UNIVERSITA’ DI MESSINA

Dipartimento di Fisica della Materia e Ingegneria Elettronica

 

Research topics

 

1.    DEVELOPMENT AND ELECTRICAL CHARACTERIZATION OF NANOSTRUCTURED MATERIAL BASED SENSORS

N. Donato, D. Aloisio, E. Patti

Collaborations: DCIIM, UniMe; Dip. Farmaco-Chimico, UniMe; CNR-ITAE, Messina; Dip. MECMAT, UniRC; Unità Operativa Complessa di Terapia Subintensiva e Tecniche Dialitiche, Policlinico Universitario, UniMe; Dip. di Elettronica Informatica e Sistemistica, Università della Calabria; CNR-IMM, Catania; Gruppo Sensori - Enea Brindisi; Dip. di Fisica, Università di Ferrara; Dip. di Scienze e Tecnologie Chimiche, UniRoma2; Istituto Nazionale di Ricerca Metrologica (INRIM), Torino; UTAGRI - Laboratorio Innovazione Agro-Industriale, ENEA C.R. Casaccia; Dept. of Physics, VMKV Eng. College, Salem, India; Nanotechnology Laboratory, Dept. of Physics, Vidyalaya College of Arts and Science, Coimbatore, India; Dept. of Computer and Software Engineering, University of Almustansiriya, Baghdad, Iraq; School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Korea; Dept. of Chemistry, CICECO, Univ. of Aveiro, Portugal; Institut für Angewandte Physik, Justus-Liebig-Universität Gießen, Germany; Faculty of Science, Dept. of Chemistry, University of Paderborn, Germany; Institute of Inorganic Chemistry, Georg-August-Universität, Göttingen, Germany.

 
2.    LOW NOISE AND HIGH SENSITIVITY MEASUREMENTS: INSTRUMENTATION AND APPLICATIONS

C. Ciofi, G. Scandurra, G. Cannatà

 

3.    DEVELOPMENT OF SENSOR SYSTEMS ON PLASTIC SUBSTRATES

C. Ciofi, G. Scandurra, G. Cannatà


 
DEVELOPMENT AND ELECTRICAL CHARACTERIZATION OF NANOSTRUCTURED MATERIAL BASED SENSORS

N. Donato, D. Aloisio, E. Patti

The research group was involved on the development and the electrical characterization of sensors realized on both flexible and alumina ceramic substrates for gas mixtures and volatile organic compounds (VOCs) with several transduction mechanisms.

Ceramic resistive sensors, working at operating temperature ranging from room temperature to 400 °C and based on nanostructured metal oxides (MOX) prepared by a number of conventional and advanced physical and chemical synthesis approach such as microwave synthesis, ALD (Atomic Layer Deposition), electrospinning, laser ablation, CVD, etc., were developed for the monitoring of several gas targets for industrial applications[1-14]. Examples of these devices include CO and NO₂ sensors for the detection of very low concentrations of these toxic gases in environmental applications. Hydrogen sensors were also developed and characterized for the fuel cells field. The performances of innovative acetone MOX sensors for biomedical applications in breath analysis diagnostic systems were also evaluated[15,16].

Humidity capacitive sensors, based on hybrid organic/inorganic composites, were also developed. The optimization of these devices finds high interest in the  monitoring and control of low water vapor pressure in the working ambient of the semiconductor industry[17].

The development of novel organic/inorganic inks, deposited by a custom inkjet printing system on commercial plastic substrates, allowed the fabrication of flexible sensing devices operating at room temperature. These studies were finalized to design and develop devices with low power consumption[18-19].

Acoustic devices, based on bulk and surface acoustic wave transductions, were developed, characterized, and investigated as gas sensors in clinical diagnostics for the monitoring of breath ammonia, a biomarker of important pathologies[15,20-22].

Part of the experimental activity was focused on the development of algorithms for measurement optimization[23],the main goal in this area was the realization of standalone monitoring prototypes for advanced applications in the mentioned sectors.

