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Patterning of semiconductor polymers is pertinent to preparing and applying organic field-effect transistors (OFETs). In this study, coaxial focused electrohydrodynamic jet printing (high resolution, high speed, and convenient) was used to pattern polymer semiconductors. The influence of the key printing parameters on the width of polymer sub-microwires was evaluated. The width decreased with increasing applied voltage, printing speed, and concentration of the polymer ink. However, the width increased gradually with increasing polymer ink flow rate. A regression analysis model of the relationship between the printing parameters and width was established. Based on a regression analysis/genetic algorithm, the optimal printing parameters were obtained and the correctness of the printing parameters was verified. The optimized printing parameters stabilized the width of the arrays to

Artificial compound eyes (ACEs) endowed with durable superhydrophobicity, wide field-of-view (FOV), and antireflection properties are extremely appealing in advanced micro-optical systems. However, the simple and high-efficiency fabrication of ACEs with these functions is still a major challenge. Herein, inspired by moth eyes, ACEs with hierarchical macro/micro/nano structures were fabricated using the combination of nanotip-focused electrohydrodynamic jet (NFEJ) printing and air-assisted deformation processes. The NFEJ printing enables the direct and maskless fabrication of hierarchical micro/nanolens arrays (M/NLAs) without intermediate steps. The introduction of M/NLAs on the eye surface significantly improves the water hydrophobic performance with a water contact angle of 161.1° and contact angle hysteresis (CAH) of 4.2° and generally decreases the reflectance by 51% in the wavelength range of 350-1600 nm in comparison to the macroeye without any structures. The contact angle remains almost unchanged, and the CAH slightly increases from 4.2° to 8.7° after water jet impact for 20 min, indicating a durable superhydrophobicity. Moreover, the results confirm that the durable superhydrophobic ACEs with antireflection properties exhibit excellent imaging quality and a large FOV of up to 160° without distortion.

Ultra-high temperature thin-film sensors（UTTSs）have drawn enormous attention due to their wide application prospect in multiple physical parameters monitoring in harsh environment. As an important part of UTTSs, the insulation film between workpiece and sensors plays a crucial role to ensure the accuracy of UTTSs. High insulation resistance (IR) is essential for the reliability improvement of the UTTSs and the reduction of their testing error. However, the defects in the insulation film will form the conductive path between the sensors and their mounting surface at high temperature, leading to a rapid IR drop and stability deterioration of the insulation film. In this work, 10 μm thick alumina film was prepared with suspension made out of alumina gel and alumina nano-powder using layer-by-layer electrohydrodynamic jet (E-jet) deposition (LLED). By adopting this technique, the process defects in one layer can be remedied in situ by the next deposition layer. The prepared film shows satisfactory insulation performance at elevated temperature, and IR of the film can reach 80 MΩ, 3 MΩ and 38 kΩ at 500 °C, 800 °C and 1200 °C, respectively. The thickness-normalized IR of the alumina film at 800 °C in this work is at least 7.8 times that obtained by other methods reported in the literatures. Moreover, after subjected to three thermal cycles from room temperature to 1200 °C, the IR of the film can still remain at 14 kΩ. The high performance of the alumina insulation film in this work can be attributed to the effective reduction of the minor defects in the LLED deposition process.

This paper proposes a lead zirconate titanate (PZT) thick-film piezoelectric microstator based on a high-performance PZT thick film fabricated by electrohydrodynamic jet (E-jet) printing. The PZT thick film element was printed directly on the elastic body from a PZT composite slurry to form the piezoelectric microstator. This fabrication process does not require conventional machining techniques such as thinning, bonding, and etching, and can be compatible with microelectromechanical systems (MEMS) technology. The printed PZT thick-film element exhibited compact and uniform features. The thick-film microstator produced a travelling wave with an amplitude of 345 nm, and the mechanical quality factor was found to be 736. The combination of E-jet printing and PZT thick-film technology simplified the manufacturing process and enhanced the performance of the piezoelectric stator, enabling the fabrication of a unique MEMS rotary ultrasonic motor device.

