Determination of the Wind Speed and Direction by Means of Fluidic-Domain Signal Processing

This paper presents an analytical model for a recently introduced class of 2-D directional anemometers based on fluidic structures capable of averaging the differential pressure developed by the wind across distinct diameters of the transverse cross-section of a single cylinder. In previous works, it was found that performing the average over a proper set of diameters produces a differential pressure that depends on the wind direction according to a cosine law, allowing simple direction estimation. This fact, which was not investigated in previous articles, is explained in this paper taking into account symmetry and angular spectral properties of the pressure distribution. Besides analyzing previously proposed devices, this paper introduces several new configurations, which are classified according to the type of average and number of diameters involved. Comparison of the estimated performances with the experimental results obtained in earlier works clearly shows that prototypes proposed so far were far from achieving the best theoretical accuracy, suggesting that significant improvements can be obtained by re-design of the fluidic structures

In-Network Programmability for Next-generation Personal Cloud Service Support (INPUT)

Abstract In order to overcome the cloud service performance limits, the INPUT Project aims to go beyond the typical IaaS-based service models by moving computing and storage capabilities from the datacenters to the edge network, and consequently moving cloud services closer to the end users. This approach, which is compatible with the concept of fog computing, will exploit Network Functions Virtualization (NFV) and Software Defined Networking (SDN) to support personal cloud services in a more scalable and sustainable way and with innovative added-value capabilities

A Compact CMOS Compatible micro-Pirani Vacuum Sensor with Wide Operating Range and Low Power Consumption

A micro-Pirani vacuum sensor with an operating pressure range of more than 5 decades is described. The device is fabricated by applying a low-resolution and potentially low-cost front-side bulk micromachining step to a chip produced with a commercial CMOS technology. Maximization of the thermally coupled surfaces has been obtained by stacking all layers available by default in the CMOS process. This design choice and the integration of a low-noise, low-power readout interface allowed achievement of state-of-art performances with a fabrication approach affordable even to SMEs and small University laboratories

A Compact, Dual Channel Flow-based Differential Pressure Sensor with mPa Resolution and Sub-10 mW Power Consumption

In this work, we propose a single-chip sensor for the detection of two extremely low, independent differential pressures. The operating principle consists in measuring the airflow induced by the pressure through a channel of sub-millimeter cross-section [1]. The airflow is measured by differential thermal flow sensors, implementing a recently proposed drift-free offset compensation approach. Use of a low-noise, low-power readout interface, integrated on the same chip as the sensing structures, allowed the achievement of resolutions of 1.29 mPa, which are one order of magnitude lower than state-of-art devices. This performance has been obtained with power consumptions suitable for battery-powered applications

Precise measurement of gas volumes by means of low-offset MEMS flow sensors with µL/min resolution

Experiments devoted to evaluate the performance of a MEMS thermal flow sensor in measuring gas volumes are described. The sensor is a single-chip platform, including several sensing structures and a low-offset, low-noise readout interface. A recently proposed offset compensation approach is implemented obtaining low temperature drift and excellent long time stability. The sensor is fabricated by applying a simple micromachining procedure to a chip produced using the BCD6s process of STMicroelectronics. Application of a gas conveyor allowed inclusion of the sensing structure into a channel of sub-millimeter cross-section. The results of measurements performed by making controlled air volumes pass through the sensor channel in both directions at rates from 0.1 to 5 mL/min are described

Integrated smart gas flow sensor with 2.6 mW total power consumption and 80 dB dynamic range

A thermal flow sensor including sensing structures and a read-out interface in a single chip is proposed. The sensing structure is a microcalorimeter based on a double heater configuration while the low noise electronic interface performs signal reading and offset compensation. The device has been fabricated with a commercial CMOS process followed by a post-processing procedure. Post-processing has been customized in order to increase the thermal insulation of the sensing structures from the silicon substrate and improve the heat exchange between the sensor and the gas flow. Device characterization confirms the effectiveness of the proposed fabrication method in increasing the sensitivity at constant power consumption without affecting the dynamic range

A Low-cost Sensing System for Cooperative Air Quality Monitoring in Urban Areas

Air quality in urban areas is a very important topic as it closely affects the health of citizens. Recent studies highlight that the exposure to polluted air can increase the incidence of diseases and deteriorate the quality of life. Hence, it is necessary to develop tools for real-time air quality monitoring, so as to allow appropriate and timely decisions. In this paper, we present uSense, a low-cost cooperative monitoring tool that allows knowing, in real-time, the concentrations of polluting gases in various areas of the city. Specifically, users monitor the areas of their interest by deploying low-cost and low-power sensor nodes. In addition, they can share the collected data following a social networking approach. uSense has been tested through an in-field experimentation performed in different areas of a city. The obtained results are in line with those provided by the local environmental control authority and show that uSense can be profitably used for air quality monitoring

A Low-Power Interface for Capacitive Sensors With PWM Output and Intrinsic Low Pass Characteristic

A compact, low power interface for capacitive sensors, is described. The output signal is a pulse width modulated (PWM) signal, where the pulse duration is linearly proportional to the sensor differential capacitance. The original conversion approach consists in stimulating the sensor capacitor with a triangular-like voltage waveform in order to obtain a square-like current waveform, which is subsequently demodulated and integrated over a clock period. The charge obtained in this way is then converted into the output pulse duration by an approach that includes an intrinsic tunable low pass function. The main non idealities are thoroughly investigated in order to provide useful design indications and evaluate the actual potentialities of the proposed circuit. The theoretical predictions are compared with experimental results obtained with a prototype, designed and fabricated using 0.32 mu M CMOS devices from the BCD6s process of STMicroelectroncs. The prototype occupies a total area of 1025 x 515 mm(2) and is marked by a power consuption of 84 mu W. The input capacitance range is 0-256 fF, with a resolution of 0.8 fF and a temperature sensitivity of 300 ppm/degrees C

Thermal Noise-Boosting Effects in Hot-Wire-Based Micro Sensors

This article proposes an original approach aimed at modelling the noise density in sensors based on a single hot wire or pairs of thermally coupled wires. The model consists in an original combination of a previous electrothermal model of the wire with well-established assumptions on the thermal noise in conductors that carry moderate current densities. A simple method for estimating the model parameters with simple impedance spectroscopy is suggested. The predicted power spectral densities of the wire thermal noise differ from the result of previously presented analytical models, stimulating further experimental studies. The effects of the electrothermal feedback of both hot wires and hot-wire pairs on flicker noise is also intrinsically covered by the proposed approach