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We produced a graphene oxide (GO) based nitrogen dioxide (NO2) gas sensor with extremely low limit of detection (LOD), which is far below the WHO and EU annual standards. Based on the derived correlation among the band gap, adsorption energy, and sensing performance, we prepared semiconductive reduced GO (HGO) with simply modified acid washing process of traditional Hummers' method. HGO, prepared with dispersed state enables easy fabrication of sensing device by a simple drop casting process and showed great sensing performance when HGO showed band gap of semiconductor. This research is considered that opened a new route to preparing extremely sensitive NO2 gas sensors through very facile and cost effective processes.

Hierarchical architectures composed of nanomaterials in different forms are essential to improve the performance of lithium-ion battery (LIB) anodes. Here, we systematically studied the effects of hierarchical ZnO nanostructures on the electrochemical performance of LIBs. ZnO nanowire (NW) trunks were decorated with ZnO NWs or ZnO nanosheets (NSs) by successive hydrothermal synthesis to create hierarchical three-dimensional nanostructures. The branched ZnO NSs on the ZnO NW trunk exhibited a two-fold higher specific gravimetric capacity compared to ZnO NWs and branched ZnO NWs on ZnO NW trunks after 100 cycles of charging–discharging at 0.2C (197.4 mA g−1). The improvement in battery anode performance is attributable to the increased interfacial area between the electrodes and electrolyte, and the void space of the branched NSs that facilitates lithium ion transport and volume changes during cycling.

An electronic nose (e‐nose) is a device that can detect and recognize odors and flavors using a sensor array. It has received considerable interest in the past decade because it is required in several areas such as health care, environmental monitoring, industrial applications, automobile, food storage, and military. However, there are still obstacles in developing a portable e‐nose that can be used for a wide variety of applications. For practical applications of an e‐nose, it is necessary to collect a massive amount of data from various sensing materials that can transduce interactions with molecules reliably and analyze them via pattern recognition. In addition, the possibility of miniaturizing the e‐nose and operating it with low power consumption should be considered. Moreover, it should work efficiently over a long period of time. To satisfy these requirements, several different chemoresistive material platforms including metal oxides, organics such as polymers and carbon‐based materials, and two‐dimensional materials were investigated as sensor elements for an e‐nose. As an individual material has limited selectivity, there is a continuing effort to improve the selectivity and gas sensing properties through surface decoration and compositional and structural variations. To produce a reliable e‐nose, which can be used for practical applications, researches in various fields have to be harmonized. This paper reviews the progress of research on e‐noses based on a chemoresistive gas sensor array and discusses the inherent challenges and potential solutions.

Transition metal dichalcogenides (TMDs) have attracted enormous attention in diverse research fields. Especially, gas sensors are considered in a promising application exploiting TMDs. However, the...

The use of chemoresistive gas sensors based on metal oxides has expanded to various fields such as medical diagnosis and air quality systems as well as gas leakage detectors with the development of the Internet of Things. Accordingly, sensitivity, selectivity, power consumption, and reproducibility become important factors in the development of gas sensors. Herein, we developed a facile method to fabricate a gas sensor based on porous Au-incorporated tungsten trioxide (WO3) thin films for highly sensitive and selective NO2 sensing. The mixed solution of ammonium tetrathiotungstate [(NH4)2WS4] and gold chloride (AuCl3) was transformed to Au-incorporated WO3 thin films through the spin-coating and annealing process. The gas sensors based on the Au-incorporated WO3 thin films exhibited improved sensitivity, selectivity, and response time upon exposure to NO2 with a significantly low theoretical detection limit of 28 ppt at 150 ℃ compared to gas sensors based on the pristine WO3 thin film. The high sensing properties are attributed to the porous structure and catalytic effects of Au nanoparticles. In addition to these remarkable NO2 sensing properties, the facile and cost-effective fabrication process enlarges the potential of the Au-incorporated WO3 thin films for practical and commercial gas sensing applications.

