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Monitoring sweat secretion rate is essential for uncovering underlying physical conditions like hyperhidrosis, mental stress, and neural disorders. Often, flexible microfluidic sweat rate monitoring devices use tape as a means of attachment to the skin to tightly seal the collection area. While these single-use, adhesive-backed devices have lightweight and thin interfaces for mounting on the skin, their form factor complicates their potential integration with available commercial wearables, such as smartwatches. Here, a tape-free device, consisting of a 3D-printed sweat collector with a concave surface that is strapped onto the skin to form an effective seal, is presented. The materials, structure, and dimensions of the sweat collector are optimized for conformal device-to-skin contact and efficient capture of sweat. The collector is interfaced with a fluidic microchannel with embedded electrodes for continuous digital monitoring of sweat rate. Long-term exercise-induced local sweat rate from multiple body locations in both multi-subject and longitudinal studies is measured, depicting the correlation between the measured sweat profile and total body fluid loss. The simple installation procedure and reusability of this tape-free device make it a good candidate for integration with the band of a watch.

Smart speakers, which provide continuous real-time information and convenient services, increasingly permeate into users’ homes. On the other hand, the environments of the smart speaker also cause ...

Accurate transmission of biosignals without interference of surrounding noises is a key factor for the realization of human-machine interfaces (HMIs). We propose frequency-selective acoustic and haptic sensors for dual-mode HMIs based on triboelectric sensors with hierarchical macrodome/micropore/nanoparticle structure of ferroelectric composites. Our sensor shows a high sensitivity and linearity under a wide range of dynamic pressures and resonance frequency, which enables high acoustic frequency selectivity in a wide frequency range (145 to 9000 Hz), thus rendering noise-independent voice recognition possible. Our frequency-selective multichannel acoustic sensor array combined with an artificial neural network demonstrates over 95% accurate voice recognition for different frequency noises ranging from 100 to 8000 Hz. We demonstrate that our dual-mode sensor with linear response and frequency selectivity over a wide range of dynamic pressures facilitates the differentiation of surface texture and control of an avatar robot using both acoustic and mechanical inputs without interference from surrounding noise.

A human can intuitively perceive and comprehend complicated tactile information, when interacting with objects, owing to the different cutaneous receptors distributed in the fingertip skin. Many research groups have attempted to mimic the structure and receptors of the skin to develop next-generation tactile sensors that can precisely and seamlessly deliver the overall tactile sensation. In this study, we propose a real-time multimodal tactile system that mimics the sensing qualities of cutaneous receptors entirely by simultaneously acquiring four types of decoupled tactile information in real time using multiple sensors integrated into three dimensions (3D), a signal-processing module, and a transmission module. The interconnections between 3D-integrated sensors and the signal-processing module were manufactured by 3D printing methods to have an adaptable shape. Furthermore, the proposed system can differentiate between various tactile stimuli, texture characteristics, and consecutive complex motions depending on the decoupled tactile sensing signals of pressure, shear force, vibration, and temperature. We believe that the results of this study can provide a novel design for a skin-like, perceivable, tactile sensing system for application in soft robotics, human-machine interfaces, health monitoring systems, and biomedical devices.

When we touch an object, thermosensation allows us to perceive not only the temperature but also wetness and types of materials with different thermophysical properties (i.e., thermal conductivity and heat capacity) of objects. Emulation of such sensory abilities is important in robots, wearables, and haptic interfaces, but it is challenging because they are not directly perceptible sensations but rather learned abilities via sensory experiences. Emulating the thermosensation of human skin, we introduce an artificial thermosensation based on an intelligent thermo-/calorimeter (TCM) that can objectively differentiate types of contact materials and solvents with different thermophysical properties. We demonstrate a TCM based on pyroresistive composites with ultrahigh sensitivity (11.2% °Csup-1/sup) and high accuracy (lt;0.1 °C) by precisely controlling the melt-induced volume expansion of a semicrystalline polymer, as well as the negative temperature coefficient of reduced graphene oxide. In addition, the ultrathin TCM with coplanar electrode design shows deformation-insensitive temperature sensing, facilitating wearable skin temperature monitoring with accuracy higher than a commercial thermometer. Moreover, the TCM with a high pyroresistivity can objectively differentiate types of contact materials and solvents with different thermophysical properties. In a proof-of-principle application, our intelligent TCM, coupled with a machine-learning algorithm, enables objective evaluation of the thermal attributes (coolness and wetness) of skincare products.