This paper aims to present the simulation work and obtain optimized parameters for the development of drop-on-demand electrohydrodynamic jet (DoD E-Jet) to print control and stable micro-structures on a flexible insulating substrate. In this work, the novel comparison of three types of combination needle structures was developed based on the multiphase flow (liquid–air) technique, in order to achieve optimal printing conditions for a flexible PET substrate. According to simulation results, steel-quartz needle combination provides very unique compensations in the controllability and stability of E-Jet. Printing on a flexible substrate was challenging, but parameters used in simulation validate the possibilities for DoD E-Jet printing method. Optimize working parameters were achieved by the numerical simulation executed to generate developed and stable E-Jet morphology. In addition, various stable and uniform microscale droplets and structures were directly printed on a flexible polymer substrate with the help of collective impact of electrical force, viscous force, and internal pressure force throughout DoD E-Jet printing process. The results of numerical simulation and experimental work exhibited an excellent and promising E-Jet printing tool for flexible electronic systems.

Nasopharyngeal carcinoma (NPC) is a common malignant tumor of the head and neck with a high incidence rate worldwide, especially in southern China. Phototheranostics in combination with nanoparticles is an integrated strategy for enabling simultaneous diagnosis, real-time monitoring, and administration of precision therapy for nasopharyngeal carcinoma (NPC). It has shown great potential in the field of cancer diagnosis and treatment owing to its unique noninvasive advantages. Many Chinese and international research teams have applied nano-targeted drugs to optical diagnosis and treatment technology to conduct multimodal imaging and collaborative treatment of NPC, which has become a hot research topic. In this review, we aimed to introduce the recent developments in phototheranostics of NPC based on a nanoplatform. This study aimed to elaborate on the applications of nanoplatform-based optical imaging strategies and treatment modalities, including fluorescence imaging, photoacoustic imaging, Raman spectroscopy imaging, photodynamic therapy, and photothermal therapy. This study is expected to provide a scientific basis for further research and development of NPC diagnosis and treatment.

Nitrogen-doped indium tin oxide (ITO) has been applied in the thin-film strain gauges (TFSGs) due to their high stability, excellent piezoresistivity and antioxidation at elevated temperatures. However, the mechanism on the sensing and stability of the nitrogen-doped ITO TFSGs at high temperatures was not comprehensively clarified. In this work, various ITO TFSGs were fabricated by RF magnetron sputtering with different nitrogen partial pressures (NPPs) of 5%~40%. The elemental composition and band structures of the ITO TFSGs were examined by the energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), respectively. Results show that the Fermi energy level shifts closer to the valence band maximum energy (Ev) gradually with the growth of NPPs, causing a reduction in the number of electrons ionized to the conduction band. The smallest content change rates of nitrogen (3.8%) and oxygen (1.6%) after subjecting to the thermal strain test were observed in the 20%N2 ITO TFSG. In consequence, the 20%N2 ITO TFSG exhibits the lowest resistance drift rate (DR) at high temperatures due to its stable elemental composition. Moreover, we found that the band structures and elemental composition of the ITO TFSGs are the main factors affecting their piezoresistive response at different temperatures. The band structures play a major role in the gauge factors (GFs) of the ITO TFSGs at room temperature and 600 ℃. The element variation takes responsibility for the different GFs of the ITO TFSGs at 800℃, 900℃ and 1000℃. In addition, the piezoresistive stability is also dependent on the elemental composition affected by the dynamic equilibrium between the diffusion amount of oxygen and the escape number of the nitrogen in the ITO thin films at high temperatures.