One-dimensional metal oxide (MO) micro-wires and nano-wires (MOWs) can be excellent functional units for integrated and transparent electronics. However, MOWs produced using conventional synthesis methods are short, uncontrollable, and randomly-distributed, so they cannot be easily used to fabricate high-density transistor arrays with precisely-controlled MOW-channels. Here, we describe a large-scale direct-printed universal nanoscale MOW electronics which includes highly-aligned, digitally-controlled and arbitrarily-long MOW arrays and various nanoscale applications of MOW field-effect transistors (FETs), neuromorphic synaptic transistors, and gas sensors. Broad classes of pristine, doped and alloyed MOWs are fabricated, so we demonstrated all-MOWFETs composed of conducting indium oxide (In2O3) wires and semiconducting indium zinc oxide (IZO) wires; the devices show a high carrier mobility μ ~17.67 cm2 V−1 s−1, comparable to μ of MO thin-film FETs. MOW synaptic transistors show presynaptic signals dependent postsynaptic behaviors similar to biological synaptic responses; which can be promising nano-electronic units of high-density neuromorphic devices. We also demonstrated MOW gas sensors which show high response to NO2 gas. Our direct-printed, large-scale, and individually-controlled MOW electronics would be a promising approach in development of industrially-viable MOW electronics and open new horizons for precisely-controlled inorganic MOW electronics and nanoscale printed electronics.

Recently, two-dimensional (2D) materials have attracted attention for gas sensor fields due to their unique properties such as high surface to volume ratio and numerous active sites. In particular, reduced graphene oxide (rGO) and MoS2 are one of the most promising materials for humidity sensor due to the oxygen containing functional groups on the surface of rGO and dangling bonds at the edge site of MoS2. Herein, we present 2D rGO/2D MoS2 hybrid composites (MS-GOs) synthesized by hydrothermal method. rGO and MoS2 are mixed with different molar ratios and drop-casted on SiO2 substrate with Pt interdigitated electrode. At an optimized molar ratio of rGO/MoS2, the sensor device exhibits high sensitivity, good selectivity, rapid response and recovery, and good linearity for humidity sensing. The enhanced sensing properties are attributed to the p-n junction between rGO and MoS2. Our work provides an efficient way for realizing high-performance and fast responding humidity sensors utilizing 2D-2D heterojunction materials based chemoresistive humidity sensors for use in diverse applications.

Gas discrimination using a chemoresistive sensor without heater is still a challenging research topic. Designing sensor arrays composed of various types of individual sensors have been considered as a general strategy to obtain abundant data for the classification. However, fabrication process and integration of various sensors on a small substrate are complex and challenging. Here, we report voltage-dependent gas discrimination using a single sensor with varied sensing properties induced by different levels of self-activation. The sensor can be employed for a hydrogen sensor with an ultralow detection limit down to 0.219 ppt, owing to the catalytic effect of the Pt nanoparticles. In addition, abundant data can be accumulated from the single sensor using different self-activation states. The switching time of about 2 s for each activation state enables fast data acquisition for principal component analysis. This work is not only a proof-of-concept study for gas discrimination using a single sensor, but also broadens potential of graphene gas sensors decorated with noble metal nanoparticles for practical applications.

Recent advances in 3D/2D heterostructures have opened up tremendous opportunities in building highly flexible and durable optoelectronic devices. However, the inherit lack of interfacial bonding and low surface energy of van der Waals surfaces limit the nucleation and growth of 3D materials. Enhancing wettability by providing a porous buffer is effective in growing compound semiconductors on graphene while van der Waals epitaxy of Ge remains challenging. Here, the nucleation of Ge has been significantly improved from an islanded mode to granular modes by using a TiN/AlN multilayered buffer prior to Ge/graphene integration. Highly textured Ge growth with dominating (111), (220), and (311) peaks are identified by x-ray diffraction. The microstructure of the buffer TiN/AlN demonstrates a polycrystalline quality with clean interfaces between each interlayer and the substrate. Kelvin probe force microscopy measurements along the lateral TiN/AlN interface identify a potential drop corresponding to the AlN phase. This contact potential difference between TiN and AlN is the key in generating the out-of-plane dipole moment that modifies the surface energy of the monolayer graphene, resulting in enhanced wettability of the Ge adatoms nucleated on top. Surface dipole induced nucleation of 3D semiconductor thin films on 2D materials via the proper design of buffer layer is fundamentally important to enhance the 3D/2D growth toward flexible optoelectronic applications.

