MASTER THESIS PROJECTS AVAILABLE AT LABORATORY POLYSENSE IN 2024
PolySense Labs offer several Master Thesis Projects within the research topics:
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Quartz-Enhanced Photoacoustic Spectroscopy
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Multi-pass Absorption Spectroscopy
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Tunable Diode Laser Spectroscopy
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Optical Gas Sensing
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Infrared Detection with Quartz Tuning Fork
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Photonic Integrated Devices
The projects are classified in three types:
- The Experimental Master’s thesis option requires that the student complete an original research project in the laboratory. This includes the realization of an experimental setup, measurements and data analysis. The students will work with sophisticated laboratory instruments and facilities.
- A Theoretical Master’s thesis option comes with a focus on a theoretical subject. The empirical study is taken as the topic for the master’s program. The student is required to discuss unresolved aspects with numerical simulations as well to develop novel models.
- The hybrid Theoretical/Experimental Master’s thesis proposes a good overlap between theory and experiment. It includes numerical simulations supported by an experimental investigation. The experimental part is expected to validate the theoretical model and to gather data for modifying them.
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MASTER THESIS PROJECT 1
Title: Study of impact of high temperature on resonance properties of a quartz tuning fork
Type of Thesis: Theoretical/Experimental
Description: Quartz Tuning Fork (QTF) is largely used in Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) as sound detector of weak pressure waves generated by gas molecules when they absorb resonant, intensity-modulated light. The performance of a QEPAS sensor are stricly related to the resonance properties of the QTF, requiring a precise control of the temperature and pressure of the gas flowing in the cell where the QTF is immersed. For some applications, the temperature of the gas mixture can be significantly above the room temperature and its impact on the QTF properties can alter the detection sensitivity. The project aims at studying the temperature dependence of the resonance frequency, the resonance width and the electrical resistance of a QTF when it is immersed directly in a slow gas flow rate – less than 100 sccm – from room temperature up to 200 °C. A theoretical/phenomenological modeling as well as a systematic experimental characterization of the mechanical and electrical properties of the QTF will be conducted.
Referents: Marilena Giglio/Arianna Elefante
Status: AVAILABLE
MASTER THESIS PROJECT 2
Title: Realization of a Quartz-Enhanced Photoacoustic Sensor for detection of impurities in hydrogen
Type of Thesis: Experimental
Description: Hydrogen energy, as a pollution-free and efficient energy source, is gradually receiving widespread attention. In this context, fuel cells, as a type of hydrogen energy cell, have significant prospects for development. Currently, most hydrogen energy for fuel cells mainly comes from hydrocarbons reforming, which uses catalytic reactions to convert hydrocarbons into hydrogen. In the process of reforming hydrogen, there are inevitably the production of impurities, such as CO, NH3, H2S, etc. and any impurities present in hydrogen gas itself may result in substantial degradation of fuel cells. Indeed, the presence of these impurities can cause damage even when they are present at concentration levels of part-per-billion (ppb). This project aims at the realization of a trace gas sensor based on Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) for ultrasensitive and selective detection of impurities in a hydrogen matrix. The QEPAS sensor will be calibrated with certified mixtures in laboratory environment, in order to assess the sensitivity, the ultimate detection limit and the long-term mechanical stabililty.
Referents: Angelo Sampaolo/Giansergio Menduni
Status: AVAILABLE
MASTER THESIS PROJECT 3
Title: Tunable laser absorption spectroscopy exploiting a quartz tuning fork as optical detector
Type of Thesis: Theoretical/Experimental
Description: A quartz tuning fork (QTF) can be used as light detector exploiting light-induced thermo-elastic effect occurring within the quartz crystal. When the radiation hits the surface of the QTF, photothermal energy is generated because of light absorption by the quartz. Due to the thermo-elastic conversion, elastic deformations put prongs into vibration if the laser is intensity-modulated at one of the QTF resonance frequencies. Mechanical vibrations induce local strain and charges are generated via inverse piezoelectric effect. Thus, the QTF acts as a photodetector. This project aims to realize a gas sensor based on direct absorption spectroscopy in wavelength modulation and a QTF as optical detector. The light transmitted by a gas cell will be focused on the QTF surface where the maximum strain occurs. The photogenerated signal will be studied as a function of operating conditions, namely the laser spot position, the light intensity and the ambient conditions of the QTF. With the best conditions, the sensor transfer function as well as its sensitivity will be determined by a calibration procedure. Then, the ultimate detection limit and the normalized noise equivalent absorption will be evaluated and compared with state-of-the-art gas sensors.
