UNIVERSITA’ DEGLI STUDI DI TRENTO 

Dipartimento di Ingegneria e Scienza dell’Informazione

 
Research topics 

1.         ADVANCED CMOS IMAGE SENSORS

G.-F. Dalla Betta, E. Panina, O. Shcherbakova 

Collaborations: FBK, Optoelettronica Italia; Universities of: Modena e Reggio Emilia, Pavia; Technical University of Munich (Germany), University of Edinburgh (UK).

  

2.         SILICON RADIATION DETECTORS

G.-F. Dalla Betta, M. Povoli

Collaborations: FBK, INFN, CERN, SLAC; Universities of: Bergamo, Modena e Reggio Emilia, Pavia, Pisa, Trieste, Udine; Albert-Ludwig University Freiburg (Germany), University of California Santa Cruz (USA), University of Manchester (UK), Jozef Stefan Institute (Slovenia).
 


3.         EMBEDDED ELECTRONICS AND WIRELESS SENSOR NETWORKS

D. Brunelli, R. Passerone

Collaborations: University of California Berkeley, CREATE-NET, University of Moscow

 

4.      EMBEDDED SYSTEMS MODELING AND OPTIMIZATION

D. Brunelli, R. Passerone

Collaborations: University of California Berkeley, ALES S.r.l, FBK, ETHZ, VERIMAG, OFFIS, INRIA, EPFL, IST-Austria

 

5.      MULTI-SOURCE ENERGY HARVESTING DESIGN

D. Brunelli,R. Passerone,

Collaborations: University of Bologna, EPFL, FBK, University of Modena

 

ADVANCED CMOS IMAGE SENSORS

G.-F. Dalla Betta, E. Panina, O. Shcherbakova

This research activity aims at the development of novel CMOS image sensors with special functionalities (e.g., high dynamic range, high sensitivity, multispectral capabilities, etc.), with focus on 3D vision and biomedical imaging applications. CMOS 3D image sensors are mainly oriented to security and surveillance, domotics and building automation. Additionally, we have developed other CMOS sensors oriented to time-resolved fluorescence measurements, which are an investigation tool of paramount importance in imaging of molecular processes in life sciences research. Both types of applications require high-sensitivity, high-speed photodetectors.

In particular, we have thoroughly tested Single Photon Avalanche Diodes (SPAD): although their electro-optical characteristics are not optimized in some respects, owing to the integration with the read-out electronics these photodetectors are appealing for low-cost, high-performance fully integrated systems for high-sensitivity imaging applications. In 2011, we have been extensively characterizing 10x10 SPAD detector modules for fluorescence lifetime imaging microscopy (FLIM) applications. Lifetime measurement are obtained by using the time-gated technique. We have extensively tested the  dark count distribution, the dynamic range, the gating performance, and the cross talk. More than 70% of single SPADs have a dark count rate lower than 1 kHz at the excess bias voltage of 1.8V and do not exceed 2 kHz at the bias voltage of 4.8V. The cross talk was found to be in the range from 2% to 3% for lateral neighbors and between 0.3% and 0.5% for diagonal neighbors. A dynamic range exceeding 120 dB was observed with a maximum count rate before saturation of 500 MHz. Time gating resolution was found to be less than 1 ns. A fluorescent lifetime measurement of ZnS-ZnSe quantum-dot reference slides was performed and the non-uniformity of the calculated lifetime value was lower than 1% across the matrix.

As for 3D vision systems, we have designed and tested an image sensors based on a Current Assisted Photon Mixing Device (CAPD). Promising results have been obtained from the first prototypes fabricated in a 0.18m CMOS technology with a remarkably small pixel size of 10x10 m², which have shown a DC charge separation efficiency close to 100% and good demodulation capabilities up to 35MHz. A full 3D vision system prototype has been built, featuring a 160x120 CAPD pixel array and allowing for real-time 3D imaging with a worst-case accuracy of 3.3% in the distance interval from 1.2 to 3.7m. Further tests are under way on a new prototype demonstrator featuring an optimized illumination module.

We have also started to develop a new image sensor based on Avalanche PhotoDiodes (APD) operated in the linear mode with a gain in the order of 10 and low excess noise figures. These devices allow for phase demodulation at the pixel level up to very high frequencies (~100MHz), so they are very promising for high accuracy distance measurements as well as for fluorescence lifetime imaging applications. The fabrication of a test chip with a 2D array of APD-based phase-sensitive pixels is under way.

