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In recent years, sensory polymers have evolved significantly, emerging as versatile and cost-effective materials valued for their flexibility and lightweight nature. These polymers have transformed into sophisticated, active systems capable of precise detection and interaction, driving innovation across various domains, including smart materials, biomedical diagnostics, environmental monitoring, and industrial safety. Their unique responsiveness to specific stimuli has sparked considerable interest and exploration in numerous applications. However, along with these advancements, notable challenges need to be addressed. Issues such as wearable technology integration, biocompatibility, selectivity and sensitivity enhancement, stability and reliability improvement, signal processing optimization, IoT integration, and data analysis pose significant hurdles. When considered collectively, these challenges present formidable barriers to the commercial viability of sensory polymer-based technologies. Addressing these challenges requires a multifaceted approach encompassing technological innovation, regulatory compliance, market analysis, and commercialization strategies. Successfully navigating these complexities is essential for unlocking the full potential of sensory polymers and ensuring their widespread adoption and impact across industries, while also providing guidance to the scientific community to focus their research on the challenges of polymeric sensors and to understand the future prospects where research efforts need to be directed.

Traditional capacitive tactile sensor sheets usually have a three-layered structure, with a dielectric layer sandwiched by two electrode layers. Each electrode layer has a number of parallel ribbon-like electrodes. The electrodes on the two electrode layers are oriented orthogonally and each crossing point of the two perpendicular electrode arrays makes up a capacitive sensor cell on the sheet. It is well known that compatibility between measuring precision and resolution is difficult, since decreasing the width of the electrodes is required to obtain a high resolution, however, this may lead to reduction of the area of the sensor cells, and as a result, lead to a low Signal/Noise (S/N) ratio. To overcome this problem, a new multilayered structure and related calculation procedure are proposed. This new structure stacks two or more sensor sheets with shifts in position. Both a high precision and a high resolution can be obtained by combining the signals of the stacked sensor sheets. Trial production was made and the effect was confirmed.

Purpose This paper aims to study different possibilities for implementing easy-to-use and cost-effective micro-systems to detect and trace expelled gases from rotten food. The paper covers various radio-frequency identification (RFID) technologies and gas sensors as the two promoting feasibilities for the tracing of packaged food. Monitoring and maintaining quality and safety of food in transport and storage from producer to consumer are the most important concerns in food industry. Many toxin gases, even in parts per billion ranges, are produced from corrupted and rotten food and can endanger the consumers’ health. To overcome the issues, intelligent traceability of food products, specifically the packaged ones, in terms of temperature, humidity, atmospheric conditions, etc., has been paid attention to by many researchers. Design/methodology/approach Food poisoning is a serious problem that affects thousands of people every year. Poisoning food must be recognized early to prevent a serious health problem. Contaminated food is usually detectable by odor. A small gas sensors and low-cost tailored to the type of food packaging and a communication device for transmitting alarm output to the consumer are key factors in achieving intelligent packaging. Findings Conducting polymer composite, intrinsically conducting polymer and metal oxide conductivity gas sensors, metal–oxide–semiconductor field-effect transistor (MOSFET) gas sensors offer excellent discrimination and lead the way for a new generation of “smart sensors” which will mould the future commercial markets for gas sensors. Originality/value Small size, low power consumption, short response time, wide operating temperature, high efficiency and small area are most important features of introduced system for using in package food.

In the post-pandemic era, human demand for a healthy lifestyle and a smart society has surged, leading to vibrant growth in the field of flexible electronic sensor technology for health monitoring. Flexible polymer humidity sensors are not only capable of the real-time monitoring of human respiration and skin moisture information but also serve as a non-contact human–machine interaction method. In addition, the development of moist-electric generation technology is expected to break free from the traditional reliance of flexible electronic devices on power equipment, which is of significant importance for the miniaturization, reliability, and environmentally friendly development of flexible devices. Currently, flexible polymer humidity sensors are playing a significant role in the field of wearable electronic devices and thus have attracted considerable attention. This review begins by introducing the structural types and working principles of various humidity sensors, including the types of capacitive, impedance/resistive, frequency-based, fiber optic, and voltage-based sensors. It mainly focuses on the latest research advancements in flexible polymer humidity sensors, particularly in the modification of humidity-sensitive materials, sensor fabrication, and hygrosensitivity mechanisms. Studies on material composites including different types of polymers, polymers combined with porous nanostructured materials, polymers combined with metal oxides, and two-dimensional materials are reviewed, along with a comparative summary of the fabrication and performance mechanisms of related devices. This paper concludes with a discussion on the current challenges and opportunities faced by flexible polymer humidity sensors, providing new research perspectives for their future development.

This work was supported by the Regional Government of Castilla y León (Junta de Castilla y León) and by the Ministry of Science and Innovation MICIN and the European Union NextGeneration EU PRTR. The project leading to these results has received funding from “La Caixa” Foundation, under the agreement LCF/PR/PR18/51130007. We also gratefully acknowledge the grant PID2020-113264RB-I00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. Finally, we want to acknowledge the funding from Ministerio de UniversidadesEuropean Union in the frame of NextGenerationEU RD 289/2021 (Universidad Politécnica de Madrid and Universidad Autónoma de Madrid-CA1/RSUE/2021-00409).

