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In our previous work, the detailed crystal structure, optical and electrical properties of evaporated CdS (hexagonal CdS) and chemical bath deposition CdS (cubic CdS) were discussed. The hexagonal CdS film is more suitable as the buffer layer for Sb2Se3 film solar cells compared with its cubic counterpart. However, in our experiments, the influence of high annealing temperature on hexagonal CdS is difficult to control. Moreover, hexagonal CdS is unsuitable for large-area industrial production of Sb2Se3 solar cells. In this study, an electron beam evaporation-prepared CdS buffer layer (hexagonal CdS) with high quality, uniformity and low-temperature treatment was introduced in Sb2Se3 thin film solar cells. The influence of different substrate temperatures during electron beam evaporation on the crystal structure, surface morphologies, and optical properties of CdS and Sb2Se3 films was investigated. The device performance improvement from 3.52% to 5.89% was obtained after the surface roughness of the CdS film and the heterojunction interface were optimised. Lastly, the efficiency of the Sb2Se3 solar cells was obtained to be 6.71% based on the structure of FTO/EB-CdS/Sb2Se3/MoO3/Au.

Background: Distant metastasis is the major cause of treatment failure in locally advanced rectal cancer (LARC). Adjuvant chemotherapy (AC) is usually used for distant control. However, only certain subgroups of patients could benefit from AC. Our aim was to develop a radiomics model for the prediction of survival and chemotherapeutic benefits using pretreatment multiparameter MR images and clinicopathological features in patients with LARC. Methods: 186 consecutive patients with LARC underwent feature extraction from the whole tumor on T2-weighted (T2w), contrast enhanced T1-weighted (cT1w), and ADC images. Feature selection was based on feature stability and the Boruta algorithm. Radiomics signatures for predicting DFS (disease-free survival) were then generated using the selected features. Combining clinical risk factors, a radiomics nomogram was constructed using Cox proportional hazards regression model. The predictive performance was evaluated by Harrell's concordance indices (C-index) and time-independent receiver operating characteristic (ROC) analysis. Results: Four features were selected to construct the radiomics signature, which was significantly associated with DFS (P < 0.001). The radiomics nomogram, incorporating radiomics signature and two clinicopathological variables (pN and tumor differentiation), exhibited better prediction performance for DFS than the clinicopathological model, with C-index of 0.780 (95%CI, 0.718-0.843) and 0.803 (95%CI, 0.717-0.889) in the training and validation cohorts, respectively. The radiomics nomogram-defined high-risk group had a shorter DFS, DMFS, and OS than those in the low-risk group (all P Conclusion: This study demonstrated that the newly developed pretreatment multiparameter MRI-based radiomics model could serve as a powerful predictor of prognosis, and may act as a potential indicator for guiding AC in patients with LARC.

Cost and fabrication technique, as two important factors affecting the development and practical applications of electronic devices, have attracted extensive attention of researchers. In order to o...

Objective: To develop and validate a radiomics predictive model based on multiparameter MR imaging features and clinical features to predict lymph node metastasis (LNM) in patients with cervical cancer. Material and Methods: A total of 168 consecutive patients with cervical cancer from two centers were enrolled in our retrospective study. A total of 3,930 imaging features were extracted from T2-weighted (T2W), ADC, and contrast-enhanced T1-weighted (cT1W) images for each patient. Four-step procedures, mainly minimum redundancy maximum relevance (MRMR) and least absolute shrinkage and selection operator (LASSO) regression, were applied for feature selection and radiomics signature building in the training set from center I (n = 115). Combining clinical risk factors, a radiomics nomogram was then constructed. The models were then validated in the external validation set comprising 53 patients from center II. The predictive performance was determined by its calibration, discrimination, and clinical usefulness. Results: The radiomics signature derived from the combination of T2W, ADC, and cT1W images, composed of six LN-status-related features, was significantly associated with LNM and showed better predictive performance than signatures derived from either of them alone in both sets. Encouragingly, the radiomics signature also showed good discrimination in the MRI-reported LN-negative subgroup, with AUC of 0.825 (95% CI: 0.732–0.919). The radiomics nomogram that incorporated radiomics signature and MRI-reported LN status also showed good calibration and discrimination in both sets, with AUCs of 0.865 (95% CI: 0.794–0.936) and 0.861 (95% CI: 0.733–0.990), respectively. Decision curve analysis confirmed its clinical usefulness. Conclusion: The proposed MRI-based radiomics nomogram has good performance for predicting LN metastasis in cervical cancer and may be useful for improving clinical decision making.

BACKGROUND Although histological examination is the standard method for assessing genetic status, the development of a noninvasive method, which can display the heterogeneity of the whole tumor to supplement genotype analysis, might be important for personalized treatment strategies. PURPOSE To evaluate the potential role of diffusion kurtosis imaging (DKI)-derived parameters using histogram analysis derived from whole-tumor volumes for prediction of the status of KRAS mutations in patients with rectal adenocarcinoma. STUDY TYPE Retrospective. SUBJECTS In all, 148 consecutive patients with histologically confirmed rectal adenocarcinoma who were treated at our institution. SEQUENCE DKI was performed with a 3.0 T MRI system using a single-shot echo-planar imaging sequence with b values of 0, 700, 1400, and 2100 sec/mm2 . ASSESSMENT D, K, and apparent diffusion coefficient (ADC) values were measured using whole-tumor volume histogram analysis and were compared between different KRAS mutations status. STATISTICAL TESTS Student's t-test or Mann-Whitney U-test, and receiver operating characteristic (ROC) curves were used for statistical analysis. RESULTS All the percentile metrics of ADC and D values were significantly lower in the mutated group than those in the wildtype group (all P 0.05), while K-related percentile metrics were higher in the mutated group compared with those in the wildtype group (all P < 0.05). Regarding the comparison of the diagnostic performance of all the histogram metrics, K75th showed the highest AUC value of 0.871, and the corresponding values for sensitivity, specificity, positive predictive value, and negative predictive value were 81.43%, 78.21%, 77.03%, and 82.43%, respectively. DATA CONCLUSION DKI metrics with whole-tumor volume histogram analysis is associated with KRAS mutations, and thus may be useful for predicting the KRAS status of rectal cancers for guiding targeted therapy. LEVEL OF EVIDENCE 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:930-939.

