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Wide-Aperture Diffraction-Based Beam-Shaping Structures for Enhanced Directivity in Next-Generation High-Frequency Communication Systems -
Evaluation of Gap and Flush Inspection Algorithms in a Portable Laser Line Triangulation System Through Measurement System Analysis (MSA) -
A Procedure for Performing Reproducibility Assessment of the Accuracy of Impact Area Classification for Structural Health Monitoring in Aerospace Structures -
Characterization of the Extraction System of Supersonic Gas Curtain-Based Ionization Profile Monitor for FLASH Proton Therapy -
Design of Spectrometer Energy Measurement Setups for the Future EuPRAXIA@SPARC_LAB and SSRIP Linacs
Journal Description
Instruments
Instruments
is an international, peer-reviewed, open access journal on scientific instrumentation and its related methods and theory, published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within ESCI (Web of Science), Scopus, Inspec, CAPlus / SciFinder, INSPIRE, and other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 22.8 days after submission; acceptance to publication is undertaken in 3.9 days (median values for papers published in this journal in the second half of 2025).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Journal Cluster of Instruments and Instrumentation: Actuators, AI Sensors, Instruments, Metrology, Micromachines, Quantum Beam Science and Sensors.
Latest Articles
An Alvarez-Type Linac Configuration for Future Carbon and Helium Ion Therapy Facilities with Parallel Radioisotope Production
Instruments 2026, 10(1), 16; https://doi.org/10.3390/instruments10010016 - 7 Mar 2026
Abstract
The increasing demand for ion beams heavier than protons—particularly carbon and helium ions—for cancer therapy has driven the development of advanced accelerator technologies. Although proton therapy is well established, its physical properties limit its effectiveness against certain tumor types, thereby motivating the use
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The increasing demand for ion beams heavier than protons—particularly carbon and helium ions—for cancer therapy has driven the development of advanced accelerator technologies. Although proton therapy is well established, its physical properties limit its effectiveness against certain tumor types, thereby motivating the use of ions with higher linear energy transfer (LET) and greater biological effectiveness. This study presents the design of an Alvarez-type linear accelerator configuration that combines a Quasi-Alvarez Drift Tube Linac (QA-DTL) and a conventional Alvarez Drift Tube Linac (DTL). The proposed systems are intended for accelerating and injecting carbon or helium ions into a cancer therapy synchrotron, as well as accelerating helium ions for radioisotope production. The optimized QA-DTL and DTL structures provide a versatile and efficient solution for future particle therapy facilities, addressing the growing demand for compact, high-performance, and multifunctional accelerator systems. The proposed linac configurations are designed to operate at 352.2 MHz and consist of three sections. For accelerating low-velocity ions, the first section is a QA-DTL, which is the only section powered during the injection of carbon or helium ions (depending on configuration) into the therapy synchrotron at the energy of 5 MeV/u. The QA-DTL is followed by two DTL cavities forming the second and third sections, which further accelerate helium ions to energies of up to 7.1 MeV/u and 10 MeV/u, respectively. The energy of 7.1 MeV/u is chosen because it represents the production threshold of 211At, one of the most promising alpha emitters for targeted alpha therapy.
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(This article belongs to the Special Issue Compact Accelerators)
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Open AccessArticle
Smartphone-Based Quantitative Measurement of Capillary Refill Time
by
Chiho Miyazawa, Masayoshi Shinozaki, Yayoi Miwa, Satoshi Karasawa, Taka-aki Nakada, Yukihiro Nomura and Toshiya Nakaguchi
Instruments 2026, 10(1), 15; https://doi.org/10.3390/instruments10010015 - 3 Mar 2026
Abstract
Capillary refill time (CRT) is widely used in pediatric and emergency medicine as an indicator of peripheral circulation. CRT is defined as the time required for the skin to return to its original color after external compression is applied and then released. In
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Capillary refill time (CRT) is widely used in pediatric and emergency medicine as an indicator of peripheral circulation. CRT is defined as the time required for the skin to return to its original color after external compression is applied and then released. In current clinical practice, however, CRT assessment remains qualitative and relies heavily on the magnitude and consistency of compression applied by the measurer, as well as on subjective visual color perception, which together result in limited measurement reliability. To improve measurement reliability, several quantitative CRT measurement devices have been developed. Nevertheless, these devices are dedicated specifically to CRT measurement, which limits their versatility and complicates clinical implementation. In this study, we developed a simple and quantitative CRT measurement method using a smartphone. Based on skin color changes captured by the rear camera, we proposed a method to assess the adequacy of the applied compression force and implemented an application to calculate CRT. In addition, we investigated an algorithm to reduce the influence of pulse waves observed in the post-release waveform, enabling more stable CRT estimation. Furthermore, a dedicated smartphone case was designed to immobilize the finger during measurement, thereby improving measurement reliability. The feasibility of the proposed method was evaluated by examining agreement with a previously developed CRT measurement device and by assessing intraexaminer reliability, confirming its effectiveness.
