Please click anywhere to go back)


demir@lehigh.edu

Academic Positions

  • 10.2021-present

    Assistant Professor, Lehigh University, PA, USA

    5.2021-10.2021

    Inclusive Excellence Postdoctoral Fellow, Santa Clara University, CA, USA

    6.2019-5.2021

    Research Associate, Santa Clara University, CA, USA

    4.2019-5.2021

    Postdoctoral Research Fellow, Computational Science Research Center, Beijing, China

    8.2018-1.2019

    Postdoctoral Research Fellow, Sabanci University, Istanbul, Turkey

Education

Research


Helical Swimming

Low Re Environments, Non-Newtonian Fluids

coming soon

CFD and Experiments

How do they swim?! Stay tuned for details :)


Swimming of Rigid Spheres

Swimming inside Channels and Near Boundaries

coming soon

Medical Devices Exploiting Fluid Flow

Skin mountable and highly sensitive strain tensors

Cavitation for kidney stone treatment

coming soon
coming soon

Heat Transfer From Enhanced Surfaces

Microfabricated surfaces for better cooling of miniaturized electronic devices

coming soon

Interested in combining fluid dynamics with machine learning, particularly, building swimmers that can learn to swim, and using machine learning to reduce the time and computational power required for simulations that solve hard to tackle fluid dynamics problems.

Recent Publications

Wall-Induced Translation of a Rotating Particle in a Shear-Thinning Fluid

JFM Rapids, 927.

Particle–wall interactions have broad biological and technological applications. In particular, some artificial microswimmers capitalize on their translation–rotation coupling near a wall to generate directed propulsion. Emerging biomedical applications of these microswimmers in complex biological fluids prompt questions on the impact of non-Newtonian rheology on their propulsion. In this work, we report some intriguing effects of shear-thinning rheology, a ubiquitous non-Newtonian behaviour of biological fluids, on the translation–rotation coupling of a particle near a wall. One particularly interesting feature revealed here is that the wall-induced translation by rotation can occur in a direction opposite to what might be intuitively expected for an object rolling on a solid substrate. We elucidate the underlying physical mechanism and discuss its implications on the design of micromachines and bacterial motion near walls in complex fluids.

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A 3D-Printed Self-Learning Three-Linked-Sphere Robot for Autonomous Confined-Space Navigation

Advanced Intelligent Systems, 2100039.

Reinforcement learning control methods can impart robots with the ability to discover effective behavior, reducing their modeling and sensing requirements, and enabling their ability to adapt to environmental changes. However, it remains challenging for a robot to achieve navigation in confined and dynamic environments, which are characteristic of a broad range of biomedical applications, such as endoscopy with ingestible electronics. Herein, a compact, 3D-printed three-linked-sphere robot synergistically integrated with a reinforcement learning algorithm that can perform adaptable, autonomous crawling in a confined channel is demonstrated. The scalable robot consists of three equally sized spheres that are linearly coupled, in which the extension and contraction in specific sequences dictate its navigation. The ability to achieve bidirectional locomotion across frictional surfaces in open and confined spaces without prior knowledge of the environment is also demonstrated. The synergistic integration of a highly scalable robotic apparatus and the model-free reinforcement learning control strategy can enable autonomous navigation in a broad range of dynamic and confined environments. This capability can enable sensing, imaging, and surgical processes in previously inaccessible confined environments in the human body.

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Non-Local Shear-Thinning Effects Substantially Enhance Helical Propulsion

Physical Review Fluids, 5, 111301(R), 2020.

Helical propulsion is ubiquitously adopted by swimming bacteria and artificial microswimmers to move in biological fluids, which are typically viscoelastic and shear thinning. Here we present a set of theoretical and computational analyses to show that shear-thinning viscosity alone can cause the substantial enhancement reported for helical propulsion in recent experiments. Our analyses provide direct evidence to elucidate the nonlocal nature of the enhancement mechanism. Since the enhancement predicted here can be more substantial than that due to viscoelasticity, our results also suggest that shear-thinning rheology may play a more dominant role in the observed enhancement of bacterial motility in polymeric fluids.