An ultrasensitive self-powered ammonia (NH3) sensing system based on a vertical contact-separate mode triboelectric nanogenerator (TENG) has been proposed for room temperature detection of NH3 concentrations both in the ambient environment and in human exhaled gases. Owing to the special output characteristics of the TENG adjusted by the load resistance of the NH3 sensor, output voltage of the fabricated gas sensor has a proportional relationship with NH3 concentration, which is the fundamental working mechanism of the self-powered gas-sensing system. The triboelectric ammonia sensor (TEAS) based on PANI-MWCNTs composite thin film possesses a NH3-sensing response of 10% at 0.01 ppm NH3 and exhibits a great response of 255% at 100 ppm NH3. Meanwhile, the TEAS also holds fast response/recovery time (89–120 s/103–127 s for 0.6–100 ppm NH3), excellent long-term stability, satisfactory selectivity and good anti-bending ability. Furthermore, a preliminary test of human exhaled NH3 concentration has been carried out to further expand the practical application of the developed TEAS. The results not only provide an effective technique in ultrasensitive NH3 sensing but also greatly broaden the applicability of TENG in the detection of human kidney health through comparing to average NH3 concentrations within exhaled gases of healthy people.

Fully transparent electronics are of increasing interest for biological applications, where the combination of sensing and imaging can potentially improve patient healthcare diagnostics. Herein, we report high-performance, fully-transparent amorphous In-Ga-Zn-O field-effect transistor (a-IGZO FET) based biosensors fabricated directly on highly-curved glass substrates. The a-IGZO channel and indium tin oxide electrodes were patterned directly on glass tubes (1.0 mm radius) by microcontact printing self-assembled monolayers and etching the metal oxide films. This approach led to a-IGZO FETs with excellent electronic performance, with high on/off drain current ∼1.3 × 106, high average electron mobility > 7.4 cm2/Vs, low on/off hysteresis ∼0.6, V and low gate leakage current ∼10−10 A. The back-channel of the a-IGZO FETs were functionalized with glucose oxidase to make fully transparent biosensors with very high sensitivity to glucose. We have determined that the glucose limit of detection is 170 μM. These results provide insight into new methods for fabricating a-IGZO FETs and a-IGZO FET biosensors on non-planar substrates, and may open a range of new applications, including transparent sensing catheters, flexible active transparent electrode sensing arrays, and integration of FET based biosensors on optical fibers.

To develop and validate a radiomics predictive model based on pre-treatment multiparameter magnetic resonance imaging (MRI) features and clinical features to predict a pathological complete response (pCR) in patients with locally advanced rectal cancer (LARC) after receiving neoadjuvant chemoradiotherapy (CRT). One hundred and eighty-six consecutive patients with LARC (training dataset, n = 131; validation dataset, n = 55) were enrolled in our retrospective study. A total of 1,188 imaging features were extracted from pre-CRT T2-weighted (T2-w), contrast-enhanced T1-weighted (cT1-w) and ADC images for each patient. Three steps including least absolute shrinkage and selection operator (LASSO) regression were performed to select key features and build a radiomics signature. Combining clinical risk factors, a radiomics nomogram was constructed. The predictive performance was evaluated by receiver operator characteristic (ROC) curve analysis, and then assessed with respect to its calibration, discrimination and clinical usefulness. Thirty-one of 186 patients (16.7%) achieved pCR. The radiomics signature derived from joint T2-w, ADC, and cT1-w images, comprising 12 selected features, was significantly associated with pCR status and showed better predictive performance than signatures derived from either of them alone in both datasets. The radiomics nomogram, incorporating the radiomics signature and MR-reported T-stages, also showed good discrimination, with areas under the ROC curves (AUCs) of 0.948 (95% CI, 0.907-0.989) and 0.966 (95% CI, 0.924-1.000), as well as good calibration in both datasets. Decision curve analysis confirmed its clinical usefulness. This study demonstrated that the pre-treatment radiomics nomogram can predict pCR in patients with LARC and potentially guide treatments to select patients for a “wait-and-see” policy. • Radiomics analysis of pre-CRT multiparameter MR images could predict pCR in patients with LARC. • Proposed radiomics signature from joint T2-w, ADC and cT1-w images showed better predictive performance than individual signatures. • Most of the clinical characteristics were unable to predict pCR.

Flexible nitrogen dioxide (NO2) gas sensors based on organic thin-film transistors (OTFTs) were developed in this work, in which conductive indium tin oxide (ITO) coated polyethylene naphthalene-2,6-dicarboxylate (PEN) was designed for the flexible substrates, and poly methyl methacrylate (PMMA) and poly(3-hexylthiophene) (P3HT) was spin-coated as the gate dielectric layer and spray-deposited as the active layer, respectively. The effects of PMMA concentrations and P3HT solution volume on performances of flexible OTFTs were systematically investigated. The results showed that the optimized flexible OTFT exhibited high field-effect mobility (9.51×10–3 cm2/(V s) at a gate bias of –50 V) and excellent response characteristics, including high sensitivity (up to 0.169 ppm–1), good repeatability and selectivity. The flexibility of the developed OTFT sensor was also investigated, and the results showed that the electrical and gas-sensing properties were affected by the bending cycles, thus further work should be done for improving the flexibility of the sensor. This work provides an effective approach in developing high performance flexible OTFT NO2 gas sensor.

The triboelectric nanogenerator (TENG) driven self-powered gas sensor has been developed for room temperature nitrogen dioxide (NO2) detection under UV illumination (365 nm). Powered by TENG, the concentration of NO2 can be spontaneously detected via chemoresistive gas sensor based on Zinc Oxide-Reduced graphene oxide (ZnO-RGO) hybrid films, where the voltage drop across the interdigital electrodes (IDEs) has a proportional relationship with NO2 concentration. The self-powered triboelectric gas sensor (TGS) composed by ZnO-RGO composite films exhibit superior response (~ 16.8) and sensitivity as well as selectivity than that for pure ZnO film. With respect to selectivity, the response of ZnO-RGO composite film based TGS to NO2 was at least 49-fold higher than those for other gases. Furthermore, through a signal processing circuit, a self-powered NO2 gas alert system was developed for real-time monitoring the ambient NO2 concentration. This work not only promotes the applicability of TENGs as self-powered sensors but also pushes forwards the active sensing network node for environmental monitoring by harvesting ambient energy.

