Search Results (172)

Robotic hands require reliable and precise sensing systems to achieve accurate object recognition and manipulation, particularly in environments where vision- or capacitive-based approaches face limitations such as poor lighting, dust, reflective surfaces, or non-metallic materials. This paper presents a novel radiofrequency (RF) pre-touch sensing system that enables robust localization and orientation estimation of objects prior to grasping. The system integrates a compact coplanar waveguide (CPW) probe with fully passive chipless RF resonator tags fabricated using a patented flexible and stretchable conductive ink through additive manufacturing. This approach provides a low-cost, durable, and highly adaptable solution that operates effectively across diverse object geometries and environmental conditions. The experimental results demonstrate that the proposed RF sensor maintains stable performance under varying distances, orientations, and inter-tag spacings, showing robustness where traditional methods may fail. By combining compact design, cost-effectiveness, and reliable near-field sensing independent of an object or lighting, this work establishes RF sensing as a practical and scalable alternative to optical and capacitive systems. The proposed method advances robotic perception by offering enhanced precision, resilience, and integration potential for industrial automation, warehouse handling, and collaborative robotics. Full article

The integration of microstructured current collectors offers a potential pathway to enhance interface properties in solid-state battery architectures. In this work, we investigate the influence of surface morphology on the electrochemical performance of Zn/Na_2.99Ba_0.005OCl/Cu electrodeless pouch cells by fabricating copper thin films on microstructured parylene-C substrates using a combination of colloidal lithography and reactive ion etching. O₂ plasma etching times ranging from 0 to 15 min were used to tune the surface topography, resulting in a systematic increase in root-mean-square roughness and a surface area enhancement of up to ~30% for the longest etching duration, measured via AFM. Kelvin probe force microscopy-analyzed surface potential showed maximum differences of 270 mV between non-etched and 12-minute-etched Cu collectors. The results revealed that the chemical potential is the property that relates the surface of the Cu current collector/electrode with the cell’s ionic transport performance, including the bulk ionic conductivity, while four-point sheet resistance measurements confirmed that the copper layers’ resistivity maintained values close to those of bulk copper (1.96–4.5 µΩ.cm), which are in agreement with electronic mobilities (−6 and −18 cm²V⁻¹s⁻¹). Conversely, the charge carrier concentrations (−1.6 to −2.6 × 10²³ cm⁻³) are indirectly correlated with the performance of the cell, with the samples with lower CCC_bulk (fewer free electrons) performing better and showing higher maximum discharge currents, interfacial capacitance, and first-cycle discharge plateau voltage and capacity. The data were further consolidated with Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy analyses. These results highlight that the correlation between the surface morphology and the cell is not straightforward, with the microstructured current collectors’ surface chemical potential and the charge carriers’ concentration being determinant in the performance of all-solid-state electrodeless sodium battery systems. Full article

The determination of the actual crop water requirement (CWR) today represents an important prerogative for combating climate change. A three-year trial was conducted to ad-dress the need to provide adequate support to processing tomato growers in defining the correct amounts of water to be supplied. In fact, the objective of this work was to calculate the water requirement of processing tomatoes, specifically analyzing their irrigation needs using the CROPWAT 8.0 software and through capacitive and tensiometric probes. Furthermore, for both methods, the tomato yield was evaluated both by supplying 100% of its water requirement and by supplying, through regulated deficit irrigation (RDI), 70% of its water requirement. Subsequently, for each irrigation strategy employed and for each CWR calculation method, the water footprint was calculated by analyzing the blue, green, and grey components. In the years 2022 and 2023, there was an overestimation of CWR of 13.5% for IR100 and 13.94% for IR70, and 14.53% for IR100 and 11.65% for IR70, respectively, while in 2024 there was an underestimation, with values of 9.17% and 5.22% for the IR100 and IR70 treatments compared to the values obtained with the probes. The total WF of tomatoes varied between 33.42 and 51.91 m³ t⁻¹ with the CROPWAT model and between 35.82 and 47.19 m³ t⁻¹ with the probes for IR100, while for RDI70, the values ranged between 38.72 and 59.44 m³ t⁻¹ with the CROPWAT method and between 35.81 and 53.95 m³ t⁻¹ with the probe method. In water-scarce regions, integrating the CROPWAT 8.0 model (enhanced with real-world data) and implementing smart systems can significantly improve water management, refine decision-making processes, and mitigate environmental impacts. This approach directly addresses the urgent need for water security within sustainable agriculture. Full article

