DC DEP Blood

Electrodeless Dielectrophoretic (DC DEP) Lab-on-a-Chip System for Erythrocytes

Researcher

Soumya Keshavamurthy-Srivastava

Description and Motivation

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.

In this work, no electrodes are placed within the test channel, thus simplifying fabrication. Instead, a DC electric field is applied around an insulating obstacle in the microfluidic channel, which creates a spatially non-uniform electric field. This technique is commonly referred to as DC dielectrophoresis or electrodeless dielectrophoresis. In my work, I utilize PDMS obstacles of different geometrical configurations on the order of 100 microns in breadth. Device dimensions are optimized by evaluating the behaviors of fluorescent polystyrene particles of three different sizes roughly corresponding to the three main components of blood: platelets, erythrocytes and leukocytes. The optimized device will be used for continuous separation of erythrocytes according to blood types. This design will enable collection into specific channels based on the cells deflection from the high field obstacle. This developed technique can be directly applied for use in portable blood diagnostic devices for easy, accurate and rapid analysis.

My research will result into a life-saving device, which can be used as a point of care device in emergency situations like war, accidents, natural calamities, etc. They can also be further modified into disease detection devices which would make a high impact on the society. The need for reliable, fast and inexpensive device would be solved by adapting such micro-devices. A model of one such micro-device is shown below which I developed for my experiments.

References

• Srivastava, S. K.; Daggolu, P. R.; Burgess, S. C.; Minerick, A. R.; “Dielectrophoretic characterization of erythrocytes: Positive ABO blood types”, Electrophoresis (in press, July 2008)
• Keshavamurthy S. S.; Leonard K. M.; Burgess S. C.; Minerick A. R.; “Direct current dielectrophoretic characterization of erythrocytes: Positive ABO blood types”, NSTI-nanotech, 2008; 2, 401–404

Personal Motivation

My interest in choosing to work in medical diagnostic field is to advance human welfare especially for under developed countries and my willingness to pursue career in academics.