In this work, a fundamental new approach for humidity detection was proposed. By coupling triboelectric nanogenerator (TENG) with resistive humidity sensor, the degree of ambient moisture can be actively detected at room temperature, where the voltage drops across the interdigital electrodes (IDEs) has a reversely proportional relationship with relative humidity. The prepared self-powered triboelectric humidity sensor (THS) holds high humidity response of ∼7, fast response/recovery time of 2.8 s and 3.5 s, stable repeatability and excellent long term stability. With respect to selectivity, the response of THS to gaseous water was at least 2-fold higher than those for other gases. Furthermore, through a signal processing circuit, a self-powered humidity alert system was developed for real-time monitoring the ambient humidity. Finally, the underlying working principle of the proposed sensor was discussed in detail. This research not only provides a simple, low-cost and efficient means in humidity sensing but also greatly broadens the applicability of TENGs as self-powered active sensors.

To investigate potential relationships between diffusion kurtosis imaging (DKI)-derived parameters using whole-tumour volume histogram analysis and clinicopathological prognostic factors in patients with rectal adenocarcinoma. 79 consecutive patients who underwent MRI examination with rectal adenocarcinoma were retrospectively evaluated. Parameters D, K and conventional ADC were measured using whole-tumour volume histogram analysis. Student’s t-test or Mann-Whitney U-test, receiver operating characteristic curves and Spearman’s correlation were used for statistical analysis. Almost all the percentile metrics of K were correlated positively with nodal involvement, higher histological grades, the presence of lymphangiovascular invasion (LVI) and circumferential margin (CRM) (p

Increasing light absorption is of crucial importance for optimizing light-activated gas detection. However, the relevant research is still rather rare. Herein, high performance NO 2 gas sensing with plasmonic Au NPs decorated ZnO (AuZnO) nanorod array under visible light illumination at room temperature is demonstrated. It is achieved by the localized surface plasmon resonance (LSPR) and increased surface oxygen vacancies. The influence of light wavelength on the sensing behaviors was systematically investigated. It is found that the Au NPs decoration can largely promote the visible-activated gas sensing behaviors. In addition, the as-prepared sensors demonstrate robustness toward repeatability and selectivity in NO 2 sensing properties. Moreover, the sensing mechanism based on LSPR was discussed.

Aerodynamic optimization based on computational fluid dynamics (CFD) is a powerful design approach because it significantly reduces the design time compared with the human manual design. However, CFD-based optimization can still take hours to converge because it requires repeatedly running computationally expensive flow simulations. To further shorten the design optimization time, we propose a fast, interactive design framework that allows us to complete an airfoil aerodynamic optimization within a few seconds. This framework is made efficient through a B-spline-based generative adversarial network model for shape parameterization, which filters out unrealistic airfoils for a reduced design space that contains all relevant airfoil shapes. Moreover, we use a combination of multilayer perceptron, recurrent neural networks, and mixture of experts for surrogate modeling to enable both scalar (drag and lift) and vector (pressure distribution) response predictions for a wide range of Mach numbers (0.3 to 0.7) and Reynolds numbers (104 to 1010). To verify our proposed framework, we compare the optimization results with the ones computed by direct CFD-based optimization for subsonic and transonic conditions. The results show that the optimal designs and the aerodynamic quantities (lift, drag, and pressure distribution) obtained by our proposed framework agree well with the ones computed by direct CFD-based optimizations and evaluations. The proposed framework is being integrated into a web-based interactive aerodynamic design framework that allows users to predict drag, lift, moment, pressure distribution, and optimal airfoil shapes for a wide range of flow conditions within seconds.

For a long time, the daily paper and carbon ink have been used for writing and painting. With the development of the electronic technology, they are expected to play new roles in electronic devices. Herein, combining the unique characteristics of the paper (rough surface, hydrophilicity) and carbon ink (conductivity), this work rationally proposed two low-cost, eco-friendly, flexible, multifunctional pressure and humidity sensors. The results show that as-fabricated paper-based (PB) pressure sensor has a good sensitivity of 0.614 kPa−1 in the pressure range of 0–6 kPa. The PB humidity sensor has a large response of ∼2120 (current ratio at 91.5% relative humidity (RH) and 0% RH). The PB pressure sensor is proven to be useful for multiple pressure related contact detections, and the PB humidity sensor can be used for many humidity related non-contact detections. Interestingly, combining the different detecting modes of pressure and humidity sensors, some same detecting functions (e.g. switch, respiratory frequency and speech recognition) are realized from contact to non-contact using PB pressure and humidity sensors, which greatly enhance the wearable comfort. Compared with previous reports, this work demonstrates a much simpler approach without expensive raw materials, toxic reagents and high temperature treatment to achieve outstanding sensing performances of the multifunctional pressure and humidity sensors.

A single-electrode-based segmented triboelectric nanogenerator (S-TENG) was developed. By utilizing the wind-induced vibration of a fluorinated ethylene propylene (FEP) film between two copper electrodes, the S-TENG delivers an open-circuit voltage up to 36 V and a short-circuit current of 11.8 μA, which can simultaneously light up 20 LEDs and charge capacitors. Moreover, the S-TENG holds linearity between output current and flow rate, revealing its feasibility as a self-powered wind speed sensor. This work demonstrates potential applications of S-TENG in wind energy harvester, self-powered gas sensor, high altitude air navigation.

A promising approach was proposed to enhance the responsivity of a ZnO nanowires array based photodetector with metal-semiconductor-metal structure through piezo-phototronic effect. The ZnO nanowires arrays were synthesized via hydrothermal method to function as both piezoelectric and light-trapping layer. The photoresponses of the ZnO nanowires based photodetector were tuned by the modulation of local Schottky barrier heights (SBH) at the metal-ZnO interfaces as a result of strain-induced polarization charges. Subjected to a −0.62% compressive strain, the responsivity of the prepared photodetector was increased by as much as 176%. Furthermore, the devices hydrothermally synthesized at 0.10 M have a larger photoresponse and higher stress sensitivity compared to the ones prepared at 0.05 M and 0.15 M. This work not only strengthens the fundamental understanding of piezo-phototronic effect on photodetectors but also provides an efficient means for optimization/improvement of piezoelectric semiconductor nanowires based optoelectronic devices.