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(This article belongs to the Special Issue Instrumentation and Measurement Methods for Industry 4.0 and IoT)
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Open AccessFeature PaperArticle
Production and Purification of 165Er from Pressed Ho2O3:Al Targets on a 16.5 MeV Cyclotron
by
Kristina Søborg Pedersen, Claire Deville, Trine Borre, Ghazal Torabi, Clive Naidoo and Mikael Jensen
Instruments 2026, 10(1), 14; https://doi.org/10.3390/instruments10010014 - 27 Feb 2026
Abstract
Erbium-165 (165Er) is an Auger electron emitter with 7.2 electrons per decay and very few other emissions, making it an interesting candidate for Auger electron therapy. We present here a procedure for producing 165Er by the natHo(p,n)165Er
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Erbium-165 (165Er) is an Auger electron emitter with 7.2 electrons per decay and very few other emissions, making it an interesting candidate for Auger electron therapy. We present here a procedure for producing 165Er by the natHo(p,n)165Er nuclear reaction on a 16.5 MeV medical cyclotron. The target was prepared by pressing a Ho2O3:Al 1:1 (w/w) powder mixture on a Ag disc with a cylindrical depression in the center. With a 0.1 mm Nb foil in front, degrading the energy to 15 MeV, and water cooling at the back of the Ag disc, the target could withstand irradiation at currents up to 45 µA without showing any signs of damage. The beam tolerance of the target was also estimated by calculating the temperature and heat dissipation in the target via the numerical solution of the heat transport equations. For a 180 mg target, the production yield was 12.3 ± 1.9 MBq/µAh. The separation of two neighboring lanthanides is challenging, which led us to study the distribution coefficients for Er and Ho on commercially available LN2 resin for both HNO3 and HCl eluents. Based on these values, we propose a purification procedure involving two successive LN2 columns for separating the 165Er from Ho and Al, followed by a small TK221 column to concentrate the final eluate. No radionuclidic impurities were detected, and the chemical impurities found in the final formulation were traces of Ho, Er, Ca, Pb, and Fe. For three different chelators (DOTA, DTPA, and CHX-A″-DTPA), the effective molar activity of the final formulation was measured. The stability of the three complexes formed was also assessed upon incubation in mouse serum for 28 h.
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(This article belongs to the Special Issue Selected Papers from the 16th Workshop of the European Network of Research Cyclotrons (CYCLEUR 2025))
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Open AccessArticle
Enhanced Optical Triangulation Method for Piezoelectric Stack
by
Sinan Köksu and Sedat Nazlıbilek
Instruments 2026, 10(1), 13; https://doi.org/10.3390/instruments10010013 - 26 Feb 2026
Abstract
The precise control of piezoelectric actuators is limited by inherent hysteresis, creep, and nonlinear behavior, which necessitate high-resolution displacement sensing for effective closed-loop operation. Although optical interferometers can achieve nanometer and sub-nanometer resolution, their practical implementation is often constrained by complex optical alignment,
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The precise control of piezoelectric actuators is limited by inherent hysteresis, creep, and nonlinear behavior, which necessitate high-resolution displacement sensing for effective closed-loop operation. Although optical interferometers can achieve nanometer and sub-nanometer resolution, their practical implementation is often constrained by complex optical alignment, sensitivity to environmental disturbances, and limited robustness in high-speed measurements. Optical triangulation sensors offer a more robust and straightforward alternative; however, their resolution is typically insufficient for nanometer-scale displacement measurements. In this study, a novel optical triangulation sensor based on a two-stage geometric optical amplification scheme is proposed for measuring the expansion of piezoelectric stacks. The method relies purely on geometric optical amplification and does not require interferometric techniques or complex signal processing. Using off-the-shelf optical components and an industrial imaging sensor, the proposed system achieves a displacement resolution of 109.6 nm, a repeatability of 74.62 nm, and an accuracy of 98.81% with a maximum error of 207.14 nm under hysteresis measurements. The achieved resolution is primarily limited by the spatial resolution of the camera sensor, indicating that further improvements are possible through optimization of the optical configuration or the use of higher-resolution imaging devices. Owing to its simplicity and robustness, the proposed sensor is well suited for real-time closed-loop control of piezoelectric actuators.
