The present invention provides devices and systems, as well as methods, of electric field delivery and non-thermal or selective ablation of target tissue regions, including selective ablation of cancerous cells and solid tumors. A method of the present invention includes delivering an electric field to a tissue, including positioning an electrode within a target tissue region comprising cancerous cells, and applying an alternating electrical current to the target tissue so as to non-thermally ablate cancerous cells of the target tissue region around the electrodes.