We have also designed and successfully fabricated a novel hybrid image sensor based on an organic photodetector layer deposited with a simple, low-cost spray coating on a CMOS substrate embedding the read-out and control circuitry. A full optoelectronic characterization of the first prototypes has been performed, with good electro-optical figures and also including the first reported observation of different noise types in organic photodiodes, thus demonstrating the suitability of this novel device for imaging application.


Publications in 2011

1)         [1] G.-F. Dalla Betta, L. Pancheri, D. Stoppa, R. Henderson, J. Richardson, "Avalanche Photodiodes in Submicron CMOS Technologies for High-Sensitivity Imaging", in Advances in Photodiodes, ISBN 978-953-7619-X-X, pp.~225-248, INTECH, Rijeka, Croatia,  March 2011.

2)         [2] M. Benetti, G.-F. Dalla Betta, L. Pancheri, M. Repich, C. Collini, E. Morganti, L. Lorenzelli, L. Lunelli, L. Pasquardini, C. Pederzolli, D. Stoppa, "CMOS Single Photon Detectors for advanced fluorescence sensing applications", Proceedings of Biophotonics, Parma (Italy), June 8-11, 2011.

3)         [3] M. Benetti, M. Popleteeva,  G.-F. Dalla~Betta, L. Pancheri,  D. Stoppa,  "Characterization of a CMOS SPAD sensor designed for fluorescence lifetime spectroscopy", Proceedings of PRIME 2011, Madonna di Campiglio (Italy), July 3-7, 2011, pp.185-188.

4)         [4] G.-F. Dalla Betta, S. Donati, Q.D. Hossain, G. Martini, L. Pancheri, D. Saguatti, D. Stoppa, G. Verzellesi, "Design and Characterization of Current Assisted Photonic Demodulators in 0.18 m CMOS", IEEE Trans. Electron Devices, vol. 58, n.6, pp. 1702-1709, June 2011.

5)         G.-F. Dalla Betta, S. Donati, Q. D. Hossain, G. Martini, L. Pancheri, D. Stoppa, G. Verzellesi, "TOF-Range Image Sensor in 0.18 m CMOS Technology based on Current Assisted Photonic Demodulators", Proc. of IEEE/OSA CLEO 2011, Baltimore (USA), May 1-6 2011, Paper CMG6

6)         D. Stoppa, L. Pancheri, N. Massari, M. Malfatti, M. Perenzoni, G. Pedretti, G.-F. Dalla Betta, "Time Of Flight Image Sensors in 0.18m CMOS Technology: a Comparative Overview of Different Approaches”, Proceedings of 2011 International Image Sensor Workshop (IISW)}, Hokkaido (Japan), June 8-11, 2011.

7)         O. Shcherbakova, R. Mittempergher, G.-F. Dalla Betta, L. Pancheri, D. Stoppa, "Design and Characterization of a Monolithic CMOS Phase-Sensitive Pixel Based on an Avalanche Photodiode", Proceedings of PRIME 2011, Madonna di Campiglio (Italy), July 3-7, 2011, pp. 85-88.

8)         D. Baierl, M. Schmidt, G. Scarpa, P. Lugli, L. Pancheri, D. Stoppa, G.-F. Dalla Betta, "Towards a hybrid CMOS-imager with organic semiconductors as photoactive layer", Proceedings of PRIME 2011, Madonna di Campiglio (Italy), July 3-7, 2011, pp. 89-92.

 

SILICON RADIATION DETECTORS

G.-F. Dalla Betta, M. Povoli

This activity deals with high-energy radiation detectors, with emphasis on novel radiation detectors for particle tracking in high-energy physics and photon and particle detectors aimed at environmental monitoring, nuclear medicine and other scientific applications.