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(This article belongs to the Section Sensing Technologies and Precision Measurement)
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Open AccessArticle
Determination of Super Luminescent Diode Junction Temperature via Static Modulated Fourier-Transform Spectrometer
by
Ju Yong Cho and Won Kweon Jang
Instruments 2026, 10(1), 12; https://doi.org/10.3390/instruments10010012 - 8 Feb 2026
Abstract
The accurate and rapid measurement of junction temperature is critical for optimizing the performance and ensuring the longevity of a super luminescent diode. However, due to diverse diode structures, directly measuring and monitoring the junction temperature of a super luminescent diode are often
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The accurate and rapid measurement of junction temperature is critical for optimizing the performance and ensuring the longevity of a super luminescent diode. However, due to diverse diode structures, directly measuring and monitoring the junction temperature of a super luminescent diode are often challenging and impractical. We propose a non-invasive methodology to precisely determine the junction temperature and spectral characteristics of a super luminescent diode. This method utilizes a modified static modulated Fourier-transform spectrometer alongside a generalized analyzing expression derived from Gaussian components. Fast acquisition of spectral information is achieved through the modified static modulated Fourier-transform spectrometer and analyzing method. The proposed model has exceptional accuracy, yielding an average coefficient of determination R2 of 0.99 across a range of operating currents and junction temperatures. Our analysis reveals a distinct linear correlation between the extracted fitting parameters—specifically the carrier temperature, the spectral shape parameter and the physical junction temperature. These findings demonstrate that the critical internal physical conditions of the diode can be accurately inferred directly from its measured spectrum, providing a robust tool for device characterization.
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(This article belongs to the Section Optical and Photonic Instruments)
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Open AccessArticle
Calibration of a Capacitive Coupled Ring Resonator for Non-Invasive Measurement of Wood Moisture Content
by
Livio D’Alvia, Ludovica Apa, Emanuele Rizzuto, Erika Pittella and Zaccaria Del Prete
Instruments 2026, 10(1), 11; https://doi.org/10.3390/instruments10010011 - 5 Feb 2026
Abstract
The accurate and non-invasive measurement of moisture content in wood is essential for the preservation of historical and artistic artifacts. This study presents the calibration of a planar Microwave Planar Capacitive Coupled Ring Resonator (MPCCRR) designed to indirectly and non-destructively assess the water
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The accurate and non-invasive measurement of moisture content in wood is essential for the preservation of historical and artistic artifacts. This study presents the calibration of a planar Microwave Planar Capacitive Coupled Ring Resonator (MPCCRR) designed to indirectly and non-destructively assess the water content in wood samples. The method relies on analyzing shifts in the resonant frequencies and variations in the transmission parameter |S21| resulting from changes in the material’s dielectric permittivity. After preliminary characterization via parametric simulations (εr = 1–10) and validation with low-permittivity reference materials, the sensor was tested on three wood species (poplar, fir, beech), including measurements at two sensor positions and with different grain orientations. The results demonstrate a monotonic, repeatable response to increasing moisture content with frequency shifts up to ≈220 MHz and normalized sensitivities ranging from 3 to 9 MHz/% water content, depending on species and measurement position. Position 2 showed the greatest sensitivity due to stronger field–sample interaction, while Position 1 provided a quasi-isotropic response with excellent repeatability. Linear regression analyses revealed good correlations between the frequency shifts and the gravimetric water content (R2 ≥ 0.85). The MPCCRR sensor therefore proves to be a promising tool for the non-invasive monitoring of wood moisture, which is particularly suitable for the low-moisture range encountered in cultural heritage conservation, with an estimated moisture uncertainty of 0.12–0.35% under controlled laboratory conditions.
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(This article belongs to the Section Sensing Technologies and Precision Measurement)
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Open AccessArticle
Wide-Aperture Diffraction-Based Beam-Shaping Structures for Enhanced Directivity in Next-Generation High-Frequency Communication Systems
by
Vladislovas Čižas, Simonas Driukas, Andrius Masaitis, Kotryna Nacienė, Kasparas Stanaitis, Egidijus Šideika and Linas Minkevičius
Instruments 2026, 10(1), 10; https://doi.org/10.3390/instruments10010010 - 4 Feb 2026
Abstract
Sub-terahertz (sub-THz) frequencies are in the spotlight in the ongoing development of sixth-generation (6G) wireless communication systems, offering ultra-high data rates and low latency for rapidly emerging applications. However, employment of sub-THz frequencies introduces strict propagation challenges, including free-space path loss and atmospheric
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Sub-terahertz (sub-THz) frequencies are in the spotlight in the ongoing development of sixth-generation (6G) wireless communication systems, offering ultra-high data rates and low latency for rapidly emerging applications. However, employment of sub-THz frequencies introduces strict propagation challenges, including free-space path loss and atmospheric absorption, which limit coverage and reliability. To address these issues, highly directional links are required. The conventional beam-shaping solutions such as refractive lenses and parabolic mirrors are bulky, heavy, and costly, making them less attractive for compact systems. Diffractive optical elements (DOEs) offer a promising alternative by enabling precise wavefront control through phase modulation, resulting in thin, lightweight components with high focusing efficiency. Employing the fused deposition modelling (FDM) using high-impact polystyrene (HIPS) allows cost-effective fabrication of DOEs with minimal material waste and high diffraction efficiency. This work investigates the beam-shaping performance of the FDM-printed structures comparing DOEs and spherical refraction-based structures, wherein both are aiming for application in sub-THz communication systems. DOEs exhibit clear advantages over classically employed solutions.
