The Ghodssi Group
- Based in:
The MEMS Sensors and Actuators Lab (description | web site ») - About Reza Ghodssi
- Group Members' Areas of Research
- Alumni
- Presentations
- Biochip Collaborative Publications »
Featured Image: MEMS microfluidic device demonstrating the in-plane coupling of blue laser light through the patterned waveguides. (Peter Dykstra)
The Ghodssi group is focused on the design, fabrication and testing of MEMS based sensors to assist in the detection of various chemical compounds formed during the bacterial production of AI-2. Its devices make use of both optical and mechanical sensing methodologies. These lab-on-a-chip devices allow for sensitive, high-throughput testing of low-volume liquid samples at a low cost per chip.
Microfabrication enables patterned surfaces and three-dimensional structures to be constructed with precise spatial selectivity. Biomolecules (proteins and nucleic acids) offer exquisite capabilities for molecular recognition and sensing. Together, microfabrication and biotechnology offer the potential for the creation of miniaturized devices with enhanced abilities to sense contaminants, diagnose diseases, and screen drugs (e.g. MEMS Bio-Sensor). A current limitation is the integration of the biological system with the inorganic surface of typical devices. Through the Maryland Biochip Collaborative project, the group is exploring an amine-rich biopolymer—the polysaccharide chitosan—as an interface material that can be templated onto patterned surfaces and can be covalently coupled with sensing biomolecules.
Reza Ghodssi
Herbert Rabin Distinguished Professor Reza Ghodssi (Ph.D., University of Wisconsin-Madison 1996) is the Director of the Institute for Systems Research (ISR) and holds a joint appointment with the Department of Electrical and Computer Engineering. Heis an affiliate of the Fischell Department of Bioengineering, the Maryland NanoCenter, the University of Maryland Energy Research Center, and the Department of Materials Science and Engineering. He is also the Director of the MEMS Sensors and Actuators Lab.
Dr. Ghodssi's research interests are in the design and development of microfabrication technologies and their applications to micro/nano devices and systems for chemical and biological sensing, small-scale energy conversion and harvesting.
Contact Information:
- Phone: (301) 405-8158
- E-mail: ghodssi@umd.edu
Related External Links:
- Dr. Ghodssi's homepage »
- Dr. Ghodssi's web site »
- The Institute for Systems Research (ISR) »
- The Department of Electrical and Computer Engineering »
- The Fischell Department of Bioengineering »
- The Maryland NanoCenter »
- The Department of Materials Science and Engineering »
Group Members' Areas of Research
Hadar Ben-Yoav
Hadar Ben-Yoav is a post-doctorate fellow at the MEMS Sensors and Actuators Lab (MSAL) in the Department of Electrical and Computer Engineering (ECE) at the University of Maryland (UMD). Hadar's research interests are in the design and the development of micro/nano devices and their applications for chemical and biological sensing and small-scale energy conversion. Hadar received his B.Sc. degree (2004) in Physics and Biology, M.Sc. (2006) in Biotechnology and Ph.D. degree (2010) in Electrical Engineering from Tel Aviv University, Israel. During his M.Sc. degree, he studied the antimicrobial activity of silver-glucose oxidase hybrid on microbial biofilms. His Ph.D. thesis was focused on development of electrochemical low profile whole-cell biochips. In his thesis a portable whole-cell biochip was devised to allow water acute and geno-toxicity monitoring including the whole-cell functionality and signal modeling, chip design, and cell deposition and manipulation with external electric fields. Hadar is an active member of the International Society of Electrochemistry (ISE) and the Electrochemical Society (ECS), and he is the founder and the first chairman of the Tel Aviv University Student Chapter of the Electrochemical Society (2008-2010). He joined MSAL in April 2011 and his current research is in the development of bio-MEMS devices for sensing applications and their integration with micro-scale energy harvesting and conversion devices.