We have continued in the development and optimization of novel detectors with three-dimensional electrodes and active edges fabricated at FBK. We have completed the characterization of 3D-DDTC (double-sided, double-type-column) detectors with non-passing-through columns, aimed at simplifying the fabrication process while retaining the major advantages offered by 3D detectors. The ultimate limitations of this approach in the presence of high radiation damage has been investigated both with laboratory measurements and in beam tests. It has been shown that, despite column depths available in the prototypes was not optimized, these detectors offer good efficiency and satisfactory charge collection characteristics up to a particle fluence of 1x10¹⁵ n_eq/cm² at a bias voltage of just 60V. In order to improve the process reproducibility and the detector performance up to larger fluencies, we have developed an enhanced double-sided fabrication technology allowing for passing through columns. Results from the electrical characterization are promising, with low leakage currents and breakdown voltage sizably larger than the full depletion voltage. We have carried out an extensive characterization and TCAD of the breakdown voltage behavior and identified some process/design improvements. We have demonstrated that a slim edge of about 100 m is feasible, and studied some novel termination designs to further improve this results down to about 50 m. Functional tests in laboratory and under particle beam on both non irradiated and irradiated samples have been performed in the framework of the activities of the ATLAS 3D Sensor Collaboration, showing excellent charge collection properties and hit reconstruction efficiency better than 98% after a fluence of 5x10¹⁵ n_eq/cm².

In parallel, we have also completed the electrical characterization of planar sensors with active edges, studying the best trade-off between edge sensitivity and breakdown voltage. Functional tests with laser and X-ray beams are under way.

Another activity deals with portable alpha particle detectors for environmental Radon monitoring.

Based on a new batch of BJT sensors with optimized layout, a battery-powered, wireless Radon sensor has been designed and realized. Radon daughters are electrostatically collected on the detector surface. Thanks to the BJT internal amplification, real-time α particle detection is possible using simple readout electronics, which records α-particle arrival time and charge. Functional tests at known Radon concentrations, demonstrated a sensitivity up to 4.9 cph/(100 Bq/m³) and a count rate of 0.05 cph at nominally-zero Radon concentration.

We have also continued our activities on Silicon PhotoMultipliers (SiPM) coupled to scintillator crystals for medical imaging and material analysis applications. In particular, we have evaluated the use of FBK SiPMs in Positronium Time Of Flight (Ps TOF) technique. The aim of this technique is the study of the energy of Ps emitted by porous media for advanced experiments in the field of antimatter physics and, in the future, for open porosities characterization. The TOF spectrometer in operation at the positron beam of the University of Trento (Italy) is based on five gamma detectors composed of NaI(Tl) scintillators coupled to PMTs. We compared the performance of one of these standard detectors against a detector formed by two 4x4mm2 SiPMs coupled to a 4x4x30mm3 LYSO scintillator. The LYSO+SiPM detector was characterized for timing and energy resolution as well as for the background emission level. We have shown that SiPMs, thanks their small size and versatility, can be coupled successfully to small scintillators, obtaining more compact detectors than the NaI(Tl)+PMT detectors. We have later designed an array of detectors with wide angular acceptance and spatial resolution in order to improve the performances of Ps-TOF setups.


Publications in 2011

1)         P. Hansson, …,  G.-F. Dalla Betta, et al. "3D Silicon Pixel Sensors: Recent Test Beam Results", Nucl. Instr. and Meth. A, vol. 628, pp. 216-220, 2011.

2)         G.-F. Dalla Betta, M. Boscardin, G. Darbo, C. Gemme, A. La Rosa, H. Pernegger, C. Piemonte, M. Povoli, S. Ronchin, A. Zoboli, N. Zorzi, "Development of 3D-DDTC pixel detectors for the ATLAS upgrade", Nucl. Instr. and Meth. A, vol. 638-S1, pp.S15-S23, 2011.

3)         P. Grenier, … , G-F. Dalla Betta, …,  M. Povoli, et al., "Test beam results of 3D silicon pixel sensors for the ATLAS upgrade", Nucl. Instr. and Meth. A, vol. 638, pp. 33-40, 2011.

4)         A. Micelli, … , G-F. Dalla Betta, …,  M. Povoli, et al., "3D-FBK Pixel sensors: recent beam tests results with irradiated devices", Nucl. Instr. and Meth. A, vol. 650, pp. 150-157, 2011.

5)         G. Giacomini, C. Piemonte, G.-F. Dalla Betta, M. Povoli, {"Simulations of 3D detectors", (Invited paper), Proceedings of Science - 20th Workshop on Vertex Detectors (Vertex 2011), Paper  025.

6)         A. Cristofoli, P. Palestri, M.P. Giordani, V. Cindro, G.-F. Dalla Betta, L. Selmi, "Experimental Determination of the Impact Ionization Coefficients in Irradiated Silicon", IEEE Trans. Nucl. Sci., vol. 58, n. 4, pp. 2091-2096, August 2011.

