Nicolas Ticaud

Real-Time RF Exposure Setup Based on a Multiple Electrode Array (MEA) for Electrophysiological Recording of Neuronal Networks

Real-time investigations on the effects of mobile-phone exposure on neuronal activity are considered the highest priority in the health risk assessment of RF fields. Therefore, this paper describes a new real-time exposure setup for electrophysiology recordings, combining an open transverse electro-magnetic cell with a multiple electrode array. The system was numerically and experimentally characterized at a frequency of 1.8 GHz, representative of the uplink band of the GSM1800. Finite-difference time-domain simulations were performed, as well as measurements of the S11 scattering parameter and temperature increases for specific absorption rate (SAR) determination. The local mean SAR value near the solution-electrodes interface was evaluated from the temperature measurements and coincided with the simulated one. The same is true for S11 measurements that were consistent with numerical results; hence, confirming the accuracy of the modeling. Nevertheless, nonuniform SAR distributions were observed near the recording electrodes. Good system efficiency was determined from both numerical analysis and experimental data. Thermal behavior was evaluated and a small temperature increment of 0.3°C for a local experimental SAR of 3.2 W/kg was measured.

Simultaneous High Intensity Ultrashort Pulsed Electric Field and Temperature Measurements Using a Unique Electro-Optic Probe

High intensity nanosecond pulsed electric fields and temperature were simultaneously measured using a unique electro-optic (EO) probe. The measurements were performed in an electroporation cuvette with 4 mm electrode gap and filled with a buffered salt solution. High voltage generators delivering 2.6 and 10 ns duration pulses with different pulses shape and intensity were investigated. The EO probe linearity was characterized up to 2 MV/m. The temperature measurement uncertainty was found to be less than 22 mK. Excellent measurement abilities were achieved with this EO probe showing its suitability for bioelectromagnetic experiments and particularly for wideband high intensity field applications.

Electrooptic Probe Adapted for Bioelectromagnetic Experimental Investigations

In this paper, we present radio-frequency electro-magnetic field characterization of an electrooptic (EO) probe. This probe is able to simultaneously measure temperature and one component of the electric field (e-field) in a continuous wave (CW) or in a pulsed regime. For this purpose, linearity, selectivity, and sensitivity measurements are performed in air and in a cuvette filled with a water solution. The media are exposed to 1800-MHz CW electromagnetic wave through a transverse electromagnetic cell. Numerical characterization is also performed using finite-difference time-domain simulations. The EO probe presents a dynamic range exceeding 70 dB. Selectivity up to 25 dB is measured, demonstrating the ability of the EO probe to measure one unique component of the e-field. The EO probe sensitivity is equal to 0.77 and to 0.18 V · m-1Hz-½, in the air and in the water solution, respectively. This millimeter-sized EO probe is particularly suited for the measurement of ultrawide bandwidth and high-voltage e-fields up to a few megavolts per meter.

Specific Absorption Rate Assessment Using Simultaneous Electric Field and Temperature Measurements

In this letter, the temperature measurement ability of an electrooptic probe as well as specific absorption rate (SAR) assessments via simultaneous in situ temperature and electric field characterization are reported. The measurements are carried out at 1800 MHz in a Petri dish filled with a water solution and placed in a transverse electromagnetic (TEM) cell. From the temperature sensitivity measurements, a standard deviation of 27 mK is obtained. The SAR values obtained both via temperature and electric field are also compared to finite-difference time-domain (FDTD) simulated numerical results. A difference of 5% is obtained between the two experimental SAR values. These measured SAR values are consistent with those obtained by the numerical simulations.

Setup for Simultaneous Microwave Heating and Real-Time Spectrofluorometric Measurements in Biological Systems

In this paper, a delivery system allowing simultaneous microwave heating and real-time spectro∞uorometric measurements in biological systems is proposed and characterized. This system is used to investigate the phase behavior of lipid bilayers from about 15 - C to 45 - C. The delivery system is based on an open transverse electromagnetic (TEM) cell combined with a spectro∞uorometer via an optical cable system. A numerical and experimental dosimetry of the delivery system is conducted. The Speciflc Absorption Rate (SAR) e-ciency of the system is 26:1§2:1W/kg/W. Spectro∞uorometric measurements on Laurdan labeled small unilamellar vesicles (SUVs) are carried out. Generalized polarization (GP) of the SUVs membrane is obtained from the ∞uorescence intensities measured at two emission wavelengths.