A complementary activity was performed to investigate the microstructure of the synthesized materials by means of the most advanced analytical Instrumentation available today (TEM-EDX, EELS, micro-Raman, XPS, etc.) [1-24]. This activity was aimed to find correlations between the morphological and microstructural characteristics of sensing materials and their performance in term of sensitivity, selectivity and stability.


Pubblications in 2011

1)         N. Donato, F. Neri, G. Neri, M. Latino, F. Barreca, S. Spadaro, I. Pisagatti, G. Currò, CO sensing devices based on indium oxide nanoparticles prepared by laser ablation in water (2011) Thin Solid Films, 520 (3), pp. 922-926.

2)         A. Bonavita, G. Micali, G. Neri, N. Donato, M. Latino, S. Licoccia, A research study and development of a hydrogen sensor for fuel cells (2011) LNEE, 91 Springer, pp. 329-333.

3)         F. Barreca, S. Spadaro, G. Currò, N. Acacia, F. Neri, N. Donato, M. Latino, G. Neri, Gas sensing properties of indium oxide nanoparticles prepared by laser ablation in water (2011) LNEE, 91 Springer, pp. 113-117.

4)         L. De Luca, A. Donato, G. Apa, S. Santangelo, G. Faggio, G. Messina, N. Donato, A. Bonavita, G. Neri, Room temperature hydrogen sensor based on Pt/TiO₂/MWCNT composites (2011) LNEE, 91 Springer, pp. 87-91.

5)         F. Fontana, T. Caronna, N. Donato, M. Latino, A. Bonavita, G. Rizzo, G. Neri, A novel organic/MWCNTs semiconductor composite for resistive gas sensors (2011) LNEE, 91 Springer, pp. 61-65.

6)         I. Arrigo, M. Caprì, F. Corigliano, A. Bonavita, G. Rizzo, G. Neri, N. Donato, An exploratory study on the potential of zeolite P-based materials for sensing applications (2011) LNEE, 91 Springer, pp. 67-71.

7)         T. Krishnakumar, R. Jayaprakash, T. Prakash, D. Sathyaraj, N. Donato, S. Licoccia, S., M. Latino, A. Stassi, G. Neri, CdO-based nanostructures as novel CO₂ gas sensors (2011) Nanotechnology, 22 (32), art. no. 325501.

8)         C. Marichy, N. Donato, M.-G. Willinger, M. Latino, D. Karpinsky, S.-H. Yu, G. Neri, N. Pinna, Tin dioxide sensing layer grown on tubular nanostructures by a non-aqueous atomic layer deposition process (2011) Advanced Functional Materials, 21 (4), pp. 658-666.

9)         S. Lo Schiavo, P. Cardiano, N. Donato, M. Latino, G. Neri, A dirhodium(ii,ii) complex as a highly selective molecular material for ammonia detection: QCM studies (2011) J. of Materials Chem., 21 (44), pp. 18034-18041.

10)     N. Donato, D. Aloisio, D. Spadaro, M. Latino, A. Giberti, C. Malagù, Temperature characterization of the sheet resistance of MWCNTs/PDDAC based sensitive films, pp71-74, Proc. of CARBOMAT 2011- (CT, Italy) Dec. 5-7,  Ed. CNR 2012, ISBN 978-88-8080-124-5.

11)     N. Donato, D. Aloisio, E. Patti, G. Scolaro, G. Neri, D. Spadaro, S. Trocino, A. Donato, M. Latino, An inkjet deposition system for water-based solutions of MWCNT/PMA for sensing applications, pp.41-44, Proc. of CARBOMAT 2011- (CT, Italy) Dec. 5-7, Ed. CNR 2012, ISBN 978-88-8080-124-5.

12)     S. Lo Schiavo, P. Cardiano, N. Donato, M. Latino, G. Neri, Transition metal complexes as ammonia responsive materials for SAW chemical sensors (2011) LNEE, 91 Springer, pp. 99-103.

