Date of Award

Summer 2004

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical & Computer Engineering

Program/Concentration

Electrical Engineering

Committee Director

Karl H. Schoenbach

Committee Member

Mounir Laroussi

Committee Member

Richard Nuccitelli

Committee Member

R. James Swenson

Committee Member

Stephen Beebe

Committee Member

Karin Loftin

Call Number for Print

Special Collections LD4331.E55 A78 2004

Abstract

The application of high voltage microsecond pulses that are above a critical value, to biological cells, has been shown to cause electroporation (Neumann, 1989). In addition, ultra-short pulses of several tens to hundreds of nanoseconds duration have been recently shown to affect intracellular structures without disturbing the plasma membrane (Schoenbach, 2001). However, such ultra-short intense pulses are expected to cause deformation of cells due to Maxwell stresses. This deformation was studied by means of an imaging technique with 10 ns temporal resolution on HL-60 cells. The imaging system consists of an inverted microscope where a spark light source was used to illuminate the sample. The microscope slide, having two stainless steel electrodes with a gap distance of 100 μm, is placed under the microscope. The electrodes are connected to a Blumlein generator, which generates high voltage pulses 10, 60 and 300 ns long. With a load resistance of 100 Ω , the impedance of the pulse forming line is matched to the resistance of the cells in suspension between the electrodes, generating a nearly rectangular pulse. This pulse can be applied with a maximum voltage of 850 V, corresponding to an electric field of 85 kV/cm. To achieve the desired temporal resolution, we use a high intensity nanolamp with a peak output power of 500 kW, which emits a white spectrum flash of light for only 10 ns. Pulse generator and nanolamp are synchronized with a CCD camera attached to the microscope. Light flash and electric pulse can then be shifted in time against each other as needed, to observe various effects. It was found that pulsed electric fields (PEFs) of 85 kV/cm with 300 ns duration, caused two different effects depending upon the medium of the cell suspension. In low conductivity media, HL-60 cells underwent elongation in the field direction. The horizontal axis increased up to 5.4%, whereas the vertical axis decreased by 2.1%. In higher conductivity or physiological media under the same conditions, HL-60 cells showed negligible deformation effects.

Rights

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

DOI

10.25777/54zr-ch34

Download

Share

COinS