Dose-dependent dielectrophoretic response of Cryptosporidium oocysts treated with ozone.

Dielectrophoresis, the motion of particles in non-uniform electric field, was investigated as a technology with the potential for rapid analysis of ozonated Cryptosporidium parvum oocysts. The ratio of dielectrophoretic collection at two key frequencies (100 kHz and 10 MHz) was determined to compare the effect of ozonation at various dosages. A relationship was found between this ratio and the in vitro excystation value obtained at the end of the experiments. The magnitude of the ratio changed in a non-linear manner with increasing ozone dose. The results are consistent with a decrease in oocyst internal conductivity as supported by the predictions of a mathematical model for the dielectrophoresis of two-shell spherical particles.