For the fabrication of pyroelectric polyvinylidene fluoride (PVDF) film with high performance, a novel method is presented which combines the usual two steps of solution casting and stretching into one. It demonstrates that a stretch ratio as large as 15 as well as low quantity of defects and high uniformity are achieved by this new technique. The characterization results reveal that baking temperature (Tb) after stretching has significant and similar influences on relative β-phase fraction (Fβ), remnant polarization (Pr), dielectric constant and loss (e′ and e″) and pyroelectric coefficient of the samples; the highest pyroelectric coefficient, occurring at baking temperature of 80 °C without thermal poling, is 12.4 μC m−2 K−1, which is larger than that of the usually-stretched sample undergoing thermal poling. In addition, by using the prepared film as sensitive element, a novel chopperless pyroelectric infrared detector is constructed by electrostatically modulating the incident thermal irradiation; the measurement results demonstrate that the detector has excellent pyroelectric voltage response to the thermal radiation of the laser source and hot (warm) water with a sensitivity of 2.65 × 104 V/W, showing its good potential for fully flexible infrared detector and temperature sensor.

Polyvinylidene fluoride (PVDF) films possess multifunctional ability for piezo/pyro/ferroelectronic applications. One critical challenge of the traditional techniques is the complicated fabrication process for obtaining the poled films. In this work, the PVDF film is facilely prepared by the solution cast on hydrophilically treated substrates. The obtained PVDF films exhibit fairly good pyroelectricity comparable to those fabricated by thermal poling, indicating the film is self-polarized. This result is attributed to the hydrogen-bonding-induced orderly arrangement of the first sub-nanolayer at the bottom, which serves as a “seed layer” and triggered alignment of the rest of the film in a layer-by-layer approach. Additionally, to suppress the piezoelectric noise, a pyroelectric sensor with a novel bilayer structure is developed using the as-prepared PVDF film. Compared with the conventional monolayer sensor, the signal-to-noise ratio of the bilayer one is drastically improved to 38 dB from 18 dB. The above results provide great possibilities for achieving a high-performance wearable pyroelectric sensor with reduced cost and simple procedures. Electronic supplementary material The online version of this article (10.1186/s11671-019-2906-1) contains supplementary material, which is available to authorized users.

Introduction Human respiration is rich in physiological and pathological information as biomarker for health assessment and illness prediction. Respiratory diagnosis method carries various advantages, such as continuity, non-invasiveness, comfort and user-friendly [6]. Typically, ammonia (NH3) in exhaled breath can be served as biomarker for some diseases like end-stage renal disease (ESRD), ulcers caused by Helicobacter pylori or bacterial in oral cavity [12-15]. NH3 concentration in healthy people’ exhaled breath is about 0.425-1.8 ppm (mean 0.96 ppm), while the one in ESRD patients’ breathing ranges from 0.82 to14.7 ppm (mean 4.88 ppm) [12]. Even though various traditional sensors have been applied to monitor human physiological information like heartbeat or respiration, some limitations, such as bulky structure, poor portability and requirement of external power sources remarkably restricted their widespread application in smart mobile medical electronics [16]. Therefore, a self-powered ammonia sensor that can harvest energy from human body is desperately needed. In addition, it is underexplored but will be a novel and superior solution if a wearable sensor that could simultaneously chemically detect the inhalation and measure the breath rate for respiration analysis without a power supply. Device fabrication The as-developed triboelectric self-powered respiration sensor (TSRS) is composed of Ce-doped ZnO, Polydimethylsiloxane (PDMS), Au foils and PET films, as revealed in Fig. 1a. Ce-doped ZnO plays dual roles of gas sensing material and triboelectrification layer (Fig. 1b). PDMS functions as the triboelectric layer and Au foils were coated on the back of both triboelectric layers as electrodes. To improve the flexibility and air tightness, the whole device was packed with soft silica gel films. The patterned PDMS film exhibits good transparency and flexibility, as shown in Fig. 1c and 1d. Figure 1e sketches the fabrication flow of the TSRS. Driven by the continuous expansion and contraction of the chest during respiration (Fig. 1g), the deformation of TSRS inflated can be converted into electric signals and human exhaled gas can flow into the TSRS through a soft tube with the breathing process, enabling the real-time spontaneous monitoring of both respiratory behaviors and exhaled gas. Method To explore the sensing behavior of as-prepared TSRS toward NH3 from 0.1 to 10 ppm, including the trace level region (region Ⅰ, 0.1 to 1 ppm) and micro level region (region Ⅱ, 2 to 10 ppm), the NH3-sensing response-concentration fitting curves are plotted in Fig. 2a for five samples. It is found that without moisture atmosphere, the TSRS exhibits an opposite sensing behavior and the response declines with increasing ammonia concentration in both region Ⅰ (Fig. 2e) and region Ⅱ (Fig. 2f). A steeper slope is observed under humid NH3 atmosphere in comparison with the dry NH3 atmosphere, indicating that the existence of water molecular will raise the sensing performance. As a consequence, the moisture-resistant feature of the as-developed TSRS favours NH3 detection in human exhaled gas. Figure 2g elucidates dynamic response profile of TSRS when exposed to 0.01 ppm NH3 with 97.5%RH, which indicates that the TSRS is sensitive to NH3 as low as 0.01 ppm and the response time is nearly 155 s. Results and Conclusions Attached on the human chest, the as-prepared TSRS delivers a stable output voltage signal within 5 min normal breathing (Fig. 3a). The wearable sensor can be applied to distinguish different types of breathing behaviors and human respiratory states after physical exercise. Figure 3b presents the real-time output recording of diverse breathing behaviors, including normal breathing, deep breathing, shallow breathing and rapid breathing. Human respiration rate and depth can be clearly recognized in terms of frequency and amplitude of the output voltage signals. The deep breathing pattern has a bigger peak-to-peak amplitude and wider interval than normal breathing pattern due to the larger and slower change in chest circumference. In addition, the physiological process of human body after exercise can also be accurately reflected by breathing intensity and frequence. The breathing amplitude after 100 squats is more intense than that after 50 squats, as displayed in Fig. 3c. Meanwhile, the injection of exhaled NH3 gas into the TSRS apparently enlarges the amplitude of the output voltage (Fig. 3d), revealing the capability of simultaneously detecting breathing behaviors and exhaled gases. References [1] M. Righettoni, A. Amann, S.E. Pratsinis, Breath analysis by nanostructured metal oxides as chemo-resistive gas sensors, Materials Today. 18 (2015) 163–171. doi:10.1016/j.mattod.2014.08.017 [2] P. Le Maout, J.L. Wojkiewicz, N. Redon, C. Lahuec, F. Seguin, L. Dupont, , Polyaniline nanocomposites based sensor array for breath ammonia analysis. Portable e-nose approach to non-invasive diagnosis of chronic kidney disease, Sens. Actuators, B Chem. 274 (2018) 616 –626. doi:10.1016/j.snb.2018.07.178 [3] S. Wang, H. Tai, B. Liu, Z. Duan, Z. Yuan, H. Pan, Y. Su, G. Xie, X. Du, Y. Jiang, A Facile Respiration-Driven Triboelectric Nanogenerator for Multifunctional Respiratory Monitoring, Nano Energy. 58 (2019) 312–321. doi:10.1016/j.nanoen.2019.01.042 [4] Y. Jung, H.G. Moon, C. Lim, K. Choi, H.S. Song, S. Bae, S.M. Kim, M. Seo, T. Lee, S. Lee, H.H. Park, S.C. Jun, C.Y. Kang, C. Kim, Humidity-Tolerant Single-Stranded DNA-Functionalized Graphene Probe for Medical Applications of Exhaled Breath Analysis, Advanced Functional Materials. 27 (2017) 1–9. doi:10.1002/adfm.201700068 Figure 1