Although ferroelectric composites have been reported to enhance the performance of triboelectric (TE) devices, their performances are still limited owing to randomly dispersed particles. Herein, we introduce high-performance TE sensors (TESs) based on ferroelectric multilayer nanocomposites with alternating poly(vinylidenefluoride

Transfer printing of electronic functions on arbitrary surfaces is essential for next-generation applications of skin-attachable electronics, wearable sensors, and implantable/medical devices. For transfer printing of electronic functions on multidimensional surfaces, such as curved regions of the skin and different objects, various strategies have been devised based on the materials and structural design of electronic components and transfer stamps, such as ultrathin membranes or in-plane structures of electronic components, soft interfacial glues or adhesives between devices and surfaces, and smart transfer adhesives with bioinspired micro/nanostructures. These techniques enable high conformity of adhesion, mechanical robustness, and high compliance of electronic devices on arbitrary surfaces under mechanical deformation. In this Perspective, we provide an overview of recent transfer printing techniques and discuss their advantages and challenges. In addition, we report a recently developed transfer printing technique based on bioinspired smart adhesives with reversible adhesion, which enables compliant electronics on various arbitrary complex surfaces without performance degradation, providing solutions for various technical challenges remaining in transfer printing. Finally, we present potential applications of transfer printing and future perspectives for this emerging field.

Multifunctional electronic skins have attracted considerable attention for soft electronics including humanoid robots, wearable devices, and health monitoring systems. Simultaneous detection of multiple stimuli in a single self-powered device is desired to simplify artificial somatosensory systems. Here, inspired by the structure and function of human skin, an ultrasensitive self-powered multimodal sensor is demonstrated based on an interlocked ferroelectric copolymer microstructure. The triboelectric and pyroelectric effects of ferroelectric microstructures enable the simultaneous detection of mechanical and thermal stimuli in a spacer-free single device, overcoming the drawbacks of conventional devices, including complex fabrication, structural complexity, and high-power consumption. Furthermore, the interlocked microstructure induces electric field localization during ferroelectric polarization, leading to enhanced output performance. The multimodal tactile sensor provides ultrasensitive pressure and temperature detection capability (2.2 V kPa

High‐performance biodegradable electronic devices are being investigated to address the global electronic waste problem. In this work, a fully biodegradable ferroelectric nanogenerator‐driven skin sensor with ultrasensitive bimodal sensing capability based on edible porcine skin gelatine is demonstrated. The microstructure and molecular engineering of gelatine induces polarization confinement that gives rise the ferroelectric properties, resulting in a piezoelectric coefficient (d 33) of ≈24 pC N−1 and pyroelectric coefficient of ≈13 µC m−2K−1, which are 6 and 11.8 times higher, respectively, than those of the conventional planar gelatine. The ferroelectric gelatine skin sensor has exceptionally high pressure sensitivity (≈41 mV Pa−1) and the lowest detection limit of pressure (≈0.005 Pa) and temperature (≈0.04 K) ever reported for ferroelectric sensors. In proof‐of‐concept tests, this device is able to sense the spatially resolved pressure, temperature, and surface texture of an unknown object, demonstrating potential for robotic skins and wearable electronics with zero waste footprint., Fully transient ferroelectric electronic skin (e‐skin) is demonstrated based on edible porcine skin gelatine. The interlocked molecular engineering induces ferroelectricity in gelatine. The e‐skin detects and discriminates the lowest possible resolution of pressure and temperature ever reported for ferroelectric sensors. In proof‐of‐concept tests, the potential applications towards robotic skins and wearable electronics are demonstrated with zero waste footprint.

