This work proposes the combination of a cotton-based sensor with a portable, low-power, low-noise impedance meter based on AD5933 for acetone detection. This compound has been selected as a volatile probe in human breath. Carbon nanotubes act as a sensing layer, modifying their electrical properties after interaction with the target analyte. The AD5933-based impedance meter is included in a customized PCB for data acquisition and communication with a PC. Measurements performed in both dry and wet operating conditions agree with those made using a commercial laboratory-scale impedance meter as a reference. Results highlight impedance decrease, lowering the acetone concentration.

Acute skin toxicity after radiation treatments highlights the need for improved dose monitoring and measurement, as the treatment planning system does not accurately estimate skin dose. Wearable radiation detectors may be the solution for mostin vivodosimetry needs, but they require innovative materials. The purpose of this work is to overcome the challenges that limit accurate skin dosimetry by exploring the use of hydrogenated amorphous silicon (a-Si:H) fabricated on a flexible polyimide substrate for direct radiation detection. The a-Si:H detector was fabricated on a 125μm polyimide substrate with a thickness of 3.6-10μm. The detector's response to the build-up region of the percentage depth dose (PDD) of the MV photon beam was compared to Geant4 radiation transport simulations and benchmarked to Attix ionization chamber measurements. Angular dependency and surface field factors at the phantom surface were compared to Attix IC. The PDD measurement is within 2% of Geant4's simulation and the Attix chamber's response from 150m to 25 mm in a plastic water phantom. All samples showed linear dose responses with 0.37% reproducibility. The a-Si:H device matches the Attix chamber for surface field factor measurements (6-10 MV photon beams, for 5 to 25 cm field sizes). The angular dependence (-60° to +60°) compared to the Attix IC confirms the sensor's WED of 150 ± 5µm. This study demonstrates that a-Si:H sensors on flexible plastic substrates have a potential for accurate surface dose measurements and agree with reference detectors. This thin, flexible detector provides real time measurements and is stable under high radiation doses. The possibility to assemble with ease an array of a-Si:H pixels over large areas with different sizes and shapes, makes this technology attractive forin vivodosimetry.

Long-term deep space missions present critical health challenges due to prolonged exposure to space radiation and microgravity, leading to significant physiological risks for astronauts. Galactic cosmic rays, in particular, can penetrate conventional shielding and produce harmful secondary particles, emphasizing the need for innovative in-situ solutions to study the effects of these environmental conditions on astronauts’ health and mitigate the risks. We have developed an advanced lab-on-chip system designed for real-time monitoring and precise environmental control, which allows us to detect changes in living cells throughout a long-term space mission. The system is equipped with integrated photo and thermal sensors based on hydrogenated amorphous silicon functional layers and resistive heating elements for continuous environmental monitoring and precise temperature regulation. By using a modular and adaptable fabrication approach—combining laser-cut polymethyl methacrylate components, adhesive bonding, and thin-film integration—our design enables rapid prototyping and customization for various mission needs. Our platform features a tapered culture chamber that employs both passive and active fluid management techniques to maintain stable liquid positioning. This is achieved through feedback-controlled pressure modulation, addressing the unique challenges of fluid dynamics in space. We validated the system through a series of simulations and experiments demonstrating effective fluid management and accurate environmental control, essential for future biological research in space. Our results underscore the potential of this low-power, automated, and highly compact lab-on-chip solution to advance the study of space radiation effects and contribute to safer, long-duration crewed missions.

The objective of the Photo-HASPIDE experiment is the construction and test of an indirect a-Si:H (Hydrogenated Amorphous Silicon) photo-detector plus scintillator device on a flexible substrate for the detection and measurement of particles fluxes (X-rays, electrons and protons) and for dosimetric measurements. The idea behind this experimental project lies in the utilization of Hydrogenated Amorphous Silicon (a-Si:H) as photodiode material; owing to its notable attributes of radiation hardness, light detection capability and mechanical flexibility. After the implementation of the HASPIDE experiment, which explored direct radiation detection using a-Si:H devices on a polyimide (PI) substrate, we aim to delve into indirect detection by employing these devices in conjunction with flexible and rad-hard scintillators like polysiloxane. The indirect detector design holds promise for improved responsiveness to low radiation fluxes compared to direct detection methods. The indirect a-Si:H detector should be composed of arrays of small (about 5 x 5 mm2) scintillator crystals read by a-Si:H photodiodes. Through optimization of the scintillator and detector thicknesses, we expect to achieve a better performance for low minimum detectable fluxes compared to direct detection methodologies. This new detector will find application in in-vivo dosimetry during radiotherapy or hadron-therapy and also, due to its expected fast response, in FLASH therapy. Another important application will be also in Solar Physics using these devices to measure particle fluxes in solar energetic particle events.