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(This article belongs to the Section Optical and Photonic Instruments)
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Open AccessReview
The Intelligent Knife (iKnife): Revolutionizing Intraoperative Tissue Diagnosis Through Rapid Evaporative Ionization Mass Spectrometry (REIMS)
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Gabriel Amorim Moreira Alves, Mohan Dodeja, Fazal Khan, Mary Szocik and Arosh Shavinda Perera Molligoda Arachchige
Instruments 2026, 10(1), 9; https://doi.org/10.3390/instruments10010009 - 3 Feb 2026
Abstract
The intelligent surgical knife (iKnife), based on rapid evaporative ionization mass spectrometry (REIMS), represents a transformative advance in intraoperative tissue characterization. By integrating mass spectrometry with electrosurgical dissection, the iKnife enables real-time differentiation between cancerous and healthy tissues through molecular fingerprinting of the
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The intelligent surgical knife (iKnife), based on rapid evaporative ionization mass spectrometry (REIMS), represents a transformative advance in intraoperative tissue characterization. By integrating mass spectrometry with electrosurgical dissection, the iKnife enables real-time differentiation between cancerous and healthy tissues through molecular fingerprinting of the aerosol generated during cutting. This innovation significantly shortens operative time by eliminating delays associated with conventional histopathological analysis and enhances surgical precision by providing continuous feedback on tissue composition. Since its inception by Zoltán Takáts and colleagues, the iKnife has demonstrated remarkable diagnostic accuracy across multiple cancer types, including breast, ovarian, and colorectal malignancies, with reported sensitivities and specificities > 90% in selected tumour types. Beyond oncology, REIMS technology also shows promise for microbial identification and metabolomic profiling. This review provides a comprehensive overview of the iKnife’s development, underlying principles, clinical validation, and emerging applications, as well as its integration into surgical workflows and the challenges remaining for widespread clinical adoption. Future perspectives include miniaturization, AI-driven spectral interpretation, and expansion into robotic and image-guided surgery.
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(This article belongs to the Section Analytical Science and Biomedical Instruments)
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Open AccessSystematic Review
A Systematic Review of Deep Reinforcement Learning for Legged Robot Locomotion
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Bingxiao Sun, Sallehuddin Mohamed Haris and Rizauddin Ramli
Instruments 2026, 10(1), 8; https://doi.org/10.3390/instruments10010008 - 30 Jan 2026
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Legged robot locomotion remains a critical challenge in robotics, demanding control strategies that are not only dynamically stable and robust but also capable of adapting to complex and changing environments. deep reinforcement learning (DRL) has recently emerged as a powerful approach to automatically
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Legged robot locomotion remains a critical challenge in robotics, demanding control strategies that are not only dynamically stable and robust but also capable of adapting to complex and changing environments. deep reinforcement learning (DRL) has recently emerged as a powerful approach to automatically generate motion control policies by learning from interactions with simulated or real environments. This study provides a systematic overview of DRL applications in legged robot control, emphasizing experimental platforms, measurement techniques, and benchmarking practices. Following PRISMA guidelines, 27 peer-reviewed studies published between 2018 and 2025 were analyzed, covering model-free, model-based, hierarchical, and hybrid DRL frameworks. Our findings reveal that reward shaping, policy representation, and training stability significantly influence control performance, while domain randomization and dynamic adaptation methods are essential for bridging the simulation-to-real-world gap. In addition, this review highlights instrumentation approaches for evaluating algorithm effectiveness, offering insights into sample efficiency, energy management, and safe deployment. The results aim to guide the development of reproducible and experimentally validated DRL-based control systems for legged robots.
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Open AccessArticle
Evaluation of Gap and Flush Inspection Algorithms in a Portable Laser Line Triangulation System Through Measurement System Analysis (MSA)
by
Guerino Gianfranco Paolini, Sara Casaccia, Matteo Nisi, Cristina Cristalli and Nicola Paone
Instruments 2026, 10(1), 7; https://doi.org/10.3390/instruments10010007 - 26 Jan 2026
Abstract
The shift toward Industry 5.0 places human-centred and digitally integrated metrology at the core of modern manufacturing, particularly in the automotive sector, where portable Laser Line Triangulation (LLT) systems must combine accuracy with operator usability. This study addresses the challenge of operator-induced variability
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The shift toward Industry 5.0 places human-centred and digitally integrated metrology at the core of modern manufacturing, particularly in the automotive sector, where portable Laser Line Triangulation (LLT) systems must combine accuracy with operator usability. This study addresses the challenge of operator-induced variability by evaluating how algorithmic strategies and mechanical support features jointly influence the performance of a portable LLT device derived from the G3F sensor. A comprehensive Measurement System Analysis was performed to compare three feature extraction algorithms—GC, FIR, and Steger—and to assess the effect of a masking device designed to improve mechanical alignment during manual measurements. The results highlight distinct algorithm-dependent behaviours in terms of repeatability, reproducibility, and computational efficiency. More sophisticated algorithms demonstrate improved sensitivity and feature localisation under controlled conditions, whereas simpler gradient-based strategies provide more stable performance and shorter processing times when measurement conditions deviate from the ideal. These differences indicate a trade-off between algorithmic complexity and operational robustness that is particularly relevant for portable, operator-assisted metrology. The presence of mechanical alignment aids was found to contribute to improved measurement consistency across all algorithms. Overall, the findings highlight the need for an integrated co-design of algorithms, calibration procedures, and ergonomic aids to enhance repeatability and support operator-friendly LLT systems aligned with Industry 5.0 principles.
