Current Research Activities

Current research activities in the Department of Mechanical Engineering are in the areas of controls and robotics, energy and micropower generation, fluid mechanics, heat/mass transfer, mechanics of materials, manufacturing, material processing, MEMS, nanotechnology, and orthopedic biomechanics.

Biomechanics and Mechanics of Materials. Some of the current research in biomechanics is concerned with the application of continuum theories of mixtures to problems of electromechanical behavior of soft biological tissues, contact mechanics, lubrication of diarthrodial joints, and cartilage tissue engineering. (Ateshian)
In the area of the mechanics of materials, research is performed to better understand material constitutive behavior at the micro- and mesolength scales. This work is experimental, theoretical, and computational in nature. The ultimate goal is to formulate constitutive relationships that are based on physical concepts rather than phenomenology, as in the case of plasticity power-law hardening. In addition, the role that the constitutive relations play in the fracture and failure of materials is emphasized. (Kysar)
In the area of molecular mechanics in biology, mechanical effects on stem cell differentiation is studied to understand the underlying molecular mechanisms. The molecular motion in living cells is monitored to examine how the dynamics of molecules determine the specificity of stem cell differentiation. Mechanics of molecular motors is studied to correlate their functions with cell differentiation. (Liao)
Other areas of biomechanics include characterizing the structure-function behavior of the cervix during the remodeling events of pregnancy and characterizing the mechanical properties of the eye-wall in relation to glaucoma. Research in our lab includes the mechanical testing of biological soft tissues, the biochemical analysis of tissue microstructure, and material modeling based on structure-mechanical property relationships. In collaboration with clinicians, our goal is to understand the etiologies of tissue pathology and disease. (Myers)

Control, Design, and Manufacturing. Control research emphasizes iterative learning control (ILC) and repetitive control (RC). ILC creates controllers that learn from previous experience performing a specific command, such as robots on an assembly line, aiming for high-precision mechanical motions. RC learns to cancel repetitive disturbances, such as precision motion through gearing, machining, satellite precision pointing, particle accelerators, etc. Time optimal control of robots is being studied for increased productivity on assembly lines through dynamic motion planning. Research is also being conducted on improved system identification, making mathematical models from input-output data. The results can be the starting point for designing controllers, but they are also studied as a means of assessing damage in civil engineering structures from earthquake data. (Longman)
In the area of advanced manufacturing processes and systems, current research concentrates on laser materials processing. Investigations are being carried out in laser micromachining; laser forming of sheet metal; microscale laser shock-peening, material processing using improved laser-beam quality. Both numerical and experimental work is conducted using state-of-the-art equipment, instruments, and computing facilities. Close ties with industry have been established for collaborative efforts. (Yao)

Energy, Fluid Mechanics, and Heat/Mass Transfer. In the area of energy, one effort addresses the design of flow/mass transport systems for the extraction of carbon dioxide from air. Another effort addresses the development of distributed sensors for use in micrositing and performance evaluation of energy and environmental systems. The design and testing of components and systems for micropower generation is part of the thermofluids effort as well as part of the MEMS effort. (Modi)
In the area of fluid mechanics, study of low-Reynolds-number chaotic flows is being conducted both experimentally and numerically, and the interactions with molecular diffusion and inertia are presently being investigated. Other areas of investigation include the fluid mechanics of inkjet printing, drop on demand, the suppression of satellite droplets, shock wave propagation, and remediation in high-frequency printing systems. (Modi)
In the area of nanoscale thermal transport, our research efforts center on the enhancement of thermal radiation transport across interfaces separated by a nanoscale gap. The scaling behavior of nanoscale radiation transport is measured using a novel heat transfer measurement technique based on the deflection of a bimaterial atomic force microscope cantilever. Numerical simulations are also performed to confirm these measurements. The measurements are also used to infer extremely small variations of van der Waals forces with temperature. This enhancement of radiative transfer will ultimately be used to improve the power density of thermophotovoltaic energy conversion devices. (Narayanaswamy)
Research in the area of tribology—the study of friction, lubrication, and wear—focuses on studying the wear damage and energy loss that is experienced in power generation components such as piston rings, fuel injection systems, geartrains, and bearings. Next-generation lubricants, additives, surface coatings, and surface finishes are being studied in order to determine their effects on friction and wear. Additionally, environmentally friendly lubricants are also being identified and characterized. (Terrell)

