Microprocessor-Controlled Nanosecond Pulser System for Cell Manipulation

Summary form only given. Recent studies of pulsed electric fields of 10-300 ns duration have identified their remarkable capability to manipulate cellular structures and functions including programmed cell death, calcium mobilization and platelet activation. While this electrically induced cell manipulation clearly has profound implications to clinical practice, the understanding of how exactly nanosecond electric pulses penetrate the cell membrane and influence intracellular structures remains a largely uncharted territory with exciting scopes for new science. For example, it is little known what the spectral content of the penetrated pulses is. This is significant because the permittivity of many cell suspensions and human matters (e.g. fat, muscle and blood) depends sensitively on the temporal properties of the incoming pulses. This highlights the need for precision control of the temporal properties the electric pulses so that cell experiments using seemingly similar electric pulses can be compared. In this contribution, we present an experimental study of a microprocessor-controlled nanosecond pulser system for cell manipulation. We present first resistance measurement of cell suspension at different frequencies from 10 kHz to 100 MHz. For a given electric pulse of certain pulse width and risetime, this determines the load resistance and hence the impedance of the Blumlein line on which our pulser system is based. Our second study suggests that the pulse duration and risetime can be influenced sensitively by several factors including the matching between the load and the Blumlein line and the voltage ramp speed at which the spark gap is switched. A microprocessor system is then developed to control the voltage ramp speed, leading to reliable production of nanosecond voltage pulses with controlled risetime and pulse duration. In the final study, the microprocessor-controlled pulser system is used to investigate cell manipulation by electric pulses of different - eak voltage, risetime and pulse durations. Fluorescence microscopy is used to examine whether cell membrane is breached and whether sub-lethal effects are achieved