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Raman Research Group

Vibrations and nonlinear dynamics research at emerging frontiers of science and engineering

Our research uses the principles of nonlinear dynamics, vibrations, nonlinear mechanics, and fluid-structure interaction to study important and interdisciplinary problems in science and engineering.

As one example, our studies of the nonlinear oscillations of microcantilevers in atomic force microscopy (AFM) are helping scientists worldwide in nanoscience and nanotechnology to interpret images, and improve metrology, speed, and compositional contrast while scanning over a wide range of samples such as living cells, bacteria, viruses, composite materials, and semiconductor devices. Using this knowledge, we are working with biophysicists in developing new AFM based tools for biomechanical assays of living cells and viruses with the ultimate goal of helping cancer specialists and scientists understand the mechanical properties of cancer cells and viruses. Ultimately, the hope is that nanomechanical assays of cells, bacteria, and viruses can help personalized medicine and the early detection of disease. We developed and run the Virtual Environment for Dynamic Atomic Force Microscopy (VEDA) off, which is currently one of the most used AFM simulation softwares in the world.


In another example we are studying the nonlinear dynamics of micro-electromechanical systems (MEMS) such as radio-frequency (RF) switches that could be used in weapons stockpiles and high-performance wireless communication systems in order to improve their reliability and to monitor their health.


As another example we are working with the department of human kinesiology to consider how nonlinear dynamics can be used to reduce risk of fall of the billion plus prople who are either elderly, or suffer from neurological disease (Alzheimer's, Parkinson's, Multiple sclerosis, etc.), or from plantar neuropathy due to diabetes, or are recovering from concussions, stroke, or cancer treatment. We presenting new ways of identifying from experimental measurements of human sway (upright oscillations) whether or not a subject may suffer from neuromuscular disorders such as Parkinson’s disease or multiple sclerosis or may be particularly susceptible to stumbling and falling. We have built a robotic balance board with tunable stiffness and timedelay to help customize balance training for populations with balance deficits.


Temperature field of an axially moving PET web under Gaussian shaped heat flux with speed from 0 to 6m/min

The era of Internet of Things (IoT) requires the development and deployment of extremely low-cost printable sensors and communication devices. Roll-to-Roll flexible electronics manufacturing is a rapidly developing industry these days with the goal to print functional devices and sensors on flexible substrates at scale and extreemely lo costs. In this research we are focusing on the thermomechanics and vibrations of thin flexible webs with printing, heating, coating, curing, and drying processes typical of flexible electronics manufacturing and nanomanufacturing applications. The goal is to improve quality control and stability of these manufacturing process as throughputs continue to increase.

The students and postdocs in the group have a strong foundation in dynamics, vibrations, solid and fluid mechanics, and creative, open minds for learning new research areas beyond the traditional mechanical engineering applications. The research is carried out in the DSSL (Dynamic Systems and Stability Lab) in Rm. 246, ME Bldg, and in two AFM Labs and the DAMN lab (Dynamic analysis of micro- and nanosystems) at the Birck Nanotechnology Center.

Active research grants

NSF, CMMI, GOALI: Multi-frequency dynamics in the Atomic Force Microscope, 2017-2020, $ 542K. PI, co-I’s A. Bajaj and R. Reifenberger.

NSF, Scalable Nanomanufacturing Program, Large scale manufacturing of low-cost functionalized carbon nanomaterials for energy storage and biosensor applications, 2013-2017, $1.487M, PI, co-I's T. Fisher, A. Wei, A. Alexeenko, E. Bae.

NSF, Nonlinear Dynamics and Bifurcations of Human Posture on Tunable Balance Boards, 2013-2016, $550K, PI, co-I's S. Rietdyk, J. Haddad, H. Zelaznik.


Past research has been supported by the following agencies and industrial sponsors

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