Figure. 1 Photo of an integrated electrochemical sensing electrodes
Figure 2: Package of the microfluidic valve actuated electrochemical sensor
Thomas Winkler
Thomas Winkler received his Diplom in biophysics from the Johannes Kepler University in Linz, Austria in January of 2011. His thesis was on the manipulation of the carrier concentration in certain dilute magnetic semiconductors. Thomas was awarded a Fulbright Scholarship to pursue his Ph.D. degree in the United States from Fall 2011. He is enrolled in the Fischell Department of Bioengineering program, and joined MSAL in Spring 2012. Here, Thomas' research is geared toward developing a BioMEMS device utilizing electrochemical sensing methods to assist in schizophrenia treatment planning and monitoring, specifically related to the second-line drug clozapine
Young Wook Kim
Young is developing an implantable bacterial biofilm Surface Acoustic Wave (SAW) sensor for real time biofilm growth monitoring. The motivation of the work is to design a sensor which monitors in-vivo bacterial biofilms, especially in artificial implant sites, using wireless and highly sensitive methods to alert patients to a developing infection. The SAW sensor detects a biofilm through the resonant frequency shift due to mass accumulation on the surface of the sensor. All of the sensor materials are biocompatible, and the operational frequency is designed to meet wireless medical device regulations set by the Federal Communication Commission. Current work includes sensor fabrication and characterization with in-vitro bacterial biofilm studies.
Schematic of the fabricated SAW sensor used for detecting bacterial biofilm growth.
Schematic of an implantable wireless Surface Acoustic Wave sensor based on the current prototype device; RF wireless communication would be used to generate the surface acoustic wave and to probe the sensor output.
Optical microscopy images of the sensor surface before (left) and after (right) bacterial biofilm growth.
Young Wook received his B.S. degree in Electrical Engineering from Seoul National University, South Korea, in February 2007. He joined the MEMS Sensors and Actuators Lab (MSAL) at the University of Maryland in August 2008 to pursue both his M.S. and Ph.D. degrees in Electrical and Computer Engineering. He received the M.S. degree in February 2011 and is expected to receive his Ph.D. degree in 2013.
Mariana Meyer
Mariana is working on developing an optical-absorbance based sensing platform in microfluidics for monitoring the growth of bacterial biofilms that form as a result of bacterial quorum sensing. Biofilms are grown in microfluidic channels; as the biofilm increases in thickness, it becomes less permissive to light. This feature is measured by illuminating the platform with LEDs and measuring the output of photodiodes underneath the transparent substrate.
Microfluidic device integrated with fluidic and optical components.
Confocal microscopy images of fluorescently labeled 60-hour biofilms formed by a) Wild type E. coli, b) E. coli incapable of producing the quorum sensing molecule AI2 grown with extracellular AI2, c) E. coli incapable of producing AI2 grown without extracellular AI2.
By monitoring the optical density, not only can biofilm growth be monitored continuously, but the differences between biofilms grown under varying conditions can also be evaluated. This platform and measurement technique has been used to evaluate the dependence of Escherichia coli biofilm formation on quorum sensing. This device concept not only can be used by researchers as a tool to study biofilms and gather scientific information, but it can also be applied toward pharmaceutical development. Operating in parallel and leveraging small volumes, these microfluidic platforms can help streamline the drug evaluation process.
Mariana received a B.S. degree in Mechanical Engineering from Stanford University in 2007. She is currently a Ph.D. candidate in the Fischell Department of Bioengineering, and has been with Dr. Ghodssi’s group, the MEMS Sensors and Actuators Laboratory, since Fall 2007.
Alumni
Matthew Mosteller
Matthew’s research involves the analysis of a mathematical model of bacterial biofilm growth as a simulation tool for predicting biofilm development in microfluidic environments. The simulation is implemented using the object-oriented system modeling language Modelica and enables the user to alter experimental design parameters in order to determine their effects on biofilm growth characteristics. As a part of his future work, Matthew will improve upon the mathematical relationships governing this model at the microscale in order to increase the accuracy of biofilm growth simulations. To do so, a developed micofluidic device will allow for both the growth of bacterial biofilms under controlled experimental conditions and the analysis of these biofilms using confocal microscopy techniques. In addition, this microfluidic platform will feature an integrated photodiode array for continuous optical density measurement. As the thickness and density of the biofilm increases, the amount of incident light transmitted through the biofilm will decrease, thus resulting in an increase in relative optical density. This measurement is representative of the localized growth characteristics of a bacterial biofilm and has considerable merit due to its low cost of implementation, thus making it an ideal method for biological study and pharmaceutical development.
Both mechanical and biological phenomena are incorporated into the mathematical model of biofilm growth.