Referents: Andrea Zifarelli/Pietro Patimisco
Status: ASSIGNED to Lavinia MONGELLI
MASTER THESIS PROJECT 4
Title: Quartz-enhanced photoacoustic sensor with wide dynamic range operation from percent to part-per-billion
Type of Thesis: Experimental
Description: Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) is indirect absorption technique where the photo-induced acoustic wave generated in an absorbing medium is detected by a spectrophone, composed by a quartz tuning fork (QTF) and a pair of millimeter-size resonator tubes located on both sides of QTF. The two tubes act as acoustic resonator and amplify the sound wave nearby the QTF. It can be shown that the acoustic wave intensity is proportional to the gas concentration and thus a wide dynamic linear range can be supposed. In practice, the optimization of QEPAS spectrophone for low concentrations detection makes it inevitably unusable for high concentrations, primarily for non-linearity and signal saturation effects. This project aims to design and realize an innovative QEPAS module composed by a bare QTF, for high concentration measurements, and a spectrophone, for low concentrations. Both two QTFs and tubes must be aligned along the same optical axis in order to allow laser beam to pass through without touching any of them. The QEPAS module will be tested with an absorbing gas varying its concentration from percent to part-per-billion range.
Referents: Angelo Sampaolo/Pietro Patimisco
Status: AVAILABLE
MASTER THESIS PROJECT 5
Title: Broadband spectroscopy with supercontinuum laser source and an optical spectrum analyzer: a comparison with a Fourier transform spectrometer
Type of Thesis: Experimental
Description: Infrared spectroscopy for gas sensing has developed strongly during the last two decades, driven by new infrared sources and new measurement concepts. In this context, ultra-broadband spectroscopy in the mid-infrared wavelength range, where most molecular species have strong, distinct absorption features, has a great potential for gas sensing applications. Nevertheless, limitations remain for fast broadband spectroscopy, especially in multispecies detection in the gas phase. This project aims at comparing two distinct approaches for broadband operation required for multi-species detection. The first exploits a scanning Fourier transform spectrometer, where interferograms are collected by measurements of the coherence of the light in the time-domain, and translated into frequency domain through Fourier transform. The other one combines a broadband, spatially coherent supercontinuum mid-infrared source with an optical spectrum analyzer. For both approaches, the sensitivity will be enhanced by using a Herriott-type multipass cell with 31.2 m optical path.
Referents: Andrea Zifarelli/Pietro Patimisco
Status: AVAILABLE
MASTER THESIS PROJECT 6
Title: Beat-frequency Quartz-Enhanced Photoacoustic Spectroscopy for fast multi-gas detection
Type of Thesis: Experimental
Description: The potentiality to acquire data in wide and harsh environments and to guarantee the safety of the operator promotes Unmanned Aerial Vehicle (UAV)-assisted monitoring as one of the most suitable solutions for multi-gas detection in urban and industrial areas. Moreover, a sensing system to be mounted on UAVs should be reliable and fast at the same time. Among different optical sensing techniques, Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) demonstrated to be suitable and reliable to monitor multiple gas species. In QEPAS, the signal of the gas under investigation is acquired during a slow spectral scan of the laser tuning range across the gas absorption feature. This process requires several minutes, preventing the real-time monitoring of the QTF resonance parameters, necessary to validate measurements. This project aims at investigating a novel approach, named Beat-Frequency QEPAS (BF-QEPAS), to simultaneously speed up and validate data acquisitions. In BF-QEPAS, the laser modulation frequency (f) will be detuned of Δf with respect to the QTF resonance frequency, and a fast ramp will be applied to scan the laser tuning range so that the QTF results excited by a fast acoustic pulse.
Referent: Giansergio Menduni
Status: AVAILABLE
MASTER THESIS PROJECT 7
Title: Study and design of photonic integrated structures for optical gas sensors
Type of Thesis: Theoretical
Description: Mid-infrared (mid-IR) absorption spectroscopy based on Photonic Integrated Circuits (PICs) has shown great promise in trace-gas sensing applications where the mid-IR radiation directly interacts with the targeted analyte. Furthermore, the possibility to integrate laser sources, waveguides and optical detectors on the same platform could allow the realization of a fully integrated spectroscopic setup for gas sensing. Waveguide represents one of the core elements on a photonic integrated circuit: the propagation losses and the overlap factors are the main parameters affecting the performance of integrated sensors. This project aims at simulating and designing different waveguide structures for integrated gas sensors (e.g., slot waveguides, subwavelength waveguides, pedestal waveguides) and studying the influence of critical parameters on the ultimate performance of the PIC.
