Measurement of chlorophyll concentration is gaining more-and-more importance in evaluating the status of the marine ecosystem. For wide areas monitoring a reliable architecture of wireless sensors network is required. In this paper, we present a network of smart sensors, based on ISO/IEC/IEEE 21451 suite of standards, for in situ and in continuous space-time monitoring of surface water bodies, in particular for seawater. The system is meant to be an important tool for evaluating water quality and a valid support to strategic decisions concerning critical environment issues. The aim of the proposed system is to capture possible extreme events and collect long-term periods of data.

In this paper, we propose the modeling, the design, and the development of a high sensitivity cheap optical sensor for chlorophyll a and water transparency based on chlorophyll fluorescence and turbidity due to scattering for in situ monitoring of trophic status of seawater. The sensor is designed in order to detect very low chlorophyll concentration and low level turbidity by means of a numeric lock-in amplifier technique, with a common resonant input stage. The sensor is designed and implemented by considering a proper layout suitable for a good light source coupling. The presented prototype integrates on a board two LED sources emitting red and blue light to measure both chlorophyll-a and turbidity. The system assures a chlorophyll sensitivity of 1 mV/2.5 μg/l, a detectivity of 0.2 μg/l, with a 40-dB minimum attenuation of all the other light sources. It is attractive with respect to commercial systems because it guarantees considerable reliability with low manufacturing costs.

This paper proposes an innovative method for power consumption measurement in microcontroller-based systems that provides high accuracy on a wide dynamic range of current values, which makes it particularly suitable for all those applications characterized by alternating low-/high-power modes and fast current variations. We demonstrate that using an op-amp-based voltage feedback configuration, it is possible to use shunt resistor values higher than usual to obtain increased voltage drops without affecting the microcontroller's power supply voltage. Consequently, it is possible to directly use a data acquisition board to acquire the shunt voltage, eliminating all those common errors, like offset and gain, due to the use of an additional intermediate amplification stage. The proposed scheme has been successfully used to accurately characterize the power consumption of a single sensor node of a wireless sensor network.

This paper proposes the implementation of a low-cost and reliable multipurpose wireless sensor network framework. It has been designed to be easily customizable in order to adapt it to the particular application.

Thermo-Electric Modules (TEMs) are being increasingly used in power generation as a valid alternative to batteries, providing autonomy to sensor nodes or entire Wireless Sensor Networks, especially for energy harvesting applications. Often, manufacturers provide some essential parameters under determined conditions, like for example, maximum temperature difference between the surfaces of the TEM or for maximum heat absorption, but in many cases, a TEM-based system is operated under the best conditions only for a fraction of the time, thus, when dynamic working conditions occur, the performance estimation of TEMs is crucial to determine their actual efficiency. The focus of this work is on using a novel procedure to estimate the parameters of both the electrical and thermal equivalent model and investigate their relationship with the operating temperature and the temperature gradient. The novelty of the method consists in the use of a simple test configuration to stimulate the modules and simultaneously acquire electrical and thermal data to obtain all parameters in a single test. Two different current profiles are proposed as possible stimuli, which use depends on the available test instrumentation, and relative performance are compared both quantitatively and qualitatively, in terms of standard deviation and estimation uncertainty. Obtained results, besides agreeing with both technical literature and a further estimation method based on module specifications, also provides the designer a detailed description of the module behavior, useful to simulate its performance in different scenarios.