Search Results (141)

This paper introduces SmartBarrel, an innovative IoT-based sensory system that monitors and forecasts wine fermentation processes. At the core of SmartBarrel are two compact, attachable devices—the probing nose (E-nose) and the probing tongue (E-tongue), which mount directly onto stainless steel wine tanks. These devices periodically measure key fermentation parameters: the nose monitors gas emissions, while the tongue captures acidity, residual sugar, and color changes. Both utilize low-cost, low-power sensors validated through small-scale fermentation experiments. Beyond the sensory hardware, SmartBarrel includes a robust cloud infrastructure built on open-source Industry 4.0 tools. The system leverages the ThingsBoard platform, supported by a NoSQL Cassandra database, to provide real-time data storage, visualization, and mobile application access. The system also supports adaptive breakpoint alerts and real-time adjustment to the nonlinear dynamics of wine fermentation. The authors developed a novel deep learning model called V-LSTM (Variable-length Long Short-Term Memory) to introduce intelligence to enable predictive analytics. This auto-calibrating architecture supports variable layer depths and cell configurations, enabling accurate forecasting of fermentation metrics. Moreover, the system includes two fuzzy logic modules: a device-level fuzzy controller to estimate alcohol content based on sensor data and a fuzzy encoder that synthetically generates fermentation profiles using a limited set of experimental curves. SmartBarrel experimental results validate the SmartBarrel’s ability to monitor fermentation parameters. Additionally, the implemented models show that the V-LSTM model outperforms existing neural network classifiers and regression models, reducing RMSE loss by at least 45%. Furthermore, the fuzzy alcohol predictor achieved a coefficient of determination ($R^2$) of 0.87, enabling reliable alcohol content estimation without direct alcohol sensing. Full article

The fabrication of miniaturized and durable pH electrodes is a key requirement for developing advanced analytical devices for both industrial and biomedical applications. Glass electrodes are not an option in these cases. Electrodes based on metal oxides have been the most studied for pH sensing in these and other applications. Stainless steel pH electrodes have been an option for many years, both for measurement using steel as a sensitive material and using it as a substrate for the deposition of other metal oxides; in the latter case, the sensitive ability of stainless steel seems to play a crucial role. In addition, recent use as a substrate for materials such as polymers, carbon nanotubes, and metallic nanoparticles should be considered. This paper presents a review of this type of pH electrode, covering aspects related to the sensing mechanism, the treatment of stainless steel, potentiometric performances, applications, and the prospects of these sensors for use in modern analytical instruments. Sensing with the oxide passive layer and the artificial layer by oxidation treatments is analyzed. The use of metal oxides and other materials as the sensitive layer on stainless steel, their application in wearable devices, microneedle sensors, and combination with field-effect transistors for high-temperature pH sensing are covered as the most current and promising applications. Full article

In this study, an experimental device is developed and implemented to evaluate the process of heating water using photovoltaic solar energy in direct current. The prototype consists of a 147 L stainless steel tank, a 5000 W heating element, and four solar panels (370 W each). Tests were carried out with a direct photovoltaic power supply and with the use of a maximum power point tracking (MPPT) device. Temperature and electrical sensors were installed and connected to a data acquisition system. The results show that the electrical energy produced by the PV solar panels can be used directly for water heating. For the direct PV power supply, the average total efficiency is 12%; with the MPPT, the average value is 18.2%. There is a clear improvement in efficiency when using a device with maximum power tracking, improving the heating process and reducing the time needed to reach the set temperature. This technology can be applied to water heating in residences, medical centers, and other buildings that require it. Full article

In this study, a tubular spot-welded grating sensor composed of a stainless-steel tube fixed to a substrate surface by welding is developed, and the tube is filled with high-performance epoxy resin components after the grating sensor is passed through it. A smart steel strand cable is created by spot welding steel strands using portable spot-welding equipment. This method generates a small current during spot welding, with a voltage of only 3 V to 5 V, and does not damage the internal structure of the steel strand. An equation related to the temperature, tension force, and wavelength fluctuation is presented in this article. A method with a transverse temperature coordinate and a longitudinal wavelength coordinate is used. A formula for the standard temperature calibration of the force values and a procedure for temperature adjustment of the force values are presented. The correlation coefficient between the stress on the steel strand and the wavelength of the tubular spot-welded grating sensor is as high as 0.999 according to static tensile testing, demonstrating good repeatability. The temperature adjustment coefficient for varying temperatures is 0.0264 nm/°C, and the test error is essentially limited to 3.0% F.S. When subjected to a 120 h relaxation test, the steel strand with the tubular spot-welded grating sensor exhibits a relaxation rate of 4.44%. The force value obtained after the relaxation test is 1.2% off from the standard load. A tubular spot-welded grating sensor is welded onto a steel strand within a cable sealing cylinder to create an extruded anchor epoxy-coated steel strand cable. The measured cable force is compared with the standard load. The maximum error is 0.5% F.S. The discrepancy between the measured cable force and the acceleration sensor value is 1.5% in one instance involving an arch bridge employing six smart suspension cables to detect cable forces onsite. The findings provide theoretical and engineering references for smart cables and demonstrate the high accuracy, dependability, and fixation performance of the tubular spot-welded grating sensor smart cable. Full article

