Boundary element analysis of stress forces in pulsed electric field treatment of microorganism

Beyond on remarkable progresses in a technology of high-voltage pulse, it is considered to apply the high-voltage pulsed electric field to an inactivation of a microorganism. In particular, the method of the high-voltage pulse has advantage in the inactivation of bacteria in foods, since conventional methods such as heat disinfectant, X-ray or gamma-ray are expected to induce negative secondary effects, changes of flavor, taste, texture of the foods, and so on. In the treatment of the microorganism by the high-voltage pulse, the microorganism is destroyed by pure mechanical stress force created by externally applied electric field, and therefore there are no negative secondary effects. However, it should be carefully evaluated how much strong stress force can be produced by reasonable voltage and pulse duration of the high-voltage pulse for the inactivation of the microorganism. Then, evaluation of the stress force for cases of complete sphere and axis-symmetric shapes of the microorganism were presented by using an analytical formula or 2-D FEM. In this paper, an electrostatic field analysis by using 3-D BEM with a thin layer approximation for a membrane of the microorganism is presented to aim to evaluate the stress force for arbitrary shape microorganism.