Evaluation of cell characteristics by step-wise orientational rotation using optoelectrostatic micromanipulation

The characteristics of a single cell can be studied using optoelectrostatic micromanipulation (OEMM) techniques. Escherichia coli (E. coli) and Schizosaccharomyces pombe (S. Pombe) cells were characterized by step-wise orientational rotation driven by a high-frequency alternating electric field. The peak voltage and frequency of the electric field ranged from 2.5 to 80 V (average electric field: 0.25/spl times/10/sup 5/-0.8/spl times/10/sup 6/ V/m) and from 5 kHz to 2 MHz, respectively. The characteristics were measured by a microelectrode system installed on a microscope stage. An yttrium aluminum garnet (YAG) laser was introduced to hold a cell at its focal point. The characteristics show that a live cell has a peak critical orientational rotation frequency (PCRF) at 1 MHz and the PCRF of a dead cell depends on the process of killing, i.e., thermal, chemical, ultraviolet light or electric pulse. The orientational rotation can be utilized to investigate the dielectric properties of an individual cell.