Microbial fuel cells (MFCs) are a novel bioenergy technology that utilizes microorganisms to catalyze the conversion of fuels into electricity. However, traditional MFCs are constrained by the low electricity generation capacity of microorganisms, resulting in relatively low power output. Additionally, the inability of traditional MFCs to store electricity significantly limits their practical applications. In this study, we fabricate a novel oxide graphite/nickel cobalt oxide (GO/NiCo₂O₄) capacitive composite bioanode material supported on stainless-steel fiber felt (SSFF). This composite material combines the excellent biocompatibility of graphite oxide and the energy storage capacity of nickel cobalt oxide. Consequently, the prepared anode exhibits significant advantages, including high specific capacitance, efficient electron transport, and enhanced biocompatibility. The MFC with the SSFF/GO/NiCo₂O₄ anode demonstrated a significantly enhanced power density, achieving a maximum of 1267.5 mW/m²—1.38-fold and 2.23-fold higher than those of the SSFF/GO and SSFF anodes, respectively. Moreover, the modified anode (SSFF/GO/NiCo₂O₄) exhibited a stored charge (Q_s) of 1405.35 C/m², representing 2.61-fold and 35.79-fold increases compared to the SSFF/GO and SSFF anodes, respectively. High-throughput analysis revealed that SSFF/GO/NiCo₂O₄-modified anode achieved an electrogenic bacterial efficiency exceeding 81%, which was significantly higher than that of the SSFF/GO and SSFF anodes. The results of this study not only provide valuable insights and theoretical guidance for the development of MFCs using capacitive composite anode materials, they also present sustainable power solutions for low-power electronic systems, such as miniaturized sensors and IoT devices. Full article

The aim of this in vitro study was to evaluate the differences in heat generation across the drilling techniques, depths, and irrigation conditions of static computer-assisted implant surgery (S-CAIS) and conventional implant preparation (CIP) using a standardized bone model for comparative investigation. A total of 240 automated intermittent experimental procedures of 10 and 12 mm drilling depths were performed during S-CAIS and CIP using stainless steel twist drills of three drill diameters (2.2, 2.8, and 3.5 mm) and two irrigation modes (without/external cooling) at room temperature. Temperature changes were recorded in real time using multiple temperature sensors in two distances to the osteotomy site. For comparison, a linear mixed model was fitted. The level of statistical significance was set at α = 0.05. Comparing the two surgical techniques, significant temperature differences could be observed using 3.5 mm drills: CIP yielded statistically higher temperatures during 10 and 12 mm drilling without irrigation (p = 0.0115 and p = 0.0253, respectively), while statistically higher temperatures were observed with S-CAIS and external irrigation at a 12 mm drilling depth (p = 0.0101). This standardized in vitro investigation demonstrated the impact of surgical technique, drilling depth, and irrigation mode on heat generation, indicating differences especially in drills of larger diameter. Full article

Cyclic voltammetry (CV) is one of the advanced techniques used to determine various bioactive molecules, organic dyes, pesticides, veterinary drugs, heavy metals, toxic chemicals, etc. To determine all the above analytes, one needs an electrocatalyst for their electrochemical redox reaction. Many researchers have reported the use of metal nanomaterials, metal oxide nanomaterials, metal–organic frameworks, surfactants, polymers, etc., as modifiers in carbon paste electrodes to enhance their current response, stability, sensitivity, and repeatability. But some of the emerging, cost-effective, and highly efficient electrocatalysts are advanced nanostructured alloy powders. These advanced alloys are used as a modifier to determine various bioactive analytes. These alloy-modified carbon paste electrodes (MCPEs) show excellent selectivity, sensitivity, and stability due to their extraordinary electrochemical properties, as the compositional elements of most of the alloys belong to d-block elements in the periodic table, and these transition elements are famous for their brilliant electrocatalytic properties. The present review article mainly focuses on the determination of dopamine, AA (AA), uric acid, methylene blue, methyl orange, Rhodamine B, and the L-Tyrosine amino acid by various alloys like stainless steel, high-entropy alloys, and shape-memory alloys and how these alloys could change the perception of metallurgists and electrochemists in the future. These alloys could be potential candidates for the development of various electrochemical sensors because of their high porosity and surface areas. Full article