Although information privacy has been extensively investigated in the information systems discipline, research heavily focuses on cognitive frameworks and underestimates the influence of affect on users’ privacy behaviors. Psychological literature demonstrates that affect plays a significant role in individuals’ decisions in risky situations. This study aims to explore associations between cognitive factors, affective responses, and coping behaviors in the context of privacy threats. For this purpose, we conducted a laddering interview with 56 users of location-based services. Elements elicited by an emerging coding procedure were mapped by their causal relations as described in interviews. The results revealed idiosyncratic associations among privacy concerns, affects, and coping behaviors, which implies that privacy concerns can result in different coping behaviors according to the affects following the concern. Thus, the result suggests that cognition-affect appraisals can offer a reliable framework for explaining users’ privacy behaviors. This study proposes a new direction for the cognition-affect perspective in information privacy research by providing an alternative approach that reflects both cognition and affects to explain coping behaviors.

Fluorinated polymers have been widely used in triboelectric sensors, displays, and energy harvesting devices because of their superior electron affinity, which leads to the negative triboelectric materials. While previous reports have shown that the control of dielectric constants of fluorinated polymers can increase the triboelectric output performance, the exact relationship between the molecular structures of fluorinated polymers and the resulting triboelectric properties is still elusive. In this study, we demonstrate that the molecular chain structures of the fluorinated polymers depending on the number of fluorine units, the molecular weight (Mw), and conditions such as spin rate and annealing temperature directly affect the relative dielectric constants of dielectric layers and the triboelectric polarity, which are closely related to the triboelectric output performance. We observe that the polymer chain packing structures result in the increase of the relative dielectric constants, thus leading to the improvement of triboelectric output currents. Among the fluorinated polymers used in this study, a poly (2,2,2-trifluoroethyl methacrylate) polymer with three fluorine units and Mw of ~ 20 kg/mol shows the best triboelectric output performance. Our molecular engineering strategy to control the dielectric constants of fluorinated polymers can be a robust platform for the fundamental studies of triboelectric materials and their applications in diverse energy harvesting and sensing devices.

Hierarchical and gradient structures in biological systems with special mechanical properties have inspired innovations in materials design for construction and mechanical applications. Analogous to the control of stress transfer in gradient mechanical structures, the control of electron transfer in gradient electrical structures should enable the development of high-performance electronics. This paper demonstrates a high performance electronic skin (e-skin) via the simultaneous control of tactile stress transfer to an active sensing area and the corresponding electrical current through the gradient structures. The flexible e-skin sensor has extraordinarily high piezoresistive sensitivity at low power and linearity over a broad pressure range based on the conductivity-gradient multilayer on the stiffness-gradient interlocked microdome geometry. While stiffness-gradient interlocked microdome structures allow the efficient transfer and localization of applied stress to the sensing area, the multilayered structure with gradient conductivity enables the efficient regulation of piezoresistance in response to applied pressure by gradual activation of current pathways from outer to inner layers, resulting in a pressure sensitivity of 3.8 × 105 kPa-1 with linear response over a wide range of up to 100 kPa. In addition, the sensor indicated a rapid response time of 0.016 ms, a low minimum detectable pressure level of 0.025 Pa, a low operating voltage (100 μV), and high durability during 8000 repetitive cycles of pressure application (80 kPa). The high performance of the e-skin sensor enables acoustic wave detection, differentiation of gas characterized by different densities, subtle tactile manipulation of objects, and real-time monitoring of pulse pressure waveform.

Flexible pressure sensors have been widely explored for their versatile applications in electronic skins, wearable healthcare monitoring devices, and robotics. However, fabrication of sensors with characteristics such as high sensitivity, linearity, and simple fabrication process remains a challenge. Therefore, we propose herein a highly flexible and sensitive pressure sensor based on a conductive binary spiky/spherical nanoparticle film that can be fabricated by a simple spray-coating method. The sea-urchin-shaped spiky nanoparticles are based on the core-shell structures of spherical silica nanoparticles decorated with conductive polyaniline spiky shells. The simple spray coating of binary spiky/spherical nanoparticles enables the formation of uniform conductive nanoparticle-based films with hierarchical nano/microstructures. The two differently shaped particles-based films (namely sea-urchin-shaped and spherical) when interlocked face-to-face to form a bilayer structure can be used as a highly sensitive piezoresistive pressure sensor. Our optimized pressure sensor exhibits high sensitivity (17.5 kPa-1) and linear responsivity over a wide pressure range (0.008-120 kPa), owing to the effects of stress concentration and gradual deformation of the hierarchical microporous structures with sharp nanoscale tips. Moreover, the sensor exhibits high durability over 6000 repeated cycles and practical applicability in wearable devices that can be used for healthcare monitoring and subtle airflow detection (1 L/min).

