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Transduction Techniques & Sensors for Agro & Ecological Parameters

Agriculture is the oldest and perhaps the widest sector having witnessed a phenomenal change all over. This subject becomes truly interdisciplinary due to the involvement of multi faculty convergence towards the development of advanced measurement techniques and associated sensors design. Emergence of trans-disciplinary areas such as electro-optics, bio-optics, opto-mechatronics devices, bio-molecular electronics etc. are paving their way in exploring various techniques for the development of sensors relevance to agriculture, food processing and environmental monitoring. The issue become further widen when natural hazards such as seismic activity, land slide monitoring, snow avalanche studies pose new challenges for developing intelligence system for early warning.

Central Scientific Instruments Organization (CSIO), a constituent laboratory of Council of Scientific and Industrial Research (CSIR) is deeply associated in this area of research leading to the development of sensors and instrumentation systems for a variety of societal applications. The talk highlights the state of art development in the field of transduction techniques and sensors development in these areas based on the work carried out in the laboratory.

The Challenges of Developing a Geothermal Ultrasonic Borehole Imager

Geothermal energy is the cleanest form of alternative energy, as it has the least environmental impact. The United States has vast untapped geothermal energy potential; using enhanced geothermal systems (EGS) technology, geothermal wells can supply the energy consumption for the USA for 2000 years. The Department of Energy (DOE) spearheads research and innovation in tools and technologies required for successful and economical use of EGS reservoirs. Temperature in some EGS reservoirs can exceed 300° C. This paper shall describe the development of a geothermal ultrasonic borehole imager rated to operate at 300° C.

This borehole acoustic imager measures fracture patterns that convey information about the possibility of extracting heat by hot water/steam. Only if the rock is well fractured with continuous channels interconnecting large volumes of rock with a very large surface area is it possible to economically extract heat from the hole. Existing borehole imagers for oil and gas wells rely on one or a few sensors rotated in some fashion, such as by a motor or rotating mirror. Such technology is difficult to implement at high temperatures. An alternative approach is an azimuthal array of sensors that does not rely on moving parts. I shall illustrate the development of piezoelectric sensors capable of working at 300° C. I shall explain how borehole imaging is accomplished using a one-dimensional azimuthal array to optimize manufacturability and performance. Electronics shall be housed in a flask where the temperature would be below 175° C. We shall outline electronics system design strategies to make the circuit functional at 175° C and above, specifically elaborating on power management, space utilization, sensor performance, and image quality (or fracture detection).

Sensors for Human & Environment Safety in Nuclear Industry

In present day scenario keeping environment safe is a challenge. Energy requirements by modern world necessitates use of processes using fossil fuel as well as nuclear power plants that need safety measures for eliminating danger to personnel working in plants and the neighbouring environment. The talk discusses important sensors that are used in ensuring health safety by nuclear industry. Nuclear sensing techniques are emerging for dangerous material detection too.

Material development needs very high magnification viewing by using electron matter interaction. Several techniques that are used in high end sensing are dealt with in the talk.

Nuclear industry uses special equipment including various types of tele-operated agents, optical gadgets and support systems for safe working. The talk discusses some of these techniques for difficult applications. ‘Sensor fusion’ is an important aspect in surveillance applications for health safety implementations , these too will be discussed in adequate details.

Nano structured MOX for high selective multiparametric gas sensors

Metal oxide in forms of nanowires are interesting for their peculiar morphology and their exceptional crystalline features. The first assuring a high surface to volume ratio necessary to maximize surface related properties such as the ones governing chemical sensing transduction principles. The latter guaranteeing stable crystalline and therefore electrical properties over long term operation, i.e. a required quality for an industrial application of any kind of sensor in real environments.

Furthermore other peculiarities make them much more interesting than their thin or thick film counterpart, for example lateral dimensions comparable to the surface charge region, the possible modulation of the operating temperature to select the proper surface reactions, the self heated device option, catalyst can be deposited over the surface to enhance or reduce specific reactions and moreover their potential integration in field-effect transistors configuration to add a gate potential for a further opportunity to change sensitivity and selectivity.

After the first method proposed for the preparation of metal oxide in forms of nanobelts [Science, 2001 291,1947] plenty of literature was devoted to different experimental techniques that may lead to the formation of these quasi one dimensional structures. At the beginning the research was focusing of the vapour phase methods that were producing, with cheap instrumentation, high quality nanostructures in terms of crystallinity and stoichiometry.

We have thoroughly studied the deposition using evaporation and condensation from powder in controlled environment using different experimental set up. Tin oxide was preferred with respect to other oxides thanks to its well known chemical sensing properties and to the easy preparation condition, but also copper and zinc oxide were studied.

Metal oxide nanowires were integrated in functional devices for chemical sensing and then tested towards a wide range of chemicals, including odorous molecules such as ammonia, hydrogen sulfide. To further gain selectivity, innovative gas-sensor architectures, based on surface ionization mechanism and magnetic field activation, have been investigated and will be presented.

Design of CW-photoacoustic-based protocols for the noninvasive characterization of liquids: a potential alternative for blood glucose level sensing ?

Measurement of blood glucose levels (BGLs) is a basic procedure that diabetic patients need to perform several times a day. The conventional standard protocol for on-site measurement, despite several advantages such as portability, low cost, fast response time, and ease of operation, is based on the finger-prick technique to extract blood samples. This process is invasive and cannot provide continuous monitoring, which is the basic condition for optimal control.

Towards the achievement of a noninvasive and continuous BGL monitoring system, various alternative methods have been reported in the literature, involving a lot of researchers, from academic research laboratories to major industrial companies. However, due to the potential impact of the decision made on the basis of the BGL sensor, the requirements in terms of selectivity and sensitivity are so severe that, at the time of this writing, none of the proposed technologies has been able to fulfill them.

Among potential candidates, photoacoustic (PA) techniques have also been investigated, but only the pulse setup, since the continuous-wave (CW) requires a constant and reproducible local environment (i.e., cavity size) for operation, a condition impossible to realize in vivo. The CW-PA methods have then been limited to mainly gas-trace detection. However, we recently developed two CW-PA-based protocols that don't exhibit this cavity-size dependency, which opens the door to a new field of research. After a brief description of the two methods and their specific characteristics, this presentation will then discuss the in vitro (with pure aqueous solution of glucose) and in vivo first experimental results. The challenges ahead before applying these methods to BGL monitoring are still huge and require further study, both in vitro and in vivo. However, despite primarily developed for noninvasive and continuous BGL monitoring, the techniques exhibit interesting properties that may also lead to potential application in many other fields.