MEMS and Nanotechnology. In these areas, research activities focus on power generation systems, nanostructures for photonics, fuel cells and photovoltaics, and microfabricated adaptive cooling skin and sensors for flow, shear, and wind speed. Basic research in fluid dynamics and heat/mass transfer phenomena at small scales also support these activities. (Hone, Lin, Modi, Narayanaswamy, Wong)
We study the dynamics of microcantilevers and atomic force microscope cantilevers to use them as microscale thermal sensors based on the resonance frequency shifts of vibration modes of the cantilever. Bimaterial microcantilever-based sensors are used to determine the thermophysical properties of thin films. (Narayanaswamy)
Research in the area of nanotechnology focuses on nanomaterials such as nanotubes and nanowires and their applications, especially in nanoelectromechanical systems (NEMS). A laboratory is available for the synthesis of carbon nanotubes and semiconductor nanowires using chemical vapor deposition (CVD) techniques and to build devices using electron-beam lithography and various etching techniques. This effort will seek to optimize the fabrication, readout, and sensitivity of these devices for numerous applications, such as sensitive detection of mass, charge, and magnetic resonance. (Hone, Wong, Modi)
In the area of nanoscale imaging in biology, a superresolution microscopy (nanoscopy) system is built to break the diffraction limit of light. The superresolution microscopy system is to be used to observe molecular dynamics in living cells. A high-speed scanning system is designed and implemented to track molecular dynamics in a video rate. Control of sample motion in nanometer resolution is achieved by integrating single photon detection and nanopositioning systems. (Liao)
Research in the area of optical nanotechnology focuses on devices smaller than the wavelength of light, for example, in photonic crystal nanomaterials and NEMS devices. A strong research group with facilities in optical (including ultrafast) characterization, device nanofabrication, and full numerical intensive simulations is available. Current efforts include silicon nanophotonics, quantum dot interactions, negative refraction, dramatically enhanced nonlinearities, and integrated optics. This effort seeks to advance our understanding of nanoscale optical physics, enabled now by our ability to manufacture, design, and engineer precise subwavelength nanostructures, with derived applications in high-sensitivity sensors, high-bandwidth data communications, and biomolecular sciences. Major ongoing collaborations across national laboratories, industrial research centers, and multiuniversities support this research. (Wong)
Research in the area of microtribology—the study of friction, lubrication, and wear at the microscale—analyzes the surface contact and adhesive forces between translating and rotating surfaces in MEMS devices. Additionally, the tribological behavior between sliding micro- and nano-textured surfaces is also of interest, due to the prospects of enhanced lubrication and reduced friction. (Terrell)
Research in BioMEMS aims to design and create MEMS and micro/nanofluidic systems to control the motion and measure the dynamic behavior of biomolecules in solution. Current efforts involve modeling and understanding the physics of micro/ nanofluidic devices and systems, exploiting polymer structures to enable micro/nanofluidic manipulation, and integrating MEMS sensors with microfluidics for measuring physical properties of biomolecules. (Lin)

Biological Engineering and Biotechnology. Active areas of research in the musculoskeletal biomechanics laboratory include theoretical and experimental analysis of articular cartilage mechanics; theoretical and experimental analysis of cartilage lubrication, cartilage tissue engineering, and bioreactor design; growth and remodeling of biological tissues; cell mechanics; and mixture theory for biological tissues with experiments and computational analysis (Ateshian).
The Hone group is involved in a number of projects that employ the tools of micro- and nanofabrication toward the study of biological systems. With collaborators in biology and applied physics, the group has developed techniques to fabricate metal patterns on the molecular scale (below 10 nanometers) and attach biomolecules to create biofunctionalized nanoarrays. The group is currently using these arrays to study molecular recognition, cell spreading, and protein crystallization. Professor Hone is a co-PI of the NIH-funded Nanotechnology Center for Mechanics in Regenerative Medicine, which seeks to understand and modify at the nanoscale force- and geometry-sensing pathways in health and disease. The Hone group fabricates many of the tools used by the center to measure and apply force on a cellular level. (Hone)
In the area of molecular bioengineering, proteins are engineered to understand their mechanical effects on stem cell differentiation. Molecular motors are designed and engineered computationally and experimentally to identify key structural elements of motor functions. Fluorescent labels are added to the molecules of interest to follow their dynamics in living cells and to correlate their mechanical characteristics with the process of stem cell differentiation. (Liao)
Microelectromechanical systems (MEMS) are being exploited to enable and facilitate the characterization and manipulation of biomolecules. MEMS technology allows biomolecules to be studied in well-controlled micro/nanoenvironments of miniaturized, integrated devices, and may enable novel biomedical investigations not attainable by conventional techniques. The research interests center on the development of MEMS devices and systems for label-free manipulation and interrogation of biomolecules. Current research efforts primarily involve microfluidic devices that exploit specific and reversible, stimulus-dependent binding between biomolecules and receptor molecules to enable selective purification, concentration, and label-free detection of nucleic acid, protein, and small molecule analytes; miniaturized instruments for label-free characterization of thermodynamic and other physical properties of biomolecules; and subcutaneously implantable MEMS affinity biosensors for continuous monitoring of glucose and other metabolites. (Lin)
Mass radiological triage is critical after a large-scale radiological event because of the need to identify those individuals who will benefit from medical intervention as soon as possible. The goal of the ongoing NIH-funded research project is to design a prototype of a fully automated, ultra high throughput biodosimetry. This prototype is supposed to accommodate multiple assay preparation protocols that allow the determination of the levels of radiation exposure that a patient received. The input to this fully autonomous system is a large number of capillaries filled with blood of patients collected using finger sticks. These capillaries are processed by the system to distill the micronucleus assay in lymphocytes, with all the assays being carried out in situ in multi-well plates. The research effort on this project involves the automation system design and integration including hierarchical control algorithms, design and control of custom built robotic devices, and automated image acquisition and processing for sample preparation and analysis. (Yao)
A technology that couples the power of multidimensional microscopy (three spatial dimensions, time, and multiple wavelengths) with that of DNA array technology is investigated in an NIH-funded project. Specifically, a system is developed in which individual cells selected on the basis of optically detectable multiple features at critical time points in dynamic processes can be rapidly and robotically micromanipulated into reaction chambers to permit amplified DNA synthesis and subsequent array analysis. Customized image processing and pattern recognition techniques are developed, including Fisher’s linear discriminant preprocessing with neural net, a support vector machine with improved training, multiclass cell detection with error correcting output coding, and kernel principal component analysis. (Yao)