Hydrogenated amorphous silicon (a-Si:H) is a mature thin-film technology for large-area devices and thin-film sensors, and its low-temperature growth via Plasma-Enhanced Chemical Vapor Deposition (PECVD) makes it particularly suitable for biomedical flexible and wearable platforms. However, the reliable integration of a-Si:H sensors on polymer substrates requires a quantitative assessment of their electrical stability under mechanical stress, since bending-induced variations may affect sensor accuracy. In this work, we provide a quantitative, direction-dependent evaluation of the static-bending robustness of both single-doped a-Si:H layers and complete p-i-n junction stacks on polyimide (Kapton®), thereby linking material-level strain sensitivity to device-level functionality. First, n- and p-doped a-Si:H layers were deposited on 50 µm thick Kapton® and then structured as two-terminal thin-film resistors to enable resistivity extraction under bending conditions. Electrical measurements were performed on multiple samples, with the current path oriented either parallel (longitudinal) or perpendicular (transverse) to the bending axis, and resistance profiles were determined as a function of bending radius. While n-type layers exhibited limited and mostly gradual variations, p-type layers showed a stronger sensitivity to mechanical stress, with a critical-radius behavior under transverse bending and a more progressive evolution in the longitudinal one. This directional response identifies a practical bending condition under which doped layers, particularly p-type films, are more susceptible to strain-induced degradation. Subsequently, a linear array of a-Si:H p-i-n sensors was fabricated on Kapton® substrates with two different thicknesses (25 and 50 µm thick) and characterized under identical bending conditions. Despite the increased strain sensitivity observed in the single-layers, the p-i-n diodes preserved their rectifying behavior down to the smallest radius tested. Indeed, across the investigated radii, the reverse current at −0.5 V remained consistent, confirming stable junction operation under bending. Only minor differences, related to substrate thickness, were observed in the reverse current and in the high-injection regime. Overall, these results demonstrate the mechanical robustness of stacked a-Si:H junctions on polyimide and support their use as sensors for wearable biosensing architectures. By establishing a quantitative, orientation-aware stability benchmark under static bending, this study supports the design of reliable a-Si:H flexible sensor platforms for curved and wearable surfaces.

Background While low levels of zinc are generally harmless, elevated concentrations can lead to significant contamination, making their monitoring crucial for environmental and health applications. Traditional methods for zinc detection often rely on bulky and complex equipment, making them impractical for on-site analysis. The development of a Lab-on-Chip device for zinc sensing offers the advantage of in-field analysis, enabling real-time monitoring of zinc levels. This capability allows for prompt intervention and potential cost reductions. Results In this study, an aptamer with high affinity for zinc ions was initially characterized in solution using emission spectroscopy, employing two distinct fluorescence assay strategies. Based on these findings, the aptamer was immobilized within microfluidic channels and integrated with an array of amorphous silicon photosensors (a-Si:H) for fluorescence detection. This advanced setup enables on-chip detection of the fluorescent signals arising from the interaction between zinc ions and the aptamer. Significance The Lab-on-Chip device was systematically evaluated, with particular attention on its detection limits and overall performance and benchmarked against traditional laboratory-scale methods to highlight its effectiveness and potential for real-world applications.

We evaluate the performance of a lab-on-chip optoelectronic device made with a polymeric waveguide and a hydrogenated amorphous silicon (a-Si:H) photodetector. Both components are integrated onto a compact BK7 glass substrate with a small surface area. The device is designed to measure the analyte concentration in a sample by detecting changes in light power caused by the interaction between the solution droplet and the guided radiation. This power variation is related to the sample's refractive index and is detected by an a-Si:H photosensor. Through numerical simulations in the red spectrum (632.8 nm), we assess the device's efficiency for detecting zinc (Zn) and lead (Pb). We analyze the interaction between the sample and the chip in various conditions and combine these findings with experimental data on the a-Si:H detector's performance. Our results indicate that the sensor exhibits a sensitivity down to 16.6 pA/ppm for Zn and 16.2 pA/ppm for Pb, with detection limits of 9.8 ppb for Zn and 10 ppb for Pb. This compact, cost-effective, and user-friendly chip demonstrates promising performance for applications in health and environmental monitoring, particularly in detecting heavy metals in water in real-time.

