Affinity-type silicon-based nanowire biosensors rely on the biochemical interaction between target molecules and their molecular complements (recognition probes), located on the SiO2 insulator layer. This biochemical reaction is associated with twofold fluctuations through the mechanisms of binding/unbinding and regular charge thermal equilibrium processes. These fluctuations have a direct implication on the surface potential fluctuations which in turn affect, through the field effect transduction process, the electrical characteristics of the sensor device. The resulting noise could potentially contain detectable information, which can be extracted through the time constants (characteristic frequencies) related to the kinetics of the molecules under detection and their charge fluctuations. In this work, we present a comprehensive model for the fluctuations on the surface of the biosensor and attribute them to the two physical mechanisms. The spectral densities corresponding to these types of fluctuations add on the overall device noise spectrum and are directly detectable if they lie above the inherent noise level of the sensor device.

Device white noise levels in short channel Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) dictate the performance and reliability of high-frequency circuits ranging from high-speed microprocessors to Low-Noise Amplifiers (LNAs) and microwave circuits. Recent experimental noise measurements with very short devices demonstrate the existence of suppressed shot noise, contrary to the predictions of classical channel thermal noise models. In this work we show that, as the dimensions continue to shrink, shot noise has to be considered when the channel resistance becomes comparable to the barrier resistance at the source-channel junction. By adopting a semi-classical approach and taking retrospectively into account transport, short-channel and quantum effects, we investigate the partitioning between shot and thermal noise, and formulate a predictive model that describes the noise characteristics of modern devices.

High-energy cosmic rays are one of the primary sources of information for scientists investigating the elementary properties of matter. The need to study cosmic rays, with energies thousands of times larger than those encountered in particle accelerators, led to the development of modern detection hardware and experimental methodologies. We present a low power, low complexity data acquisition (DAQ) system with 100 ps resolution, suitable for particle and radiation detection experiments. The system uses a Multiple-Time-over-Threshold (MToT) technique for the treatment of the output signal of Photo Multiplier Tubes (PMTs). The use of three thresholds compensates for the slewing effects and offers a more accurate measurement of the PMT pulses' width. For the evaluation of the pulse the system uses comparators and a Time-to-Digital (TDC) converter, whereas the pulses are time-stamped using the GPS signal.The prototype card is analyzed for its noise behavior and is tested to verify its performance. The system has been designed for the HEllenic LYceum Cosmic Observatories Network (HELYCON) Extensive Air Showers (EAS) detector.

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