High-performance Permanent Magnet Synchronous Motor (PMSM) control systems typically incorporate a position and/or speed sensor. In these control systems, precise rotor position data is crucial for converting the stator currents into two independent components: one dedicated to torque control and the other aimed at regulating the magnetic flux. Nevertheless, the effectiveness of the control system declines markedly when inaccuracies arise in the measurement of rotor position.

Rotary position sensors encompass resolvers, incremental encoders, and absolute encoders. The precision of both resolvers and encoders is influenced by the variability inherent in the manufacturing process associated with a specific design. A key advantage of the resolver is its robustness. Nevertheless, its implementation tends to be relatively complex, and the processing of output signals to ascertain the rotor position presents additional challenges. Furthermore, a resolver-to-digital converter is necessary as an electronic interface to digitize the resolver signals for the controller. Position deviations may arise following rotor movement caused by voltage fluctuations.

This paper presents a fault diagnosis and fault-tolerant control scheme for handling position or speed sensor faults in salient pole PMSM drives using estimation techniques. The approach integrates a conventional vector controller with virtual sensors to ensure continuous operation across the full speed range. Fault detection relies on comparing measured and delayed rotor speed signals. This software-based method provides a reliable backup against sensor failures such as signal loss or drift. While sensorless control strategies cannot match the accuracy of resolver-based systems, they must maintain position estimation errors within acceptable limits to prevent excessive torque ripple and current.

In this work, a selective and affordable supramolecular sensor is described for the detection of alkaline phosphatase (ALP) which act as biomarker for liver, bone disorders and cancers. The sensor contains a dynamic pair of pyrene-based dye (PTS) and polyallylamine (PAA) polymer that produces a change in fluorescence when ALP works. ALP will hydrolyze adenosine triphosphate (ATP). ATP makes PAA bind, disturbs PTS-PAA complex and change the fluorescence of PTS-PAA from 500 nm to 385 nm. ATP hydrolysis acts to break down ATP and restore the aggregates, making the fluorescence reappear. With this kind of response, ALP measurements can be accurate, quick and can reliably detect at levels as low as 63.3 µU/mL and as high as 150 mU/mL in human serum.

The dual-emission approach allows the sensor to self-correct, so possible effects from pH, temperature or light are significantly reduced. Making the sensor is simple because it relies on environmentally friendly materials, Commercial available probes, without needing complex manufacturing. As checked in real serum, the sensor works equally well as ALP concentrations vary. The use of supramolecular sensing on a filter paper stage makes it easier for healthcare staff everywhere to detect enzymes, even in remote or resource-constrained areas.

Using the sensor together with filter paper makes the assay portable and simpler to use, making it perfect for point-of-care testing in poor-resource places. There is very little interference in the system, so it remains accurate when checking ALP in biological samples.

The detection of alcohol is essential in fields ranging from healthcare to industrial safety and forensic analysis. Coordination complexes (comprising transition metals and organic ligands) have emerged as protentional candidates for chemical sensing applications due to their electronic and optical properties. In the last decade these systems have been explored as alcohol sensors. Although the use of coordination complexes for alcohol detection remains rather underexplored compared to metal oxides or conducting polymers, recent advances demonstrate their potential in offering rapid, reversible, and selective sensing capabilities. The sensing mechanism typically involves changes in conductivity and/or colour upon alcohol exposure, enabling both qualitative and quantitative detection.

In the present study, a molybdenum coordination complex was used as the sensor material. The Schiff base ligand was synthesized via the condensation of o-vanillin and oxalyldihydrazide, then coordinated to a [MoO₂]²⁺ core. This synthesis, performed in methanol, resulted in the formation of the complex [Mo₂O₄(L)(MeOH)₂]·2 H₂O. The complex was exposed to methanol and ethanol vapours, leading to desolvation and decoordination of the solvent molecules with subsequent coordination of the vapor molecules. Characterization of the complex was performed using attenuated total reflectance infrared spectroscopy (IR-ATR) and thermogravimetric analysis (TGA). Impedance spectroscopy (IS) was used to confirmed structural changes and to measure the conductivity response.

Deep eutectic solvents (DESs) are an emerging class of green solvents formed by mixing hydrogen bond donors and acceptors in specific ratios, resulting in a highly structured hydrogen-bond network. When embedded into a polymeric matrix, they give rise to eutectogels (EGs)—hybrid materials that combine the tunable chemical environment of DESs with the mechanical strength and flexibility of hydrogels. These properties make EGs promising candidates for biotechnological applications, including biosensing.