Miniaturized components for enhanced integrated functionality or thin sheets for lightweight applications often consist of face-centered cubic metals. They exhibit good strength, corrosion resistance, formability and recyclability. Microfabrication technologies, however, may introduce cold work or detrimental heat-induced lattice defects into the material, with consequences for the mechanical properties. Austenitic stainless steels (1.4310, 1.4301) and aluminum alloys (EN AW-5005-H24, EN AW-6082-T6) were selected for this study. The influence of pulsed fiber laser cutting, microwaterjet cutting, and annealing on the strain–stress behavior was investigated. The micro-tensile test setup comprised a flex-structure force sensor, a laser extensometer, and a dedicated sample holder. Fiber laser cut 1.4310 samples exhibited early failure at low fracture strain in narrow shear band zones. The shear band zones were detectable on the sample surface, in the laser extensometer images, in the horizontal sections of the stress–strain curves, and in the microstructure. Inside the shear band zones, grains were strongly elongated and exhibited numerous parallel planar defects. Heat-induced chromium carbides, in combination with low stacking fault energy (SFE) and elevated carbon content, favored shear band zone formation in 1.4310. In contrast, microwaterjet cut high SFE materials EN AW-5005-H24 and EN AW-6082-T6, as well as low-carbon austenitic stainless steel 1.4301, exhibited uniform plastic deformation. Full article

This study systematically investigates the influence of heat treatment on the mechanical and magnetic properties of AISI 304 austenitic stainless steel following cold rolling. Experimental analyses were conducted on samples annealed at 50 °C to 1200 °C in 25 °C increments. The mechanical properties were characterized through chemical and metallographic analyses, microhardness testing, hardness measurements, and tear-off force evaluations. Magnetic properties were assessed using a fluxgate sensor to analyze the intrinsic magnetic field variations. The findings reveal that the magnetic field intensity peaks at an annealing temperature of 100 °C, followed by a progressive decline up to 700 °C. A pronounced reduction in magnetic properties was observed at 500 °C, with stabilization beyond 700 °C. Notably, the increase in magnetic field intensity at 100 °C suggests a potential transformation of deformation-induced martensite back into austenite. These results provide insights into the thermal stability of cold-rolled AISI 304 stainless steel and its structural evolution, contributing to a deeper understanding of its mechanical and magnetic behavior under varying heat treatment conditions. Full article

A textile electrochemical sensor manufactured with commercially available textile materials is presented to determine glucose concentration. The sensor design consists of three electrodes manufactured with two different conductive yarns, one made with a silver coating and the other with stainless steel fibres. Different combinations of them are used to prepare three different electrochemical textile sensor combinations. The first sensor is built only with silver-coated yarn and used as a reference sensor. The other two sensors are prepared with different combinations of conductive yarns. The textile sensors perform a cyclic voltammetric test, where it is demonstrated that the glucose concentration over the sensor can be related with the increase in the current measured. The results allow us to identify feeding voltages where the concentration–current relation is close to linear. The textile sensor shows a sensitivity between 0.0145 and 0.0452 $\mathsf{\mu }$A/(mg/dL) for the 45–180 mg/dL glucose concentration range and 0.0012 and 0.0035 $\mathsf{\mu }$A/(mg/dL) for the 180–1800 mg/dL range for the different sensor types presented. The regression coefficients for the sensitivities range between 0.9266 and 0.9954. This research demonstrates the feasibility to develop a fully integrated textile electrochemical sensor made completely with commercially available textile materials. Full article

Industrially applied bioelectrochemical systems require long-term stable operation, and hence the control of biofilm accumulation on the electrodes. An optimized application of biofilm control mechanisms presupposes on-line, in-situ monitoring of the accumulated biofilm. Heat transfer sensors have successfully been integrated into industrial systems for on-line, non-invasive monitoring of biofilms. In this study, a mathematical model for the description of the sensitivity of a heat transfer biofilm sensor was developed, incorporating the hydrodynamic conditions of the fluid and the geometrical properties of the substratum. This model was experimentally validated at different flow velocities by integrating biofilm sensors into cylindrical pipes and planar mesofluidic flow cells with a carbonaceous substratum. Dimensionless sensor readings were correlated with the mean biovolume measured gravimetrically, and optical coherence tomography was used to determine the sensors’ sensitivity. The biofilm sensors applied in the planar flow cells revealed an increase in sensitivity by a factor of 6 compared to standard stainless steel pipes, as well as improved sensitivity at higher flow velocities. Full article