7)         M. Koehler, …, G.-F. Dalla Betta, et al., "Beam Test Measurements with Planar and 3D Silicon Strip Detectors Irradiated to sLHC Fluences", IEEE Trans. Nucl. Sci., vol. 58, n.~3, pp. 1308-1314, June 2011.

8)         M. Koehler, , …, G.-F. Dalla Betta, et al., "Measurements with Irradiated 3D Silicon Strip Detectors", Nuclear Physics B. Proc. Suppl., vol.215(1), pp. 247-249, 2011.

9)         A. Cristofoli, A. Dalla Costa, M. Boscardin, V. Cindro, G.-F. Dalla Betta, F. Driussi, G. Giacomini, M. P. Giordani, P. Palestri, M. Povoli, S. Ronchin, L. Selmi, E. Vianello, "Simulations and Electrical Characterization of Double-side Double Type Column 3D Detectors", IEEE NSS-MIC’11 Conference Record , paper N10-5, Valencia (Spain), October 23-29, 2011.

10)     E. Vianello, A. Bagolini, P. Bellutti, M. Boscardin, G.-F. Dalla Betta, G. Giacomini, F. Mattedi, C. Piemonte, M. Povoli, N. Zorzi, "Optimization of double side 3D detector technology for first production at FBK", IEEE NSS-MIC’11 Conference Record , paper N10-6, Valencia (Spain), October 23-29, 2011.

11)     G.-F. Dalla Betta, A. Bagolini, M. Boscardin, G. Giacomini, M. Povoli, E. Vianello, N. Zorzi, "Development of Active and Slim Edge Terminations for 3D and Planar Detectors", IEEE NSS-MIC'11, Conference Record, paper N24-5, Valencia (Spain), October 23-29, 2011.

12)     M. Povoli, M. Boscardin, A. Bagolini, G.-F. Dalla Betta, G. Giacomini, E. Vianello, N. Zorzi, "Development of planar detectors with active edge", Nucl. Instr. and Meth. A, vol. 658, pp. 103-107, 2011.

13)     V. Tyzhnevyi, G.-F. Dalla Betta, L. Rovati, G. Verzellesi,  N. Zorzi, "BJT detector with FPGA-based read-out for alpha particle monitoring", Journal of Instrumentation, JINST 6, C01051, 2011.

14)     V. Tyzhnevyi, G.-F. Dalla Betta, G. Verzellesi, L. Bosisio, G. Batignani, G. Giacomini, A. Picciotto, "BJT detector for alpha-particle and Radon detection and monitoring", IEEE NSS-MIC'11, Conference Record, paper N39-1, Valencia (Spain), October 23-29, 2011.

15)     M. Benetti, A. Tarolli, G. Giacomini, C. Piemonte, G.-F. Dalla Betta, "Simulation and characterization of different setups for gamma ray detection using SiPMs and LYSO scintillators", Nucl. Instr. and Meth. A, vol. 658, pp. 61-65, 2011.



EMBEDDED ELECTRONICS AND WIRELESS SENSOR NETWORKS

D. Brunelli, R. Passerone

The research spans various aspects of the design, analysis, optimization and testing of devices and systems for wireless sensor networks.

In the area of Wireless Sensor Network (WSN) Design, the research deals with the study of novel techniques aimed at creating scalable and reliable networks of smart low-power sensor nodes. In the last year, we have worked on various complementary problems, from network optimization to network design.

We have experimented with sensor networks employing different kinds of sensor nodes. In particular, we have developed in collaboration with CREATE-NET and the University of Moscow a sensor network for the detection of hazardous gases and fire. The node has been designed to conserve power by using new ways of driving a semiconductor based gas detector. The design, which uses different forms of energy storage, has been shown to achieve a lifetime of close to two years. Concurrently, we have experimented with new ways of storing the energy on the sensor node. Of interest is the realization, in collaboration with the University of California, Berkeley, of supercapacitors which are printed directly on the board of the node, thus minimizing the space requirements. This technology, which still requires improvement, has been shown effective in simple monitoring nodes.

