PolySense

New Publication on Sensors and Actuators B Chemical Journal

The PolySense and Polysense Innovations teams have just published a new article on Sensors and Actuators B Chemical Journal (IF 7.7) reporting on a dual-spectral (QEPAS-LITES) multi-gas detection system based on a single customized quartz tuning fork (QTF). By applying second-harmonic (2 f) wavelength modulation at 1368.6 nm and 1653.7 nm, the fundamental and first-overtone resonance modes of the QTF are excited concurrently, enabling intrinsic frequency-domain separation and parallel demodulation of photoacoustic and photothermal signals.
This streamlined architecture enables truly simultaneous monitoring of percent-level H2O and ppm-level CH4, effectively overcoming the dynamic-range limitations of standard multi-gas sensing. Excellent linearity is obtained for both species (R² = 0.9999 for H₂O and 0.998 for CH₄), with minimum detection limits of approximately 30 ppm and 660 ppb, respectively. Allan-Werle deviation analysis confirms stable long-term operation for both detection channels. By overcoming the dynamic-range and saturation limitations of conventional multi-gas sensors, the proposed dual-mode approach provides a robust and scalable platform for wide-dynamic-range gas sensing in applications including atmospheric greenhouse gas monitoring, industrial emission analysis, and complex open-path environments.

The following link provides access to the article: http://polysense.poliba.it/wp-content/uploads/2026/04/1-s2.0-S0925400526005794-main.pdf

New Publication on International Journal of Hydrogen Energy

The PolySense and Polysense Innovations teams have just published a new article on the International Journal of Hydrogen Energy (IF 8.3) regarding the use of Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) for the detection of CO impurities in hydrogen . Due to the high speed of sound in hydrogen, the geometry of the spectrophone was specifically selected to ensure efficient sound wave amplification. Therefore, a QEPAS spectrophone was designed by exploiting a custom quartz tuning fork operating at first overtone mode (~44,0 kHz) in combination with compact resonator tubes. The spectrophone was integrated into a QEPAS sensor for CO trace detection at 2193.36 cm􀀀 1 in a hydrogen matrix. The QEPAS sensor was calibrated using certified mixtures, returning a detection limit of 1.5 ppm for 10 s.

The following link provides access to the article: http://polysense.poliba.it/wp-content/uploads/2026/04/1-s2.0-S036031992601774X-main.pdf

New Publication on Nature Communications

The PolySense and Polysense Innovations teams have just published a new article on Nature Communications Journal (IF=15.7) reporting on a multi-functional platform (LN-MFP) that seamlessly integrates photoacoustic spectroscopy, light-induced thermoelastic spectroscopy and photodetection into a single on-chip device. The proposed LN-MFP operates over a broad spectral range spanning from the visible to the mid infrared. We experimentally demonstrate trace gas detection of nitrogen dioxide, water v***r, acetylene, carbon dioxide, methane and ammonia, achieving parts-per billion detection limits.We implement a custom packaging solution where the LN-MFP chip and a 4.6 μm quantum cascade laser chip are mounted on a printed circuit board together with transimpedance amplification, demonstrating system-level integration. Using this co- packaged module, we demonstrate carbon monoxide detection via second-harmonic measurements, outlining a clear route towards fully integrated on-chip implementations. This compact, hybrid, multi-functional architecture markedly reduces system complexity and footprint compared with conventional benchtop systems and is intrinsically compatible with the rapidly developing lithium niobate integrated photonics ecosystem. The LN-MFP provides a core sensing building block for future all-lithium-niobate spectroscopic chips for environmental monitoring, point-of-care diagnostics and on-site chemical analysis.

The following link provides access to the article:
http://polysense.poliba.it/wp-content/uploads/2026/03/Nat-comm-QEPAS-on-chip.pdf

New Publication on Photoacoustics Journal

The PolySense and Polysense Innovations teams have just published a new article on Photoacoustics Journal Elsevier (IF 6.8) reporting on an online breath sensing system based on photoacoustic spectroscopy (PAS), achieving real-time simultaneous monitoring of multiple exhaled gases using PAS. The system exploits the inherent difference in response amplitude between the fundamental and overtone resonances of the photoacoustic cell, where the highly sensitive fundamental signal is used to detect trace methane (CH4), while the weak overtone response enables the measurement of high concentration carbon dioxide (CO2). This approach allows a single photoacoustic cell to simultaneously detect multi-component gases spanning several orders of magnitude in concentration. The minimum detection limits for CH4 and CO2 reach 320 ppb and 450 ppm, respectively. Real-time breath measurements from multiple volunteers demonstrate excellent stability, sensitivity, and repeatability of the system, confirming its feasibility and application potential for early disease screening.

The following link provides access to the article: http://polysense.poliba.it/wp-content/uploads/2026/03/Multi-gas-photoacoustic-cell-exhaled-gas-sensor_Photoacoustics-2026.pdf

New Publication on Journal of Breath Research
The PolySense and Polysense Innovations teams have just published a new article on Journal of Breath Research (IOP) reporting on a computational method to identify volatile organic compound (VOC) artifacts introduced by breath sampling hardware. To exclude endogenous biological variability, ambient air was collected using two sampling devices working in the same experimental conditions: the Mistral end-tidal breath sampler and the ACTI-VOC PLUS pump, a low-emission reference system. VOCs were pre-concentrated on sorbent-packed thermal desorption (TD) tubes and analyzed by TD–gas chromatography–mass spectrometry (TD–GC–MS). Differential chromatograms obtained by subtracting ACTI-VOC signals from Mistral traces were processed using stationary wavelet transform (SWT) to selectively enhance high-frequency features indicative of artifactual emissions. Four new compounds not previously associated with Mistral sampling hardware were consistently detected in Mistral samples and were absent in ACTI-VOC pump controls: 1,3,5- trioxane, 1,3,5,7-tetroxane, (Acetyloxy)acetic acid, and N,N-dimethylformamide. These molecules are indicative of polymer degradation, acetal resin breakdown, and material off-gassing specific to the breath sampler.

