Compact measurement setup and test structure for nanosecond electroporation of biological cells were demonstrated. The test structure was based on a coplanar waveguide with a defected ground structure that afforded broadband impedance match with little dispersion or parasitic. The defected ground structure with a 10-μm gap formed a microchamber to readily accept biological solutions and to allow the measurement to be quickly performed before the solution evaporated or the cell activity changed. The measured results in conjunction with detailed electromagnetic analysis of a three-layer spherical cell model showed that the present measurement setup was capable of delivering a nanosecond 0.1-V potential across a plasmatic membrane. This transmembrane potential, although an order of magnitude lower than the typical threshold for membrane poration, could be increased by using nanosecond pulses with order-of-magnitude higher amplitude or 10-ns pulses with three times higher amplitude. © 2011 IEEE.