An interesting orthogonal problem is optimal coverage. In this respect, we are developing efficient scalable techniques for the computation of optimal schedules for the duty cycle of the nodes of a WSN that guarantees the largest coverage given a desired lifetime of the system.  The optimization takes advantage of the redundancy in coverage present in the system to distribute the monitoring task over time, and let nodes work in power-save mode when not required.  The results include the proof of convergence of a distributed optimization algorithm, which was also positively evaluated with respect to an exact optimization procedure.  Centralized algorithms have also been developed to cope with the exponential complexity of the problem.  At the same time, we have looked at the problem of employing optimal strategies for the use of different channels for spectrum co-existence.

An extension of this work involves the analysis of power consumption in Wireless Sensor Networks.  For this purpose, we have developed a tool that incorporates models of battery charge and discharge cycles, as well as models of the architecture and application, to analyze the energy behavior of nodes in the context of a network.  The model is structured in layers that make it easy to change mapping of applications to architectural services.  Recently, we have added support for mobility of the nodes, and a full model of the network to extend the simulator capabilities from a single node to a collection of nodes. The results show that high accuracy can be achieved using physical models of the battery, compared to actual measurements on a deployed system.  Higher level models have been developed to improve the simulation performance. Currently we are working on communication models for multi-hop networks and to incorporate general protocols.


Publications in 2011

1)         Andrey Somov, Alexander Baranov, Alexey Savkin, Denis Spirjakin, Andrey Spirjakin, Roberto Passerone, “Development of wireless sensor network for combustible gas monitoring”, Sensors and Actuators A: Physical, 171(2):398-405, November 2011.

2)         Luigi Palopoli, Roberto Passerone, Tizar Rizano, “Scalable Off-line Optimization of Industrial Wireless Sensor Networks”, IEEE Transactions on Industrial Informatics, vol 7(2), pp. 328-339, May 2011.

3)          [5] Md. Akbar Hossain, Roberto Passerone, “Power Adaptive Cognitive Pilot Channel for Spectrum Co-existence in Wireless Networks”, in Proceedings of the 25th IEEE International Conference on Advanced Information Networking and Applications (AINA11), Singapore, March 22-25, 2011.

 

EMBEDDED SYSTEMS MODELING AND OPTIMIZATION

D. Brunelli, R. Passerone

This research area deals with the design, implementation of models for the design, verification and optimization of embedded systems. In the field of hybrid and heterogeneous systems, we are developing methodologies for modeling and interchanging models across different tools.  In particular we have considered metamodels as a means to encompass a variety of models of computation and communication according to two different strategies, one that maintains separation, and one that uses a common refinement model.  The Heterogeneous Rich Component (HRC) model has been developed to account for both discrete and continuous behaviors, and methods have been developed for verification and simulation.  As part of this work, we have developed a link between the Modular Performance Analysis toolbox, developed at ETHZ, and our Parametric Schedulability Analysis framework.

In the area of circuits, we are developing innovative imaging sensors characterized by an extremely low power profile. The sensors include on board processing to increase the efficiency of the computation.  Also, a model to test the performance of image contrast sensor has been recently developed. This kind of sensors could be very useful for non-invasive surveillance purposes. We have also integrated one such sensor, developed at the “Fondazione Bruno Kessler'' (FBK), in a novel system for road line recognition, whose purpose is to estimate the orientation of a road line in real--time when a vehicle is moving at a high speed, for automatic trajectory correction.

In the area of system modeling we have extended the concept of interface theories to a more complete notion of design contract.  In a contract, the designer expresses both the assumptions of use of a software or hardware components, as well as its guarantees under the stated assumptions.  We have developed specification methods using a special class of automata and defined operators for parallel composition and for the conjunction of contracts covering different aspects of a design.  We have in particular addressed the problem of equalizing the alphabets of multi-viewpoint specifications which poses interesting theoretical problems. We have shown how to achieve specification neutrality with respect to other viewpoints, and implemented the methods using acceptance automata.

We are currently applying platform-based design techniques to the exploration and the optimization of architectures. We are concentrating on modeling non-functional attributes and their correct manipulation in high integrity systems and safety critical systems.  In particular, we have applied our techniques to the design of the embedded control of a hybrid vehicle.  From a tool point of view, we have established links between the BIP framework developed at Verimag with the Metro II framework developed at UC Berkeley, to which we are contributing, for a more extensive design space exploration.

In addition to that, we are studying techniques for the analysis of parametric systems using formal methods.  A case study based on a heterogeneous cabin communication systems has been developed and analyzed to identify the region of parameters that result in a correct operation.  We are currently studying means to make the analysis more efficient using abstraction techniques.


