High-voltage 10 ns delayed paired or bipolar pulses for in vitro bioelectric experiments

International audienc

A microfluidic biochip for the nanoporation of living cells

International audienceThis paper deals with the development of a microfluidic biochip for the exposure of living cells to nanosecond pulsed electric fields (nsPEF). When exposed to ultra short electric pulses (typical duration of 3-10ns), disturbances on the plasma membrane and on the intra cellular components occur, modifying the behavioral response of cells exposed to drugs or transgene vectors. This phenomenon permits to envision promising therapies. The presented biochip is composed of thick gold electrodes that are designed to deliver a maximum of energy to the biological medium containing cells. The temporal and spectral distributions of the nsPEF are considered for the design of the chip. In order to validate the fabricated biochip ability to orient the pulse towards the cells flowing within the exposition channels, a frequency analysis is provided. High voltage measurements in the time domain are performed to characterize the amplitude and the shape of the nsPEF within the exposition channels and compared to numerical simulations achieved with a 3D Finite-Difference Time-Domain code. We demonstrate that the biochip is adapted for 3 ns and 10 ns pulses and that the nsPEF are homogenously applied to the biological cells regardless their position along the microfluidic channel. Furthermore, biological tests performed on the developed microfluidic biochip permit to prove its capability to permeabilize living cells with nanopulses. To the best of our knowledge, we report here the first successful use of a microfluidic device optimized for the achievement and real time observation of the nanoporation of living cells

Comparative study between radiofrequency-induced and muscimol-induced inhibition of cultured networks of cortical neuron

Previous studies have shown that spontaneously active cultured networks of cortical neuron grown planar microelectrode arrays are sensitive to radiofrequency (RF) fields and exhibit an inhibitory response more pronounced as the exposure time and power increase. To better understand the mechanism behind the observed effects, we aimed at identifying similarities and differences between the inhibitory effect of RF fields (continuous wave, 1800 MHz) to the γ-aminobutyric acid type A (GABAA) receptor agonist muscimol (MU). Inhibition of the network bursting activity in response to RF exposure became apparent at an SAR level of 28.6 W/kg and co-occurred with an elevation of the culture medium temperature of ~1°C. Exposure to RF fields preferentially inhibits bursting over spiking activity and exerts fewer constraints on neural network bursting synchrony, differentiating it from a pharmacological inhibition with MU. Network rebound excitation, a phenomenon relying on the intrinsic properties of cortical neurons, was observed following the removal of tonic hyperpolarization after washout of MU but not in response to cessation of RF exposure. This implies that hyperpolarization is not the main driving force mediating the inhibitory effects of RF fields. At the level of single neurons, network inhibition induced by MU and RF fields occurred with reduced action potential (AP) half-width. As changes in AP waveform strongly influence efficacy of synaptic transmission, the narrowing effect on AP seen under RF exposure might contribute to reducing network bursting activity. By pointing only to a partial overlap between the inhibitory hallmarks of these two forms of inhibition, our data suggest that the inhibitory mechanisms of the action of RF fields differ from the ones mediated by the activation of GABAA receptors

Nouvelle approche de mesure de l’activité cérébrale sous RF: Imagerie ultrasonore fonctionnelle du cerveau de rongeurs sous exposition RF

La neuro-imagerie est une technique récente d’imagerie cérébrale. Grâce à une nouvelle méthode « fUS », elle permet d’ « imager » en temps quasi-réel l’activité cérébrale chez de petits animaux (ex. rongeurs) avec une grande résolution spatiale et temporelle. Pour la première fois, nous avons évalué dans cette étude, la possibilité d’analyser les réponses cérébrales en temps réel des souris lors d’une exposition aux radiofréquences

Generators and applicators for nanosecond pulsed electric field

International audienceThis paper describes nanosecond electric pulse generator and applicator for biological experiment. For the generator, an optoelectronic switching embedded in a frozen wave generator is obtained in the linear regime. In this way, square electrical pulses with adjustable duration and monocycle nanosecond pulses with balanced or unbalanced positive and negative components are obtained. In biological experiments, these nsPEF generators are frequently coupled with a standard electroporation cuvette, 50-Ω matched, containing the biological sample. A numerical and experimental characterization of a 50-Ω applicator is presented

Microchamber Array Technology and Microdosimetry for Nanosecond Pulsed Electric Fields Cell Exposure

International audienc

Experimental setup for exposure to tunable ultrashort high-intensity pulsed electric fields and real-time dosimetric measurements

International audienc

Design of patch antennas using a 2D multistructure method of moments

International audienc

Antennes imprimées à forme non-intuitive et a sensibilité réduite aux tolérances de fabrication

National audienc

Antennes imprimées à forme non-intuitive et a sensibilité réduite aux tolérances de fabrication

National audienc