Humidity Sensor Research Articles

Durable wind energy harvesting by mode-switch triboelectric nanogenerator for self-powered sensors

Purpose The imperative for sustainable energy systems is increasingly pressing as the world transitions toward renewable energy sources. Among these, triboelectric nanogenerators (TENGs) have emerged as a viable option for wind energy harvesting. However, they face significant challenges, including material durability under varying wind conditions; the intricacy of material selection and performance; and the trade-off between wear resistance and triboelectric efficiency. This study aims to address the above issues. Design/methodology/approach Herein, a mode-switch TENG (MS-TENG) was designed to overcome these limitations and serve as a self-powered energy solution for Internet of Things (IoT) sensor networks. The MS-TENG incorporates a multi-stage functional layer and an automatic mode-switching mechanism between contact and non-contact operation, thereby enhancing both efficiency and durability. Findings It is demonstrated that the MS-TENG achieves a maximum instantaneous output power of 0.069 mW with minimal mechanical wear, effectively capturing wind energy. Its capability to charge capacitors and power a range of electronic devices, such as temperature and humidity sensors, electronic watches and water immersion guards, underscores its practical utility across diverse settings. Originality/value This research situates the MS-TENG as a pioneering technology in smart sensor applications for future energy-harvesting endeavors, optimizing energy acquisition under fluctuating wind conditions and reinforcing the sustainability of IoT networks.

Smart Building Application in Revitalization of Historic Buildings Case Study: The Museum Bahari, Jakarta

Historical buildings are cultural heritages that require preservation while adapting to modern demands. The Museum Bahari in Jakarta faces challenges in revitalizing its historical architectural elements while integrating adaptive technologies. This research examines the application of smart building systems in revitalizing the museum with minimal intervention to maintain historical integrity. A descriptive qualitative method is used, involving condition analysis, identification of smart technologies, and strategy development. Data collection includes observation, literature review, and case study analysis. Findings indicate that technologies such as humidity sensors, adaptive lighting, and environmental monitoring can enhance building performance and visitor experience without compromising heritage values. This study recommends placing devices in non-structural areas, integrating energy management with conservation needs, and using real-time monitoring systems. These strategies align with heritage conservation principles. The study concludes that smart building technology with minimal intervention offers a sustainable solution for revitalizing historic buildings like the Museum Bahari while enhancing functionality and relevance in the modern era.

Enhancing the Performance of Perovskite Environmental Sensors through the Synergistic Effect of the Natural Antioxidant.

All-inorganic perovskite CsPbX3 is considered to be the next-generation optical material due to its excellent optical properties and potential applications in optoelectronics. However, the inherent ionic crystal property makes it susceptible to interaction with moisture and oxygen in the ambient atmosphere and hinders the development of stable perovskite devices. Herein, a natural and nontoxic molecule, ascorbic acid (AA), is introduced to improve the performance of perovskite nanocrystals. Experimental results reveal that the strong coordination between carbonyl groups and undercoordinated Pb2+, together with the hydrogen bonding interaction between hydroxyl groups and defects of halide ions in AA, suppress nonradiative recombination. In addition, with the synergistic effect of the C═O and -OH groups in AA, the perovskite crystal structure exhibits excellent stability due to hydrogen bonding. Finally, the demonstration of humidity sensing based on perovskites has been presented. It is shown that the humidity sensor exhibits good sensitivity in the range of 30%-80% relative humidity, with a detection limit of 3.9% and a response time of 46 s. This work provides a low-cost, nontoxic, and efficient modification approach and demonstrates an easy way to improve the performance and humidity stability of perovskite.

Hydrothermal Synthesis of Single-Crystal Europium Tungstate Hydroxide Nanobelts for Enhanced Humidity Sensing.

