M.D.-ERL Projects

A listing of all of the projects in progress at M.D.-ERL

DC DEP Blood

Medical lab work, such as blood testing, will soon be rapid and inexpensive via capabilities enabled by the fast growing world of microtechnology. Lab-on-a-chip systems having the capacity to perform a variety of tasks ranging from DNA analysis to protein recognition and can also be catered to point-of-care medical diagnostic tools. Lab-on-a-chip devices commonly utilize electrokinetics to move analytes because electric fields are versatile and can be precisely controlled for specific, quantifiable analyte responses. Furthermore, devices employing electric fields can eventually be simplified to only require a battery for power – a key characteristic for true portable diagnostic devices. One type of electrokinetics, dielectrophoresis, uses spatially nonuniform AC electric fields, which depends on the polarizability of dielectric particles or erythrocytes. Previous research by me and my colleagues have shown that blood types respond differently in AC dielectrophoretic fields [1, 2]. These results suggest that spatial separation in the electric field depends on the blood type antigen expressed on the surface of the erythrocytes. This attribute forms the foundation for the continuous flow, DC dielectrophoretic research for my doctoral studies.

AC DEP Blood

Medical microdevices have the potential to influence the way diseases are diagnosed. One tool used in these microdevices is dielectrophoresis, or the movement of particle in an inhomogenous electric field. The use of a medical microdevice or lab-on-a-chip to identify blood related problems is a particularly attractive field in emergency medicine however the most important first step is to quantify the blood’s natural response to an electric field. Research is currently focused on defining the baseline responses of the eight blood types in the ABO typing system to an alternating current dielectrophoretic field.

AC DEP Rupture

Current work is focused on quantifying the rupturing rate of the various blood types when subjected to 1kHz alternating current field. Initial results show that the rate of rupture differs based on blood type and the amount of time the blood has been out of the body [Leonard, 2007 and Leonard, 2008]. Further research will explore the effects of electric field strength and concentration on the rupture rate.

pH Gradients

The development of pH gradients can be observed in electrolytic solutions flowing through 20 micron ID capillaries using fluorescence video microscopy. The pH gradients are induced by electrolysis reactions at the electrodes in a linear electric field and are a function of electrolyte concentration. If this phenomenon can be quantified, microdevices can be easily screened to detect ion gradients and thus avoid unexpected behaviors in new device designs.

Microelectrodes

Platinum is a relatively inert material, and it is often taken for granted that the properties of platinum microelectrodes stay constant during microdevice experiments. However, a former member of our laboratory observed that used platinum microelectrodes disrupt red blood cells (in an AC electric field) better than new ones [1]. This research aims to reveal the nature of the chemical and morphological changes causing this change in performance and the extent to which these changes occur. Variability in performance of platinum microelectrodes could have a serious impact on the operation of microdevices, where they are utilized, eletrode lifetime and field consistency, among other things. To understand the chemical changes, we have been using techniques such as X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). We have been employing scanning electron microscopy (SEM) to investigate morphological changes. Our results so far suggest the oxidation of platinum and reaction of platinum take place readily when platinum microelectrodes are in AC electric fields [2]. This research is fundamental in nature and will generate important background knowledge that will help other researchers across the globe develop robust microdevices.

Bio-oil Electrocatalysis

Bio-oil researchers have explored the commercialization of a liquefied fuel made from low-grade wood. Bio-oil is an organic, liquid fuel produced through a process known as pyrolysis. This procedure produces three products: a liquid, char, and gas. The technology that is the subject of review in this opportunity analysis—fast pyrolysis—is specifically designed to maximize the output of liquid, or bio-oil.

Optically Patterned Surface

Engineering structurally colored materials that mimic biological color generation and are structurally responsive is critical for developing materials for camouflage applications. By mimicking light-structure mechanisms used to generate structural colors in many butterflies and reptiles, we hope to design a material capable of changing its surface color in response to the surrounding environment. There are two ways of creating structural color, incoherent light scattering and coherent light scattering. To date, attempts to produce structurally colored materials have employed mechanisms of coherent light which is not responsive to the environment. The approach taken here is novel. The approach employs mechanisms of incoherent light scattering, whereby light is reflected off particles at a wavelength approximating the particle’s diameter. The goal of this project was to create a micro-patterned surface of gold nanoparticles on a functionalized glass slide, comparing two methods of surface patterning (stamping and microfluidics). Fourier transform infrared spectrometry and contact angle analysis were used to determine the effectiveness of the procedure used to functionalize the surface. Confocal and electron microscopies were used to characterize the surface pattern. Once controlled patterning has been optimized, future efforts will focus on environmentally responsive structural color and color pattern change.