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(This article belongs to the Special Issue Instrumentation and Measurement Methods for Industry 4.0 and IoT)
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Open AccessArticle
A Procedure for Performing Reproducibility Assessment of the Accuracy of Impact Area Classification for Structural Health Monitoring in Aerospace Structures
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Luciano Chiominto, Giulio D’Emilia, Antonella Gaspari, Emanuela Natale, Francesco Nicassio and Gennaro Scarselli
Instruments 2026, 10(1), 6; https://doi.org/10.3390/instruments10010006 - 26 Jan 2026
Abstract
The principal objective of this work is to develop an optimized procedure that guarantees the reproducibility of results across different applications and laboratories, facilitating potential field applications of methodologies for Structural Health Monitoring in aerospace structures. The focus is to accurately detect and
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The principal objective of this work is to develop an optimized procedure that guarantees the reproducibility of results across different applications and laboratories, facilitating potential field applications of methodologies for Structural Health Monitoring in aerospace structures. The focus is to accurately detect and localize impact areas on planar structures using in situ transducers and Machine Learning (ML) techniques. The research concentrates on an aluminum plate where impacts are generated by metal spheres of different masses dropped from a fixed height. The resulting Lamb waves are detected by PZT sensors glued on the surface. Various data processing and feature extraction algorithms are implemented and compared to extract the differences in Time of Flight (ΔToF). The obtained features are used for training ML classification models. Then, the influence of various parameters in signal acquisition and data processing are assessed along with the reproducibility of the results. For this reason, an interlaboratory comparison is conducted in which the trained models are applied to data collected under varying conditions. The experimental results show that the most influencing factors for impact area classification are the algorithm for ΔToF estimation, the number of training points used in ML models, the type of classification model, the distribution of the impact points on the component, and their balance in the classification area. This evidence suggests approaches for reducing both issues, therefore improving the reproducibility of results.
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(This article belongs to the Special Issue Instrumentation and Measurement Methods for Industry 4.0 and IoT)
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Open AccessArticle
Button Sample Holders for Infrared Spectroscopy
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Robert L. White
Instruments 2026, 10(1), 5; https://doi.org/10.3390/instruments10010005 - 26 Jan 2026
Abstract
The design features and applications of button sample holders are described. The similarities and contrasts between the button method and the transmission cell and attenuated total reflection techniques are discussed. Different button sample holder analysis methodologies are outlined, and examples are provided for
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The design features and applications of button sample holders are described. The similarities and contrasts between the button method and the transmission cell and attenuated total reflection techniques are discussed. Different button sample holder analysis methodologies are outlined, and examples are provided for mid-infrared spectroscopy measurements of solids, liquids, and pastes. Results obtained for 10-nonadecanone powder, a vitamin C tablet, a soil sample, and poly(methyl methacrylate) are used to illustrate different solid sample analysis approaches. Time-dependent spectrum variations detected during evaporation of a blood drop are elucidated and spectra obtained from different quantities of liquid chlorobenzene loaded into buttons and transmission cells are characterized. Infrared spectra derived from three toothpaste brands are compared and a sample perturbation study to identify temperature-dependent changes to the structure of poly(bisphenol A carbonate) is provided as an example of variable temperature infrared spectroscopy.
