A General Purpose Lock-In Amplifier Enabling Sub-ppm Resolution

A novel architecture for digital lock-in amplifiers (LIAs) able to overcome the resolution limit of standards implementations is proposed. The slow gain fluctuations of both the DAC and ADC of the generation and acquisition stages of the LIA are compensated using two ADCs alternately acquiring the signal coming from the device under test (DUT) and the stimulus (STIM) signal. Experimental results demonstrate a resolution enhancement of more than an order of magnitude with respect to state of art LIAs, enabling sub-ppm resolution measurements with an instrument working up to 5 MHz without imposing any constraint to the DUT or to the experimental setup

A Pipe-Embeddable Impedance Sensor for Monitoring Water Leaks in Distribution Networks: Design and Validation

Water leakage is one of main problems of distribution infrastructures, reaching unacceptable peaks of 50% of water lost in old networks in several countries. In order to address this challenge, we present an impedance sensor able to detect small water leaks (below 1 L of released volume). The combination of real-time sensing and such a sensitivity allows for early warning and fast response. It relies on a set of robust longitudinal electrodes applied on the external surface of the pipe. The presence of water in the surrounding medium alters its impedance in a detectable way. We report detailed numerical simulations for the optimization of electrode geometry and sensing frequency (2 MHz), as well as the successful experimental proof in the laboratory of this approach for a pipe length of 45 cm. Moreover, we experimentally tested the dependence of the detected signal on the leak volume, temperature, and morphology of the soil. Finally, differential sensing is proposed and validated as a solution to reject drifts and spurious impedance variations due to environmental effects

Non-invasive monitoring and control in silicon photonics by CMOS integrated electronics

As photonics breaks away from today's device level toward large scale of integration and complex systems-on-a-chip, concepts like monitoring, control and stabilization of photonic integrated circuits emerge as new paradigms. Here, we show non-invasive monitoring and feedback control of high quality factor silicon photonics resonators assisted by a transparent light detector directly integrated inside the cavity. Control operations are entirely managed by a CMOS microelectronic circuit, hosting many parallel electronic read-out channels, that is bridged to the silicon photonics chip. Advanced functionalities, such as wavelength tuning, locking, labeling and swapping are demonstrated. The non-invasive nature of the transparent monitor and the scalability of the CMOS read-out system offer a viable solution for the control of arbitrarily reconfigurable photonic integrated circuits aggregating many components on a single chip

Parallelizable Microfluidic Resistive On-Line Detector of Micrometric Aggregates of Biopharmaceutical Antibodies

A microfluidic device based on the differential measurement of the ionic resistance of a micropore for detection of aggregates of antibodies in biopharmaceutical downstream process is presented. The main novelty of this contribution regards the experimental demonstration that, despite the poor solidness of proteins, their aggregates, in their standard production buffer, can be electrically detected down to 2.4 μm diameter with sub-ms transit time (flow rate of 5 μl/min). Thanks to the simple PDMS fluidic fabrication, compact DC readout circuit and convenient use of the same metallic silver tubing for both electrical and fluidic interconnection, the device can be straightforwardly parallelized in tens of units, thus combining single micrometric sensitivity with larger flow rates (>100 μl/min), suitable for in-line installation in pharmaceutical plants

Micro-USB Connector Pins as Low-Cost, Robust Electrodes for Microscale Water Conductivity Sensing in Oceanographic Research

Motivated by the widespread need to sense water conductivity in oceanography, as well as in other applications in fluid dynamics and environmental monitoring, we propose using the exposed gold-plated pins of readily available micro-USB connectors as miniaturized, parallel finger electrodes. Since the electrodes are 600 μm apart, they grant sub-mm spatial resolution, suitable for most applications. Standard micro-USB cables are an ideal, ready-to-use solution, since they are shielded, are preassembled in different lengths, and enable 2 and 4-wire measurements. In order to take full advantage of these USB probes, we have designed a custom, open-source 4-channel measuring circuit, named "Conduino", consisting of a low-noise (SNR = 60 dB) shield board coupled to an Arduino microcontroller. Experimental results demonstrate sensing performances comparable with state-of-the-art reference instrumentation (0.1% resolution in the 0.1-15 S/m range), with significantly lower cost and increased versatility and reliability

An affordable, open-source, microscale conductivity and temperature probe for density measurements in stratified flows

In stratified flows, conductivity (combined with temperature) is often used to measure density. The conductivity probes typically used can resolve very fine spatial scales, but can be fragile, expensive to replace, and sensitive to environmental noise. A complementary instrument, comprising a low-cost and robust probe, would prove valuable in a wide range of applications where resolving extremely small spatial scales is not needed. We propose using micro-USB connectors as the actual conductivity sensors; these have five gold-plated microelectrodes that can be readily exposed for two-wire or four-wire measurements. To take advantage of our choice of sensor, we design a custom electronic board for simultaneous acquisition from four sensors, with conductivity resolution of 0.1%, comparable to typical existing probes. We demonstrate our system through stratified flow experiments. The multi-channel capability can be used to approximately reconstruct density fields, whereas the customizable design enables measuring density near complex boundaries

Gli accordi di ristrutturazione dei debiti

Il lavoro analizza la disciplina degli accordi di ristrutturazione dei debiti prevista dall'art. 182 bis L.F., che costituisce uno dei più innovativi strumenti di gestione della crisi d'impresa, in quanto consente all'imprenditore ed ai suoi creditori di gestire la crisi aziendale attraverso lo strumento negoziale. Nell'elaborato dopo una accurata disamina della disciplina normativa, si evidenziano alcuni profili critici nella fase applicativa degli accordi di ristrutturazione, rilevandosi un vuoto normativo e giurisprudenziale

Advances in High-Resolution Microscale Impedance Sensors

Sensors based on impedance transduction have been well consolidated in the industry for decades. Today, the downscaling of the size of sensing elements to micrometric and submicrometric dimensions is enabled by the diffusion of lithographic processes and fostered by the convergence of complementary disciplines such as microelectronics, photonics, biology, electrochemistry, and material science, all focusing on energy and information manipulation at the micro- and nanoscale. Although such a miniaturization trend is pivotal in supporting the pervasiveness of sensors (in the context of mass deployment paradigms such as smart city, home and body monitoring networks, and Internet of Things), it also presents new challenges for the detection electronics, reaching the zeptoFarad domain. In this tutorial review, a selection of examples is illustrated with the purpose of distilling key indications and guidelines for the design of high-resolution impedance readout circuits and sensors. The applications span from biological cells to inertial and ultrasonic MEMS sensors, environmental monitoring, and integrated photonics