Multifidelity methods are introduced to the nondestructive evaluation (NDE) of measurement systems. In particular, Cokriging interpolation metamodels of physics-based ultrasonic testing (UT) simulation responses are utilized to accelerate the uncertainty propagation in model-assisted NDE. The proposed approach is applied to a benchmark test case of UT simulations and compared with the current state-of-the-art techniques. The results show that Cokriging captures the physics of the problem well and is able to reduce the computational burden by over one order of magnitude compared to the state of the art. To the best of the author’s knowledge, this the first time multifidelity methods are applied to model-assisted NDE problems.

Amorphous indium gallium zinc oxide (IGZO) field effect transistors (FETs) are a promising technology for a wide range of electronic applications. Herein, we fabricated and characterized FETs with a nanostructured IGZO network as a sensing transducer. The IGZO was patterned using colloidal lithography and electrohydrodynamic printing, where an 8 μm wide nanostructured close-packed hexagonal IGZO network was obtained. Electrical characterization of the nanostructured IGZO network FET demonstrated a drain–source current on–off ratio of 6.1 × 103 and effective electron mobilities of 3.6 cm2 V−1 s−1. The nanostructured IGZO network was functionalized by aminosilane groups with cross-linked glucose oxidase. The devices demonstrated a decrease in drain–source conductance and a more positive VON with increasing glucose concentration. These changes are ascribed to the acceptor-like surface states associated with positively charged aminosilane groups attached to the nanostructured IGZO surface. Continuous monitoring of the drain–source current indicates a stepwise and fully reversible response to glucose concentrations with a short response time. The specific catalytic reaction between the GOx enzyme and glucose eliminates interference from acetaminophen/ascorbic acid. We demonstrate that nanostructured IGZO FETs have improved sensitivity compared to non-nanostructured IGZO for sensing glucose and can be potentially extended to other biosensor technologies.

To investigate the feasibility of using Spectral CT imaging with low contrast medium in abdominal CT angiography (CTA).70 consecutive patients (40 men, 42.6 ± 20.4 years; 30 women, 46.7 ± 18.8 years) with suspected abdominal focal lesions were referred to CTA exam. They were randomly assigned into two groups. Group A: 35 patients underwent conventional CT scan of Tube voltage 120 kVp, automatic current modulation with a Noise Index of 12, ASIR 30%, and injected with Iohexol (350 mgI/ml). Group B: 35 patients underwent Spectral CT Imaging, with Tube current of 600 mA, injected with Iodixanol (270 mgI/ml). The optimal mono-energy keV was achieved using the optimal contrast noise ratio in abdominal aorta at the renal artery level relative to the erector spine muscle. Both groups were injected with an injection rate of 3.5 ml/s, and a contrast volume of 1.5 ml/kg body weight. The Hounsfield units (HU) and noise of the bilateral renal arteries and muscle of both groups, as well as the optimal monochromatic image set of Group B were measured. Two radiologists assessed all images with a 5-points scale. CTDIvol and DLP were recorded. Data were analyzed using student t test.The total iodine intake of Group B was 28% lower than that of Group A. The CNR of abdomen artery, celiac trunk, superior mesenteric artery, and renal artery in spectral group (at the best mono-energy of 53.0 keV) were higher than those in conventional CTA group (p 0.001). The subjective image quality score of spectral CTA group was also rated higher than conventional CTA group (p 0.001). CTDIvol, DLP, and effective dose of spectral group were all lower than conventional group, but there were no significant differences (p 0.05).With 28% contrast medium reduction and reduced radiation dose, CT angiography using spectral imaging and lower concentration contrast agent provided better image quality than conventional CTA.

Wetting states of droplets on partially micro-grooved surfaces were investigated. Grooves were fabricated using soft lithography and the width of the grooves was smaller than the droplet diameter. On the partially micro-grooved surfaces, the apparent contact angle parallel to the grooves is larger than the one on the smooth surface, while the microstructures have little effect on the contact angle perpendicular to the grooves. Increasing the fraction of the grooved area and the surface energy of the surface will result in a more anisotropic droplet. When a droplet impinged upon these partially grooved surfaces, the spreading process was similar to that on a smooth surface. However, the recoiling process was found to be quite anisotropic. The grooves enhanced the recoiling velocity in the direction parallel to the grooves while hindering the recoiling process in the perpendicular direction. The recoiling process will become more anisotropic by increasing the fraction of the grooved area. The effect of the grooves on both the contact angle and the impinging process is independent of the groove width scale and is only dependent on the fraction of the grooved area in the Cassie state.