Publications in 2011

1)         Jean-Baptiste Raclet, Eric Badouel, Albert Benveniste, Benoît Caillaud, Axel Legay, Roberto Passerone, “A Modal Interface Theory for Component-based Design”, Fundamenta Informaticae, 108(1-2):119-149, 2011.

2)         Alena Simalatsar, Yusi Ramadian, Roberto Passerone, Kai Lampka, Simon Perathoner, Lothar Thiele, “Enabling Parametric Feasibility Analysis in Real-time Calculus Driven Performance Evaluation”, in Proceedings of the International Conference on Compilers, Architectures and Synthesis of Embedded Systems (CASES11), Taipei, Taiwan, October 9-14, 2011.

3)         Tizar Rizano, Roberto Passerone, David Macii, Luigi Palopoli, “Model-Based Design of Embedded Control Software for Hybrid Vehicles”, in Proceedings of the 6th IEEE International Symposium on Industrial Embedded Systems (SIES11), Västerås, Sweden, June 15-17, 2011.

 

MULTI-SOURCE ENERGY HARVESTING DESIGN

D. Brunelli,R. Passerone

UNITN has addressed the modelling of miniaturized energy harvesting devices for perpetually powered systems, capable to convert concurrently different environmental energy sources. In particular design of ultra low size wind energy harvester for distributed embedded systems was optimized with a methodology which can be easily applied to embedded systems in order to extend battery lifetime. 

In addition, UNITN has also improved the design of a scavenger prototypes which exploits miniaturized photovoltaic modules to perform automatic maximum power point tracking. UNITN has proposed a detailed model of the solar cell that predicts the instantaneous power collected by the panel and improves the simulation of harvester systems. Furthermore, UNITN focused on a methodology for optimizing the design of MPPT solar harvesters for self-powered embedded systems and presented innovations in the circuit architecture with respect to our previous implementation.

Finally, UNITN worked on Optimization-centric MPSoC Design and on optimal management of smart sensors with energy harvesting capabilities. Wireless sensor networks are a very relevant example hardware platform with very tight energy constraints. The limited battery lifetime can be extended indefinitely if the node is equipped with energy harvesters that collect and store energy from the environment. However, given the erratic nature of environmental energy sources, the rate at which sensing, computation and storage operations can be performed should be dynamically adjusted to the energy availability using a closed-loop optimal control policy.

Thanks to all these contributions, UNITN introduced an hybrid power architecture which improves embedded systems power availability. We present a Smart Power Unit (SPU) that is a power supply architecture which manages both energy harvesting and novel fuel cells technologies. SPU provides an efficient air-flow and solar energy harvesting stage and a hydrogen micro fuel cell interface. Each harvester stores energy in a local supercapacitor and, when full, a lithium-ion battery is charged. Micro fuel cell acts as reservoir source for recharging battery in low environmental power condition. The core of the SPU is the microcontroller based power manager that exploits MPPT, energy prevision, battery monitoring and communications with user node.

 
Publications in 2011

1)         B. O'Flynn, E. Popovici, D. Boyle, M. Magno, D. Brunelli, and C. Petrioli, "GENESI: Wireless Sensor Networks for Structural Monitoring," in Proc. 35th International Conference of IMAPS - CPMT IEEE, 2011.

2)         D. Carli, D. Brunelli, L. Benini, and M. Ruggeri, "An effective multi-source energy harvester for low power applications," in Proc. Design, Automation Test in Europe Conference Exhibition (DATE), 2011, pp. 1–6.

3)         A. Lanza, M. Magno, D. Brunelli, L. Di Stefano, and L. Benini, "Energy-aware objects abandon / removal detection," in Proc. of 8th IEEE International Conference on Advanced Video and Signal-Based Surveillance (AVSS), 2011, pp. 443–448.

4)         D. Boyle, M. Magno, B. O'Flynn, D. Brunelli, E. Popovici, and L. Benini, "Towards Persistent Structural Health Monitoring Through Sustainable Sensor Networks," in Proc. Seventh International Conference on Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP), 2011, pp. 323–328.

5)         V. Jelicic, M. Magno, G. Paci, D. Brunelli, and L. Benini, "Design, characterization and management of a wireless sensor network for smart gas monitoring," in Proc. of 2011 4th IEEE International Workshop on Advances in Sensors and Interfaces (IWASI), pp. 115–120.