The ALCYONE project, funded under the EU Horizon Europe program, aims to develop a lab-on-chip (LoC) platform for biological studies in space environments. This study focuses on validating the system’s bioluminescence detection capability using genetically engineered Escherichia coli MG1655 cells. The cells, transformed with a luciferase-expressing plasmid, were irradiated with UV-C light for two minutes to induce stress responses, while unirradiated cells served as controls. Bioluminescence emission (520–530 nm) was measured using hydrogenated amorphous silicon (a-Si:H) photosensors integrated into the LoC platform. The experimental results confirm the system’s ability to differentiate between irradiated and control samples, demonstrating its potential for real-time, low-power monitoring of biological responses in space environments. Future work will integrate thermal control and fluidic automation to enhance biological experiment autonomy.

Hydrogenated amorphous silicon (a-Si:H) p-type/intrinsic/n-type junctions are widely used in thin film-based microelectronics. Recently, they have been investigated as photodiodes and temperature sensors integrated on a single glass substrate to develop lab-on-chip systems featuring compactness and lightweight. In such applications, a-Si:H photodiodes can detect chemiluminescence, bioluminescence or fluorescence. Depending on the wavelength to be revealed, the spectral response of the photosensor could be properly tuned. In the present work, we report on the fabrication and optoelectronic characterization of a-Si:H p-i-n junctions to study the effect of the intrinsic layer thickness on quantum efficiency and temperature sensitivity of the sensors. Results show that the photo-diode spectral response is highly affected by the i-layer thickness, while the temperature sensor performances do not show any significant dependence on it.

Hydrogenated amorphous silicon (a-Si:H) is widely adopted in thin-film electronics due to its compatibility with large-area deposition, low fabrication temperatures, and cost-effectiveness. In recent years, a-Si:H photodiodes have gained interest for integration into Lab-on-Chip (LoC) systems, where they are used to detect light signals generated during biomolecular recognition events. However, a key concern in such applications is light-induced degradation (LID), which can affect the reproducibility and stability of the photodiode’s response during continuous operation. This study investigates the light stability of a-Si:H photodiodes with varying intrinsic layer thicknesses (0.4 μm, 1.25 μm and 2.5 μm), exposed to monochromatic light at 450 nm, 550 nm, and 620 nm—wavelengths relevant to fluorescence and chemiluminescence detection. Devices were fabricated using conventional thin-film microfabrication techniques and a comprehensive characterization was conducted, including quantum efficiency (QE) measurements and photocurrent monitoring under continuous illumination for one hour. Despite the relatively high illumination intensities used (up to 2.3 μW), no appreciable degradation in photocurrent or QE was observed for any of the devices or wavelengths tested. These results indicate a high level of photoresponse stability across a range of device thicknesses and operational wavelengths. The findings confirm the suitability of a-Si:H photosensors for long-term use in LoC systems and support their application in sensitive and repeatable optical biosensing platforms.

Textile-based sensors are regarded as an attractive investigation field because they can provide cost-effective, easy to manufacture and disposable devices. In this work we present the activation of multiwalled-carbon nanotubes (MWCNTs) and their deposition on cotton textile for ammonia (NH3) detection. Indeed, COOH terminations of MWCNTs allow for ammonia binding by amide bonds predicating on a resistivity change upon ammonia interaction with the active sites. We found that deposition of MWCNTs caused a homogeneous textile resistance drops (from 1010 Ω to 103 Ω) with respect to the pristine cotton sample. Monitoring of the resistance variation over time after pipetting the analyte suggest an initial ammonia diffusion throughout the porous CNTs film deposited over the textile which determines a resistance increase and a subsequent resistance reduction due to the ammonia high volatility. These results suggest the feasibility of MWCNTs deposited on cotton fabric as sensor for ammonia detection.