Humidity sensing is critical for environmental monitoring and industrial processes, yet existing sensors often struggle with sensitivity and response time. This work addresses these challenges by introducing a novel material, EuWO4(OH) nanobelts, synthesized via a hydrothermal method. These nanobelts exhibit exceptional sensing performance, with a response value of 2.3×103 at 85% RH, a rapid response time of 6.3 s, and a recovery time of 0.6 s. Unlike traditional materials, EuWO4(OH) nanobelts offer superior stability and reproducibility, making them a promising candidate for advanced humidity sensors. The unique electronic properties and high crystallinity of EuWO4(OH) nanobelts contribute to their high sensitivity and fast response, setting them apart from existing sensors. This study not only demonstrates the potential of EuWO4(OH) nanobelts for humidity sensing but also provides a new direction for the development of next-generation humidity sensors.

Smart Tags as Enablers for Digital Product Passports in Circular Electronics Value Chains

Abstract The electronics industry is expected to adopt more sustainable and circular product concepts and operations. Since the electronics value chains are complex, digital product passports (DPPs) that provide value chain transparency and traceability can be seen as one key enabler for shifting towards circular economy. Data carriers that are physical identifiers attached to products provide access to product data stored in the cloud and databases. Smart tags that combine item-level identification with condition monitoring are proposed to enable access also to dynamic lifecycle data of products to improve decision-making at end-of-life based on conditions that the product has been exposed to during its lifecycle. This dynamic information could be effectively used together with product data to decide on which circular economy strategy to adopt: reuse, remanufacture, repair, recycle etc. This paper analyses the data requirements of electronics value chain for DPPs, specifically focusing on which conditions to monitor with the help of smart tags. The data for this analysis was collected from ten developmental value chains aiming for sustainability and circularity with a questionnaire related to data needs, data access, data gaps, and data availability. The responses highlighted the need for data exchange and tools to monitor performance of components during storage and use. A printed visual humidity sensor is developed and analyzed as an experimental case study to help the value chains to dynamically monitor lifecycle conditions of products. This smart tag principal was functional with a visible colour change over time at different humidities between 33–72%RH, while not reacting at 0%RH. The relevance of different smart tag concepts is discussed and other important aspects, such as sustainability and durability of the smart tags, are included in the discussion.

Mechatronic System Based on Bluetooth Communication with a Mobile Application for Automatic Irrigation in Greenhouses

Non-automatic irrigation in greenhouses presents significant disadvantages, such as waste of water and loss of time, although they are highly widespread and low cost. Research highlights the importance of rationally managing and using water through information technologies to improve crop quality, recommending the use of automated irrigation systems, although challenges are faced in the proper integration of electronic devices in agricultural environments. For this reason, it is considered that the use of drip irrigation, the integration of embedded systems with Bluetooth connection, and mobile applications facilitates its use. This paper describes the design and implementation of a prototype mechatronic system to manage greenhouse irrigation, using an embedded system based on a microcontroller. In this case, temperature and humidity sensors are used that control a water pump, monitor environmental factors, and display data in the mobile application connected via Bluetooth, activating the water pump automatically. The results show that the prototype is functional, meets the stated objectives, and proposes improvements related to the range of Bluetooth communication and the implementation of a solar panel for use in areas without electricity supply. Doi: 10.28991/ESJ-2025-09-01-02 Full Text: PDF

Wireless wearable multifunctional sensor based on carboxylated cellulose nanofibers/silver nanowires for ultra-sensitive, fast humidity response and body temperature monitoring.

Humidity and temperature sensors are considered as hotspots for the next generation of wearable multifunctional electronics. However, it is still a notable challenge to realize multifunctional sensors with high-performance humidity response, excellent mechanical properties, and accurate temperature monitoring capability. In this work, a hydrogen-bond cross-linked hybrid network was constructed between carboxystyrene-butadiene rubber (XSBR) and hydrophilic carboxylated cellulose nanofibers (CNF) noncovalently modified silver nanowires (AgNWs). The abundant hydroxyl and carboxyl groups of CNF chains have excellent affinity for water, and the apparent distinction in thermal expansion coefficient between the XSBR matrix and AgNWs has an outstanding response to instantaneous temperature change. The material exhibits a humidity sensitivity up to 22.15 and a humidity response time as low as 390ms, yet with excellent tensile strength of 4.10MPa and stretchability of 342%. In addition, the as-prepared multifunctional sensor possesses an excellent thermal response of 0.5625%/°C. Based on the superior performance, the sensor has been applied to recognize and monitor different respiration rates in the human body, locate moist objects in close proximity, and also accurately record and respond to the changes in skin surface temperature.