The preparation of crystalline materials on incommensurate substrates has been a key topic of epitaxy. van der Waals (vdW) epitaxy on two-dimensional (2D) materials opened novel opportunities of epitaxial growth overcoming the materials compatibility issue. Therefore, vdW epitaxy has been considered as a promising approach for the preparation of building blocks of flexible devices and thin film-based devices at the nano/microscale. However, an understanding of vdW epitaxy has not been thoroughly established. Especially, controlling nucleation during vdW epitaxy has not been achieved although nucleation in vdW epitaxy is suppressed due to the absence of surface dangling bonds on 2D materials. Here we show an enhancement of nucleation probability of germanium on graphene via introducing an out-of-plane dipole moment without any change in the chemical nature of graphene. A graphene/hexagonal boron nitride stack and transferred graphene on a polarized ferroelectric thin film were employed to demonstrate the significant enhancement of Ge nucleation on graphene. Theoretical calculations and chemical vapor deposition were employed to elucidate the effect of the out-of-plane dipole moment on nucleation in vdW epitaxy.

Reduced graphene oxide (rGO) and MoS2, the most representative two-dimensional (2D) materials, are receiving significant attention for the fabrication of sensing devices owing to their high surface area, many abundant sites, and excellent mechanical flexibility. Herein, we demonstrated chemoresistive humidity sensors with fast response, excellent selectivity, and ultrahigh sensitivity based on 2D rGO and 2D MoS2 hybrid composites (RGMSs). The RGMSs were fabricated by simple ultrasonication without the addition of additives and additional heating. Compared to pristine rGO, the RGMS exhibited a 200 times higher response to humidity at room temperature. The significant enhancement in the sensing performance of the composite was attributed to electronic sensitization due to p–n heterojunction formation and porous structures between rGO and MoS2. The synergistic combination of rGO and MoS2 could be applied to construct a flexible humidity sensor. The sensing performance of an RGMS flexible device remains the same before and after bending; this indicates that the use of rGO and MoS2 is a viable new and simple strategy to realize a humidity sensor for use in wearable electronics.

Two-dimensional (2D) materials as contacts for semiconductor devices have attracted much attention due to minimizing Fermi level pinning. Schottky–Mott physics has been widely employed to design 2D material-based electrodes and to elucidate their contact behavior. In this study, we revealed that charge transfer across a 2D/semiconductor heterointerface and materials characteristics besides work function should be accounted for in fabrication of electrodes based on 2D materials. Our density functional theory (DFT) calculations predicted that charge transfer between ZnO and NbSe2 lowers the barrier height at the heterojunction and that conductive surface states of ZnO provide an additional conduction channel in the ZnO/NbSe2 heterostructures. Crystalline ZnO/NbSe2 heterostructures were prepared by the hydrothermal method. Electrical characterizations of the ZnO/NbSe2 heterostructures showed Ohmic-like behavior as predicted by the DFT calculations, opposed to the prediction based on the Schottky–Mott model.

Recent advances in nanoscience have opened ways of recycling substrates for nanomaterial growth. Novel materials, such as atomically thin materials, are highly desirable for the recycling substrates. In this work, we report recycling of monolayer graphene as a growth template for synthesis of single crystalline ZnO nanowires. Selective nucleation of ZnO nanowires on graphene was elucidated by scanning electron microscopy and density functional theory calculation. Growth and subsequent separation of ZnO nanowires was repeated up to seven times on the same monolayer graphene film. Raman analyses were also performed to investigate the quality of graphene structure along the recycling processes. The chemical robustness of graphene enables the repetitive ZnO nanowire growth without noticeable degradation of the graphene quality. This work presents a route for graphene as a multifunctional growth template for diverse nanomaterials such as nanocrystals, aligned nanowires, other two-dimensional materials, and semiconductor thin films.

Chemoresistive gas sensors based on two-dimensional (2D) materials including graphene-based materials have attracted significant research interest owing to their potential use in next-generation technologies including the Internet of Things (IoT). The functionalization of 2D materials is considered as a key strategy to achieve superior gas sensing properties such as high selectivity, high sensitivity, and reversible response and recovery, because it can modulate the chemical and electrical properties of 2D materials for more efficient gas sensing. Herein, we present a facile solution process and the room temperature gas sensing properties of chemically fluorinated graphene oxide (CFGO). The CFGO sensors exhibit improved sensitivity, selectivity, and reversibility upon exposure to NH3 with a significantly low theoretical detection limit of ∼6 ppb at room temperature in comparison to NO2 sensing properties. The effect of fluorine doping on the sensing mechanism is examined by first-principles calculations based on density functional theory. The calculations reveal that the fluorine dopant changes the charge distribution on the oxygen containing functional groups in graphene oxide, resulting in the preferred selective adsorption and desorption of NH3 molecules. We believe that the remarkable NH3 sensing properties of CFGO and investigation by first-principles calculations would enlarge the possibility of functionalized 2D materials for practical gas sensing applications such as the IoT.