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(This article belongs to the Section Optical and Photonic Instruments)
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Open AccessArticle
Characterization of the Extraction System of Supersonic Gas Curtain-Based Ionization Profile Monitor for FLASH Proton Therapy
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Farhana Thesni Mada Parambil, Milaan Patel, Narender Kumar, Bharat Singh Rawat, William Butcher, Tony Price and Carsten P. Welsch
Instruments 2026, 10(1), 4; https://doi.org/10.3390/instruments10010004 - 25 Jan 2026
Abstract
FLASH radiotherapy requires real-time, non-invasive beam monitoring systems capable of operating under ultra-high dose rate (UHDR) conditions without perturbing the therapeutic beam. In this work, we characterized the extraction system of Supersonic Gas Curtain-based Ionization Profile Monitor (SGC-IPM) for its capabilities as a
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FLASH radiotherapy requires real-time, non-invasive beam monitoring systems capable of operating under ultra-high dose rate (UHDR) conditions without perturbing the therapeutic beam. In this work, we characterized the extraction system of Supersonic Gas Curtain-based Ionization Profile Monitor (SGC-IPM) for its capabilities as a transverse beam profile and position monitor for FLASH protons. The monitor utilizes a tilted gas curtain intersected by the incident beam, leading to the generation of ions that are extracted through a tailored electrostatic field, and detected using a two stage microchannel plate (MCP) coupled to a phosphor screen and CMOS camera. CST Studio Suite was employed to conduct electrostatic and particle tracking simulations evaluating the ability of the extraction system to measure both beam profile and position. The ion interface, at the interaction region of proton beam and gas curtain, was modeled with realistic proton beam parameters and uniform gas curtain density distributions. The ion trajectory was tracked to evaluate the performance across multiple beam sizes. The simulations suggest that the extraction system can reconstruct transverse beam profiles for different proton beam sizes. Simulations also supported the system’s capability as a beam position monitor within the boundary defined by the beam size, the dimensions of the extraction system, and the height of the gas curtain. Some simulation results were benchmarked against experimental data of 28 MeV proton beam with 70 nA average beam current. This study will further help to optimize the design of the extraction system to facilitate the integration of SGC-IPM in medical accelerators.
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(This article belongs to the Special Issue Plasma Accelerator Technologies)
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Open AccessArticle
Scalable Relay Switching Platform for Automated Multi-Point Resistance Measurements
by
Edoardo Boretti, Kostiantyn Torokhtii, Enrico Silva and Andrea Alimenti
Instruments 2026, 10(1), 3; https://doi.org/10.3390/instruments10010003 - 31 Dec 2025
Abstract
In both research and industrial settings, it is often necessary to expand the input/output channels of measurement instruments using relay-based multiplexer boards. In research activities in particular, the need for a highly flexible and easily configurable solution frequently leads to the development of
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In both research and industrial settings, it is often necessary to expand the input/output channels of measurement instruments using relay-based multiplexer boards. In research activities in particular, the need for a highly flexible and easily configurable solution frequently leads to the development of customized systems. To address this challenge, we developed a system optimized for automated direct current (DC) measurements. The result is based on a switching platform that simplifies measurement procedures that require instrument routing. The platform is based on a custom-designed circuit board controlled by a microcontroller. We selected bistable relays to guarantee contact stability after switching. We finally developed a system architecture that allows for straightforward expansion and scalability by connecting multiple platforms. We share both the hardware design source files and the firmware source code on GitHub with the open-source community. This work presents the design and development of the proposed system, followed by the performance evaluation. Finally, we present a test of our designed system applied to a specific case study: the DC analysis of complex resistive networks through multi-point resistance measurements using only a single voltmeter and current source.
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(This article belongs to the Section Sensing Technologies and Precision Measurement)
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Open AccessArticle
Shoulder Muscle Strength Assessment: A Comparative Study of Hand-Held Dynamometers and Load Cell Measurements
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Carla Antonacci, Arianna Carnevale, Letizia Mancini, Alessandro de Sire, Pieter D’Hooghe, Michele Mercurio, Rocco Papalia, Emiliano Schena and Umile Giuseppe Longo
Instruments 2026, 10(1), 2; https://doi.org/10.3390/instruments10010002 - 20 Dec 2025
Abstract
Accurate measurement of shoulder muscle strength is important for diagnosis, treatment planning, and monitoring recovery. Hand-held dynamometers (HHDs) are widely used in clinical practice but are affected by operator strength, patient positioning, and device stabilization, particularly under high-load conditions. No previous study has
[...] Read more.
Accurate measurement of shoulder muscle strength is important for diagnosis, treatment planning, and monitoring recovery. Hand-held dynamometers (HHDs) are widely used in clinical practice but are affected by operator strength, patient positioning, and device stabilization, particularly under high-load conditions. No previous study has directly compared HHD measurements with a reference load cell in a rigid serial configuration or evaluated the effect of different load cell signal processing strategies on the final strength value. The aim of this study was to compare HHD measurements with those obtained from a reference load cell in a rigid serial configuration and to assess how different signal processing strategies applied to load cell data influence the final outcomes. A custom 3D-printed support was developed to align a commercial HHD and a load cell in series, ensuring identical loading conditions. Measurements were performed under two conditions: (i) application of known weights (9.81–98.10 N) and (ii) standardized strength tasks in five healthy volunteers. Agreement between instruments was evaluated using Bland–Altman analysis and Root Mean Square Error (RMSE). In static validation (i.e., experiments applying know weights), the load cell demonstrated stable performance, with standard deviations below 1% of the applied load. HHD variability increased with load, with RMSE rising from 0.55 N at 9.81 N to 5.06 N at 98.10 N. In human testing, the HHD consistently underestimated muscle strength compared with the load cell, with mean differences ranging from −15 N to −19 N, over exerted force ranges of approximately 20–90 N. Overall, the load cell provided stable reference measurements, while the choice of signal processing strategy influenced the results: plateau-phase analysis tended to reduce systematic bias but did not consistently narrow the limits of agreement.