Peter Dykstra
Peter's research involves the design and testing of microfluidic devices for chemical and biological sensing. He has demonstrated the use of in-plane optics on-chip for performing absorbance measurements through a chitosan film. The chitosan is patterned via an electrodeposition method on a sidewall geometry. This platform was used for the concentration detection of the phenol, catechol. The oxidation of the catechol induced an absorbance change in the chitosan film which could be optically detected. Peter is currently testing a fabricated micro-array of electrochemical sensors within a multiple-channel microfluidic device. This array aims to provide a robust tool for both drug screening research as well as disease diagnosis. The sensors are being utilized to explore affinity based binding reactions between DNA and protein as well as hybridization reactions between various DNA sequences.
Peter received his B.S. degree in Electrical Engineering from Bucknell University in 2006. He joined the MEMS Sensors and Actuators Lab (MSAL) at the University of Maryland in 2007 to pursue both his M.S. and Ph.D. degrees in Electrical Engineering. He received the M.S. degree in 2008 and is expected to receive his Ph.D. degree in 2011.
Photograph of an array of sensors within microfluidic channels currently under test. Three probe needles make electrical contact to patterned pads along the top of the chip. Plastic tubing connectors are used to create fluid inlets and outlets for the three parallel channels.
Stephan Koev
Stephan received his Ph.D. in Electrical Engineering in May 2009. In his dissertation research, he worked on developing microcantilever sensors with integrated optical readouts. These devices are miniature light-guiding beams that deflect when molecules bind to their surface. The sensors are used for detecting the chemical homocysteine, which is a by-product of the bacterial communication. The output of the cantilevers can confirm the inhibition of certain bacterial enzymes by potential drugs. If the cantilever surface is functionalized with selective probe bimolecules, it can also serve for detection of specific target biomolecules.
Schematic of a microcantilever sensor with integrated optical readout.
Top-down microscope image of a fabricated cantilever with waveguides prior to release.
Top-down monochromatic microscope image of a fully released fabricated cantilever. An interference pattern forms between the beam and substrate.
Optical testing setup used to couple light in and out of the microcantilever chip. Optical fibers are mounted on XYZ positioning stages and aligned with the waveguides on the chip.
Presentations
Y.W. Kim, M.P. Mosteller, M.T. Meyer, H. Ben-Yoav, W.E. Bentley, and R. Ghodssi, "Microfluidic Biofilm Observation, Analysis, and Treatment (Micro-BOAT) Platform," Hilton Head Workshop 2012: A Solid-State Sensors, Actuators and Microsystems Workshop, Hilton Head, SC, June 3-7, 2012
Hadar Ben-Yoav, Adam D. Brown, Ekaterina Pomerantseva, Deanna L. Kelly, James N. Culver, and Reza Ghodssi, "Tobacco Mosaic Virus Biotemplated Electrochemical Biosensor," Hilton Head Workshop 2012: A Solid-State Sensors, Actuators and Microsystems Workshop, Hilton Head, SC, June 3-7, 2012.
Y.W. Kim, S.E. Sardari, M.T. Meyer, A.A. Iliadis, H.C. Wu, W.E. Bentley, and R. Ghodssi, "An ALD aluminum oxide passivated Surface Acoustic Wave sensor for early biofilm detection," Biosensors 2012, Cancun, Mexico, May 15-18, 2012.
Ben-Yoav, H., Dykstra, P. H., Bentley, W. E., and Ghodssi, R. “A programmable microfluidic electrochemical nano-biochip for label-free diffusion-restricted DNA hybridization analysis”. Oral paper presented at the 22ndAnniversary World Congress on Biosensors, May, 2012, Cancun, Mexico.
H. Ben-Yoav, P. H. Dykstra, W. E. Bentley, and R. Ghodssi, "A Programmable Microfluidic Electrochemical Nano-Biochip for Label-Free Diffusion-Restricted DNA Hybridization Analysis," Biosensors 2012 conference, Cancun, Mexico, May 15-18,2012.
H. Ben-Yoav, P. H. Dykstra, W. E. Bentley, and R. Ghodssi, "A Microfluidic-based Electrochemical Nano-Biochip for Label-Free Diffusion-Restricted DNA Hybridization Analysis," Biosensors 2012 conference, Cancun, Mexico, May 15-18,2012.
Y. W. Kim, S. E. Sardari, A. A. Iliadis, and R. Ghodssi, "Atomic Layer Deposition of Aluminum Oxide for Effectie Surface Passivation of a MEMS Biosensor," 11th International Conference on Atomic Layer Deposition, Cambridge, MA, June 26-29, 2011.