Facilities for Teaching and Research

The undergraduate laboratories, occupying an area of approximately 6,000 square feet of floor space, are the site of experiments ranging in complexity from basic instrumentation and fundamental exercises to advanced experiments in such diverse areas as automatic controls, heat transfer, fluid mechanics, stress analysis, vibrations, microcomputer-based data acquisition, and control of mechanical systems.
Equipment includes microcomputers and microprocessors, analog-to-digital and digital-to-analog converters, lasers and optics for holography and interferometry, a laser-Doppler velocimetry system, a Schlieren system, dynamic strain indicators, a servohydraulic material testing machine, a photoelastic testing machine, an internal combustion engine, a dynamometer, subsonic and supersonic wind tunnels, a cryogenic apparatus, computer numerically controlled vertical machine centers (VMC), a coordinate measurement machine (CMM), and a rapid prototyping system. A CNC wire electrical discharge machine (EDM) is also available for the use of specialized projects for students with prior arrangement. The undergraduate laboratory also houses experimental setups for the understanding and performance evaluation of a complete small steam power generation system, a heat exchanger, a solar cell system, a fuel cell system, and a compressor. Part of the undergraduate laboratory is a staffed machine shop with machining tools such as standard vertical milling machines, engine and bench lathes, programmable surface grinder, band saw, drill press, tool grinders, and a power hacksaw. The shop also has a tig welder.
A mechatronics laboratory affords the opportunity for hands-on experience with microcomputer-embedded control of electromechanical systems. Facilities for the construction and testing of analog and digital electronic circuits aid the students in learning the basic components of the microcomputer architecture. The laboratory is divided into work centers for two-person student laboratory teams. Each work center is equipped with several power supplies (for low-power electronics and higher power control), a function generator, a multimeter, a protoboard for building circuits, a microcomputer circuit board (which includes the microcomputer and peripheral components), a microcomputer programmer, and a personal computer that contains a data acquisition board. The data acquisition system serves as an oscilloscope, additional function generator, and spectrum analyzer for the student team. The computer also contains a complete microcomputer software development system, including editor, assembler, simulator, debugger, and C compiler. The laboratory is also equipped with a portable oscilloscope, an EPROM eraser (to erase microcomputer programs from the erasable chips), a logic probe, and an analog filter bank that the student teams share, as well as a stock of analog and digital electronic components.
The department maintains a modern computer-aided design laboratory equipped with fifteen Silicon Graphics workstations and software tools. The research facilities are located within individual or group research laboratories in the department, and these facilities are being continually upgraded. To view the current research capabilities please visit the various laboratories within the research section of the department website. The students and staff of the department can, by prior arrangement, use much of the equipment in these research facilities. Through their participation in the NSF-MRSEC center, the faculty also have access to shared instrumentation and the clean room located in the Schapiro Center for Engineering and Physical Science Research. Columbia University’s extensive library system has superb scientific and technical collections.