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Skin Mountable Capillaric Strain Sensor with Ultra-High Sensitivity and Direction Specificity

Advanced Materials Technologies, 5, 2000631, 2020

Microfluidic devices filled with conductive liquids exhibit a unique potential to integrate fluid physics and electronics while maintaining low mechanical load (i.e., extremely soft and stretchable) for skin mounted wearable device applications. Here, a novel microfluidic strain sensing mechanism is presented, which provides a theoretically unlimited tunable gauge factor, directionally specific and linear response, and negligible hysteresis for skin deformation measurements. The control over flow dynamics enables signal filtering, thresholding, and basic logic operations to be performed in the fluidic-domain potentially simplifying the electronic and digital processing components. The capillaric strain sensor technology relies on the ultrahigh electrical resistance modification due to the capillary flow of conductive ionic liquids in response to the elastomeric deformation of silicone microchannels. The directional specificity and ultrahigh sensitivity (e.g., gauge factor > 3000) are demonstrated for distinguishing facial activity types and the subtle differences in facial muscle-strengthening activities.

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Realization of a Push-Me-Pull-You Swimmer at Low Reynolds Numbers

Bioinspiration & Biomimetics, 2020.

Locomotion at low Reynolds numbers encounters stringent physical constraints due to the dominance of viscous over inertial forces. A variety of swimming microorganisms have demonstrated diverse strategies to generate self-propulsion in the absence of inertia. In particular, ameboid and euglenoid movements exploit shape deformations of the cell body for locomotion. Inspired by these biological organisms, the ‘push-me-pull-you’ (PMPY) swimmer (Avron J E et al 2005 New J. Phys. 7 234) represents an elegant artificial swimmer that can escape from the constraints of the scallop theorem and generate self-propulsion in highly viscous fluid environments. In this work, we present the first experimental realization of the PMPY swimmer, which consists of a pair of expandable spheres connected by an extensible link. We designed and constructed robotic PMPY swimmers and characterized their propulsion performance in highly viscous silicone oil in dynamically similar, macroscopic experiments. The proof-of-concept demonstrates the feasibility and robustness of the PMPY mechanism as a viable locomotion strategy at low Reynolds numbers.

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Roads to Smart Artificial Microswimmers

Advanced Intelligent Systems, 2(8), p.1900137, 2020.

Artificial microswimmers offer exciting opportunities for biomedical applications. The goal of these synthetics is to swim like natural micro‐organisms through biological environments and perform complex tasks such as drug delivery and microsurgery. Extensive efforts in the past several decades have focused on generating propulsion at the microscopic scale, which has engendered a variety of artificial microswimmers based on different physical and physicochemical mechanisms. Yet, these major advancements represent only the initial steps toward successful biomedical applications of microswimmers in realistic scenarios. A next step is to design “smart” microswimmers that can adapt their locomotion behaviors in response to environmental factors. Herein, recent progress in the development of microswimmers with intelligent behaviors is surveyed in three major areas: 1) adaptive locomotion across different media, 2) tactic behaviors in response to environment stimuli, and 3) multifunctional swimmers that can perform complex tasks. The emerging technologies and novel approaches used in developing these “smart” microswimmers, which enable them to display behaviors similar to biological cells, are discussed.

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Wall-Induced Translation of a Rotating Particle in a Shear-Thinning Fluid

Chen*, Y., Demir*, E., Gao, W., Young, Y.-N., Pak, O.S.
Journal of Fluid Mechanics, 927.

* Co-first authors listed alphabetically

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A 3D Printed Self-Learning Three-Linked Sphere Robot for Autonomous Confined Space Navigation

Elder, B., Zou, Z., Ghosh, S., Silverberg, O., Greenwood, T., Demir, E. , Su, V.S.-E., Miranda, A., Pak, O.S., Kong, Y.L.
Advanced Intelligent Systems, 2100039

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Non-Local Shear-Thinning Effects Substantially Enhance Helical Propulsion

Demir, E., Lordi, N., Ding, Y. and Pak, O.S.
Physical Review Fluids, 5, 111301(R), 2020.

Read the Article

Skin Mountable Capillaric Strain Sensor with Ultra-High Sensitivity and Direction Specificity

Yepes, L.R., Demir, E., Lee, J.Y., Sun, R., Smuck, M.W. and Araci, I.E.
Advanced Materials Technologies, 2020.

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Realization of a Push-Me-Pull-You Swimmer at Low Reynolds Numbers

Silverberg, O., Demir, E., Mishler, G., Hosoume, B., Trivedi, N.R., Tisch, C., Plascencia, D., Pak, O.S. and Araci, I.E.
Bioinspiration & Biomimetics, 15(6), 2020.

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Roads to Smart Artificial Microswimmers

Tsang, A.C., Demir, E., Ding, Y. and Pak, O.S.
Advanced Intelligent Systems, 2(8), p.1900137, 2020.

