Low-cost Discrete Off-the-shelf Components 1MHz Analogue Lock-in Amplifier for Fast Detection of Organic Compounds through Pulsed Lasers

Abstract We report on a low-cost analogue Lock-In Amplifier (LIA) designed to measure amplitude variations of 100 ns pulsed signals at operating frequencies f 0 up to 1MHz. The fabricated prototype PCB, implemented through discrete off-the-shelf components, allowed to validate the solution and to perform circuit testing and characterisations. The LIA architecture is simple and based on the classic phase-sensitive synchronous demodulation technique including two different amplification stages together with suitable filtering blocks that allow setting the instrument gain, sensitivity and resolution. With respect to conventional LIAs typically working at lower operating frequencies, the reported solution provides also high-speed DC output of about 1ms. By employing short voltage pulses, the LIA is capable to detect fast and small variations of the signal amplitude envisaging its use in sensor applications to measure reduced variations of chemical and physical phenomena through high-speed systems with very small time constants

Effetti della polarizzazione del core, valutati ab-inizio, sugli stati legati e sul continuo di Mg(l) fino alla terza soglia di ionizzazione: spettro delle energie e transizioni a uno e due fotoni

Dottorato di ricerca in scienze chimiche. 8. ciclo. Coordinatore S. Cabani Supervisore R. Moccia. Supervisore esterno P. DeclevaConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Additively Manufactured Detection Module with Integrated Tuning Fork for Enhanced Photo-Acoustic Spectroscopy

Starting from Quartz-Enhanced Photo-Acoustic Spectroscopy (QEPAS), we have explored the potential of a tightly linked method of gas/vapor sensing, from now on referred to as Tuning-Fork-Enhanced Photo-Acoustic Spectroscopy (TFEPAS). TFEPAS utilizes a non-piezoelectric metal or dielectric tuning fork to transduce the photoacoustic excitation and an optical interferometric readout to measure the amplitude of the tuning fork vibration. In particular, we have devised a solution based on Additive Manufacturing (AM) for the Absorption Detection Module (ADM). The novelty of our solution is that the ADM is entirely built monolithically by Micro-Metal Laser Sintering (MMLS) or other AM techniques to achieve easier and more cost-effective customization, extreme miniaturization of internal volumes, automatic alignment of the tuning fork with the acoustic micro-resonators, and operation at high temperature. This paper reports on preliminary experimental results achieved with ammonia at parts-per-million concentration in nitrogen to demonstrate the feasibility of the proposed solution. Prospectively, the proposed TFEPAS solution appears particularly suited for hyphenation to micro-Gas Chromatography and for the analysis of complex solid and liquid traces samples, including compounds with low volatility such as illicit drugs, explosives, and persistent chemical warfare agents

A MEMS-Enabled Deployable Trace Chemical Sensor Based on Fast Gas-Chromatography and Quartz Enhanced Photoacousic Spectoscopy

This paper reports on a portable selective chemical sensor for hazardous vapors at trace levels, which combines a two-stage purge and trap vapor pre-concentration system, a Micro-Electro-Mechanical-System (MEMS) based fast gas-chromatographic (FAST-GC) separation column and a miniaturized quartz-enhanced photoacoustic spectroscopy (QEPAS) detector. The integrated sensing system provides two-dimensional selectivity combining GC retention time and QEPAS spectral information, and was specifically designed to be rugged and suitable to be deployed on unmanned robotic ground vehicles. This is the first demonstration of a miniaturized QEPAS device used as spectroscopic detector downstream of a FAST-GC separation column, enabling real-world analyses in dirty environments with response time of a few minutes. The main modules of the GC/QEPAS sensor device will be described in detail together with the system integration, and successful test results will be reported and discussed

Bacillus spp. Cells Captured Selectively by Phages and Identified by Surface Enhanced Raman Spectroscopy Technique

Surface Enhanced Raman Spectroscopy (SERS), has been employed as a rapid and accurate tool for recognition and classification of different microorganisms. The vibrational spectrum intrinsically provides the fingerprint of the molecular structure of microorganisms, without sample preparation. The characterization of Bacillus spp., used as a simulants of the dangerous Bacillus anthracis by means of SERS technique has been carried out. The positive results on the use of the SERS substrate functionalized with phages specific for bacteria are showed. This work is a part of the RAMBO project (Rapid Air particle Monitoring against BiOlogical threats) funded by EDA (European Defense Agency) whose goal is the development of an advanced “detect to warn sensor” of cells and spores of dangerous bacteria, with high performance, good selectivity and reliability

VO2 thermochromic metamaterial-based smart optical solar reflector

Optical solar reflector smart radiators are able to control the temperature of spacecraft. This work demonstrates a novel smart optical solar reflector using a patterned thermo-chromic VO2 plasmonic meta-surface design. The VO2 meta-surface combines the temperature induced phase transition of VO2 with plasmonic resonances resulting in a significant enhancement of the infrared absorption. The enhanced absorption obtained at a reduced VO2 coverage results in superior emittance tunability Δε and lower solar absorptance α compared to a corresponding thin-film reflector. An emittance tunability of 0.48 is obtained for the meta-reflector design, representing a 30% improvement compared to the unstructured film. Meta-surface based smart optical solar reflectors offer a new route toward energy-efficient and cost-effective passive thermal control systems of spacecraft and other surfaces

Dataset for VO2 thermo-chromic metamaterial-based smart optical solar reflector

Data supporting the paper: Sun, K., Riedel, C. A., Urbani, A., Simeoni, M., Mengali, S., Zalkovskij, M., ... Muskens, O. L. (2018). VO 2 Thermochromic Metamaterial-Based Smart Optical Solar Reflector. ACS Photonics. DOI: 10.1021/acsphotonics.8b00119</span