Research Projects: George Nnanna

Rapid Electrokinetic Trapping with Plasmonic Nanostructures

(Sponsor: DOE)

The successive trapping and concentration of micro and nanosized particles on plasmonic structures can be utilized to develop advanced plasmonic biosensors that are capable of rapidly concentrating target particles (e.g bacteria, cells, and DNA) of target size to the most sensitive regions of the sensor where the optical localized fields are significantly enhanced. Such a biosensor would completely eliminate the limitations of diffusion-limited reactions on which conventional biosensors rely on to transport target anlytes to functionalized regions. Thus, sensitivity, selectivity, and response time can potentially be improved. The concept can be further extended to design arrays of plasmonic sensors functionalized with receptors to sense different strains of bacteria or other biomolecules, and tuned to the right AC frequency to rapidly capture and transport biomolecules of interest to respective sensing regions.

Nanomechanical Cantilever Sensing Of Biomolecules With Rapid Electrokinetic Patterning

(Sponsor: DOE)

Micro and nanocantilever based biosensors have been widely applied for detection of small molecules based on stress induced on cantilever surface resulting from bimolecular interaction. One major challenge in this field and with other nanobiosensors is non-specific adsorption, slow response time and insufficient sensitivity. Most of the biosensor works reported have simply demonstrated a concept for detecting specific target molecules in friendly, buffered solution. However, clinical and environmental application of biosensors would necessitate their use in complex matrix such as serum and for which the target biomolecules such as proteins may only be 1 part in 1 million of the matrix (the circulating tumor cells in blood is 1-1000 cells/mL which is very small with respect to others blood cells (18)). It is proposed to integrate nanocantilever sensors with hybrid optoelectronic particle manipulation techniques (Rapid electrokinetic patterning, REP) to dynamically and rapidly manipulate target analytes to sensing sites.

Real -Time Measurement Of Fouling Of Membranes Using Ultrasonic Time-Domain Reflectometry (UTDR)

(Sponsor: DOE)

UTDR measurements rely on the absolute amplitude or differential amplitude to demonstrate the development of fouling on membrane surface. The aims of this project are to develop methodology to improve the resolution of UTDR measurements, and to develop protocols to use UTDR measurements for backwash control

Discrete Opto-Fluidic Chemical Spectrophotometry System (Docss) For Online In-Situ Monitoring Of Dissolved Contaminants In Aqueous Media

(Sponsor: DOE)

This project presents the fabrication of a discrete chemical analyzer system for online monitoring of dissolved ions in water using UV-VIS absorption spectrophotometry. The device is composed of three main components, fluidic, optical and control. The test-cell is designed to function as a non-invasive volume sensor, and the volume sensing principle was based on light scattering by entrapped water droplets.

Dithizone as a HalochromicMaterial for Fabricating Evanescent Wave-1 based Chemical Sensors

( Sponsor: DOE)

This project presents the use of dithizone as a pH sensitive material in the fabrication of clad-modified optical fiber evanescent wave sensors. The response characteristics of the sensor were evaluated for ammonia detection in water. Preliminary results show that the response is nonlinear, this is in agreement with the prediction by Hale and Payne [19] for evanescent wave sensor response.

Low Voltage Electrohydrodynamic Conduction Micropumps

(Sponsor: DOE)

The use of electrohydrodynamic (EHD) conduction micropumps in cooling technology, drug delivery, and sensor applications is very limited in part because of the high voltage requirement necessary to drive the fluid, and as a result have not gained wide applications. The focus of this work is on theoretical and experimental study of the means of lowering the high voltage requirement and the sustainability of the flow rate. Different ratio of the dielectric permittivity over the viscosity is used to gain understanding of the impact of dielectric properties on the voltage applied with the flow rate.

Direct Evaporative Cooling

(Sponsor: ASHRAE)

Direct Evaporative Cooling (DEC) process approximates an adiabatic-saturation process in which the heat flow path lies on constant enthalpy line. Sensible heat released from the incoming air is transferred to the wetted media resulting in latent heat of evaporation. The rate of heat transfer hence the cooling efficiency is a function of various thermodynamic properties. This project presents an empirical relationship between system parameters (frontal air velocity and dry-bulb temperature, and water temperature) and cooling efficiency.

Lake Michigan Water Resources Study

(Sponsor: IDEM)

This study will provide important information concerning current and projected future water use in the Lake Michigan basin. Furthermore, the information will be utilized in developing policies to optimize water use and reuse; and in assessing the future availability of water and its quality in the Great Lakes. The main objectives of this proposal are to:

  • characterize water quality constituents including chlorides, cyanide, dissolved oxygen and heavy metals, existing in the system which includes loads coming from point and non-point sources.
  • analyze reported water withdrawal data from 1990 to 2010 in the Indiana section of the Great Lakes Basin. Utilizing the Winter Base-Rate Method and return-flow data, this project will assess and predict consumptive water-use via historical data; and projects water withdrawal data through 2015 using nonlinear regression analysis and artificial neural network models.

Water-Energy Nexus: Reducing Makeup Water Usage through Reactive Filtration and Reuse of the Blowdown Water

(Sponsor: Water Institute)

Water usage and water quality are essential to the operation of a power plant. In order to reduce the consumption of natural water resources, advanced water treatment technologies for contaminant removal and reuse of processed water are highly desired. The aim of this study is to treat the blowdown water of the power plant cooling tower so that treated effluent may meet the requirements for the makeup water. The power plant cooling tower blowdown water contains wide varieties of contaminants, including but not limited to dissolved solids, suspended solids, heavy metals, minerals, and silica.

Study of the Total Suspended Solids Profiles- East Chicago Drinking Water Plant

(Sponsor: East Chicago)

In this study, an investigation to measure the total suspended solids in the various water streams including the sand filtration backwash, the Lake Michigan raw water, the water entering the membrane filtration unit, and the reject stream generated by the membrane filtration process will be performed. The aim of this work is to understand the impact of suspend solid concentrations on the membrane filtration plant at East Chicago.