This work presents the validation of a low-cost measurement system based on an open-ended coaxial SMA (SubMiniature version A) probe for the characterization of complex permittivity in the microwave frequency range. The system combines a custom-fabricated probe, a vector network analyzer, and a dedicated software application that implements three analytical models: capacitive, radiation, and virtual transmission line models. A comprehensive experimental campaign was carried out involving pure polar liquids, saline solutions, and biological tissues, with the measurements compared against those obtained using a high-precision commercial probe. The results confirm that the proposed system is capable of delivering accurate and reproducible permittivity values up to at least 6 GHz. Among the implemented models, the radiation model demonstrated the best overall performance, particularly in biological samples. Additionally, reproducibility tests with three independently assembled SMA probes showed normalized deviations below 3%, confirming the robustness of the design. These results demonstrate that the proposed system constitutes a viable alternative for cost-sensitive applications requiring portable or scalable microwave dielectric characterization. Full article

Germanium/tin-containing silicon oxide [SiO–(GeO/SnO)] nanoclusters have been designed with different Si/Ge/Sn particles and characterized as electrodes for magnesium-ion batteries (MIBs) due to forming MgBe [SiO–GeO], MgBe [SiO–SnO], MgCa [SiO–GeO], and MgCa [SiO–SnO] complexes. In this work, alkaline earth metals of magnesium (Mg), beryllium (Be), and calcium (Ca) have been studied in hybrid Mg-, Be-, and Ca-ion batteries. An expanded investigation on H capture by MgBe [SiO–(GeO/SnO)] or MgCa [SiO–(GeO/SnO)] complexes was probed using computational approaches due to density state analysis of charge density differences (CDD), total density of states (TDOS), and electron localization function (ELF) for hydrogenated hybrid clusters of MgBe [SiO–GeO], MgBe [SiO–SnO], MgCa [SiO–GeO], and MgCa [SiO–SnO]. Replacing Si by Ge/Sn content can increase battery capacity through MgBe [SiO–GeO], MgBe [SiO–SnO], MgCa [SiO–GeO], and MgCa [SiO–SnO] nanoclusters for hydrogen adsorption processes and could improve the rate performances by enhancing electrical conductivity. A small portion of Mg, Be, or Ca entering the Si–Ge or Si–Sn layer to replace the alkaline earth metal sites could improve the structural stability of the electrode material at high multiplicity, thereby improving the capacity retention rate. In fact, the MgBe [SiO–GeO] remarks a small enhancement in charge transfer before and after hydrogen adsorption, confirming the good structural stability. In addition, [SiO–(GeO/SnO)] anode material could augment the capacity owing to higher surface capacitive impacts. Full article

In this study, a Zn(CN)₂–V₂O₃–C composite cathode was synthesized via AC electrophoretic deposition (EPD) and evaluated for application in aqueous zinc-ion batteries (ZIBs). Here, we report for the first time a binder-free Zn(CN)₂–V₂O₃–C composite cathode, using AC-EPD to create an ultrathin architecture optimized for probing the electrode–electrolyte interface without interference from additives or bulk effects. The composite combines Zn(CN)₂ for structural support, V₂O₃ as the redox-active material, and carbon for improved conductivity. X-ray diffraction confirmed the presence of Zn(CN)₂ and V₂O₃ phases, while scanning electron microscopy revealed a uniform, ultrathin film morphology. Electrochemical analysis demonstrated a hybrid charge storage mechanism with a b-value of 0.64, indicating both capacitive and diffusion-controlled contributions. The electrode delivered a high specific capacity (~250 mAh/g at 500 mA/g) with stable cycling performance. These results highlight the potential of metal–organic framework-derived composites for high-performance ZIB cathodes. The composite is especially effective when prepared via AC-EPD, which yields ultrathin, uniform films with strong adhesion and low agglomeration. This enhances energy storage performance and provides a reliable platform for focusing on interfacial charge storage, excluding the effect of binders on electrochemical performance. Full article

Combining carbon materials with oxides in a hybrid electrode is an effective way to control supercapacitor performance in terms of balancing energy and power density with cycling stability. However, it is still unclear how the mixing method of each component affects the supercapacitor performance. In this study, the influence of mixing reduced graphene oxide (rGO) with ilmenite-type nickel-manganese oxide (NiMnO₃) on the capacitive behaviour of the resulting composites is investigated. Two preparation methods are compared: mechanical mixing and ultrasonication. The capacitive characteristics were evaluated in hybrid supercapacitors using 6M KOH electrolyte. The bulk, surface, and morphological changes of the composites after long-term cycling were probed by EIS and ex situ XRD, XPS, and SEM analyses. It is established that the composites obtained by mechanical mixing exhibit better performance due to the stable contact between rGO and NiMnO₃ particles, favourable surface reactions with KOH and preserved morphology of rGO. These findings indicate that efficient hybrid electrodes can be achieved without relying on costly synthesis techniques such as hydrothermal or ultrasonic treatments. Full article