DESs have demonstrated the ability to enhance enzyme solubility, stability, and activity, opening new avenues for their use in biocatalysis and biosensor design. However, their integration into functional biosensing platforms remains underexplored. In this work, we report the development of a versatile biosensor based on EGs incorporating pancreatic lipase (PL), aimed at detecting lipase inhibitors with potential anti-obesity effects.

PL was selected as a model enzyme due to its central role in lipid digestion and its relevance as a therapeutic target for obesity. The enzyme was solubilized in various DES formulations, and its catalytic activity and structural stability were evaluated using intrinsic fluorescence spectroscopy. EGs were subsequently synthesized via UV-initiated radical polymerization, allowing efficient enzyme entrapment within the gel matrix.

The biosensor was successfully validated using orlistat, a clinically approved PL inhibitor, demonstrating its potential for anti-obesity drug screening. Importantly, this platform is adaptable and can be extended to other enzymes and therapeutic targets, highlighting its broader applicability in drug discovery and biosensing.

Enzyme-based biosensors are promising tools for the detection of pollutants due to their specificity and environmentally friendly nature. Nonetheless, their practical performance is often limited by enzyme stability, reusability, and optimal operating conditions. Here, we present a hybrid sol-gel platform co-immobilizing laccase and gold nanoparticles (AuNPs) within a silica matrix, designed to integrate biocatalytic and photothermal functionalities for biosensing applications.

AuNPs were synthesized via the Turkevich method, stabilized with PVP, and embedded into the silica matrix during the sol-gel process. Laccase was co-immobilized in the same matrix, resulting in a monolithic material where both components coexist in a stable network. Photothermal characterization demonstrated that embedded AuNPs effectively generated heat upon laser irradiation at 520 nm, producing a localized temperature increase without affecting the bulk solution. This thermal modulation was intended to enhance enzymatic activity transiently.

Enzymatic activity assays using ABTS as a model substrate confirmed that the immobilized enzyme retained catalytic function. Independent thermal stability analysis by fluorescence spectroscopy indicated a slight decrease compared to the free enzyme. Importantly, comparison between monoliths with and without AuNPs in the absence of laser irradiation revealed no significant difference in activity, indicating that the photothermal effect—activated exclusively under laser exposure—is responsible for the observed enhancement in catalytic performance.

Although target-specific analyte detection remains to be demonstrated, the platform shows potential as a modular system adaptable to various enzymes and applications. These findings highlight the promise of photothermally responsive sol-gel materials for biosensors capable of faster response times through controlled, localized heating.

Abstract:

Electrochemical detection of antioxidants using low-cost, simple, and reliable analytical devices is gaining a huge interest nowadays. Amongst the traditional analytical methods employed in the antioxidants quantification, the chromatographic and spectrochemical methods provide high sensitivity, selectivity, and accuracy. The need for rapid and simple detection methodologies including in vivo monitoring emerged in recent years thanks to the development of portable electroanalytical devices. In this work, we have developed a sensing platform containing a hybrid material composed of an inorganic redox mediator, namely Prussian Blue (PB), and an organic polymer like poly(3,4-ethylenedioxythiophene), for thioctic acid detection. The hybrid material is prepared onto glassy carbon electrodes using alternate current protocol. This protocol consists in the application of an excitation sinusoidal current having defined frequency and amplitude over a dc constant current. The hybrid sensing material has been electrochemically synthesized in two steps: firstly, the organic polymer is prepared in the presence of ferricyanide ions. In the second step, the ferricyanide-doped polymer layer is subjected to the in situ electrochemical reduction of Fe(III) via the alternate current protocol. This approach ensured the in-situ formation of the PB inorganic redox mediator within the organic matrix. The sensing platform was characterized by cyclic voltammetry and electrochemical impedance spectroscopy revealing the electrochemical activity of the PB component in aqueous solutions containing potassium ions. The as developed sensing platform was tested for the determination of thioctic acid in real samples. The response was linear on the concentration range from 50 to 500 μM, and with a detection limit of 7.5 μM, respectively. The accuracy of the sensing platform was proved by measuring broccoli ethanolic extract enriched with known amounts of thioctic acid. The obtained recovery values were in the range 99.38 % – 103%, confirming the good accuracy of the electroanalytical sensing platform.