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Low Reynolds Number Swimming of Helical Structures in Circular Channels

Demir, E., Yesilyurt, S.
Journal of Fluids and Structures, 74, pp. 234-246, 2017.

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Assessment of Probe-to-Specimen Distance Effect in Kidney Stone Treatment with Hydrodynamic Cavitation

Uzusen, D., Demir, E.,, Perk, O.Y., Oral, O., Ekici, S., Unel, M., Gozuacik, D., Kosar, A.
ASME Journal of Medical Devices, 2015.

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The Effect of Nanostructure Distribution on Subcooled Boiling Heat Transfer Enhancement on Nanostructured Plates Integrated into a Rectangular Channel

Demir, E., Izci, T., Khudhayer, W., Alagoz, A.S., Karabacak, T., and Kosar, A.
Nanoscale and Microscale Thermophysical Engineering, 18, pp. 313-328, 2014 (Cover Article).

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Effect of Silicon Nanorod Length on Horizontal Nanostructured Plates in Pool Boiling Heat Transfer with Water

Demir, E., Izci, T., Alagoz, A.S., Karabacak, T., and Kosar, A.
Journal of Thermal Sciences, 82, pp.111-121, 2014.

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Hydrodynamic Cavitation Kills Prostate Cells and Ablates Benign Prostatic Hyperplasia Tissue

Itah, Z., Oral, O., Perk, O. Y., Sesen, M., Demir, E., Erbil, S., Dogan-Ekici A.I., Ekici S., Kosar, A., Gozuacik, D.
Experimental Biology and Medicine, 2013.

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Jet Impingement Cooling of Nanostructured Plates

Sesen, M., Demir, E., Izci, T., Khudhayer, W., Karabacak, T., Kosar A.
International Journal of Heat and Mass Transfer, 59, pp. 414-422, 2013.

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The Effect of Particle Geometry on Swimming in a Shear-Thinning Fluid

van Gogh, B., Demir, E., Palaniappan, D. and Pak, O.S.
Bulletin of the American Physical Society, 2021.

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Modeling Helical Swimming in Shear-Thinning Fluids

Lordi, N., Demir, E., Ding, Y. and Pak, O.S.
Bulletin of the American Physical Society, 64, 2019.

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Rolling and Sliding of Spheres Inside Horizontal Channels

Demir, E., and Yesilyurt, S.
International Conference on Manipulation, Automation and Robotics at Small Scales, Nagoya, Japan, July 2018.

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Propulsion by Helical Strips in Circular Channels

Demir, E., and Yesilyurt, S.
Bulletin of the American Physical Society, 61, 2016.

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Geometric Optimization of Helical Tail Designs to Calibrate Swimming Velocities of Microswimmers

Demir, E., and Yesilyurt, S.
Bulletin of the American Physical Society, 59, 2014.

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Subcooled Flow Boiling Over Nanostructured Plate Integrated into a Rectangular Channel

Demir, E., Izci, T., Sesen, M., Khudhayer, W., Karabacak, T., and Kosar, A.
Proceedings of the ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels, Sapporo, Japan, June 2013.

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Multiphase Submerged Jet Impingement Cooling Utilizing Nanostructured Plates

Demir, E., Izci, T., Perk, O.Y., Sesen, M., Khudhayer, W., Karabacak, T., and Kosar, A.
Proceedings of the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels, Puerto Rico, July 2012.

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A Compact Pool Boiler Utilizing Nanostructures for Microscale Cooling Applications

Izci, T., Demir, E., Izci, T., Alagoz, A.S., Karabacak, T. and Kosar, A.
Proceedings of 8th ECI International Conference on Boiling and Condensation, Lausanne, Switzerland, June 2012.

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Jet Impingement Cooling of Nanostructured Plates

Sesen, M., Kosar, A., Demir, E., Kurtoglu, E., Kaplan, N., Erk, H.C., Khudhayer, W. and Karabacak, T.
ASME International Mechanical Engineering Congress &s; Exposition, Vancouver, Canada, November 2010.

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Teaching

Contact

    Dr. Ebru Demir

  • Lehigh University
  • P.C. Rossin College of Engineering and Applied Science
  • Department of Mechanical Engineering and Mechanics

demir@lehigh.edu Office: 610-758-4494
  • Packard Laboratory 562
  • 19 Memorial Drive West
  • Bethlehem, PA 18015