While silicon (Si) is considered to be an excellent candidate for next-generation lithium ion battery (LIB) anodes due to its abundance and high gravimetric capacity, Si suffers from large volume expansion as a result of lithiation. Nanowires (NWs) allow for radial expansion and strain release. Due to this volume expansion, the formation of bulk-like Si structures during the NWs growth process significantly degrades battery performance. Here we report suppression of bulk-like Si formation by interfacial energy contrast between the NWs nucleation catalysts (spontaneously formed gold (Au) nanodots) and titanium nitride (TiN) films. The TiN film promoted a narrow distribution of Si NWs’ diameters and a direct electrical connection to the stainless steel current collector. The characteristics of the solid electrolyte interphase and lithiation/charge transfer mechanisms in Si NWs were also investigated using electrochemical impedance spectroscopy (EIS). The EIS data suggest that the impedance to lithium diffusion within the NWs is approximately 40 % smaller in the NWs grown on TiN than the NWs grown directly on stainless steel. LIB anodes fabricated with the Au-catalyzed Si NWs on TiN films displayed enhanced specific gravimetric capacities (>30 %) under diverse charge/discharge rates and significantly improved capacity retention over 500 cycles.

Graphene is one of the most promising materials for high-performance gas sensors due to its unique properties such as high sensitivity at room temperature, transparency, and flexibility. However, the low selectivity and irreversible behavior of graphene-based gas sensors are major problems. Here, we present unprecedented room temperature hydrogen detection by Au nanoclusters supported on self-activated graphene. Compared to pristine graphene sensors, the Au-decorated graphene sensors exhibit highly improved gas-sensing properties upon exposure to various gases. In particular, an unexpected substantial enhancement in H2 detection is found, which has never been reported for Au decoration on any type of chemoresistive material. Density functional theory calculations reveal that Au nanoclusters on graphene contribute to the adsorption of H atoms, whereas the surfaces of Au and graphene do not bind with H atoms individually. The discovery of such a new functionality in the existing material platform holds the key to diverse research areas based on metal nanocluster/graphene heterostructures.

Two-dimensional (2D) molybdenum disulfide (MoS2) has been attracting rapidly increasing interest for application in chemoresistive gas sensors owing to its moderate band gap energy and high specific surface area. However, the mechanism of chemoresistive sensing via the adsorption and desorption of gas molecules and the influence of the shape of 2D materials are not well understood yet. Herein we investigate the oxygen sensing behavior of MoS2 microflakes and nanoparticles prepared by mechanical and liquid exfoliation, respectively. Liquid-exfoliated MoS2 nanoparticles with an increased number of edge sites present high and linear responses to a broad range of oxygen concentrations (1–100%). The energetically favorable oxygen adsorption sites, which are responsible for reversible oxygen sensing, are identified by first-principles calculations based on density functional theory. This study serves as a proof-of-concept for the gas sensing mechanism depending on the surface configuration of 2D materials and broadens the potential of 2D MoS2 in gas sensing applications.

Graphene is considered as one of leading candidates for gas sensor applications in the Internet of Things owing to its unique properties such as high sensitivity to gas adsorption, transparency, and flexibility. We present self-activated operation of all graphene gas sensors with high transparency and flexibility. The all-graphene gas sensors which consist of graphene for both sensor electrodes and active sensing area exhibit highly sensitive, selective, and reversible responses to NO2 without external heating. The sensors show reliable operation under high humidity conditions and bending strain. In addition to these remarkable device performances, the significantly facile fabrication process enlarges the potential of the all-graphene gas sensors for use in the Internet of Things and wearable electronics.