Referent: Angelo Sampaolo/ Giansergio Menduni
Status: AVAILABLE
MASTER THESIS PROJECT 8
Title: Trace gas detector based on Lithium niobate resonators
Type of Thesis: Theoretical/Experimental
Description: In the last couple of decades, lithium niobate (LiN) has arisen as a promising piezoelectric material in the integrated photonics field for the realization of transducers. Lithium niobate tuning forks (LiNTF) have been employed as viscosimeters or, very recently, as sound wave detector for gas sensing in Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS). The same type of resonator could be implemented as infrared photodetector in Light-Induced Thermoelastic Spectroscopy (LITES). This project aims at studying the performance and the resonance properties of LiNTFs, when employed as sound detector and photodetector in QEPAS and LITES technique, respectively, and in the realization of a gas chamber where the LiNTF can be employed for trace gas sensing.
Referent: Angelo Sampaolo/ Giansergio Menduni
Status: AVAILABLE
MASTER THESIS PROJECT 9
Title: Study of the Signal-to-Noise Ratio trend in Quartz Tuning Fork-based gas sensors at different working conditions
Type of Thesis: Theoretical/Experimental
Description: Quartz Tuning Forks (QTF) have been widely employed in the last years as sound wave detector in Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS), and as photodetector in Light-Induced Thermoelastic Spectroscopy (LITES). In both techniques, the signal depends on the pressure of the gas chamber. Furthermore, the ultimate noise level is determined by the QTF thermal noise, depending on the quality factor of the resonator, and in turn on the working pressure. This project aims at modeling different noise contributions affecting both techniques and at defining the working pressure that optimizes the Signal-to-Noise ratio (SNR), both in QEPAS and LITES technique. A QEPAS and LITES sensor will be realize to assess and validate the theoretical model.
Referent: Pietro Patimisco/ Giansergio Menduni
Status: AVAILABLE
MASTER THESIS PROJECT 10
Title: Characterisation of a buffer-gas-cooled molecular source
Type of Thesis: Experimental
Description: Buffer gas cooling is the workhorse to produce the initial molecular beam for direct laser cooling experiments. Buffer gas cooling works on the simple concept of bringing molecules in direct contact with a bath of He gas at around 4 K inside a cell. Molecules exit the cell through a nozzle and form an effusive beam with typical speed of the order of 150 m/s. The setup we are building in Sesto Fiorentino is the first in Italy. We will initially use CO molecules to characterise the beam. The first excited electronic state of CO is metastable with a lifetime of 2.6 ms and has enough energy to be detected directly with an imaging MCP. Therefore it is possible to do a complete time-and-space characterisation of the molecular beam.
Referents: Gabriele Santambrogio/Pietro Patimisco
Status: ASSIGNED to Francesco Pio MERAFINA
MASTER THESIS PROJECTS within PASSEPARTOUT EUROPEAN PROJECT
Within the European Innovation Action with topic “Advancing photonics technologies and application driven photonics components and the innovation ecosystem” and sub-topic “Smart Photonic Sensing for Environmental Pollution Detection”,
PolySenSe is pleased to inform Master Thesis Projects are available within the European Project PASSEPARTOUT “Photonic Accurate and Portable Sensor Systems Exploiting Photo-Acoustic and Photo-Thermal Based Spectroscopy for Real-Time Outdoor Air Pollution Monitoring”.
PASSEPARTOUT aims to develop hyperspectral optical sensors based on Quartz Enhanced Photoacoustic Spectroscopy and Photothermal Interferometry for a wide range of ambient pollutants. PASSEPARTOUT will realize the first 3D mobile optical gas analyzer network capable of operating in an urban area. Innovative and high-performance technologies for high accuracy and flexible environmental air quality monitoring will be built on robust drone-mounted, low-cost vehicle-mounted and stationary sensors. The network will provide real-time information about the concentration of polluting gases (NOx, SO2, NH3, CH4, CO and CO2) and black carbon within urban areas, around landfills and seaports with extremely high precision and good spatial resolution. The collected data will be combined with weather data and analyzed in a Cloud, exploiting machine learning algorithms.
Visit us for more info: PASSEPARTOUT EU PROJECT