The aim of this work is to simulate the formation of coaxial electrohydrodynamic jet (CE-Jet) and obtain the optimized working parameters for coaxial electrohydrodynamic focused jet printing (CEFJP), then further direct writing nanoscale structures. In this paper, a pioneering simulation of CE-Jet process based on three phase flow of liquid–liquid–air model was developed. The photoresist (AZ703)/silicone oil was employed to verify the simulation. The simulated result of the CE-Jet consisted with the experimental result very well, which proves the correction of the CE-Jet model. Based on the simulation, the effect of working parameters including the applied voltage and the flow rate of inner coaxial liquid on the morphology and size of the CE-Jet were examined. With the use of the optimized working parameters obtained from the simulation and taking the materials of lead zirconate titanate (PZT) and photoresist (AZ703) as inner liquid, the stable nanoscale inner jet was focused by the compound effect of electrical shearing force, viscous shearing force and internal pressure. Then, the nanostructures of various patterns with diameter of 70 nm were directly printed. The CE-Jet model developed in this work provides a powerful tool to investigate the CEFJP process, and the CEFJP technique exhibited a promising method for producing nanoscale structures for M/NEMS devices.

This paper proposes a novel way of preparing a PZT thick film micro vibrator using the electrohydrodynamic jet (E-Jet) printing technique. Initially, a micro piezoelectric vibrator was simulated and designed for obtaining optimized structure, which has a total thickness of less than 600 µm. Subsequently, the PZT thick film element was directly printed on the elastic body using the E-Jet printing. This method avoids the glue fabrication process involved in the bulk piezoelectric fabrication, thus avoiding the limits of voltage drops, isolating and absorbing amplitude usually occurred in the vibrator having glue interface. It was observed that B02 and B03 modes were generated at frequencies of 29.74 and 79.14 kHz, respectively, and the amplitudes of B02 and B03 modes were 406 and 176 nm, respectively. The error between the simulation and test result in the B03 modal is only 0.35%, which indicates the accuracy of the simulation analysis and the fabrication process. The PZT thick film traveling-wave micro vibrator successfully realized bidirectional rotation of a rotor, with a maximum speed of 681 rpm, which also shows a linear relationship between excitation voltage and rotary speed. This paper provides an effective method for preparing a micro piezoelectric vibrator for MEMS ultrasonic devices, which simplifies the manufacturing process and enhances the performance of the piezoelectric vibrator.

Electrospinning is a simple, cost-effective, and versatile technique for fabrication of nanofibers. However, nanofibers obtained from the conventional electrospinning are typically disordered, which seriously limits their application. In this work, we present a novel and facile technique to obtain aligned nanofibers with high efficiency by using parallel inductive-plates assisted electrospinning (PIES). In this new electrospinning setup, the electrostatic spinneret is contained in a pair of parallel inductive-plates, which can change the shape and direction of the electric field line during the electrospinning so as to control the flight trajectory and spatial alignment of the spinning nanofibers. This electrospinning setup can divide the electric field line into two parts which are respectively directed to the edge of the upper and lower inductive-plates. Then the nanofibers move along the electric field line, suspend and align between the parallel inductive-plates. Finally, the well aligned nanofibers could be easily transferred onto other substrates for further characterizations and applications. The aligned nanofibers with an average diameter of 469 ± 115 nm and a length as long as 140 mm were successfully achieved by using PIES technique. Moreover, nanofiber arrays with different cross angles and three-dimensional films formed by the aligned nanofibers were also facilely obtained. The novel PIES developed in this work has been proved to be a facile, cost-effective and promising approach to prepare aligned nanofibers for a wide range of applications.

Ultra-high temperature thin film sensors (UTTSs) are ideally suited on the surface of the hot sections for in-situ measurement at high temperature. Indium tin oxide (ITO), an N-type semiconductor ceramic with a wide band gap, used as the active elements of sensors exhibited a promising application in UTTSs. As one of the most important parameters of UTTSs, temperature coefficient of resistance (TCR) still has many problems to be clarified. In this paper, ITO films were deposited on alumina substrates with Various N 2 /Ar ambients using magnetron sputtering to investigate the effect of nitrogen-doped concentration on the TCR of ITO films in the temperature range of 50~1200°C.The composition and properties of films were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy(XPS) and multi-function digital four-probe tester, respectively. The mechanism of TCR curve fluctuation from 50~1200°C with different nitrogen partial pressure was revealed. It was found that more nitrogen-doped concentration can make the TCR more stable at higher temperature.