Reduced graphene oxide (rGO) is one of the promising sensing elements for high-performance chemoresistive sensors because of its remarkable advantages such as high surface-to-volume ratio, outstanding transparency, and flexibility. In addition, the defects on the surface of rGO, including oxygen functional groups, can act as active sites for interaction with gaseous molecules. However, the major drawback of rGO-based sensors is the extremely sluggish and irreversible recovery to the initial state after a sensing event, which makes them incapable of producing repeatable and reliable sensing signals. Here, we show that pristine GO can be used as the active sensing material with reversible and high response to NO 2 at room temperature. First-principles calculations, in conjunction with experimental results, reveal the critical role of hydroxyl groups rather than epoxy groups in changing metallic graphene to the semiconducting GO. We show that the adaptive motions of the hydroxyl groups, that is, the rotation of these groups for the adsorption of NO 2 molecules and relaxation to the original states during the desorption of NO 2 molecules, are responsible for the fast and reversible NO 2 sensing behavior of GO. Our work paves the way for realizing high-response, reversible graphene-based room-temperature chemoresistive sensors for further functional convergence.

Vertically ordered SnO2 nanorods with Au nanoparticles deposited in multiple steps, namely, SnO2 nanobamboos are synthesized by a glancing-angle deposition technique. The highly ordered porous structures enable us to detect sub-ppb levels of volatile reducing gases with a fast response speed by maximizing the sensitization effects of the Au nanoparticles.

WO3 nanoigloos decorated with Ag-, Pd-, and Au nanoparticles are fabricated by soft-template method and self-agglomeration of metal films. The responses of WO3 nanoigloos decorated with metal nanoparticles to various gases such as NO2, CH3COCH3, C2H5OH, and H2 are much higher than those of bare WO3 nanoigloos. According to the surface decoration, WO3 nanoigloos show significantly different behaviors in the response enhancement, revealing that Pd-decorated WO3 nanoigloos exhibit the highest response to H2 together with fast response time to H2, C2H5OH, and CH3COCH3 (below 10 s), Au-decorated WO3 nanoigloos exhibit the highest response to NO2. The catalytic effect of Ag is relatively weaker than Pd and Au nanoparticles, however, it exhibit the fastest response time to NO2. These are attributed to not only the varied catalytic activities of the metal nanoparticles, but also the different work function energies of them. Our results show that highly sensitive and selective WO3 nanoigloos decorated with metal nanoparticles can be an effective platform to fabricate an electronic nose for the further application of semiconducting metal oxide gas sensors.

One of surgical complications in cochlear implantation is the necrosis of the skin flap above the receiver-stimulator coil. We present a case of 55-year-old woman who underwent cochlear implantation and developed a bluish skin necrosis due to bone marking. The planned position for the receiver-stimulator was marked using methylene blue through skin to bone. She did not undergo skin flap thinning and underwent successful implantation with complete electrode insertion. Few weeks postoperatively, the patient developed bluish discoloration with progressive thick, blue eschar formation and skin flap necrosis. She subsequently underwent wound debridement and skin flap closure. Cochlear explantation was not necessary. Timely diagnosis and management about this complication is necessary to prevent further skin breakdown and subsequent device extrusion. This report identifies the marking using methylene blue as another possible source of skin flap necrosis in cochlear implantation, and surgeons should be aware of this potential complication.

Developing simple, low-cost, sensitive, and reliable gas sensors has been attracting great attraction due to promising applications to handheld devices such as smartphones, tablet computers, and remote air quality control. Simplicity in operation, high sensitivity, low cost, flexibility in production, and small size make chemoresistive gas sensors based on semiconducting materials including metal oxides and carbon nanomaterials as the prime candidate for the use in handheld devices over other types of gas sensors. In this chapter, we introduce the heaterless operation of chemoresistive gas sensors based on nanostructured metal oxide thin films to lower power consumption. Furthermore, we propose a route to develop high-performance chemoresistive gas sensors using 2-dimensional nanomaterials such as graphene, transition metal disulfide, and metal oxide nanosheets for room temperature operation which can dramatically reduce the power consumption.

One of the top design priorities for semiconductor chemical sensors is developing simple, low cost, sensitive and reliable sensors to be built in handheld mobile devices. In this chapter, we discuss critical issues for the realization of miniaturized and integrated chemoresistive thin film sensors based on metal oxides and introduce notable recent achievements.