Advances in quartz crystal microbalance relative humidity sensors: A review

Advances in quartz crystal microbalance relative humidity sensors: A review

Advances in humidity sensors based on Self-Powered technology

Advances in humidity sensors based on Self-Powered technology

A novel optical fiber humidity sensor based on Mach-Zehnder interference and AIEgens

A novel optical fiber humidity sensor based on Mach-Zehnder interference and AIEgens

Highly sensitive humidity sensors based on Ag-BVO composites

Highly sensitive humidity sensors based on Ag-BVO composites

Smart electronic device for air quality and exposure risk assessment

ABSTRACT This article reports on the measurement of air pollutants and assessment of health exposure risks in two reference hospitals in the city of Yaoundé, using a locally manufactured smart electronic device for the measurement of highly toxic air pollutants. This low-cost device is based on an Atmega328 microcontroller, toxic gas sensors (O3, PM2.5, CO, CO2 and NO2), temperature (T), relative humidity (RH) sensors, and XBee modules to establish the Internet of Things (IoT). In each of the two hospitals, 2 weeks of measurements conducted from October 15 to 30, 2023 at Biyem-assi Hospital and from September 1 to 15, 2023 at Central Hospital. The average values obtained were 0.96 ± 0.06 ppm and 0.37 ± 0.09 ppm for O3, 39.66 ± 10 µg/m3 and 39.72 ± 10 µg/m3 for PM2.5, 0.41 ± 0.01 ppm and 0.42 ± 0.02 ppm for CO, 316.55 ± 63 ppm and 305.84 ± 89 ppm for CO2, and 0.43 ± 0.01 ppm and 0.45 ± 0,02 ppm for NO2 in Biyem-assi and Central Hospitals, respectively. These values were used to assess the risk of exposure through the Air Quality Index (AQI) and the Air Quality Health Index (AQHI2.5).

An Analysis of Farmer Awareness for Banana Production from a Technological and Geographic Perspective in Indapur Tahsil of Pune District, India

The Indapur tehsil an arid climate region is gaining recognition as a prime location for banana cultivation. The identification of water sources, fertile soil, favourable climate, and income resulted in a shift towards cultivating bananas. This research identified a gap between the practices of farmers and modern agricultural techniques. The study is the first to survey farmers' understanding of geography, farming techniques, challenges faced, and factors for successful production in the region. Data was gathered from 270 banana farmers in various villages using qualitative and quantitative research methods, official documents, and on-site observations. The findings indicated that the farmers displayed a good understanding of drip irrigation and the use of liquid fertilizer through this method. Farmers showed a moderate understanding of soil quality, organic farming, tissue culture plantlets, banana variety selection, year-round farming, and crop protection. Factors such as land ownership, gender of the family head, family size, age, education, farming experience, subsidies, crop insurance, and access to information influence modern agricultural practices which is evident in the perception index. The perception index also highlights the necessity for focused attention on aspects such as application of agrochemicals to leaves, bunch feeding, the use of humidity sensors in irrigation, mulching, crop rotation, diseases caused by fungus, intercropping, cold storage, and ISO certification. Dry environments and the adoption of plantlets grown through tissue culture can reduce the risk of pest and disease issues. Rise in fertilizer and raw material cost, price fluctuations, commissions, middlemen’s dishonesty, domestic and export market support and labour costs are major issues. It is recommended to offer awareness programs and training on modern farming techniques and banana export, along with strengthening of farmers organizations and communication channels. The findings will provide important information to support sustainable banana farming for researchers, farmers, policymakers, and agricultural services.