Electrohydrodynamic jet (E-Jet) printing is a promising manufacturing technique for micro-/nano-patterned structures with high resolution, high efficiency and high material compatibility. However, further improvement of the necking ratio of the E-Jet is still limited by the focusing principle. Moreover, ink viscosity is limited to values well below 90 mPa s owing to the high probability of nozzle blockage. Here, we propose a microtip focused electrohydrodynamic jet (MFEJ) printing to overcome these limitations. This technique uses a solid microtip with a radius of curvature (ROC) of several micrometers rather than a hollow nozzle, which is very simple and highly efficient to prepare and can effectively avoid nozzle clogging problems even with high-viscosity printing ink. High-resolution patterns in diverse geometries were printed using different inks with a wide range of viscosities (8.4–3500 mPa s). Nanodroplets with an average diameter of 73 nm were achieved. Moreover, nanofibers with a diameter of 30 nm were obtained using a 4 μm ROC microtip and the necking ratio was as high as 266 : 1. To the best of our knowledge, this is the smallest droplet or fiber diameter directly obtained via E-Jet printing to date without further physical or chemical processing. This MFEJ printing technique can improve printing resolution at the nanoscale, significantly enlarge the material applicability and effectively avoid nozzle clogging for the fabrication of nanodevices.

This paper reports the preparation of dense and substrate-free PZT thick films. Electrohydrodynamic jet deposition and sol infiltration were utilized to produce dense PZT thick film, then wet chemical etching was employed to successfully remove the silicon substrate. Subsequently, a pure PZT thick film having a thickness of 14 µm without substrate was produced. The piezoresponse force microscopy technique was used to examine the piezoelectric constant (d33, f), it was found that the d33 was increased from 71 pm V−1 to 140 pm V−1, having a double increase. It was also observed that the remnant polarization (Pr) and relative permittivity (εr) of PZT film were distinctly improved after the removal of silicon substrate. The experimental result shows that the substrate clamping had great effects on the electrical properties of PZT films and its effect value was evaluated. In addition, the systematic theoretical analysis of the substrate clamping on film was deeply studied. The theoretical analysis agrees well with the experiment results, which can be used to estimate the effect value caused by the substrate clamping.

Oxygen starvation caused by water flooding in cathode is a key performance bottleneck for air-breathing direct methanol fuel cell (DMFC). To solve this problem, we present a new water management system consists of superhydrophilic capillary network and evaporation wings in this work. The cathode flow field (CFF) with water management system (WMCFF) is obtained by fabricating capillary network on titanium substrates with micromachining techniques. A pair of evaporating wings made of carbon papers are used to collect water from the capillary network and further evaporate them into the air quickly. Results show that, before a long-term discharge test, the initial peak power density (Pmax) of WMCFF-DMFC is 38.9% higher than that of the conventional cathode flow field DMFC (CCFF-DMFC). After 2 and 4 h discharge, the performance gaps between the two DMFCs become larger, and the Pmax of WMCFF-DMFC increases by 55.6% and 74.3% compared with that of the CCFF-DMFC, respectively. Moreover, the corresponding Pmax decline rate in the WMCFF-DMFC is only about 12% and 27% of that in the CCFF-DMFC. This suggests that the new water management system can effectively prevent water flooding in cathode and significantly improve the performance and stability of the air-breathing DMFCs.

Electrohydrodynamic jet (E-Jet) is an approach to the fabrication of micro/nano-structures by the use of electrical forces. In this process, the liquid is subjected to electrical and mechanical forces to form a liquid jet, which is further disintegrated into droplets. The major advantage of the E-Jet technique is that the sizes of the jet formed can be at the nanoscale far smaller than the nozzle size, which can realize high printing resolution with less risk of nozzle blockage. The E-Jet technique, which mainly includes E-Jet deposition and E-Jet printing, has a wide range of applications in the fabrication of micro/nano-structures for micro/nano-electromechanical system devices. This technique is also considered a micro/nano-fabrication method with a great potential for commercial use. This study mainly reviews the E-Jet deposition/printing fundamentals, fabrication process, and applications.