Humidity measurement is required in various fields. We previously developed a sensor that leverages the sudden change in the transmitted light intensity when switching from leakage mode to waveguide mode. By adjusting the low-refractive-index polymer of the cladding, we achieved measurements at 60% RH. However, for practical use, measurements at low humidity are essential. Therefore, in this study, we developed a sensor using a leakage mode that enables measurements at low humidity. To measure the leakage mode, it is necessary to increase the absorbance of the cladding and the incident angle at the core–cladding interface. Therefore, we developed a sensor in which the core was stretched, and the cladding was doped with a high concentration of dye. The experimental results confirmed that a sensor with a polymer concentration of 4% and a dye concentration of 3% could measure from 0% RH to 95% RH. The sensitivity was 0.1 dB/% RH from 0% RH to 70% RH and 0.32 dB/% RH from 70% RH to 95% RH. The estimated response time for a change from 10% to 90% light transmission for a sensor with 4% polymer concentration and 0.5% dye concentration was 22 s from 45% RH to 0% RH and 50 s from 0% RH to 45% RH.

High precision and fast measurement of gas concentrations is important for both understanding and monitoring various phenomena, from industrial and environmental to medical and scientific applications. This article deals with the recent progress in ammonia detection using in-situ solid-state and optical methods. Due to the continuous progress in material engineering and optoelectronic technologies, these methods are among the most perceptive because of their advantages in a specific application. We present the basics of each technique, their performance limits, and the possibility of further development. The practical implementations of representative examples are described in detail. Finally, we present a performance comparison of selected practical application, accumulating data reported over the preceding decade, and conclude from this comparison.

A novel 3 × 4 colorimetric sensing platform, named the chemometric-assisted litmus test (CLT), has been developed by covalently anchoring commercial pH indicators to ethylene vinyl alcohol (EVOH). The proposed device can be exploited for pH determinations in a wide range from 1 to 13 and in specific narrow ranges, achieving sufficient accuracy and errors below 0.5 pH units. The experimental procedure is simple, quick and reliable; equilibration is reached in less than 2 h, CLT pictures are acquired by a camera, and data treatment is performed applying chemometric techniques such as principal component analysis (PCA) and partial least square regression (PLS) to RGB indices.

Acute and chronic neurodegenerative diseases (NDs), including multiple sclerosis (MS), Alzheimer’s disease (AD), and Parkinson's disease (PD), are characterized by neurodegeneration, which is the gradual malfunction and damage of neurons and axons in the central nervous system. Improved clinical diagnostic workups and the development and tracking of successful disease-modifying treatments are made possible by detecting appropriate neurodegenerative disease (ND) biomarkers. Important biomarkers, such as Tau proteins, amyloid-β, and α-synucleins, are essential for precise identification but are often evaluated using time-consuming, expensive, and traditional techniques like polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Due to its exceptional selectivity and sensitivity, electrochemical biosensing has become a popular, low-cost substitute for more conventional diagnostic methods. Nanoparticles in biosensors are particularly noteworthy because they improve electron transport and aid in immobilizing biorecognition components. Conducting polymers have shown great potential in the field of electrochemical sensing. Conducting polymers have shown great potential in electrochemical sensing. Additionally, research has shown that polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene), and poly(thiophene) are often regarded as among the best conducting polymers for fabricating electrochemical sensors. Moreover, a hydrogel biosensor allows for the detection of many parameters simultaneously with real-time monitoring, allowing for more accurate and timely tracking of multiple indicators of a patient. Hydrogel nano(bio)composite sensors that use electrochemical transduction methods to detect analytes are also available. Hydrogel-based polymer sensors for early-stage neurodegenerative diagnosis are examined in this review in a novel way. Afterward, we reviewed electrochemical sensors developed for detecting biomarkers related to diseases, including multiple sclerosis, Alzheimer's, Parkinson's, and Huntington's. There have also been developments devised to enhance efficacy of electrochemical diagnostic tools to address their limitations. In this respect, we have also reviewed many polymers used in electrochemical diagnosis of neurological disorders. Finally, we have also evaluated the limits and prospects of clinical trials involving these electrochemical means of diagnoses. Graphical Abstract

This review (with (318) refs) describes progress made in the design and synthesis of morphologically different metal oxide nanoparticles made from iron, manganese, titanium, copper, zinc, zirconium, cobalt, nickel, tungsten, silver, and vanadium. It also covers respective composites and their function and application in the field of electrochemical and photoelectrochemical sensing of chemical and biochemical species. The proper incorporation of chemical functionalities into these nanomaterials warrants effective detection of target molecules including DNA hybridization and sensing of DNA or the formation of antigen/antibody complexes. Significant data are summarized in tables. The review concludes with a discussion or current challenge and future perspectives. Graphical abstract ᅟ