This work presents a portable system developed to perform biochemical analyses requiring both temperature sensing for the thermal sample treatment and optical sensing to detect the analyte. To achieve this goal, we coupled a system-on-glass, hosting on a single glass substrate a thin film transparent heater and two temperature sensors, with interface electronics able to drive the heating source and control the temperature. The system-on-glass has been optimized to ensure temperature uniformity better than ±1.4 °C over a large-area (6 cm 2 ) and sensor resolution better than 0.01 °C. Moreover, the presented device operates at a remarkably low power of only 2.4 W/cm 2 to achieve a temperature of 100 °C, significantly below the power requirements of most comparable devices available on the market. The electronics has been designed to minimize electromagnetic interferences between the heater and the biological samples. The temperature-controlled platform has been enclosed in a 3D-printed black resin-made box whose dimensions are 11 cm · 10 cm · 2.4 cm, while the electronics is enclosed in a metallic box (12.55 cm · 8.05 cm · 4.32 cm), connected with the 3D-printed box by an Ethernet cable. The compactness and low weight (below 0.5 kg) of the two boxes ensures the system portability while the easy coupling of the system-on-glass with different kinds of microfluidic networks allows its employment for a large variety of biosensing applications.

This paper presents the development of chemo resistive sensors for the detection of volatile organic compounds (VOCs). The proposed sensor is based on citrate-functionalized gold nanoparticles (AuNPs) serving as a sensitive layer deposited on cotton fabric. Impedance variations due to VOC/substrate interaction are used as a detection principle. Specifically, this work focuses on acetone detection after exposing the AuNP-decorated cotton to a CH3COCH3 aqueous solution. Such an interaction resulted in a reduction of the total impedance (i.e., magnitude) of the system. This behavior can be ascribed to Van der Waals forces existing between the C=O group and the citrate moieties adsorbed on the gold nanoparticles, which favor charge injection to the substrate. Response to water was also tested for comparison, assuring that the solvent interacts with the sensitive layer by a different adsorption mechanism, not influencing the overall results. Sensor selectivity was also verified by considering ethanol (representative of alcohol group). Indeed, impedance curves reflect the different type of chemical interaction between the analyte and the substrate. In addition, sensor limit of detection for acetone was found to be 1% v/v, in the considered frequency range. Furthermore, sensor performance in terms of reusability was evaluated, showing that the Au-cotton ability in VOCs detection could be restored after about 90 min with a percentage up to 97 % in the frequency of 1Hz. These results can be considered the starting point for the development of portable, sensitive and user-friendly devices.

This paper presents a novel system for ammonia detection, integrating a carbon-nanotube-based textile sensor, an electronic board optimized for rapid measurements, and a machine learning model for accurate concentration prediction. The system employs spread-spectrum excitation signals, enabling ultra-fast measurements with a response time of 8.2 milliseconds, making it highly suitable for real-time applications. The textile-based sensor provides flexibility, allowing for potential integration into wearable devices or portable sensing platforms. Experimental validation was conducted using 6 ammonia concentrations (0%, 0.1%, 1%, 10%, 20%, and 30%), with 50 consecutive measurements per value to ensure statistical reliability. The collected data was analyzed using multiple regression models, and results demonstrated the Gaussian Process Regression model's superiority, achieving a root mean square error of 2.08 during 10-fold cross-validation. Future research will focus on testing the system with ammonia at parts-per-million (ppm) levels, optimizing the sensor's performance under different environmental conditions, and exploring integration into wearable electronics for biomedical systems.

Lab-on-Chip (LoC) technology has emerged as a powerful tool for biomedical diagnostics, chemical analysis, and environmental monitoring, offering compact and portable solutions. One key application is DNA amplification via Polymerase Chain Reaction (PCR), which replicates specific DNA sequences through thermal cycling. A challenge in conventional PCR is the time required for heating and cooling cycles. Spatial PCR addresses this limitation by allowing the sample to flow through a microfluidic network, where dedicated heaters maintain optimal thermal conditions across different regions of the chip. However, real-time detection of amplified products remains a challenge. Integrating photosensors in the annealing zone enables real-time monitoring of DNA amplification. This study focuses on the design, fabrication, and testing of thin-film heaters for spatial PCR. Using COMSOL Multiphysics, we simulated coupled thermal and electrical phenomena to optimize heater performance. The heaters, fabricated as a Cr/Al/Cr stack on a 5 × 5 cm2 glass substrate, were designed to ensure uniform temperature distribution while minimizing thermal crosstalk. The configuration included a central heater for the denaturation phase (95 ℃) and two lateral heaters for the annealing phase (62 ℃). Thermal imaging confirmed uniform heating, assessing the integration of spatial PCR into LoC systems for efficient, real-time DNA amplification.