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(This article belongs to the Special Issue Instrumentation and Measurement Methods for Industry 4.0 and IoT)
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Open AccessArticle
Gamma and Neutron Irradiation Effects on Wavelength Shifting Materials for Nuclear and High Energy Physics Applications
by
Jessica Scifo, Beatrice D’Orsi, Francesco Filippi, Silvia Cesaroni, Andrea Colangeli, Ilaria Di Sarcina, Basilio Esposito, Davide Flammini, Stefano Loreti, Daniele Marocco, Guglielmo Pagano, Adriano Verna and Alessia Cemmi
Instruments 2026, 10(1), 1; https://doi.org/10.3390/instruments10010001 - 20 Dec 2025
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Wavelength-shifting (WLS) materials are used in radiation detectors to convert ultraviolet photons into visible light, enabling improved photon detection in systems such as scintillators and optical diagnostics for nuclear fusion devices. However, the long-term performance of these materials under radiation is still a
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Wavelength-shifting (WLS) materials are used in radiation detectors to convert ultraviolet photons into visible light, enabling improved photon detection in systems such as scintillators and optical diagnostics for nuclear fusion devices. However, the long-term performance of these materials under radiation is still a critical issue in high-dose environments. In this work, we investigated the radiation tolerance of three WLS compounds (TPB, NOL1, and SB2001), each deposited on reflective substrates (ESR and E-PTFE), resulting in six distinct WLS/substrate systems. The samples underwent gamma irradiation at absorbed doses of 100 kGy, 500 kGy, and 1000 kGy, as well as fast neutron (14.1 MeV) irradiation up to a fluence of 1.9 × 1013 n/cm2. Qualitative photoluminescence and reflectance measurements were performed before and after irradiation to assess changes in optical performance. Gamma exposure caused spectral broadening in several samples, particularly those with TPB and SB2001, with variations of the two metrics used to compare the performance of the materials exceeding 10% at the highest doses. Neutron-induced effects were generally weaker and did not exhibit a clear fluence dependence. Reflectance degradation was also observed, with variations depending on both the WLS material and the deposition method. These findings contribute to the understanding of WLS material stability under radiation and support their qualification for use in optical components exposed to harsh nuclear environments.
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Open AccessArticle
Design of Spectrometer Energy Measurement Setups for the Future EuPRAXIA@SPARC_LAB and SSRIP Linacs
by
Danilo Quartullo, David Alesini, Alessandro Cianchi, Francesco Demurtas, Luigi Faillace, Giovanni Franzini, Andrea Ghigo, Anna Giribono, Riccardo Pompili, Lucia Sabbatini, Angelo Stella, Cristina Vaccarezza, Alessandro Vannozzi and Livio Verra
Instruments 2025, 9(4), 34; https://doi.org/10.3390/instruments9040034 - 17 Dec 2025
Abstract
EuPRAXIA@SPARC_LAB is an FEL (Free-Electron Laser) user facility currently under construction at INFN-LNF in the framework of the EuPRAXIA collaboration. The electron beam will be accelerated to 1 GeV by an X-band RF linac followed by a plasma wakefield acceleration stage. This high-brightness
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EuPRAXIA@SPARC_LAB is an FEL (Free-Electron Laser) user facility currently under construction at INFN-LNF in the framework of the EuPRAXIA collaboration. The electron beam will be accelerated to 1 GeV by an X-band RF linac followed by a plasma wakefield acceleration stage. This high-brightness linac requires diagnostic devices able to measure the beam parameters with high accuracy and resolution. To monitor the beam energy and its spread, magnetic dipoles and quadrupoles will be installed along the linac, in combination with viewing screens and CMOS cameras. Macroparticle beam dynamics simulations have been performed to determine the optimal energy measurement setup in terms of accuracy and resolution. Similar diagnostics evaluations have been carried out for the spectrometer installed at the 100 MeV RF linac of the radioactive beam facility SSRIP (IFIN-HH, Romania), whose commissioning, foreseen for 2026, will be performed by INFN-LNF in collaboration with IFIN-HH. Optics measurements have been performed to characterize the resolution and magnification of the optical system that will be used at SSRIP, and probably also at EuPRAXIA@SPARC_LAB, for beam energy monitoring.