Flexible electronic devices are regarded as one of the key technologies in wearable healthcare systems, wireless communications and smart personal electronics. For the realization of these applications, wearable energy and sensor devices are the two main technologies that need to be developed into lightweight, miniaturized, and flexible forms. In this review, we introduce recent advances in the controlled design of device structures into bioinspired micro/nanostructures and 2D/3D structures for the enhancement of energy harvesting and multifunctional sensing properties of flexible electronic skins. In addition, we highlight their potential applications in flexible/wearable electronics, sensors, robotics and prosthetics, and biomedical devices.

Electronic skins (e-skins) with high sensitivity to multidirectional mechanical stimuli are crucial for healthcare monitoring devices, robotics, and wearable sensors. In this study, we present piezoresistive e-skins with tunable force sensitivity and selectivity to multidirectional forces through the engineered microstructure geometries (i.e., dome, pyramid, and pillar). Depending on the microstructure geometry, distinct variations in contact area and localized stress distribution are observed under different mechanical forces (i.e., normal, shear, stretching, and bending), which critically affect the force sensitivity, selectivity, response/relaxation time, and mechanical stability of e-skins. Microdome structures present the best force sensitivities for normal, tensile, and bending stresses. In particular, microdome structures exhibit extremely high pressure sensitivities over broad pressure ranges (47,062 kPa−1 in the range of

The increasing difficulty in managing one's online personal data leads to individuals feeling a loss of control. Additionally, repeated consumer data breaches have given people a sense of futility, ultimately making them weary of having to think about online privacy. This phenomenon is called “privacy fatigue.” Although privacy fatigue is prevalent and has been discussed by scholars, there is little empirical research on the phenomenon. This study aimed not only to conceptualize privacy fatigue but also to examine its role in online privacy behavior. Based on literature on burnout, we developed measurement items for privacy fatigue, which has two key dimensions —emotional exhaustion and cynicism. Data analyzed from a survey of 324 Internet users showed that privacy fatigue has a stronger impact on privacy behavior than privacy concerns do, although the latter is widely regarded as the dominant factor in explaining online privacy behavior.

This study aimed to examine predictors of the intention to protect personal information on Facebook. We conducted an online survey of 679 Facebook users in the Republic of Korea. The findings of this study showed that usefulness and ease of use had significant effects on attitudes toward protection behavior. The results also revealed that risk factors (privacy risk severity and vulnerability) had significant effects on protective behaviors. Based on our findings, we discussed the information protection of privacy on Facebook.

Piezoelectric polyvinylidene fluoride (PVDF) has been widely utilized in flexible and self-powered tactile sensors, which require high ferroelectricity of polar phase PVDF. Herein, we demonstrate self-powered piezoelectric e-skins with high sensitivity and broad sensing range based on 3D porous structures of MXene (Ti3C2Tx)/PVDF. MXene was used as a nucleation agent to increase the ferroelectric properties of PVDF. This was carried out considering its 2D geometry and abundant surface functional groups that facilitate intermolecular hydrogen bonding between the surface functional groups of MXene and the CH2 group of PVDF. In addition, porous structures can increase the variation in contact area and localized stress concentration in response to applied pressure. This further enhances the piezoelectric sensitivity. Owing to structural deformation and localized stress concentration, the piezoelectric sensitivity of porous MXene/PVDF e-skin is 11.9 and 1.4 nA kPa−1 for low (

Output performance of triboelectric devices critically depends on their surface charge density that is greatly influenced by the dielectric constant of material. However, contrary to polymer composites, the dielectric constant cannot be substantially increased in pure polymers. This study shows that interfacial polarization in bilayer polymer films significantly enhances their dielectric constants, increasing the surface charge density and triboelectric performance. This is the first report of the introduction of interfacial polarization of dielectric materials for the enhancement of triboelectric output performance. The elastic bilayer films consisting of polydimethylsiloxane (PDMS) coated with poly (2,2,2-trifluoroethyl methacrylate) (PTF) and poly ( L -lysine) (PLL) as negative and positive triboelectric materials, respectively, are utilized in triboelectric devices, which show a dramatic increase in the dielectric constants (24.4 for PTF-PDMS and 15.2 for PLL-PDMS bilayers at 10 kHz) through interfacial polarization, resulting in significant enhancement of triboelectric performance when compared with hard single-layer films. For proofs of concept, we fabricated a temperature-sensitive triboelectric sensor and vibration-based triboelectric nanogenerator. The sensor showed the highest temperature sensitivities among triboelectric sensors whereas the nanogenerator provided vibration-induced sustainable power for LED operation without rectification, which was attributed to the charge accumulation in the bi-layered dielectric films.

