Jean-Pierre Rostaing

BioMEA™: A versatile high-density 3D microelectrode array system using integrated electronics

Microelectrode arrays (MEAs) offer a powerful tool to both record activity and deliver electrical microstimulations to neural networks either in vitro or in vivo. Microelectronics microfabrication technologies now allow building high-density MEAs containing several hundreds of microelectrodes. However, dense arrays of 3D micro-needle electrodes, providing closer contact with the neural tissue than planar electrodes, are not achievable using conventional isotropic etching processes. Moreover, increasing the number of electrodes using conventional electronics is difficult to achieve into compact devices addressing all channels independently for simultaneous recording and stimulation. Here, we present a full modular and versatile 256-channel MEA system based on integrated electronics. First, transparent high-density arrays of 3D-shaped microelectrodes were realized by deep reactive ion etching techniques of a silicon substrate reported on glass. This approach allowed achieving high electrode aspect ratios, and different shapes of tip electrodes. Next, we developed a dedicated analog 64-channel Application Specific Integrated Circuit (ASIC) including one amplification stage and one current generator per channel, and analog output multiplexing. A full modular system, called BIOMEA, has been designed, allowing connecting different types of MEAs (64, 128, or 256 electrodes) to different numbers of ASICs for simultaneous recording and/or stimulation on all channels. Finally, this system has been validated experimentally by recording and electrically eliciting low-amplitude spontaneous rhythmic activity (both LFPs and spikes) in the developing mouse CNS. The availability of high-density MEA systems with integrated electronics will offer new possibilities for both in vitro and in vivo studies of large neural networks.

Integrated electronics for a CdTe based PET system

In this paper, we present two circuits designed for pulse readout of a semiconductor PET system: a fast low noise low power front-end preamplifier/shaper, and a processing circuit performing time tagging, energy measurement and digital interfacing with the data acquisition system. Considerations on noise, speed and power consumption are discussed.

A high-speed 2nV/Hz 1/2 16-channel current amplifier IC for PET

A 16 channel front-end IC dedicated to small animal positron emission tomography has been developed for cross-strip CdTe detectors. Each channel, designed to handle up to 20 pF detector capacitance, includes both low voltage (2 nV/Hz1/2) and low current (40 fA/Hz1/2) noise, high bandwidth (50 MHz at 20 pF detector capacitance) current amplifier with a gain of 100 for a power consumption of 4.7 mW. Both anode and cathode connection to the detector are possible thanks to an external control signal selecting the input common polarity. Input has been designed for maximum peak current of +/-1 A. Additional ¿charge amplifier¿ functionality is available via a single external control pin, extending functionality to X-ray or gamma-ray detection, fast instrumentation. Circuit size is 2×8 mm2 in 0.35 ¿m 3.3 V CMOS process. Each channel differential output is buffered by a transconductance amplifier with two balanced differential current outputs compliant with 50 Ohm terminations.