Full article
(This article belongs to the Special Issue Selected Papers from the 14th International Beam Instrumentation Conference (IBIC2025))
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Open AccessArticle
Deep-Learning-Based Bearing Fault Classification Using Vibration Signals Under Variable-Speed Conditions
by
Luca Martiri, Parisa Esmaili, Andrea Moschetti and Loredana Cristaldi
Instruments 2025, 9(4), 33; https://doi.org/10.3390/instruments9040033 - 4 Dec 2025
Abstract
Predictive maintenance in industrial machinery relies on the timely detection of component faults to prevent costly downtime. Rolling bearings, being critical elements, are particularly prone to defects such as outer race faults and ball spin defects, which manifest as characteristic vibration patterns. In
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Predictive maintenance in industrial machinery relies on the timely detection of component faults to prevent costly downtime. Rolling bearings, being critical elements, are particularly prone to defects such as outer race faults and ball spin defects, which manifest as characteristic vibration patterns. In this study, we introduce a novel bearing vibration dataset collected on a testbench under both constant and variable rotational speeds (0–5000 rpm), encompassing healthy and faulty conditions. The dataset was used for failure classification and further enriched through feature engineering, resulting in input features that include raw acceleration, signal envelopes, and time- and frequency-domain statistical descriptors, which capture fault-specific signatures. To quantify prediction uncertainty, two different approaches are applied, providing confidence measures alongside model outputs. Our results demonstrate the progressive improvement of classification accuracy from 87.2% using only raw acceleration data to 99.3% with a CNN-BiLSTM (Convolutional Neural Network–Bidirectional Long Short-Term Memory) ensemble and advanced features. Shapley Additive Explanation (SHAP)-based explainability further validates the relevance of frequency-domain features for distinguishing fault types. The proposed methodology offers a robust and interpretable framework for industrial fault diagnosis, capable of handling both stationary and non-stationary operating conditions.
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(This article belongs to the Special Issue Instrumentation and Measurement Methods for Industry 4.0 and IoT)
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Open AccessFeature PaperArticle
RF Characterization and Beam Measurements with Additively Manufactured Fast Faraday Cups
by
Stephan Klaproth, Rahul Singh, Samira Gruber, Lukas Stepien, Herbert De Gersem and Andreas Penirschke
Instruments 2025, 9(4), 32; https://doi.org/10.3390/instruments9040032 - 28 Nov 2025
Abstract
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The early stages of most particle accelerator chains produce sub-ns bunches with velocities in the range of 1% to 20% of the speed of light. Fast Faraday Cups (FFCs) are designed to measure the longitudinal charge distribution of these short bunches of free
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The early stages of most particle accelerator chains produce sub-ns bunches with velocities in the range of 1% to 20% of the speed of light. Fast Faraday Cups (FFCs) are designed to measure the longitudinal charge distribution of these short bunches of free charges. Coaxial designs have been utilized at the GSI Helmholtz Centre for Heavy Ion Research (GSI)’s linear accelerator UNILAC to characterize ion bunches with bunch lengths ranging from a few hundred ps to a few ns. The typical design goals are to avoid the pre-field of the charges and to suppress secondary electron emission (SEE) while preserving the capability of bunch-by-bunch measurements. This contribution presents a novel FFC design manufactured using additive manufacturing, e.g., laser powder bed fusion (LPBF), and compares it with a traditionally produced FFC. The article highlights the design process, RF characterization, and selected measurements with ion beam carried out at GSI.
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Open AccessArticle
Synchronous Biaxial Straining of Foils and Thin Films with In Situ Capabilities
by
Michael Pegritz, Philipp Payer, Alice Lassnig, Stefan Wurster, Megan J. Cordill and Anton Hohenwarter
Instruments 2025, 9(4), 31; https://doi.org/10.3390/instruments9040031 - 26 Nov 2025
Cited by 1
Abstract
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A common method to examine the reliability of thin films and small volumes of irradiated materials being used in aerospace, energy, and protective coating applications is biaxial straining. With such tests, the fracture and deformation mechanisms occurring under multi-axial stress states can be
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A common method to examine the reliability of thin films and small volumes of irradiated materials being used in aerospace, energy, and protective coating applications is biaxial straining. With such tests, the fracture and deformation mechanisms occurring under multi-axial stress states can be investigated, which can strongly differ from the simpler uniaxial one. However, devices that can apply a precise and synchronously applied biaxial strain tend to be too large for foils or thin films and do not allow for additional observation methods to be applied to examine film fracture or deformation during the test. A prototype device that can apply synchronous equi-biaxial and semi-biaxial strains and can be combined with multiple in situ methods is introduced. The device is light and compact in design, which allows it to be mounted on optical light microscopes, atomic force microscopes, inside scanning electron microscopes, and even on X-ray beamlines for reflection or transmission measurements. Additionally, digital image correlation was utilized in two geometries to measure strains on a local or global level. The possible errors associated with the device and experiments on polyimide foils and a 100 nm tungsten film on polyimide are presented.
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