Monitoring the water status of fruit orchards is required to optimize crop water management and determine irrigation scheduling. For this purpose, capacitance probes are commonly used to measure soil water content (θ_s). However, when these probes are not calibrated, the estimates of θ_s are, therefore, unreliable. Our objective was to relate the measurements of capacitance probes, without a site-specific calibration, with a reliable indicator of the water status (stem water potential at solar noon (Ψ_stem)) of rain-fed grapevines grown under contrasting soil management strategies (tillage and spontaneous vegetation) and of irrigated peach and pear trees. During the 2023 growing season, θ_s was monitored in a peach and a pear orchard and in a vineyard in northeast Spain using capacitance sensors at three depths: 0.15, 0.30, and 0.45 m. Correlation coefficients ranged from 0.75 to 0.87 in peach trees, from 0.53 to 0.56 in pear trees, and from 0.56 to 0.90 in grapevines, depending on soil depth. These relationships were significant for both peach trees and grapevines but not for pear trees. Under the conditions of this study, uncalibrated capacitance measurements of θ_s could be useful to assess grapevine and peach tree water status in real time but were limited for pear trees. Full article

Cross quantum capacitance (CQC) has been proposed as an extension to traditional quantum capacitance (TQC) in systems where strong interfacial screening between spatially separated charge layers modifies the total capacitance—particularly in electric-double-layer-gated transistors (EDLTs) based on two-dimensional (2D) crystals. In this work, we revisit a theoretical model of CQC to evaluate its relevance under experimentally realistic conditions. By systematically analyzing the model’s behavior across key parameter spaces, we identify the specific conditions under which CQC leads to the non-monotonic dependence of capacitance on inter-plate distance—a proposed experimental signature of CQC. However, we find that these conditions—requiring similar effective masses, high charge densities, and strong charge asymmetry—are highly restrictive and difficult to realize in typical EDLTs. Instead, we highlight a more experimentally accessible regime in which CQC enhances total capacitance beyond TQC predictions, even in the absence of non-monotonicity. These results clarify the limitations of the existing model and suggest concrete strategies for probing CQC in nanoscale devices, emphasizing the need for new theoretical frameworks that explicitly incorporate both ionic and electronic conductors. Full article

The detection of short circuits in a medium-voltage (MV) network is a complex issue due to the way the neutral point works. An additional difficulty is the relatively large load asymmetry. The methods used so far include complex equipment (e.g., a system of voltage transformers) for use mainly in power stations. The detection of short circuits deep in the network is therefore difficult, and this could facilitate the process of fault localization and limit the areas that should be disconnected for the time of fault removal. This article presents the new concept of using a system of capacitive probes as a simple and cheap tool that allows for the detection of a short circuit in an MV network based on the assessment of the zero-voltage component. This component is considered to be one of the basic starting criteria for various types of specialist earth-fault protections. Appropriately placed capacitive probes—through the existence of capacitive coupling with phase conductors—record the voltages of individual phases, including the total resultant voltage, which is the criterion for detecting a short circuit in the system. An important advantage of using such a solution is that capacitive probes allow for voltage measurement and assessment of line asymmetry in a non-contact and, therefore, safe manner. The presented concept has been tested in the laboratory and supported by simulation studies. The modeling of the system was based on the parameters of real structures used in overhead lines, recreated in laboratory conditions. Obtaining positive results of the simulation studies—primarily the appropriate sensitivity of short-circuit detection, confirmed in the laboratory—allows for the creation of a prototype of the device and the commencement of field tests, which will be the subject of further work conducted by the authors. Full article

An emerging alternative to conventional piezoelectric technologies, which continue to dominate the ultrasound medical imaging (US) market, is Capacitive Micromachined Ultrasonic Transducers (CMUTs). Ultrasound transducers based on this technology offer a wider frequency bandwidth, improved cost-effectiveness, miniaturized size and effective integration with electronics. These features have led to an increase in the commercialization of CMUTs in the last 10 years. We conducted a review to answer three main research questions: (1) What are the commercially available CMUT-based clinical sonographic devices in the medical imaging space? (2) What are the medical imaging applications of these devices? (3) What is the performance of the devices in these applications? We additionally reported on all the future work expressed by modern studies released in the past 2 years to predict the trend of development in future CMUT device developments and express gaps in current research. The search retrieved 19 commercially available sonographic CMUT products belonging to seven companies. Four of the products were clinically approved. Sonographic CMUT devices have established their niche in the medical US imaging market mainly through the Butterfly iQ and iQ+ for quick preliminary screening, emergency care in resource-limited settings, clinical training, teleguidance, and paramedical applications. There were no commercialized 3D CMUT probes. Full article