Transition metal disulfides have been attracting significant attentions in recent years. There are extensive applications of transition metal disulfides, especially on gas sensing applications, due to their large specific surface-to-volume ratios, high sensitivity to adsorption of gas molecules and tunable surface functionality depending on the decoration species or functional groups. However, there are several drawbacks such as poor gas selectivity, sluggish recovery characteristics and difficulty in the fabrication of large-scale devices. Here, we provide a review of recent progress on the chemoresistive gas sensing properties of two-dimensional transition metal disulfides. This review also provides various methods to enhance the gas sensing performance of two-dimensional disulfides, such as surface functionalization, decoration receptor functions and developing nanostructures.

Background Otolaryngologists encounter cases of various foreign bodies in the oral and pharyngeal regions. One commonly found foreign body is a fish bone, ingested in most cases by carelessness or an accident. These foreign materials are removed by endoscopy or through a simple procedure. However, hypopharyngeal damage is rarely caused by a foreign body in the pharynx following the swallowing of a toothbrush. Case presentation A 44-year-old Asian male visited the emergency room with chief complaints of intraoral pain and dysphagia that had started on the same day. The patient had paranoid-type schizophrenia that began 10 years ago; he had been hospitalized and was being treated at another clinic, and was transferred to the emergency room by the medical staff after swallowing a toothbrush. We successfully removed a toothbrush located within the pharynx of a patient with a history of a psychologic disorder via surgery and conservative treatment. Conclusion The case with this patient, and a rapid diagnosis as well as treatment is imperative. The presence and state of a foreign body must be determined through a careful physical examination and imaging, followed by the immediate removal of the foreign body, all while keeping in mind the possibility of accompanying damage to nearby tissues.

The decoration of p-type nickel oxide (NiO) with n-type hematite (α-Fe2O3) to achieve vertically ordered 1D nanostructures is an attractive strategy to enhance gas sensing properties. Herein, the authors report a facile method for α-Fe2O3 decoration of the whole surface of vertical NiO nanorods. An NiO/Fe heterostructure is deposited in multiple steps using a glancing angle deposition method, which is followed by the oxidation of Fe into α-Fe2O3. Thermally agglomerated α-Fe2O3 nanoparticles are uniformly distributed on the whole surface of the NiO nanorods. Due to the α-Fe2O3 decoration, the NiO nanorods exhibit a coral-like rough surface and, more interestingly, their preferential crystallographic orientation changed from (111) to (200). Compared to bare NiO nanorods, the α-Fe2O3-decorated NiO nanocorals exhibit a 45.4 times higher response to 50 ppm toluene (C7H8) at 350 °C. Their theoretical detection limit for C7H8 is calculated to be ≈22 ppb. The observed unprecedented synergetic effects of α-Fe2O3-decorated NiO nanocorals for the extremely selective C7H8 sensing, as well as their facile synthetic route, establish a new perspective on heterostructured metal oxide 1D nanostructures for selective gas sensing.

Purpose Although the concept of "one airway, one disease," which includes the middle ear space as part of the united airway is well recognized, the role of allergens in otitis media with effusion (OME) is not clearly understood. We aimed to investigate the effect of the interaction between Dermatophagoides farinae (Der f) and lipopolysaccharide (LPS) on the induction of epithelial inflammatory response in vitro. Methods Primary human middle ear epithelial cells were exposed to Der f, LPS, or both in different sequences, and the magnitude of the immunologic responses was compared. The mRNA expressiona of mucin (MUC) 4, 5AC, 5B, 8, GM-CSF, TNF-α, TLR4, and MD-2 were evaluated using real-time PCR. MUC levels before and after siRNA-mediated knockout of TLR4 and MD-2 were assessed. Lastly, the involved cell signaling pathway was evaluated. Results The expressiona of cytokines, and the MUC 4, 5AC, 5B, and 8 genes were augmented by pretreatment with Der f followed by LPS; however, reverse treatment or combined treatment did not induce the same magnitude of response. Increased MUC expression was decreased by TLR4 knockdown, but not by MD-2 knockdown. The signal intensity of MUC 8 was higher in MD-2 over-expressed cells than in those exposed to LPS only. The translocation of nuclear factor-κB was observed in cells pretreated with Der f followed by LPS. Conclusions When Der f treatment preceded LPS exposure, Der f and LPS acted synergistically in the induction of pro-inflammatory cytokines and the MUC gene, suggesting an important role in the development of OME in patients with concealed allergy airway sensitization.