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This paper presents the NeuroSelect software for managing the electronic depth control of cerebral CMOS-based microprobes for extracellular in vivo recordings. These microprobes contain up to 500 electronically switchable electrodes which can be appropriately selected with regard to specific neuron locations in the course of a recording experiment. NeuroSelect makes it possible to scan the electrodes electronically and to (re)select those electrodes of best signal quality resulting in a closed-loop design of a neural acquisition system. The signal quality is calculated by the relative power of the spikes compared with the background noise. The spikes are detected by an adaptive threshold using a robust estimator of the standard deviation. Electrodes can be selected in a manual or semi-automatic mode based on the signal quality. This electronic depth control constitutes a significant improvement for multielectrode probes, given that so far the only alternative has been the fine positioning by mechanical probe translation. In addition to managing communication with the hardware controller of the probe array, the software also controls acquisition, processing, display and storage of the neural signals for further analysis.

This paper reports a novel generation of CMOS stress mapping chips comprising 32 square field effect transistors (FET) with four source/drain contacts (piezoFETs) exploiting the shear piezoresistive effect in n-type (NMOS) or p-type (PMOS) inversion layers. The sensor chips with a total die area of 2.5 x 2 mm2 are integrated with analog circuitry and digital logic. When exposed to homogenous shear or normal stress, all 32 integrated stress sensors show a linear response in excellent agreement with theoretical predictions and exhibit identical stress sensitivities. Piezo-FETs fabricated as separate devices are characterized with respect to stress sensitivity, intrinsic offset, and noise behavior. Stress sensitivities are enhanced by incorporating a central hole into the piezo-FETs. Sensitivities of -448 iV/(V MPa) and 477 iV/(V MPa) were measured for NMOS and PMOS devices, respectively.

Thispaper reports on the mechanical characterization of microtensile specimens made of silicon nitride (SiN x ) thin-films with integrated 2D reflective gratings. By applying an axial force, the structures respond mechanically with an elongation and contraction in the longitudinal and transversal directions, respectively. The corresponding variations of both periods of the grating are monitored in real time by measuring the diffraction pattern resulting from the illumination of the grating with monochromatic light. The strain components are thus evaluated locally in the structure. By integrating such an optical technique with an efficient test structure previously developed, the extraction of materials' Young's modulus E, Poisson's ratio , residual strain res and stress res and fracture strength 0 is in principle made possible from the measurement of a single test structure. Here we demonstrate the extraction of E, res , res and 0 of the nitride films.