The paper presents a computational framework for assessing quantitatively the detection capability of structural health monitoring (SHM) systems for flat plates. The detection capability is quantified using the probability of detection (POD) metric, developed within the area of nondestructive testing, which accounts for the variability of the uncertain system parameters and describes the detection accuracy using confidence bounds. SHM provides the capability of continuously monitoring the structural integrity using multiple sensors placed sensibly on the structure. It is important that the SHM can reliably and accurately detect damage when it occurs. The proposed computational framework models the structural behavior of flat plate using a spring-mass system with a lumped mass at each sensor location. The quantity of interest is the degree of damage of the plate, which is defined in this work as the difference in the strain field of a damaged plate with respect to the strain field of the healthy plate. The computational framework determines the POD based on the degree of damage of the plate for a given loading condition. The proposed approach is demonstrated on a numerical example of a flat plate with two sides fixed and a load acting normal to the surface. The POD is estimated for two uncertain parameters, the plate thickness and the modulus of elasticity of the material, and a damage located in one spot of the plate. The results show that the POD is close to zero for small loads, but increases quickly with increasing loads.

Probability of detection (POD) is used for reliability analysis in nondestructive testing (NDT) area. Traditionally, it is determined by experimental tests, while it can be enhanced by physics-based simulation models, which is called model-assisted probability of detection (MAPOD). However, accurate physics-based models are usually expensive in time. In this paper, we implement a type of stochastic polynomial chaos expansions (PCE), as alternative of actual physics-based model for the MAPOD calculation. State-of-the-art least-angle regression method and hyperbolic sparse technique are integrated within PCE construction. The proposed method is tested on a spherically-void-defect benchmark problem, developed by the World Federal Nondestructive Evaluation Center. The benchmark problem is added with two uncertainty parameters, where the PCE model usually requires about 100 sample points for the convergence on statistical moments, while direct Monte Carlo method needs more than 10000 samples, and Kriging based Monte Carlo method is oscillating. With about 100 sample points, PCE model can reduce root mean square error to be within 1% standard deviation of test points, while Kriging model cannot reach that level of accuracy even with 200 sample points.

In this work, a fundamental new approach for humidity detection was proposed. By coupling triboelectric nanogenerator (TENG) with resistive humidity sensor, the degree of ambient moisture can be actively detected at room temperature, where the voltage drop across the interdigital electrodes (IDEs) has a reversely proportional relationship with relative humidity. The prepared self-powered triboelectric humidity sensor (THS) holds high humidity response of ∼7, fast response/recovery time of 2.8 s and 3.5 s, stable repeatability and excellent long term stability. With respect to selectivity, the response of THS to gaseous water was at least 2-fold higher than those for other gases. Furthermore, through a signal processing circuit, a self-powered humidity alert system was developed for real-time monitoring the ambient humidity. Finally, the underlying working principle of the proposed sensor was discussed in detail. This research not only provides a simple, low-cost and efficient means in humidity sensing but also greatly broadens the applicability of TENGs as self-powered active sensors.

This work introduces multifidelity metamodeling for reliability analysis of nondestructive testing (NDT) systems. Specifically, the Cokriging metamodel is utilized to accelerate the uncertainty propagation within model-assisted probability of detection (MAPOD) analysis of ultrasonic testing (UT) systems. The Cokriging multifidelity metamodel fuses a limited amount of data obtained from high-fidelity (HF) physics-based UT models, which are accurate but time-consuming to evaluate, with a conservative to large amount of data from low-fidelity (LF) physics-based UT models, which are less accurate but faster to evaluate. The resulting Cokriging metamodel is fast to evaluate and yields an accurate estimate of the output of the HF model. The proposed approach is demonstrated on three benchmark UT MAPOD cases involving spherically-void and pill-box shaped defects in flat aluminum plates using planar and focused transducers. The results show that a two-level Cokriging metamodel is capable of yielding estimations of the HF model that are globally accurate within 1% of the standard deviation of the testing points. Furthermore, the result show that the Cokriging metamodeling approach needs around one order of magnitude fewer training data points when compared to the current state-of-the-art approaches that rely on metamodels constructed with Kriging.

Nitrogen dioxide sensors with high sensitivity and low energy consumption are demanded for atmosphere sensing networks. Here, a self-powered room temperature NO2 sensor has been developed based on the conjugation between the triboelectric and photoelectric effect. By converting the mechanical motions into electricity, a triboelectric nanogenerator (TENG) serves as a power source to simultaneously drive chemoresistive gas sensing and UV illumination. Under a 5 Hz external impact, the output voltage drop across interdigital electrodes has a proportional relationship with the NO2 concentration. A self-powered optomechatronic gas sensor (OGS) with hydrothermal ZnO nanowires synthesized at a concentration of 0.035 mol/l exhibits a superior response (∼14.8) and sensitivity (0.302 ppm−1) than those synthesized at other concentrations. Furthermore, the influence of the external force frequency and rectification on the gas sensing properties was systematically investigated. It is found that the TENG induced built-in electric field can effectively modulate the internal quantum efficiency and thus the sensing performance of OGSs. This work not only paves the way for constructing self-powered optomechatronic devices and systems but also pushes forward the active multifunctional network node for environmental monitoring.

Supercapacitor have attracted much attention due to its fast power supply, long cycle life, simple principle, etc. Supercapacitors are widely used in consumer electronics. Activated carbon is a typical material for electric double layer capacitor. Here, we study the electrochemical performance of an activated carbon (TF-B520) bulky paper electrode made by vacuum filtration method. Cyclic Voltammetry and Constant Current Charge/Discharge were used to test the electrode capacitance and the rate performance. The results showing that TF-B520 activated carbon balky paper electrodes have the highest capacitance of 120F/g at scan rate 1mV/s and good capacitor behaviour at scan rate below 20mV/s and current density below 250mA/g.