Silver nanowire (AgNW) networks are considered to be promising structures for use as flexible transparent electrodes for various optoelectronic devices. One important application of AgNW transparent electrodes is the flexible touch screens. However, the performances of flexible touch screens are still limited by the large surface roughness and low electrical to optical conductivity ratio of random network AgNW electrodes. In addition, although the perception of writing force on the touch screen enables a variety of different functions, the current technology still relies on the complicated capacitive force touch sensors. This paper demonstrates a simple and high-throughput bar-coating assembly technique for the fabrication of large-area (>20 × 20 cm2), highly cross-aligned AgNW networks for transparent electrodes with the sheet resistance of 21.0 Ω sq–1 at 95.0% of optical transmittance, which compares favorably with that of random AgNW networks (sheet resistance of 21.0 Ω sq–1 at 90.4% of optical transmi...

Biological tissues are multiresponsive and functional, and similar properties might be possible in synthetic systems by merging responsive polymers with hierarchical soft architectures. For example, mechanochromic polymers have applications in force-responsive colorimetric sensors and soft robotics, but their integration into sensitive, multifunctional devices remains challenging. Herein, a hierarchical nanoparticle-in-micropore (NP-MP) architecture in porous mechanochromic polymers, which enhances the mechanosensitivity and stretchability of mechanochromic electronic skins (e-skins), is reported. The hierarchical NP-MP structure results in stress-concentration-induced mechanochemical activation of mechanophores, significantly improving the mechanochromic sensitivity to both tensile strain and normal force (critical tensile strain: 50% and normal force: 1 N). Furthermore, the porous mechanochromic composites exhibit a reversible mechanochromism under a strain of 250%. This architecture enables a dual-mode mechanochromic e-skin for detecting static/dynamic forces via mechanochromism and triboelectricity. The hierarchical NP-MP architecture provides a general platform to develop mechanochromic composites with high sensitivity and stretchability.

Development of broadband photodetectors is of great importance for applications in high-capacity optical communication, night vision, and biomedical imaging systems. While heterostructured photodetectors can expand light detection range, fabrication of heterostructures via epitaxial growth or wafer bonding still faces significant challenges because of problems such as lattice and thermal mismatches. Here, a transfer printing technique is used for the heterogeneous integration of InGaAs nanomembranes on silicon semiconductors and thus the formation of van der Waals heterojunction photodiodes, which can enhance the spectral response and photoresponsivity of Si photodiodes. Transfer-printed InGaAs nanomembrane/Si heterojunction photodiode exhibits a high rectification ratio (7.73 × 104 at ±3 V) and low leakage current (7.44 × 10–5 A/cm2 at −3 V) in a dark state. In particular, the photodiode shows high photoresponsivities (7.52 and 2.2 A W–1 at a reverse bias of −3 V and zero bias, respectively) in the broad...

In this study, method for selecting an appropriate nitrogen separation process in the liquefied natural gas (LNG) plant is suggested and its validity is confirmed using a well-known decision making technique of analytic hierarchy process. In order to develop an objective decision methodology, various decision parameters, sub-parameters as well as the concept of scale of assessment were introduced, and its consistency among these parameters was also checked by calculating the consistency index (C.I.). The methodology suggested in this article will contribute in selecting an appropriate nitrogen separation process in the LNG plant with less bias and subjectivity associated with the decision making procedure.