Amplifying Electron-Donor Signal of the "Water Gate" Enabled Low Detection Ability of a Field-Effect Transistor-Based Humidity Sensor.

Low humidity detection down to the parts per million level is urgently demanded in various industrial applications. The hardly detected tiny electrical signal variations caused by a very small amount of water adsorption are one of the intrinsic reasons that restrain the detection limit of the humidity sensors. Herein, a carbon-based field-effect transistor (FET) humidity sensor utilizing adsorbed water as the dual function of a sensing gate and analyte was proposed. Owing to the electron donor property of the "water gate" that can serve as a negative voltage exerted on the dielectric layer, the electrical conductivity of the FET's channel can be significantly modulated, therefore realizing signal amplification. The proposed sensor presents a detection limit of lower than 1% RH. Besides, the fabricated sensors show good batch consistency (response deviation of 0.5%), repeatability, long-term stability, and acceptable hysteresis (6.3% relative humidity (RH)) in humidity detection. We hope that our work can offer a novel strategy for the application and integration of low humidity detection from the device aspect rather than sensing materials synthesis.

Functional Graphene Fiber Materials for Advanced Wearable Applications

Abstract Graphene fiber materials have emerged as key enablers in the advancement of wearable electronics due to their outstanding electrical conductivity, mechanical strength and flexibility. This review explores the fabrication techniques of graphene fibers, including wet spinning, electrospinning and dry spinning, which have been refined to produce high-performance fibers tailored for various wearable applications. Graphene fibers demonstrate exceptional functionality in wearable sensing technologies, such as strain, pressure and humidity sensors, while also showing promises in flexible energy storage devices like supercapacitors and batteries. Moreover, fabrication techniques like weaving, spinning and additional encapsulations have enabled the integration of graphene fibers into smart textiles, enhancing flexibility and durability. These methods ensure seamless electronic integration into fabrics for applications in flexible displays and wearable systems. By summarizing all the advances of graphene fibers in wearable electronics, this review provides a roadmap for future research directions. Future developments will focus on enhancing structural performance, hybridization with other materials and scalable fabrication techniques to support commercialization. These advancements position graphene fibers as a critical material for next-generation wearable electronics, offering seamless integration of functionality, comfort and durability. Graphical Abstract

Development of a Peltier-based chilled-mirror hygrometer, SKYDEW, for tropospheric and lower-stratospheric water vapor measurements

Abstract. We have developed a Peltier-based non-cryogenic chilled-mirror hygrometer named SKYDEW to measure water vapor from the surface to the stratosphere. Several chamber experiments were conducted to investigate the characteristics and performance of the instrument under various conditions. The stability of the feedback controller that maintains the condensate on the mirror depends on the controller setting, the condensate condition, and the frost point in ambient air. The results of condensate observation by a microscope and proportional-integral-derivative (PID) tuning in a chamber were used to determine the PID parameters of the controller such that slight oscillations of the scattered light signal from the mirror and mirror temperature are retained. This allows for the detection of steep gradients in the humidity profile, which are otherwise not detected because of the slower response. The oscillation of the raw mirror temperature is smoothed with a golden point method that selects the equilibrium point of the frost layer. We further describe the details of the data processing and the uncertainty estimation for SKYDEW measurements in terms of the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) requirements. The calibration uncertainty of the mirror temperature measurement is < 0.1 K for the entire temperature range from −95 to 40 °C. The total measurement uncertainty of SKYDEW measurements can exceed 0.5 K in regions where large oscillations of the mirror temperature remain. Intercomparisons with relative humidity (RH) sensors on radiosondes, the cryogenic frost point hygrometer (CFH), and the Aura Microwave Limb Sounder (MLS) were performed at various latitudes in the Northern Hemisphere to evaluate the performance of SKYDEW. These results show that SKYDEW can reliably measure atmospheric water vapor up to 25 km altitude. Data from several SKYDEW and CFH measurements predominantly agree within their respective uncertainties, although a systematic difference of ∼ 0.5 K between SKYDEW and CFH was found in the stratosphere, the reason for which is unknown. SKYDEW shows good agreement with Aura MLS for profiles that are not affected by contamination.

