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Overlay of 7 consecutive pulses applied to a tissue sample matched with an additional 150-Ω in parallel with the load. Inset: Blumlein pulse forming network and exposure system (L = 4 μH, C = 667 pF).
Box-whisker plots for the number of pre-breakdown pulses (pulses that need to be applied to a matched tissue load before a spark discharge is observed) with respect to pulse amplitude. The boxes show the range of the 25th–75th percentile with the median indicated by the center line. (a) Results for a needle tip separation of 3 mm. (b) Results for a needle tip separation of 5 mm.
Absolute impedance drop for different exposure conditions of adipose tissue samples. The dashed line indicates the average impedance measured for the first pulse applied to the sample (3015 Ω, standard deviation 1032 Ω). The symbols describe the impedance for the last exposure preceding breakdown. The solid line describes the average of all experiments (1688 Ω, standard deviation 843 Ω).
(Color) Ablation of adipose tissue by 30 spark discharges following 150 pre-breakdown pulses with 25-kV amplitude between needle tips 5 mm apart. Top: Tissue damage is limited to a nearly straight, narrow line between the needle tips. Thermal damage becomes apparent only after an increasing number of spark discharges following the first breakdown and is more prominent at the location of the needle tips. Bottom: Histological analysis (H&E stain) of a cross section of the discharge channel. Cells presumably disintegrated by the shockwave are not found after histological preparation, while cells at the periphery appear to be intact. Cells that suffered thermal damage are not found in this histological slide. (One needle tip was located in the open space on the right, while the other tip to the left was outside the field of view.)
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