The accurate measurement of soil suction is essential for understanding the behavior of unsaturated soils, particularly in soil–vegetation–atmosphere (SVA) interactions, where both energy and hydraulic gradients due to climatic action exhibit their maximum intensity. This study assesses the performance of the TEROS 21 probe, a capacitance-based water potential sensor, for measuring soil matric suction and temperature in clayey soils of the South Apennines, Italy. Laboratory tests were conducted on soil samples with varying moisture contents, and the results were compared with those obtained using the traditional filter paper (FP) method and high-capacity tensiometers (HCTs). The TEROS 21 (METER Group, Inc., Pullman, WA, USA) sensor demonstrated a reliable performance, especially at suction levels between 300 and 2000 kPa, though there was some dependency on the initial sensor conditions (wet or dry). The temperature data obtained from the TEROS 21 were verified by using a thermocouple, showing the high consistency of the readings. This study showed that the filter paper and sensor measurements aligned at a water content lower than 30% but diverged at higher levels due to method-specific accuracy limitations. The consistent sensor results confirmed the measurement’s reliability. The air-entry value (AEV) of the soil water retention data was identified at around 800 kPa, which is consistent with previous findings. Full article

A new radio frequency (RF) probe using pogo pin tips for integrated chip (IC) measurement up to 50 GHz is proposed. It offers high durability due to the pogo pins and meets three key design criteria for general IC measurement: (1) a 45° tilted shape with a 70 μm tip protrusion for easy microscope inspection, (2) linear pogo pin alignment for commercial chip pad contact, and (3) a 250 μm pitch compatible with standard IC pad pitches. This design is distinct from traditional pogo pin probe cards which place pogo pins in vertical form, in a diagonal arrangement, and at wide intervals. The probe exhibits a low insertion loss of 1.6 dB at 45 GHz. A printed circuit board (PCB)-based calibration standard for the calibration of the designed probe is constructed, which is adjusted to inductance and capacitance values using a simulation to form the Vector Network Analyzer (VNA) calibration set. The measurements of a commercial amplifier IC using this probe show a nearly identical performance to commercial RF probes, confirming its accuracy and reliability. Full article

A capacitively coupled radio-frequency argon plasma, used for tungsten sputtering deposition, is characterized using Langmuir probe measurements. Druyvesteyn’s method is used to evaluate plasma parameters through the integral of the Electron Energy Distribution Function (EEDF). In the pressure range analyzed (0.6–10 Pa), the obtained distributions are not Maxwellian, which suggests some depletion of electrons with higher energies. The obtained plasma parameters are compared with those derived from the graphical method. The electron temperature obtained via the graphical method is always lower than the effective temperatures derived from EEDFs, and vice versa, the electron density is overestimated by the graphical method. Optical Emission Spectroscopy is used to monitor the atoms sputtered in the plasma process. The behavior of excited species correlates with the plasma parameters. Full article

Perfluorooctanoic acid (PFOA) is one of the most persistent and bioaccumulative water contaminants. Sensitive, rapid, and in-field analysis is needed to ensure safe water supplies. Here, we present a single step (one shot) and rapid sensor capable of measuring PFOA at the sub-quadrillion (ppq) level, 4.5 × 10⁻⁴ ppq, within 10 s. This innovative sensor employs a synergistic combination of a molecularly imprinted polymer (MIP)-modified gold interdigitated microelectrode chip and AC electrothermal effects (ACETs), which enhance detection sensitivity by facilitating the accelerated movement of PFOA molecules towards specific recognition sites on the sensing surface. The application of a predetermined AC signal induces microfluidic enrichment and results in concentration-dependent changes in interfacial capacitance during the binding process. This enables real-time, rapid quantification with exceptional sensitivity. We achieved a linear dynamic range spanning from 0.4 to 40 fg/L (4 × 10⁻⁷–4 × 10⁻⁵ ppt) and demonstrated good selectivity (~1:100) against other PFAS compounds, including perfluorooctanoic acid (PFOS), in PBS buffer. The sensor’s straightforward operation, cost-effectiveness, elimination of the need for external redox probes, compact design, and functionality in relatively resistant environmental matrices position it as an outstanding candidate for deployment in practical applications. Full article