We identified a loose upper panicle mutant (lup) from a japonica-type rice variety, Hwacheongbyeo, treated by Ethyl Methane Sulfonate (EMS). The lup mutant displayed an increased distance between spikelets particularly in the first primary branches, and the number of spikelet was reduced. In addition, aborted spikelets in the tip of first primary branches were observed. Besides these morphological changes in the panicle, the lup mutant also displayed overall reduction in culm length, panicle length, grain weight, and tiller number. On the contrary, the chlorophyll content was relatively high in lup mutant in comparison to wild-type plants, and displayed a "stay-green" phenotype even after physiological maturity. Genetic analysis (using F2 population of lup/M.23) revealed that a single recessive gene is involved in the above-mentioned morphological changes in the lup mutant. A candidate genomic region was fine-mapped at an interval of 1.04 Mb flanked by two molecular markers, 18170 and D0052, on the long arm of chromosome 8. In this region, we found a total of 348 mutation points using a slightly modified MutMap method. Based on these results, we expect the candidate genomic region containing a putative LUP gene will provide an important clue in developmental regulation of spikelets and panicle in rice.

Flexible tactile sensors capable of detecting the magnitude and direction of the applied force together are of great interest for application in human-interactive robots, prosthetics, and bionic arms/feet. Human skin contains excellent tactile sensing elements, mechanoreceptors, which detect their assigned tactile stimuli and transduce them into electrical signals. The transduced signals are transmitted through separated nerve fibers to the central nerve system without complicated signal processing. Inspired by the function and organization of human skin, we present a piezoresistive type tactile sensor capable of discriminating the direction and magnitude of stimulations without further signal processing. Our tactile sensor is based on a flexible core and four sidewall structures of elastomer, where highly sensitive interlocking piezoresistive type sensing elements are embedded. We demonstrate the discriminating normal pressure and shear force simultaneously without interference between the applied forces. The developed sensor can detect down to 128 Pa in normal pressure and 0.08 N in shear force, respectively. The developed sensor can be applied in the prosthetic arms requiring the restoration of tactile sensation to discriminate the feeling of normal and shear force like human skin.

The widespread diffusion of mobile devices has led to a new method of value transfer that retains the features of mobile devices: mobile payments. Many researchers have investigated consumers’ responses to mobile payment services, which is a key indicator of the success of a service, and have examined determinants of consumer adoption. Although many studies have addressed consumer adoption of mobile payment services, only the general and abstract factors affecting adoption (e.g., perceived usefulness) have been intensively investigated. However, these studies have rarely examined the idiosyncratic and concrete aspects of mobile payment services. To improve our understanding of why consumers adopt certain mobile payment services, this study investigated consumers’ evaluations of the explicit attributes of the services. Three hundred seventy-three consumers of mobile payment services participated in an online conjoint survey. Their preference structure was generated from a conjoint analysis including five service attributes (mobile payment platform, assurance policy, mileage program, authentication method, and affiliated stores), which were identified through a literature review and focus group discussion. The results showed that an assurance policy is the most critical factor influencing consumers’ choices, and a mileage program is considered to be as imperative as the platform. We also compared the findings by two consumer clusters (safety seekers vs. platform adherers), which were classified by preference. Because this study examines concrete and specific attributes of mobile payment services beyond abstract and general adoption factors, it provides insights into consumers’ actual adoption of services.

Remote sensing (RS) and GIS together provide an efficient and inexpensive way to assess vegetation characteristics and cultivated areas. Precision vegetation mapping provides important information for understanding crop conditions through the calculation of the vegetation index. In this study, a multispectral sensor was installed on an eBee (Sensefly), which is suitable for wide area photography taken by an unmanned aerial vehicle (UAV). UAV imagery acquisition was used to obtain spatial information on soybean and paddy rice cultivation areas in a wider region. The study area selected was Gimje, which is in the southwest of South Korea. Based on the designation of main areas according to the Ministry of Agriculture, Food, and Rural Affairs (MAFRA), the area was selected considering the cultivation area, production volume, number of farm households, and self-sufficiency ratio. The main producing areas are soybean cultivation areas defined as a city or county with a cultivation area of 30∼1500 ha or more, respectively. The identification of the cultivation area of soybeans was made based on images taken in early September, when the growth characteristics of soybeans were clearly distinguished from other crops. The accuracy of the soybean and paddy rice cultivation area identification was improved by using the farm map (FM) prepared by the MAFRA in South Korea. The NDVI was analyzed based on the two periods of high growth activity of soybean and paddy rice. The accuracy of the cultivated area was improved by using the UAV images and the FM prepared by the MAFRA. As a result, this study shows that UAV images can be used more effectively by linking GIS with the FM as a basic map.