The effect of photonic crystal films as Bragg reflection mirrors on the fluorescence of quantum dots was investgated. Quantum dots have vast application prospects in several fields, especially lead halide perovskite quantum dots, which have many advantages, such as good luminescence performance, low cost, and compatibility with industrial printing technology. Photonic crystals reveals Bragg reflection, which can reduce the loss of fluorescence caused by transmission, it is a good way to enhance the fluorescence efficiency of quantum dots. Firstly, the photonic crystals with different photonic bandgaps were fabricated by vertical deposition. Secondly, the reflection spectra of photonic crystal films were measured by optical fiber spectrometer, and the transmission spectra were obtained by UV-Vis spectrophotometer. Finally, the emission spectra of perovskite quantum dots were tested by a fluorescence spectrometer, and the effects of photonic crystal films on the fluorescence intensity of quantum dots were tested and analyzed with the quantum dots directly coated on the surface of glass substrate as a reference, in order to infer the general results. The results confirmed that the fluorescence of quantum dots is significantly enhanced by photonic crystal films, which might due to the effective reflection of fluorescence by photonic crystals. However, excessively thick photonic crystal films can cause fluorescence quenching, block the reflection of fluorescence, and weaken the fluorescence intensity. This study is anticipated to contribute to the development of novel photonic crystal-quantum dot sensors and high brightness display materials.

The demand for low-cost, portable, and sensitive analytical devices has fueled the development of 3D-printed biosensors. This study evaluates the effect of silk fibroin incorporation on the electrical properties of graphite-PLA electrodes manufactured via 3D printing. Electrochemical Impedance Spectroscopy (EIS) method was utilized to assess capacitive–resistive behavior under dry conditions, and with PBS buffer, at fibroin concentrations of 0%, 0.04%, 0.4%, and 4%. Fibroin modulated impedance magnitude values without a clear trend, indicating the presence of additional influencing factors. The results promote better understanding of biofunctionalization effects in 3D-printed electrodes and support their potential for biomedical, environmental, and industrial sensing applications.

Traditional medical techniques are constrained by macro-scale detection methods, making it difficult to capture dynamic changes at the cellular level. The miniaturization and high-throughput capabilities of integrated circuit technology enable precise manipulation and real-time monitoring of biological processes. In this study, COMSOL Multiphysics software was used to model electrode units, simulating the interaction between cells and their biological environment. From the perspective of electrode arrays, the influence of varying electrode-cell contact areas on electrical signals was investigated, and the structure and layout of the microelectrode array (MEA) were optimized. The research explored the relationship between cellular activity and electrical properties, as well as the effect of cellular activity on membrane permeability. Simulation results demonstrated that larger electrode coverage areas improve potential distribution. The intact phospholipid bilayer and functional membrane proteins of living cells create a significant current-blocking effect, with impedance values reaching 10⁵–10⁶ Ω·cm². In contrast, apoptotic or necrotic cells exhibit structural damage and ion channel inactivation, leading to significantly enhanced membrane permeability, with impedance decreasing by 1–2 orders of magnitude. Further simulations involved modeling microfluidic channels to study cellular behavior within them. Frequency response analysis and Bode plots revealed that impedance differences between low and high frequencies could distinguish living cells (higher impedance) from apoptotic cells (lower impedance). Therefore, Bode plot analysis can assess membrane permeability and infer cellular health or apoptotic state. Additionally, this study examined micro-nanofabrication techniques, particularly the lift-off process for microelectrode fabrication, and optimized photoresist selection in photolithography.

Microfluidic impedance cytometry enables label-free and real-time single-cell analysis by detecting changes in electrical impedance as cells traverse microchannels. Electrode configuration plays a critical role in determining detection sensitivity, signal quality, and spatial resolution. In this study, finite element simulations were conducted to model the impedance response of mammalian red blood cells under various electrode designs, including coplanar, parallel, tilted, and parabolic configurations, as well as electrode layouts coupled with flow velocity. A multiphysics simulation model is established to analyze the effects of geometric parameters on electric field distribution and impedance response. The results demonstrate that optimized electrode arrangements significantly enhance detection performance and enable multi-parameter analysis. Furthermore, the influence of flow dynamics and dielectric properties on impedance signals is explored. These findings provide both theoretical and experimental guidance for the development of high-efficiency, integrated impedance cytometry platforms, contributing to the advancement of microfluidic systems in biomedical diagnostics and single-cell characterization.