The following link provides access to the article:http://polysense.poliba.it/wp-content/uploads/2026/02/Ardito_2026_J._Breath_Res._20_016013.pdf

New Publication on Optics & Laser Technology Journal

The PolySense and Polysense Innovations teams have just published a new article on Optics & Laser Technology journal (IF 5.0) reporting on a comparison between quartz-enhanced photoacoustic spectroscopy (QEPAS) and beat-frequency QEPAS (BF-QEPAS) techniques for the sequential detection of methane (C1) and ethane (C2) in the near-infrared spectral range. Experiments were performed using a laser diode emitting at a central wavelength of 1683.53 nm, targeting C1 and C2 absorption features. Our results demonstrate that the BF-QEPAS approach significantly reduces measurement time from minutes to few seconds and maintains comparable detection sensitivity, also for broadband absorbers such as ethane. For methane, minimum detection limits (MDLs) of 1.7 parts-per-million (ppm) and 5 ppm were achieved with QEPAS and BF-QEPAS techniques, respectively, while for ethane MDLs of 20 ppm and 62 ppm were obtained, respectively. The BF-QEPAS technique enables continuous, uninterrupted monitoring of both target gases in sequential detection mode, with the simultaneous validation of the measurement through the evaluation of the QTF resonance parameters.

The following link provides access to the article: http://polysense.poliba.it/wp-content/uploads/2026/02/BF-QEPAS_2026.pdf

Buon Natale dal team PolySense
💥💥🌲🌲
Merry Christmas by the Polysense team.
🎅🤶🧑‍🎄👼

New Publication on ACS Sensors journal

The PolySense and Polysense Innovations teams have just published a new article on ACS Sensors Journal (IF 9.1) reporting on the development of a dual-gas Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) sensor operating in the mid-infrared range for the simultaneous detection of 12CH4 and 13CH4. The sensor employs a frequency-modulated multiplexing scheme using two distributed-feedback quantum cascade lasers to independently excite the fundamental (fo) and overtone (f1) vibrational modes of a quartz tuning fork coupled with resonator tubes. Calibration measurements demonstrated a linear response of the QEPAS signal to varying 13CH4 concentrations in CH4-based samples diluted in N2, with a precision of 1‰ in detecting isotopic delta ratio variations for 1% CH4 mixtures at 0.8 s integration time. The proposed system is suitable for real-time, high-precision isotopic methane sensing aimed at applications such as environmental monitoring, geochemical tracing, and industrial process control.

The following link provides access to the article:
http://polysense.poliba.it/wp-content/uploads/2025/12/simultaneous-detection-of-12ch4-13ch4-and-related-isotope-ratio-exploiting-a-frequency-multiplexed-mid-infrared-quartz.pdf

New Publication on Sensors and Actuators B Chemical Journal

The PolySense and Polysense Innovations teams have just published a new article on Sensors and Actuators B Chemical Journal Elsevier (IF 7.7) reporting on an investigation of the relaxation dynamics of the ν3 energy level of nitrous oxide (N2O) molecules in synthetic air using a 4.5 μm distributed feedback quantum cascade laser (DFB-QCL) combined with photoacoustic spectroscopy (PAS) technique. A comprehensive theoretical model coupling vibration-translation (V-T) relaxation processes and vibration-vibration (V-V) energy transfer was developed, enabling a rigorous theoretical derivation of the system-wide vibrational relaxation time. Through in-depth analysis of photoacoustic signal phase characteristics, the molecular relaxation times of both N2O (ν3) (1.6 μs atm) and H2O (0.33 μs atm) were simultaneously extracted. This research not only validates the technical feasibility and analytical superiority of PAS phase technology in measuring gas relaxation times but also introduces a novel high-precision spectroscopic analysis method for studying vibrational dynamics in complex molecular systems, showcasing its potential applications in environmental monitoring and molecular dynamics research.

The following link provides access to the article:
http://polysense.poliba.it/wp-content/uploads/2025/11/Investigation-of-the-role-of-photoacoustic-phase-in-N2Ov3-vibrational-relaxation-rate-determination_sens-act_B_2025.pdf

New Publication on OSA Optics Express Journal

The PolySense team has just published a new article on OSA Optics Express (IF 3.3) reporting on a broadband gas sensor based on direct absorption spectroscopy in the mid-infrared range for the simultaneous detection of methane, ethane, and propane in natural gas-like mixtures. The system employs a broadband supercontinuum light source, coupled with an absorption cell and an optical spectrum analyzer with a resolution of 0.5cm−1. A comparative study between multiple linear regression (MLR) and partial least-squares regression (PLSR) was conducted to determine the concentration of each individual component. The results highlight the superior performance of PLSR in the presence of unbalanced concentration ratios (1:10) among the three alkanes, achieving mean prediction accuracy of 98%, 93% and 94% for methane, ethane, and propane, respectively.

The following link provides access to the article:
http://polysense.poliba.it/wp-content/uploads/2025/11/2025_Opex_supercontinuum-natural-gas.pdf