This study introduces an innovative, non-contact method for classifying the hardness of austenitic stainless steels (grade AISI 304) based on their intrinsic magnetic fields. Utilizing a 3 × 3 matrix sensor system, this research captures weak magnetic fields to produce precise 2D magnetic field maps of the samples. A key advancement is the application of a modified GoogleNet convolutional neural network, optimized with the stochastic gradient descent with momentum algorithm, which achieves exceptional classification accuracy, ranging from 95% to 100%, and median accuracies of 97.5% to 99%. This method stands out by revealing a novel correlation between annealing temperature and magnetic field strength, particularly a pronounced decline in magnetic properties at temperatures near 1000 °C. This observation underscores the sensitivity of magnetic profiles to heat treatments, offering a groundbreaking approach to material characterization. By enabling reliable, efficient, and fully automated hardness evaluation based on magnetic signatures, this work has the potential to transform materials engineering and manufacturing, setting a new benchmark for non-destructive material analysis techniques. Full article

Vibration sensors are integral to a multitude of engineering applications, yet the development of low-cost, easily assembled devices remains a formidable challenge. This study presents a highly sensitive flexible vibration sensor, based on the piezoresistive effect, tailored for the detection of high-dynamic-range vibrations and accelerations. The sensor’s design incorporates a polylactic acid (PLA) housing with cavities and spherical recesses, a polydimethylsiloxane (PDMS) membrane, and electrodes that are positioned above. Employing femtosecond laser ablation and template transfer techniques, a parallel groove array is created within the flexible polymer sensing layer. This includes conductive pathways, and integrates stainless-steel balls as oscillators to further amplify the sensor’s sensitivity. The sensor’s performance is evaluated over a frequency range of 50 Hz to 400 Hz for vibrations and from 1 g to 5 g for accelerations, exhibiting a linear correlation coefficient of 0.92 between the sensor’s voltage output and acceleration. It demonstrates stable and accurate responses to vibration signals from devices such as drills and mobile phone ringtones, as well as robust responsiveness to omnidirectional and long-distance vibrations. The sensor’s simplicity in microstructure fabrication, ease of assembly, and low cost render it highly promising for applications in engineering machinery with rotating or vibrating components. Full article

Toxic materials are a threat in workplaces and the environment, as well as households. In them, gaseous substances are included, especially ones without any colour or fragrance, due to their non-detectability with the human senses. In this article, an attempt was made to find a solution for its detection in various conditions with the use of intelligent textiles. The approach was to perform modification on fifteen materials by screen printing using carbon nanotubes paste with expanded graphite and embroidery with stainless steel thread and then investigate their reaction with risky gases such as acetone, methanol and toluene. Four combinations of samples were tested: before tests, after the washing test and after the alkaline and acidic sweat contact test. Three materials can be highlighted. Para-aramid knitwear which reacted well to all tested gases. The biggest value of sensory percentage response was 144%. Screen-printed linen knitwear showed properly detecting skills after washing test for toluene. The biggest value of sensory percentage response was noted at 186%. The third most promising material was low surface mass cotton knitwear with embroidery which had a visible response at every stage of testing for acetone. The biggest value of sensory percentage response was 94% and the smallest one was 27%. For these three materials, repeated contact with harmful gases was tested. Simulations showed also repeated responses expressed in changes in surface resistance under changed conditions. After analysis, there is a possibility to create textile sensors for the detection of hazardous substances. Full article

To evaluate the long term corrosion potential stability of stainless steel (SS) in environmental water, the corrosion potential of SUS304, SUS316, SUS316L, and SUS430 was measured for 1 week in a solution of 0.9 mM NaHCO₃ and 0.5 mM CaCl₂, referred to as “sub-tap water.” The potential of the SSs upon initial immersion in sub-tap water was approximately 10 times less stable than the potentials of Fe and Cu. However, as immersion continued, the stability of the corrosion potential of the SS improved and became equivalent to those of Fe and Cu. The stability could be manipulated by pretreatment (pre-immersion) before samples were immersed in sub-tap water. The stability was increased by pre-immersion in an acidic solution but was reduced by a passivation treatment. The formation of iron oxides on the SS surface stabilized the potential, whereas surface enrichment with Cr led to instability. This behavior can also be inferred from a comparison of the polarization curves, where the passive current after the passivation treatment was the largest. This result is also speculatively attributed to the corrosion potential in sub-tap water decreasing over time after the passivation treatment. The charge transfer resistance likely contributes significantly to the potential stability, as indicated by an equivalent circuit analysis based on electrochemical impedance spectroscopy. The results showed that, when stabilizing the corrosion potential of SS, there is no need to reduce the charge transfer resistance as with existing reference electrodes. Stability is achieved when the surface thickness is such that the pseudo-capacitance in a dilute solution is less than 10 µF s^α−1cm⁻² and potential stability does not influence a few changes in the CPE₁ value after potential stability is achieved. The results of this study show that SS can be used as a quasi-reference electrode material. We expect the findings presented herein to strongly affect the development of electrochemical sensors that can be easily used in long term continuous measurements and in situ applications. Full article