This study details the use of printing and other additive processes to fabricate a novel amperometric glucose sensor. The sensor was fabricated using a Au coated 12.7 μm thick polyimide substrate as a starting material, where micro-contact printing, electrochemical plating, chloridization, electrohydrodynamic jet (e-jet) printing, and spin coating were used to pattern, deposit, chloridize, print, and coat functional materials, respectively. We have found that e-jet printing was effective for the deposition and patterning of glucose oxidase inks with lateral feature sizes between ~5 to 1000 μm in width, and that the glucose oxidase was still active after printing. The thickness of the permselective layer was optimized to obtain a linear response for glucose concentrations up to 32 mM and no response to acetaminophen, a common interfering compound, was observed. The use of such thin polyimide substrates allow wrapping of the sensors around catheters with high radius of curvature ~250 μm, where additive and microfabrication methods may allow significant cost reductions.

Here a promising approach is proposed to enhance the responsivity of a ZnO nanowires array based photodetector with metal-semiconductor-metal structure through piezo-phototronic effect. The ZnO nanowires arrays were synthesized on the surface of ZnO seedlayer via hydrothermal method. Using polarization charges created at metal-ZnO interface under strain to modulate the local Schottky barrier height (SBH), the responsivity of the prepared photon sensor was increased by as much as 107% when the device was subjected to a −0.67% compressive strain. This work not only strengthens the fundamental understanding of piezo-phototronic effect on photodetectors but also provides an efficient means for optimization/improvement of piezoelectric semiconductor nanowires based optoelectronic devices.

Superhydrophobic patterns were fabricated on hydrophilic surfaces by selective painting. The impinging process of water droplets on these hybrid surfaces was investigated. The droplet can be split by impinging on the hydrophilic surface with a single stripe at a high velocity. The time to split the droplet is independent of the impact velocity and it is smaller than the contact time of a droplet impinging on the fully superhydrophobic surface. The volume ratios of the split mini-droplets could be precisely controlled by adjusting the landing position of the original droplet. The droplet could be split uniformly into more mini-marbles by increasing the stripe numbers.

Chemical warfare agents (CWAs) are recognized as serious threats of terrorist acts against the civilian population. Minimizing the impact of these threats requires early detection of the presence of CWAs. Cavity ring-down spectroscopy (CRDS) is an exquisitely sensitive technique for the detection of trace gaseous species. In this letter, the CRDS technique is employed using a pulsed quantum cascade laser for the detection of dimethyl methylphosphonate (DMMP). A limit of DMMP detection of approximately 77 ppb is achieved. The best achievable sensitivity that corresponds to noise-equivalent absorption is approximately 2 x 10(-7) cm(-1).

SummaryObjective To compare the image quality of spectral CT monochromatic imaging and conventional CT polychromatic imaging for analysing CTAs in patients with cervical cancer. Methods In this IRB approved prospective study, 60 patients who had been diagnosed with cervical cancer underwent pelvic arterial CTA between May 2013 and July 2013. They were randomly divided into two groups; one group (30 patients) received 120 kVp polychromatic imaging (conventional CT group) and the other group (30 patients) received spectral CT imaging (spectral CT group), while all patients in both the groups received injections of 1 ml/kg of contrast agent. A total of 101 sets of monochromatic images (40–140 keV) were obtained via data reconstruction in the spectral CT group, and the monochromatic images with the best contrast-to-noise ratio (CNR) between the common iliac artery and pelvic fat (i.e. the best monochromatic energy) were selected. The best monochromatic images for the spectral CT group and the polychromatic images for the conventional CT group were postprocessed and visualised in MIP, VR and CPR mode. The CT attenuation value, noise and CNR of bilateral common iliac arteries were measured with the best monochromatic energy, as well as with 70 keV, in the spectral CT group and in the conventional CT group. The quality of the CT images was evaluated with a 5-point scale. The CTDIvol and the dose-length product (DLP) of the two groups were measured, and the results were statistically analysed. Results When images were at 50±1 keV, the common iliac artery and pelvic fat had the highest CNR, which was 72.00% higher than the images at 70 keV (P=.001) in the spectral group, and thus, the images at 50±1 keV were considered to have the best monochromatic energy. The average CT value of the internal iliac artery, which had the best monochromatic energy from the spectral CT group, was higher than that of the images from the conventional CT group (603.96±62.68 vs 251.24±28.77; P

Thin films of β-BaB2O4 were deposited by rf magnetron sputtering on bare Si wafers and optical glass plates. The result of crystallization was sensitive to the substrate crystal structure state and crystallographic orientation of Si cuts.

We have developed a free-standing-mode based triboelectric nanogenerator (F-TENG) that consists of indium tin oxide (ITO) foils and a polytetrafluoroethylene (PTFE) thin film. By utilizing the wind-induced resonance vibration of a PTFE film between two ITO electrodes, the F-TENG delivers an open-circuit voltage up to 37 V and a short-circuit current of 6.2 μA, which can be used as a sustainable power source to simultaneously and continuously light up tens of light emitting diodes (LEDs) and charge capacitors. Moreover, uniform division of the electrode into several parallel units efficiently suppresses the inner counteracting effect of undulating film and leads to an enhancement of output current by 95%. The F-TENG holds prominent durability and an excellent linear relationship between output current and flow rate, revealing its feasibility as a self-powered sensor for detecting wind speed. This work demonstrates potential applications of the triboelectric generator in gas flow harvesters, self-powered air navigation, self-powered gas sensors and wind vector sensors.

The Uncooled Focus Plane Array (UFPA) infrared detector is widely used in military and civil fields. With the features of small size and not being cooled, the Uncooled Infrared Focal Plane Array (UIRFPA) has become the focus in the current infrared thermal imaging research. A data acquisition system has been designed and implemented for measurement of the UIRFPA. The system includes driver module, acquisition module and signal processing module. The acquisition module based on virtual instrument can achieve high-speed, stable and accurate data acquisition. Meanwhile, combined with visual C+ + (VC) platform, the system realizes data acquisition and real time imaging. Through testing a 240×320 FPA using the test system, the superior performance of the device has been performed. In addition, the imaging effect has been enhanced by eliminating the bad pixels and proofreading the non-uniformity. A new test system for the test of UIRFPA and the exploration of the real-time correction imaging system is presented.

Dual channel surface acoustic wave (SAW) oscillators of two-port SAW resonators were designed for sensor application. A feedback loop were determined by measuring the corresponding open loop and adjusting the point of 0° total phase to exist near to the point of peak gain by variation of coupling inductance value. Two such feedback loops, a mixer and a TTL invertor comprise a dual channel SAW sensor oscillator. To achieve a stable oscillation, incorporation of a power conditioning components and the use of microstrip techniques (50 Ω characteristic impedance and the least inductance path for RF return currents) are necessary. The standard deviation of difference frequency stability of the oscillator of 433.92 MHz is about 3.92. Finally, the dual channel SAW sensor oscillator is used to detect dimehylmethylphosphonate (DMMP) vapor.

