Fig. 7 (a) The constructed cellular experimental model. (b) The cross-sectional distribution of the electric field strength. (c)-(f) he electric field distribution by various dielectric constant of ceramic section (100, 1000, 10000, 25000) when AC field with 200 kHz and 5 V is applied. (g) The percentage of area where electric field distribution is above 1.5 V/cm by various dielectric constant of ceramic section (100, 1000, 10000, 25000).

Results on Cell Viability

In order to improve the calculation accuracy of electric field distribution, we measure the current waveforms during cell experiments (Fig. 8a) to match the simulation current. The voltage of AC field is 5 V, the experimental current peak could reach to 43 mA. The simulated current is 40 mA, which is similar with the experimental current. The simulation shows that the field strength distribution between the two electrode ranges from 2.0 V/cm to 3.0 V/cm (Fig. 7d). The average electric field strength is 2.38 V/cm.
Fig. 8b shows the representative U251 cell morphology of the control and experimental groups at 24 h, and 48 h, after treatment. For control group, U251 cells shows an elongated morphology at 24 h, which indicates that U251 cells grow well. For 48 h, U251 cells grow rapidly, compared with 24 h. For experimental groups, some cells show a round-like morphology (blue arrow), at 24 h after treatment. Moreover, the cell density is lower than control group. At 48 h after treatment, more round-like cells occur on the experimental groups. The cell density is significantly lower, compared with 48 h control group. Fig. 8c shows the cell viability at 24 h, and 48 h, after treatment. The cell viability of experimental group (85.1±5.8%) at 24 h is significantly lower than that by control group. At 48 h, the cell viability of experimental group (70.2±4.5%) is further lower that by control group. Figs 8a and 8b show that the designed high frequency AC generator could inhibit cell proliferation significantly