Interest in solar energy, which is clean energy, is growing due to continuously high oil prices because of the unstable situation in the Middle East and the explosion of the Fukushima nuclear-power plant in Japan. South Korea has made various efforts to develop renewable energy, and facilities using solar energy are rapidly growing. Periodic inspection of solar panels is very important for the effective management of photovoltaic (PV) modules. In this study, a method to monitor and diagnose faulty solar modules through an Unmanned Aerial Vehicle (UAV)-based thermal infrared camera and GIS spatial analysis is discussed. First, the image of the PV module was taken by installing an RGB camera and thermal infrared camera on the rotor blade of the UAV. The images were generated by using Pix4D SW, and the normal operation of the PV module was diagnosed using the orthoimage. In particular, thermal infrared cameras are very sensitive to reaction speed, unlike optical sensors, so it is very important to find appropriate monitoring methods, such as shooting speed. Therefore, we suggest a way to utilize an optical sensor and thermal infrared sensor together through various attempts. In the images, GIS spatial analysis was used to extract abnormal heat or faulty modules. Using the Virtual Reference Service (VRS) survey method, UAV images could be 3D-mapped with a very precise temperature, within 2 cm in x, y, and z direction errors. The rapid development of PV powergeneration facilities and of monitoring technologies is a very important factor for improving energy efficiency. The result of this study is providing a stable solar-panel-monitoring technology by comparing features of ground observation and UAV-based thermal infrared sensor observation. The developed monitoring technology was able to accurately analyze the failure point and temperature of the PV module.

Flexible pressure sensors with a high sensitivity over a broad linear range can simplify wearable sensing systems without additional signal processing for the linear output, enabling device miniaturization and low power consumption. Here, we demonstrate a flexible ferroelectric sensor with ultrahigh pressure sensitivity and linear response over an exceptionally broad pressure range based on the material and structural design of ferroelectric composites with a multilayer interlocked microdome geometry. Due to the stress concentration between interlocked microdome arrays and increased contact area in the multilayer design, the flexible ferroelectric sensors could perceive static/dynamic pressure with high sensitivity (47.7 kPa–1, 1.3 Pa minimum detection). In addition, efficient stress distribution between stacked multilayers enables linear sensing over exceptionally broad pressure range (0.0013–353 kPa) with fast response time (20 ms) and high reliability over 5000 repetitive cycles even at an extremely hi...

Nanomembranes and nanowires build tiny, transparent loudspeakers and sensitive, voice-recognition microphones that attach to skin., We demonstrate ultrathin, transparent, and conductive hybrid nanomembranes (NMs) with nanoscale thickness, consisting of an orthogonal silver nanowire array embedded in a polymer matrix. Hybrid NMs significantly enhance the electrical and mechanical properties of ultrathin polymer NMs, which can be intimately attached to human skin. As a proof of concept, we present a skin-attachable NM loudspeaker, which exhibits a significant enhancement in thermoacoustic capabilities without any significant heat loss from the substrate. We also present a wearable transparent NM microphone combined with a micropyramid-patterned polydimethylsiloxane film, which provides excellent acoustic sensing capabilities based on a triboelectric voltage signal. Furthermore, the NM microphone can be used to provide a user interface for a personal voice-based security system in that it can accurately recognize a user’s voice. This study addressed the NM-based conformal electronics required for acoustic device platforms, which could be further expanded for application to conformal wearable sensors and health care devices.

The development of electronic skin (e-skin) is of great importance in human-like robotics, healthcare, wearable electronics, and medical applications. In this paper, a bioinspired e-skin design of hierarchical micro- and nano-structured ZnO nanowire (NW) arrays in an interlocked geometry is suggested for the sensitive detection of both static and dynamic tactile stimuli through piezoresistive and piezoelectric transduction modes, respectively. The interlocked hierarchical structures enable a stress-sensitive variation in the contact area between the interlocked ZnO NWs and also the efficient bending of ZnO NWs, which allow the sensitive detection of both static and dynamic tactile stimuli. The flexible e-skin in a piezoresistive mode shows a high pressure sensitivity (−6.8 kPa−1) and an ultrafast response time (