Time: 10:00-11:00am, July 18 (Mon.)
Venue: F207 Mechanical Building A
Topic: Carbon Nanotube Sensors Integrated Inside Microfluidic Channels for Environmental Monitoring

Abstract:
Single-walled carbon nanotubes (SWNTs) with their unique electrical properties and large surface area are promising materials for the detection of low concentrations of toxic and hazardous chemicals (both from the gaseous and liquid phases). In addition, several SWNT based pH and chemical sensors have been demonstrated. However, most of these nanosensors require bulky external components to test the response of SWNTs to ions in liquid. Here, we report a water quality monitoring sensor composed of SWNTs integrated inside microfluidic channels with on-chip testing components and a wireless transmission board. To detect multiple analytes in water requires the functionalization of SWNTs with different chemistries.  In addition, microfluidic channels are needed to isolate the sensors from each other and to guide liquids into the nanotube sensors in an efficient manner. Furthermore, the microfluidic system enables sample mixing, separating multiple components and guiding the liquid flow over SWNTs sensor. To realize the nanosensors, first, microelectrodes were fabricated on an oxidized silicon substrate.  Next, PDMS micro channels were fabricated and bonded on to the substrate.  These microchannels can be incorporated into a larger micro fluidic system which can be designed to manipulate different analytes for detecting specific molecules. Low temperature, solution based Dielectrophoretic (DEP) assembly was next conducted inside the microfluidic channels and successfully bridged the SWNTs between the microelectrodes. The SWNT nanosensors integrated with a microfluidic system is a versatile platform and can be utilized to detect numerous water pollutants, including toxic organics (TNT, DMMP) and microorganisms (E. coli) down to low concentrations. On-chip processing and wireless transmission enables the realization of a full autonomous system for real time monitoring of water quality.

 
About the Speaker:
Ming L. Wang is a Professor of Civil and Environmental Engineering at the Northeastern University. Professor research areas are in Sensor Technology and Sensor Networks for Civil Infrastructure applications. He is currently the PI and Director for VOTERS sensor system, VOTERS (versatile onboard traffic-embedded roaming sensors) aims to provide a continuous stream of accurate, up-to-date information about the state of roadways and bridge decks gathered by sensor systems mounted on vehicles of opportunity, while also eliminating the hazardous, congestion-prone work zones that are often set up to gather this critical data. The VOTERS project is funded under the TIP program of the NIST and will run for five years at a total cost of $18.8 million, including cost-sharing by the project participants. The VOTERS team includes about 40 members including faculties, research scientists, administrative staffs, and graduate students from three universities as well as the research engineers and consultants from several industrial partners. Professor Wang has developed several new sensor technologies for civil infrastructure applications. He has published more than 200 papers in various journals (80), conference proceedings (150), chapters, and edited books. Dr. Wang was also awarded a United States patent (number 5,254,857) on the “Fast Scanning Electron Microscope” in 1993. He has also filed several disclosures and provisional patents for VOTERS as well as patents on EM sensor technologies currently under worldwide use.