The early detection of plant pathogens is of crucial importance in agriculture since it reduces crop losses and disease spreads preventing excessive pesticide applications, thus improving food safety and economic losses. To challenge this issue, we present here the application of a Lab-on-Chip system, based on thin film devices, for in-field detection of Xylella fastidiosa and Pyrenochaeta lycopersici through a real-time polymerase chain reaction (RT-PCR). The results show the feasibility of the system to correctly detect those plant pathogens.

Hydrogenated amorphous silicon (a-Si:H) devices on flexible substrates are currently being studied for application in dosimetry and beam flux measurements. The necessity of in vivo dosimetry requires thin devices with maximal transparency and flexibility. For this reason, a thin (<10 µm) a-Si:H device deposited on a thin polyimide sheet is a very valid option for this application. Furthermore, a-Si:H is a material that has an intrinsically high radiation hardness. In order to develop these devices, the HASPIDE (Hydrogenated Amorphous Silicon Pixel Detectors) collaboration has implemented two different device configurations: n-i-p type diodes and charge-selective contact devices.Charge-selective contact-based devices have been studied for solar cell applications and, recently, the above-mentioned collaboration has tested these devices for X-ray dose measurements. In this paper, the HASPIDE collaboration has studied the X-ray and proton response of charge-selective contact devices deposited on Polyimide. The linearity of the photocurrent response to X-ray versus dose-rate has been assessed at various bias voltages. The sensitivity to protons has also been studied at various bias voltages and the wide range linearity has been tested for fluxes in the range from 8.3 × 107 to 2.49 × 1010 p/(cm2 s).

Radiation damage tests in hydrogenated amorphous silicon (a-Si:H) flexible flux and dose-measuring devices have been performed with a 3-MeV proton beam, to evaluate combined displacement and total ionizing dose damage. The tested devices had two different configurations and thicknesses. The first device was a 2-mu m-thick n-i-p diode having a 5 x 5 mm area. The second device was a 5-mu m-thick charge-selective contact (CSC) detector having the same area. Both the devices were deposited on a flexible polyimide substrate and were irradiated up to the fluence of 1016 neq/cm(2). The response to different proton fluxes has been measured before irradiation and after irradiation at 1016 neq/cm(2) for CSCs and n-i-p devices. The effect of annealing for partial performance recovery at 100 degrees C for 12 h was also studied, and a final characterization on annealed devices was performed. This test is the first combined displacement and total ionizing dose test on flexible a-Si:H devices.

Gas sensing has been drawing attention over the years in terms of environmental remediation and health diagnostic potential. Volatile organic compounds (VOCs) qualitative/quantitative monitoring is indicative of air quality and people health status. However, VOC analysis is often performed by means of expensive and time-consuming lab-based equipment. Thus, this study proposes the fabrication and characterization steps for the development of a simple, eco-friendly and relatively inexpensive gas impedentiometric sensor. The sensing layer is comprised of gold nanoparticles (AuNPs) obtained from gold tetra chloric acid (HAuCl4) and sodium citrate by means of a green synthesis approach. The analyte under investigation is acetone, one of the principal breath volatiles, also reported by plenty of studies as a potential biomarker of various diseases. Cotton textiles, with specific texture and grammage, were used as substrate. Conductive traces over the samples were patterned either with carbon/8B pencil or with a stencil-applied conductive ink. The sensor working principle is predicated on the correlation between substrate impedance changes and Van der Waals interactions between acetone and citrate-functionalized AuNPs. Charge injection and transport processes originating from acetone adsorption on the sensor reflected electrical properties variation. Impedance magnitude for the pristine sample turned out to be around 1010 Ω, while AuNPs functionalization brought impedance down to 107 Ω range. On the other hand, when acetone was dripped on the sensor, a two orders of magnitude variation (from 107 Ω to 105 Ω) was observed. Hence, the sensor can be considered amenable to acetone detection by means of functionalized textiles.