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.

This paper presents the design and manufacturing of initial lab-on-chip micro-incubator prototypes within the ALCYONE project, to study different types of cell cultures in space. ALCYONE is a project funded by the EU under the Horizon Europe program, jointly developed by the School of Aerospace Engineering of Sapienza University of Rome (SIA), Bologna University, Kayser Italia Srl, Tor Vergata University, Twente University, and the Karlsruher Institut fuer Technologie. Envisioned as a key component for understanding the effects of prolonged space exposure on biological systems, the project focuses on creating an on-chip micro-incubator featuring integrated thin-film sensors and actuators to study the effect of space radiation environment on four different types of cell cultures. Genetically modified cells designed to express bioluminescence under given metabolic conditions enable real-time monitoring of cells status. This is achieved through specifically designed photosensors able to collect the emitted light, while on-chip actuators maintain a controlled environment within the chip incubator for precise experimentation and providing the required nutrients. The electronic system integrated into the platform characterizes the radiation environment, correlating biological responses with radiation exposure. This technology, with attributes such as low power consumption, compactness, high data efficiency, and full automation, aligns perfectly with CubeSat missions, culminating in the design of a comprehensive payload. This paper presents a pivotal aspect of the ALCYONE project, focusing on the design and manufacturing processes involved in creating the first micro-incubator prototypes. Different geometries and configurations have been evaluated and a first bench of incubator has been produced to make the first chemical experiments to define the protocol with engineered cell cultures. In addition, the design and manufacturing of the on-chip sensors is described.

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.

The Biofilm Onboard Radiation Exposure Assessment Lab In Space (BOREALIS) mission is a 6U CubeSat initiative funded by the Italian Space Agency under the ALCOR program, executed through a collaboration among the School of Aerospace Engineering of Sapienza University of Rome, Interdepartmental Centre for Industrial Aerospace Research (CIRI Aerospace) of the University of Bologna and Kayser Italia Srl. BOREALIS is equipped with a lab-on-chip payload for studying the effects of microgravity and ionising radiation on microbial biofilms, which are crucial for understanding and preventing persistent infections in space environments. The satellite will operate across multiple orbits, moving from low to medium Earth orbit, to distinctly analyse the impacts of radiation separate from microgravity. The required orbital transfer not only tests the autonomy of its on-board systems in challenging conditions but also places BOREALIS among the first and few CubeSats to have ever attempted such a complex manoeuvre. This study explores the systematic application of Model-Based Systems Engineering to satellite design, from conceptualisation to trade-offs, using a tradespace analysis approach supported by Monte Carlo simulations to optimise mission configurations against performance and cost. Additionally, the adaptability of Model-Based Systems Engineering tools and the reusability of such an approach for other satellite projects are discussed, illustrating the BOREALIS mission as a case study for small mission design considering constraints and requirements.

This paper presents an in-depth analysis of APHRODITE, a collaborative project involving the School of Aerospace Engineering (SIA) at Sapienza University of Rome, the Department of Chemistry "Giacomo Ciamician" of the University of Bologna, and Kayser Italia. Funded by the Italian Space Agency (ASI), APHRODITE serves as a technological demonstrator for deployment on the International Space Station (ISS) in late 2025, focusing on the determination of astronauts' salivary biomarkers through an innovative biosensor. The manuscript delves into the design, manufacturing, and testing of its microfluidic chip focusing on the detection subsystem and detailing its microfluidic simulations, magnet selection study, and critical role in the assay process. The microfluidic chip integrates thin-film sensors in hydrogenated amorphous silicon (a-Si:H) for dual-analyte competitive chemiluminescence (CL) immunoassays. In addition, the work outlines the assay protocol, emphasizing the use of functionalized magnetic microbeads (MBs) for chip reusability and assay versatility, enabling multiple successive assays, and consecutively analyzing different target analytes. The project outlined herein seeks to advance biosensing technologies for health monitoring in space, offering an in-depth description of the APHRODITE detection subsystem and its essential role in performing real-time analysis of salivary biomarkers throughout space missions.

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.

The Cleopatra ASIC is a 12-channel prototype ASIC for the readout of hydrogenated amorphous silicon sensors used for real-time dosimetry in radiation diagnostic and radiation therapy. The architecture is based on a current to frequency conversion based on the recycling integrator principle in order to cover a dynamic range of four orders of magnitude with high linearity. Three different input amplifier configurations have been implemented in order to check the trade-off between detector capacitance and maximum output frequency. Cleopatra has been designed in CMOS 28 nm technology and succesfully tested in laboratory.

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 describes an experimental characterization of a planar double-spiral resistive temperature microsensor. The proposed microsensor has been fabricated by means of a thermal evaporation process by employing a 1.2 mm-thick borofloat glass substrate and by depositing a 100 nmthick aluminum (Al) layer stacked between two 20 nm-thick chromium (Cr) layers. The fabricated microsensor has a track width of 50 mu m with an inter-track spacing of approximately 300 mu m. The experimental characterization has been performed by means of a tailored PID controlled temperature chamber including two Peltier cells, two fans and a Pt100 resistive temperature detector (RTD) for temperature control and monitoring. A sensitivity of 1.2 Omega/degrees C in the considered temperature range of 16 - 66 degrees C has been achieved showing a maximum nonlinearity error of 0.41 % referred to the span. The obtained experimental results confirm the possibility to exploit the proposed microsensor for temperature measurements.

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.

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).

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.

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.

Lab-on-Chip (LoC) devices can integrate onto a small single circuit one or more laboratory functions, reducing consumption of samples and reagents with consequent low pollution and low costs. LoC typically uses electrochemical or optical detection methods for quantifying the analysis. Among the others, optical methods rely on the detection of fluorescence radiation, induced by an excitation light. Nowadays, a filter is commonly used to properly distinguish between the two different lights. To avoid this additional technological step, this paper proposes the use of an amorphous silicon p-i-n photodiode, whose spectral response is modulated by changing the voltage applied across the diode. A simple algorithm allows to extract the two different lights intensities through a straightforward implementation.