Present work shows recent progresses in thin film-based flexible and wearable thermoelectric generator (TEG), finalized
to support energy scavenging and local storage for low consumption electronics in Ambient Assisted Living (AAL)
applications and buildings integration. The proposed TEG is able to recover energy from heat dispersed into the
environment converting a thermal gradient to an effective electrical energy available to power ultra-low consumption
devices. A low cost fabrication process based on planar thin-film technology was optimized to scale down the TEG
dimensions to micrometer range. The prototype integrates 2778 thermocouples of sputtered Sb2Te3 and Bi2Te3 thin films
(1 μm thick) on an area of 25 cm2. The electrical properties of thermoelectric materials were investigated by Van der
Pauw measurements. Transfer Length Method (TLM) analysis was performed on three different multi-layer contact
schemes in order to select the best solution to use for the definition of the contact pads realized on each section of the
thermoelectric array configuration to allow electrical testing of single production areas. Kapton polyimide film was used
as flexible substrate in order to add comfortable lightweight and better wearability to the device. The realized TEG is
able to autonomously recover the thermal gradient useful to thermoelectric generation thanks to an appropriate package
designed and optimized by a thermal analysis based on finite element method (FEM). The proposed package solution
consists in coupling the module realized onto Kapton foil to a PDMS layer opportunely molded to thermally insulate
TEG cold junctions and enhance the thermal gradient useful for the energy scavenging. Simulations results were
compared to experimental tests performed by a thermal infrared camera, in order to evaluate the real performance of the
designed package. First tests conducted on the realized TEG indicate that the prototype is able to recover about 5°C
between hot and cold thermocouples junctions with a thermal difference of 17°C initially available between body skin
and environment, generating about 2 V of open circuit output voltage.
Present work proposed design, finite element tools simulation and prototype fabrication of a low cost energy
autonomous, maintenance free, flexible and wearable micro thermoelectric generator (μTEG), finalized to power very
low consumption electronics Ambient Assisted Living (AAL) applications. The prototype, integrating an array of 100
thin films thermocouples of Sb2Te3 and Bi2Te3, generates, at 40 °C, an open circuit output voltage of 430 mV and an
electrical output power up to 32 nW with matched load. In real operation conditions of prototype, which are believed to
be very close to a thermal gradient of 15°C, the device generates an open circuit output voltage of about 160 mV, with
an electrical output power up to 4.18 nW. In this work we proposed design, thermal simulation and fabrication of a
preliminary flexible and wearable micro thermoelectric generator (μTEG), finalized to power very low consumption
electronics for Ambient Assisted Living (AAL) applications. Presented simulations show the performances of different
fabrication solution for the PDMS/Kapton packages, considering flat and sloped walls approach for thermal gradient
enhancement.
Electronic Tongue systems have been widely used during last decades, reaching an high level of
performances in the detection and quantification of several matrices, such as for example waters, soft
and alcoholic drinks. Next step in research is represented by the miniaturization of these systems: it
is made possible by the integration of the knowledge on materials suitable for sensorial purpose and
the silicon technology, which allows the development of micro-dimensioned sensors. In this work
we report the development of a sensor array composed of 8 electro-polymerized porphyrin based
membranes, with an active area exposed to liquid of 0.5 mm2. The miniaturized system, integrated
on a single silicon wafer and completed by read-out electronics, was firstly tested towards standard
analytes and then applied on real white wine samples for the detection of some analytes mimicking
wine defects, namely H2S, SO2 and CH3CO2H.