Ultrathin Screen‐Printed Plant Wearable Capacitive Sensors for Environmental Monitoring

AbstractPrintable and wearable plant sensors offer an approach for collecting critical environmental data at high spatial resolution to understand plant conditions and aid land management practices. Here, screen printed capacitive devices that can measure relative humidity (RH) directly at the plant‐environment interface, are demonstrated in an ultra‐thin (<6 µm) form factor. Using screen printing and a temporary tattoo transfer process, a simple technique is established to: 1) enclose printed electronic features between two layers of ethyl cellulose (EtC), 2) mount printed microparticle carbon‐based electronics onto a variety of plant structures, and 3) dramatically increase the capacitance and sensitivity for humidity sensors when compared to unencapsulated devices. This sandwich tattoo capacitor (STC) platform exhibits an RH sensitivity up to 1000 pF/%RH and stability while mounted to living plant leaves over several days. Electrochemical impedance spectroscopy (EIS) validates the formation of electric double layers within the EtC films that encapsulate the printed electrodes providing tunable capacitance values based on the ionic concentration of the device transfer fluid.

Preparation of a PEO/ZnO composite for high-sensitivity humidity sensors and its humidity-sensing mechanism

Preparation of a PEO/ZnO composite for high-sensitivity humidity sensors and its humidity-sensing mechanism

Titanium Dioxide/Graphene Oxide Nanocomposite-Based Humidity Sensors with Improved Performance

Accurate relative humidity (RH) measurement is critical in many applications, from process control and material preservation to ensuring human comfort and well-being. This study presents high-performance humidity sensors based on titanium oxide nanoparticles/graphene oxide (TiO2/GO) composites, which demonstrate excellent sensing capabilities compared to pure GO-based sensors. The multilayer structure of the TiO2/GO composites enables the enhanced adsorption of water molecules and improved dynamic properties while providing dual-mode sensing capability through both resistive and capacitive measurements. Sensors with different TiO2/GO ratios were systematically investigated to optimize performance over different humidity ranges. The TiO2/GO sensor achieved remarkable sensitivity (8.66 × 104 Ω/%RH), a fast response time (0.61 s), and fast recovery (0.87 s) with minimal hysteresis (4.09%). In particular, the sensors demonstrated excellent mechanical stability, maintaining reliable performance under bending conditions, together with excellent cyclic stability and long-term durability. Temperature dependence studies showed consistent performance under controlled temperature conditions, with the potential for temperature-compensated measurements. These results highlight TiO2/GO nanocomposites as promising candidates for next-generation humidity sensing applications, offering enhanced sensitivity, mechanical flexibility, and operational stability. The dual-mode sensing capability combined with mechanical durability opens up new possibilities for flexible and wearable humidity-sensing devices.

Engineering Group VI Transition Metal Dichalcogenides for Designing Various Sensors

AbstractRecent advancements in sensor technology are driven by progress in materials science and increasing demands from applications such as health diagnostics. Particularly, with the push from nanotechnology and biocompatible materials, sensor technology has made significant progress. Sensor applications have been greatly enhanced by the unique properties of transition metal dichalcogenides (TMDs). These high‐performance sensors not only improve the accuracy of measurements but also provide robust support for real‐time data analysis. To further demonstrate the latest advancements in sensor technology, this paper specifically introduces the recent researches of sensors based on WS2, MoS2, and their composites. Herein, the structures and the properties of TMDs are systematically described, highlighting their strong potential for advancing sensor development. Then, the recent progress of Group VI TMDs in various sensor domains, including humidity sensors, temperature sensors, gas sensors, biosensors, image sensors, and strain sensors, is further discussed. Through detailed analysis of the function and performance of Group VI TMDs in these areas, this paper aims to emphasize their advantages as sensor materials. The performance of TMDs in various sensor applications is also systematically summarized, and a glimpse into what the future holds for sensors using TMDs is offered.