Surface transverse wave(STW) resonator was evaluated for the potential use in detecting dimethyl methyl phosphonate (DMMP) vapors. The device’s noise was decreased by the resonator’s low insertion loss and high Q value, while a ZnO wave guide layer was coated on the STW device surface to generate Love wave effect, which enhanced the mass sensitivity of the device. Those contributed to improving the limit of detection(LOD) of sensor. The DMMP sensor is obtained by coating a sensitive layer on the device. The maximum mass sensitivity of 625cm 2 g 1 was obtained and the sensitivity to DMMP vapor was further ehanced by increasing the sensitive layer thickness, which benefited from the low insertion loss of STW device, thus a response of about 5.5kHz upon exposure to 0.1mg/m 3

In this paper, the gas-sensing characteristics of gas sensors for Organic Thin-Film Transistors (OTFTs) with the different ratio of the channel length to width and thickness of the insulating layer were studied. The results showed that the device parameters had the influence on the sensitivity and response time of sensors, and the optimized parameters of OTFT sensors were obtained, that was, the ratio of the channel length to width was between 160 and 640, and the insulating layer was 195 nm in thickness. The OTFT sensor with the α-Sexithiophene (α-6T) film incorporated into a sensitive layer was observed to respond strongly to the trace nitrogen dioxide (NO2) vapor ranging from 0.2 to 1 ppm at room temperature.

An OLED-based gas sensor is fabricated with the device structure as ITO/N,N’-bis(naphthalen-1-yl)N,N’-bis(phenyl)-benzidine (NPB)(30 nm)/tris(8-hydroxy-quinolinatoo)aluminium (Alq3)(50 nm)/poly(3hexylthiophene-2,5-diyl) (P3HT)(x nm)/Mg: Ag (300 nm). The P3HT is applied as the sensitive layer in the OLED-based gas sensor, while red light emission can be observed from the OLED. The response of the device in NO2 and NH3 circumstance is investigated respectively by analyzing its effect on variation of the current density. The results show that the NO2 concentration has an obvious influence on the current density of the device, and the current density decreases faster under the higher NO2 concentration. Meanwhile, the current density of the device increases when it is exposed in the NH3 circumstance. The sensing mechanism of the device is also discussed.

Surface acoustic wave (SAW) devices have been widely used for various chemical sensing applications because the sensor signal can be detected by simple and inexpensive electronics. The interactions between target analyte and the sensor surface cause changes in the mechanical, electrical, dielectric properties of the sensing coating deposited onto acoustic transducer. The changes in these properties will lead to changes in the velocity and amplitude of wave modes, which can be measured by frequency and insertion loss (IL) changes when the acoustic element is realized as a delay line or resonator. Among the different sensing coatings, the supermolecules are of considerable interest because the host molecules can be thought as original receptors allowing a specific recognition of guest molecules based on "key-lock" system. In this paper, SAW ethanol gas sensors that utilize the supermolecule of cryptophane-A as sensitive layer have been studied. We synthesized cryptophane-A from vanillyl alcohol using a double trimerisation method and deposited it on the SAW devices to fabricate cryptophane-A based SAW gas sensors. The SAW frequency and insertion loss (IL) were measured using a network analyzer. The frequency shift as the response of the cryptophane-A based SAW sensors to different concentration ethanol was measured at room temperature. It is found that the cryptophane-A based SAW sensor has high sensitivity and good reproductivity to ethanol. The frequency response increased linearly with the concentration of the ethanol.

A bottom contact organic field effect transistor (OFET) was fabricated with poly(3-hexylthiophene) (P3HT) as the channel semiconductor. P3HT thin film was deposited onto a SiO 2 /n-Si substrate by spin coating and electrical characteristics of the P3HT-FET were investigated in a nitrogen flux. A change in the saturation drain-source current (IDS) was observed when device was exposed to different concentrations of nitrogen dioxide (NO 2 ) gas. It was found that the variation in the IDS was remarkable with NO 2 injected in a short time.

A bottom contact pentacene based organic thin film transistor (OTFT) was fabricated in this paper. Pentacene thin film acting both as gas sensing layer and the active layer was formed by vacuum evaporation and was characterized by atomic force microscopy (AFM) and x-ray diffraction (XRD). The results show that the film is highly ordered and has a polycrystalline morphology. The current-voltage characteristics of the OTFT was also investigated. The drain-source current in the saturation region would changed when the OTFT was exposed to alcohol vapor compared to that under an exposure to nitrogen gas. It indicates that the drain-source current can be considered as a key parameter to monitoring chemical species. Such OTFTs devices are promising to act as a novel class of chemical sensors.

A visual management platform is designed for wireless temperature and humidity sensor network. The platform offers a multifunctional visual interface, including data management, curve plotting of sensor node, display of topology and data sending and receiving situation, etc, so that the receiving data from sensors can be accessed more conveniently to be used for optimization of network performance. Since ZigBee is specially developed for wireless network of low-rate, low power and low cost, and the platform has been operated efficiently with good compatibility, which is promising for wireless sensor network.

The authors present a facile, low-cost methodology to fabricate high-performance In-Ga-Zn-O (IGZO) bottom contact, bottom gate thin-film transistors (TFTs) by soft lithography. The IGZO channel and indium tin oxide (ITO) source and drain were patterned using microcontact printing of an octadecylphosphonic acid self-assembled monolayer (SAM). A polymer stamp was used for the pattern transfer of the SAMs, which were then used as a chemical protection layer during wet etching. Excellent pattern transfer was obtained with good resolution and sharp step profiles. X-ray photoelectron spectroscopy indicated that the microcontact printed SAMs can be effectively removed from the ITO source/drain surfaces, allowing a high-quality interface to the IGZO channel for good device performance. Scanning electron microscopy cross-sections of the devices indicate a smooth and defect-free transition regions between the source/drain and semiconductor regions. The fabricated TFTs have negligible gate-leakage currents, high ave...