We developed a novel method to detect the presence of unburned diesel fuel in used diesel fuel engine oil. The method is
based on the use of an array of different gas microsensors based on metal oxide thin films deposited by sol-gel technique
on Si substrates. The sensor array, exposed to the volatile chemical species of different diesel fuel engine oil samples
contaminated in different percentages by diesel fuel, resulted to be appreciable sensitive to them. Principal Component
Analysis (PCA) and Self-Organizing Map (SOM) applied to the sensor response data-set gave a first proof of the sensor
array ability to discriminate among the different diesel fuel diluted lubricating oils. Moreover, in order to get information
about the headspace composition of the diesel fuel-contaminated engine oils used for gas-sensing tests, we analyzed the
engine oil samples by Static Headspace Solid Phase Micro Extraction/Gas Chromatograph/Mass Spectrometer (SHS-SPME/
GC/MS).
Pulse voltammetry was employed to discriminate among different concentrations of defects in wine. The microelectrodes were fabricated as patterned platinum thin films on silicon wafers by means of silicon fabrication technology. The film pattern was as interdigitated fingers having a 2 μm fingers gap and active area of 100x100 μm2; a silicon nitride passivation permits a selective exposure of microelectrodes to electrolyte. Principal Component Analysis (PCA) of the current responses indicated that concentrations of acetaldehyde and L-ascorbic acid could be discriminated in a white wine electrolyte. Finally the capability of defects concentrations detection in two-defects solutions (acetaldehyde + L-ascorbic acid) has been investigated.
A cheap nanofabrication process for Titania (TiO2) polycristalline nanowire array for gas sensing applications with lateral size ranging from 90 to 180 nm, and gas sensing characterizations are presented. Alternatively to typical pattern transfer techniques for submicron fabrication, authors focused on a standard 365 nm UV photolithographic process able to fabricate sol-gel nanostructured titania nanowires from a solid thin film. Main aim of present work is the experimental validation of enhanced gas sensing response of nanopatterned metal oxide thin film sensors. Two different kind of gas sensor with nanopatterned sensitive area have been realized onto silicon substrates and tested towards different EtOH concentrations; experimental tests have been carried out with a contemporary output signals collection from a nanowires-based gas sensor and a second device with solid sensitive film without patterning, in order to validate effects of nano-machining on sensitive material response.
The aim of this work is the fabrication of a cheap sol-gel Pt-doped TiO2 thin film sensor on silicon substrate, evaluate electrical performances of electrical interconnections and responses of sensitive film in severe environment like exhaust of combustion process. The sensor will be implemented as microsensors for NOx or oxygen detection, while a preliminary investigation on real operative conditions shows that the transducers perform a response time (t90) in real condition smaller than 1 second at 600 °C. Application field of this type of transducer will be evaluated in a real spark ignition engine, to monitor air/fuel ratio and also monitoring the combustion quality in other industrial combustion processes like domestic heating systems. The production process of this devices, and particularly thin film deposition, can be carried out on a 3" silicon wafer and obtaining with a single batch process more than 300 sensors for wafer, 2x2 mm2. The sensors are provided with an integrated heater and a thermometer to perform temperature compensation. Actually this work try to develop an affordable process to integrate cheap sol-gel deposition process with silicon technology; a particular study is devoted to a complete photolithographic patterning of titania sensitive film, that is very difficult to etch after complete annealing, in order to have sensitive film only onto well defined areas of wafer. Same process, with little modification, can be applied to different kind of sensitive film, pure and doped ones. Different strategies on protective coating were evaluated to reduce electrical contacts degradation at high temperatures, obtaining long time stability of overall microsensor.
In this work, we describe the design implementation, validated by experimental results, of an innovative gas sensor array
for wine quality monitoring. The main innovation of this integrated array deals with the simultaneous outputs, from a
single chip on TO-12 socket, of 8 different signals coming from a WO3 thin film structure heated in a linear temperature
gradient mode, allowing an overall evaluation of gas sensing properties of the material in a 100°C-wide window,
typically from 300 to 400°C. The implemented sensitive layer is a WO3 film deposed by RF-sputtering. Preliminary tests
of gas sensing showed good responses to the target analytes for the specific application (1-heptanol, 3-methyl butanol,
benzaldehyde and ethyl-hexanoate).
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