Electrohydrodynamic jet (E-jet) deposition technique was used to prepare thin film porous electrodes for all-solid-state electrochemical supercapacitors. The performance of thin film graphene/PANI electrodes separately prepared by E-jet deposition and brush-coating were comparatively studied in supercapacitors. Results show that the specific capacitance of the supercapacitor by E-jet deposition can reach 228F·g-1 at 0.5A·g-1and remain 92% after 1000 charge-discharge cycles. Compared to those electrodes made by traditional brush coating techniques, the capacitance and cycling stability of the supercapacitors in this work were respectively increased by 11% and 7%, means that E-jet deposition can be an ideal technique for fabrication of high performance supercapacitor electrodes.

The electric breakdown voltage (Vbd) is a fundamental performance index for insulation thin film in MEMS, and plays a dominant role for the operation reliability of this kind of devices. In this work, positive polyimide (PI) photoresist was used to prepare thin films by spin-coating and thermal imidization. Electric breakdown experiments were carried out under DC voltage mode. The effect of imidization temperature on Vbd was also studied by setting three different imidization temperature profiles. XRD was applied to test the composition and microstructure of the PI thin films. Results show that the imidization degree of the PI thin film will be increased with the raising of the imidization temperature from 280 to 350°C. This means that a more completed imidization process can be achieved in the PI thin film by using higher imidization temperature. The highest Vbd of about 2740V and an average Vbd of 343kV/mm can be achieved on a 8.5μm thick PI thin film imidized at 350°C.

This paper proposes a miRNA-mediated regulatory network of heat stress response in a tree, Betula luminifera. Plants are sessile organisms that must gauge stressful conditions to ensure survival and reproductive success. In nature, plants often encounter chronic or recurring abiotic stresses, such as heat stress, although the strategies to cope with high temperature are poorly understood in woody plants. In this study, we investigated the potential roles of microRNAs (miRNAs) in heat stress response in Betula luminifera. Using next-generation deep sequencing, we identified a total of 206 miRNAs, comprising 115 known and 84 novel miRNAs, and seven potential miRNA candidates. Of these miRNAs, 98 (57 known and 41 novel miRNAs) were differentially expressed under heat stress. A total of 101 miRNA-target pairs consisting of 44 miRNAs and 71 target genes were verified by degradome sequencing. Target annotation suggested that these miRNAs might be important in the regulation of specific stress-responsive genes, including many transcription factors and a series of genes encoding important enzymes of functional proteins targeted by miRNAs. Further functional analysis suggested that these target genes were related to protein synthesis, transport and turnover, cell wall organization, protein folding, antioxidation, defense response, and modulation of attenuated plant growth and development under heat stress. The expression patterns of 15 randomly selected miRNAs derived from quantitative reverse transcription PCR had similar trends as those derived from high-throughput sequencing, as well as the expression patterns of six target genes under heat stress. These results improve our understanding of the miRNA-mediated regulatory network of heat stress response in B. luminifera, which will contribute to improving heat stress-resistant breeding in woody plants.

Capillary blocking caused by CO2 bubbles in anode flow field (AFF) is one of the bottlenecks for performance improvement of a micro direct methanol fuel cell (μDMFC). In this work, we present a novel AFF structure with nested layout of hydrophilic fuel channels and superhydrophobic degassing channels which can remove most of CO2 from AFF before it is released to the fuel channels. The new AFFs are fabricated on Ti substrates by using micro photochemical etching combined with anodization and fluorination treatments. Performance of the μDMFCs with and without superhydrophobic degassing channels in their AFF is comparatively studied. Results show that the superhydrophobic degassing channels can significantly speed up the exhaust of CO2 from the AFF. CO2 clogging is not observed in the new AFFs even when their comparison AFFs have been seriously blocked by CO2 slugs under the same operating conditions. 55% and 60% of total CO2 produced in μDMFCs with N-serpentine and N-spiral AFF can be respectively removed by the superhydrophobic degassing channels. The power densities of the μDMFCs equipped with new serpentine and spiral AFFs are respectively improved by 30% and 90% compared with those using conventional AFFs. This means that the new AFFs developed in this work can effectively prevent CO2-induced capillary blocking in the fuel channels, and finally significantly improve the performance of the μDMFCs.