13)     V. Scuderi, A. La Magna, A. Pistone, N. Donato, G. Neri, S. Scalese, Use of the electric fields for the manipulation of MWCNTs, pp.86-90, Proc. of CARBOMAT 2011- (CT, Italy) Dec. 5-7, Ed. CNR 2012, ISBN 978-88-8080-124-5.

 

LOW NOISE AND HIGH SENSITIVITY MEASUREMENTS: INSTRUMENTATION AND APPLICATIONS

C. Ciofi, G. Scandurra, G. Cannatà

Low frequency noise measurements are among the most sensitive tools for the characterization of the quality and reliability of electron devices. However, sensible noise measurements can be easily done only if the background noise of the measurement system is much lower than the noise generated by the device under test (DUT).

Within this context, we developed a new differential input ultra low noise amplifier with an equivalent input noise level as low as 1.4 nV/√Hz at 1 Hz and < 1 nV/√Hz for f> 10 Hz[1].

We devised a new approach to cross correlation demonstrating that if N measurement channels (N>2) are employed and the average among the N(N-1)/2 independent cross-spectra across any pair of channels is performed, the time required for reducing the contribution of the uncorrelated noise sources  below a given threshold is reduced by the same factor with respect to the conventional two channel cross correlation approach . This means that, when using N=8, measurement requiring 1 hour averaging time in the conventional approach will require about 2 minutes for obtaining the same sensitivity[2].

It has been demonstrated that by means of a three channel cross correlation approach it is possible to develop a versatile and highly sensitive impedance meter system that does not require any external source for sample excitation as it is the very noise produced by the passive and active components in the circuit that acts as wide bandwidth stimulus for the device under test[3].

It has been demonstrated that it is possible to take advantage of the large capacitances offered by supercapacitors for the design of programmable very lo noise voltage and current sources[4].

A new circuit topology for realization of nanovoltmeter amplifiers has been developed and tested. Such a topology is an evolution of an approach that was developed in the past consisting in employing a time varying resistance as a probe for detecting the sign and magnitude of the equivalent input offset of an operational amplifier in a series-shunt feedback configuration coupled with a proper control feedback for allowing the continuous nulling of the input offset of the amplifier. By means of the new improved approach, residual input offsets as low as 20 nV have been obtained[5].

We have also obtained some interesting results in the field of temperature measurement based on thermal noise measurements (Johnson Noise Thermometry or JNT). In the classical approach to JNT, the thermal noise across a resistance is measured and, from an independent measurement of the resistance value, one can estimate the absolute temperature at which the resistance, that acts as a sensor, is operating. We have demonstrated that is possible to measure the absolute temperature of a generic two terminals device using noise measurements only. In particular, since our method allows to estimate, at the same time, the admittance and the thermal noise produced by a generic two terminal device, this means that one does not need to resort to an independent measure of the resistance of the device. Moreover, even strongly non linear devices or devices with a frequency dependent impedance and/or with  an impedance that is temperature dependent can  be employed as temperature sensors[5]. Finally we have developed a new approach for reducing the measurement time in JNT, that is one of the limiting factors for its application as a routine temperature measurement systems. It has been demonstrated that by means of the proper calibration of a strongly temperature dependent device, noise measurements lasting a few seconds are sufficient to provide accuracies in the order of a small fraction of 1 K by employing standard low cost instrumentation[7].
 

Pubblications in 2011

1)         G. Scandurra, C. Ciofi, G. Cannatà, “Differential Ultra Low Noise Amplifier for Low Frequency Noise Measurements”, AIP Advances, Vol.1, Issue 2, 022144 (2011).

2)         G. Scandurra, C. Ciofi, “Impedance meter based on cross correlation noise measurements”, ICNF 2011, pp. 385-388, Toronto, Canada, 12-16 June 2011.