Tinospora sagittata is a perennial vine of the family Menispermaceae and distributed in Hunan, Hubei, Guangxi, and Sichuan province of P. R. China. It has been used in Chinese traditional medicine ...

In this work, an instrument of drop-on-demand electrohydrodynamic jet (DoD E-Jet) printing device equipped with a current measurement and control system was designed and developed for finely controlling the printing process. The relationships between the current and printing parameters of voltage, frequency, and flow rate were deeply investigated, and the examination data and conclusion were obtained under the condition of the needle size remaining unchanged. Especially, the equation relationship between the flow rate and current was established, which can be used for the modification of the DoD E-Jet printing process. The map describing the stable printing range, droplet size, and current was also recognized, which can help us to select parameters for stable printing. Based on the current measurement and control system and the established relationship, the optimized current and printing parameters were chosen to print uniform graphene microstructures. This instrument provides an effective method for monitoring, adjusting, and controlling the DoD E-Jet printing process and further improving the quality of the printed structures for micro/nanoelectromechanical system (M/NEMS) devices.

The consensus of most recent researches is that rich training data which includes more different object forms in different situations is beneficial to improve the performance of deep networks. Deep learning is very dependent on data diversity. So, we provide a novel and principle method called adaptive adversarial example generating network (AAEGN) to generate examples with occlusions for object detection. AAEGN can generate occlusion examples which are rare in current dataset and are difficult to localize and classify. Compared to the traditional adversarial network for the example generation, AAEGN employs several innovations to simplify the architecture of adversarial network and improve the example generation and training speed. What’s more, AAEGN can adjust the hyper-parameters of the adversarial network in the process of training adaptively. The results of our experiments show that using AAEGN to train Fast-RCNN pipeline can get a 1.8% boost on VOC2007 dataset and 3.8% boost on VOC2012 dataset.

Object detection refers to the classification and localization of objects within an image by learning their diversified features. However, the existing detection models are usually sensitive to the important features in some local regions of the object. The existing algorithms cannot learn the diversified features regarding to each region effectively, which limit the performance of the model to a certain range. In this paper, we propose a novel and principle method called Multi-region Occlusion Example Generating (MOEG) to guide the detection model in fully learning the features of the various regions of the object. MOEG can generate completely new occlusion examples and it enables our detection model to learn the features of the remaining regions in the object by blocking the important regions in the proposal. It is a general method to generate occlusion examples and it can be implemented to most mainstream region-based detectors very easily such as Fast-RCNN and Faster-RCNN. Our experimental results indicate a \(2.4\%\) mAP boost on VOC2007 dataset and a 4.1% mAP boost on VOC2012 dataset compared to the Fast-RCNN pipeline. And as datasets become larger and more challenge, our method MOEG become more effective as demonstrated by the results on the MS COCO dataset.

This study aimed to regulate the stability of electrohydrodynamic cone-jet morphology by modifying the needle structure and conical point electrode by drawing upon high AC voltage and low flow velocity values. Accordingly, stability is achieved by the electrohydrodynamic jet (E-Jet) printing, considered an effective tool in micro and nanofabrication for flexible electronic systems. In the present study, 2-phase-field method was employed to draw a comparison of the volume of fraction method to optimize parameters for stable cone-jet on a PET substrate surface by exploiting a range of copper control electrodes. With COMSOL Multiphysics software, the equations of electric potential and electrical body forces were successfully solved. The validation study was compared with ensure the optimization parameters of cone-jet morphology, as retained in the boundaries of Melcher-leaky dielectric model. Moreover, the simulation parameters were directly adopted to print continuous line patterns on the PET substrate, which are considered prominent and promising E-Jet printing methods for flexible electronic systems.