3)         G. Scandurra, C. Ciofi, “Supercapacitors in bias systems for low frequency noise measurements”, ICNF 2011, pp. 393-396, Toronto, Canada, 12-16 June 2011.

4)         G. Scandurra, C. Ciofi, A. Gambadoro, “A new approach to Johnson noise thermometry based on noise measurements only”, Fluctuation and Noise Letters, Vol. 10, n.2, pp. 133-145 (2011).

 

DEVELOPMENT OF SENSOR SYSTEMS ON PLASTIC SUBSTRATES

C. Ciofi, G. Scandurra, G. Cannatà

Commercially available resistive gas sensors, usually detect the presence of their specific target by exploiting the reversible electrical conductivity changes experimented by a thick or a thin metal oxide film deposited onto interdigitated platinum contacts applied on alumina or silicon substrates. The sensing mechanisms of metal oxide gas sensors is somehow thermally activated, therefore these kinds of devices often require working temperature higher than 150°C. Power consumption can be remarkably lowered by using sensing materials including doped conjugated polymers, organic-inorganic composites, semiconductor nanowires, and functionalised carbon nanotubes, able to detect the presence of the gas target at low temperature. To avoid the interference of relative humidity, and the drifts of the sensing material’s electrical conductivity with the temperature, room temperature gas sensing applications require the sensor’s temperature to be settled and controlled, and the RH level to be measured. In such a framework, the idea is the integration of low temperature sensing materials deposited onto Inter Digitated electrodes (IDEs), thin films temperature detectors and a heater, on the same plastic foils. This kind of approach can be used to provide cost-effective sensing platforms for a variety of sensing applications including environmental monitoring, food quality testing, indoor and outdoor air analysis. The choice of plastic substrates, offers benefits such as light weight, flexibility, conformability and ease of disposal, and in addition is fully compatible with inexpensive process technologies including inkjet printing. Sensing platforms able to detect the presence of ammonia at the ppm level, measuring the sensor temperature and evaluating the RH, have been developed using copier grade transparency sheets as substrates [1]. The sheets are double side coated with copper by thermal evaporation in vacuum, and then patterned using local chemical etching to develop IDEs and a resistive temperature detector on the top face, and a spiral heater on the back. Corrosion effects and electrical degradation of the metallic patterns with ageing in atmosphere, and after prolonged bending of the substrate, are evaluated using structural and morphological analysis (XPS and SEM), and by means of low frequency noise measurements. Humidity and ammonia sensing are achieved by monitoring the resistance of a polyaniline film and of a Multi Walled Carbon Nanotubes (MWCNT) composites applied on the IDEs [1]. Flexible sensors fully compatible with inkjet deposition processing, having improved sensitivity and faster transient response compared to those based on polyaniline only, are developed by applying on copier grade transparency sheets thick layers of nanostructured titanium dioxide, and then by infiltrating polyaniline into the highly porous inorganic layer [2]. Capacitive humidity sensors based on MWCNT having a dynamic range wider than resistive humidity sensors, are developed by interposing a polyeletrolyte blended with nanosized iron oxide, between Aluminum and MWCNT electrodes. The sensor is integrated on a flexible substrate having a copper spiral heater on the back, and a resistive temperature detector on the top [3]. Organic Field Effect Transisors  (OFET) developed starting form p doped monocrystalline silicon wafer having 100 nm oxide on the top as substrates, and by using as active material polyhexylthiophene (P3HT) deposited onto the 100 mm gap between gold drain and source contacts, have been prepared and characterized. It has been observed that the device degradation that follows from exposure to air moisture can be prevented by depositing the P3HT solution onto a porous nanostructured titanium dioxide layer [4].

 
Pubblications in 2011

1)         G. Scandurra, A. Arena, C. Ciofi, A. Gambadoro, F. Barreca, G. Saitta, G. Neri, “Low temperature gas sensing applications using copier grade transparency sheets as substrates”, Sensors and Actuators B, Vol. 157, n. 2, pp. 473-481 (2011).