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Luminescent cerium(III) complexes based on the d-f transition have characteristics of broad emission spectra, tunable emission colors, and short excited state lifetimes, showing potential applications in display, lighting, and other fields. Thus it is important to construct luminescent Ce(III) complexes with high photoluminescence efficiency and good stability. In this work, five Ce(III) complexes with dihydrobis(pyrazolyl)borate or diphenylbis(pyrazolyl)borate ligands, where pyrazolyl stands for pyrazolyl, 3-methylpyrazolyl, or 3,5-dimethylpyrazolyl, were designed and synthesized, showing emission colors from deep blue to yellow with a maximum wavelength in the range of 390-560 nm, short excited state lifetimes of 30-80 ns, and photoluminescence quantum yields exceeding 75% in solid powder. By comparing these complexes, it is found that higher photoluminescence efficiency and better thermal/air stability could be achieved in the complexes with dihydrobis(pyrazolyl)borate ligands.

Compared with red and green organic light-emitting diodes (OLEDs), blue is the bottleneck that restricts the wide development of OLEDs from being the next-generation technology for displays and lighting. As a new type of emitter, a Ce(III) complex shows many satisfactory advantages, such as a short excited-state lifetime, 100% theoretical exciton utilization efficiency, and tunable emission color. Herein we synthesized three heteroleptic Ce(III) complexes Ce(TpMe2)2(dtfpz), Ce(TpMe2)2(dmpz), and Ce(TpMe2)2(dppz) with the hydrotris(3,5-dimethylpyrazolyl)borate (TpMe2) main ligand and different substituted pyrazole ancillary ligands, namely, 3,5-di(trifluomethyl)pyrazolyl (dtfpz), 3,5-dimethylpyrazolyl (dmpz), and 3,5-diphenylpyrazolyl (dppz), and studied their structures and luminescence properties. All the Ce(III) complexes exhibited a near-unity photoluminescence quantum yield both in solution and as a powder with maximum emission wavelengths in the range of 450-486 nm. The OLED employing Ce(TpMe2)2(dppz) as the emitter showed the best performance, including a turn-on voltage, maximum luminance, and external quantum efficiency of 3.2 V, 29 200 cd m-2, and 12.5%, respectively.

Organic light-emitting diodes (OLEDs) have had commercial success in displays and lighting. Compared to red and green OLEDs, blue OLEDs are still the bottleneck because the high-energy and long-lived triplet exciton in traditional blue OLEDs causes the short operational lifetime of the device. As a new type emitter, lanthanide complexes with a 5d-4f transition could have short excited-state lifetimes on the order of nanoseconds. To achieve a high-efficiency 5d-4f transition, we systematically tuned the steric and electronic effects of tripodal tris(pyrazolyl)borate ligands and drew a full picture of their Ce(III) complexes. Intriguingly, all of these complexes show bright blue emission with high photoluminescence quantum yields exceeding 95% and short decay lifetimes of 35-73 ns both in the solid powder and in dichloromethane solutions. Using the Ce(III) complex emitter, we show a blue OLED with a maximum external quantum efficiency of 14.1% and a maximum luminance of 33,160 cd m-2, and the specific electroluminescence mechanism of direct exciton formation on the Ce(III) ion with a near-unity exciton utilization efficiency is also confirmed. The discovered photoluminescence and electroluminescence property-structure relationships may shed new light on the rational design of highly efficient lanthanide-based blue emitters and their optoelectronic devices such as OLEDs.

This paper presents a reliability optimization design method for a hydraulic system that considers oil contamination. The proposed method applies the quantitative relationship between oil contamination and system reliability to the reliability design of a hydraulic system, while considering the performance, layout, and other design factors. A global reliability model of the hydraulic system is constructed based on the oil contamination control model. Further studies aiming at an optimization design model of the hydraulic system is established where the cost is the objective function, reliability index, size and structure range, performance requirements are constraints, structure size and oil change period are design variables. For illustration, a case study on the reliability optimization design of the oil supply point branch of the static pressure bracket of a certain type of heavy CNC horizontal lathe is considered.

Organic light-emitting diodes (OLEDs) are considered as next-generation displays and lighting technologies. During the past three decades, various luminescent materials such as fluorescence, phosphorescence, and thermally activated delayed fluorescence materials have been subsequently investigated as emitters. To date, blue OLEDs are still the bottleneck as compared to red and green ones because of the lack of efficient emitters with simultaneous high exciton utilization efficiency and long-term stability. Recently, d-f transition rare earth complexes have been reported as new emitters in OLEDs with potential high efficiency and stability. In this Perspective, we present a brief introduction to OLEDs and an overview of the previous electroluminescence study on d-f transition rare earth complexes. This is followed by our recent developments in cerium(III) complex- and europium(II) complex-based OLEDs. We finally discuss the challenges and opportunities for OLED study based on d-f transition rare earth complexes.

Luminescent EuII complexes with a characteristic 5d-4f transition have potential applications in many fields. However, their instability in ambient conditions impedes further exploration and application. Herein, we report two new EuII complexes, bis[hydrotris(3-trifluoromethylpyrazolyl)borate]europium(II) (Eu-1) and bis[hydrotris(3-methylpyrazolyl)borate]europium(II) (Eu-2). Intriguingly, the blue emissive Eu-1 showed high air stability arising from fluorine protection and close molecular packing, as maintaining a photoluminescence quantum yield (PLQY) of 91 % (initial 96 %) upon exposure to air over 2200 hours. While the orange emissive Eu-2 showed a maximum luminance of 30620 cd m-2 , and a maximum external quantum efficiency (EQE) of 6.5 %, corresponding to an exciton utilization efficiency around 100 % in organic light-emitting diodes (OLEDs). These results could inspire further research on stable and efficient EuII complexes and their application in OLEDs.

As a kind of photoluminescent material, CuI complexes have many advantages such as adjustable emission, variable structures, and low cost, attracting attention in many fields. In this work, two novel two-coordinate CuI -N-heterocyclic carbene complexes were synthesized, and they exhibit unique dual emission properties, fluorescence and phosphorescence. The crystal structure, packing mode, and photophysical properties under different conditions were systematically studied, proving the emissive mechanism to be the locally excited state of the carbazole group. Based on this mechanism, ultralong room-temperature phosphorescence (RTP) with a lifetime of 140 ms is achieved by selective deuteration of the carbazole group. These results deepen the understanding of the luminescence mechanism and design strategy for two-coordinate CuI complexes, and prove their potential in applications as ultralong RTP materials.

Luminescent rare earth Eu(II) complexes with a characteristic 5d–4f transition have shown potential in various applications. However, the exploration and further application of typical Eu(II) complexes are strongly impeded by their instability arising from the easily oxidation of Eu2+ ions. In this work, three new Eu(II) complexes bis(hydro-tris(3-phenyl-5-methylpyrazolyl)borate)europium(II) (Eu(TpPh,Me)2), bis(hydro-tris(3-phenylpyrazolyl)borate)europium(II) (Eu(TpPh)2), and bis(hydro-tris(3,5-diphenylpyrazolyl)borate)europium(II) (Eu(TpPh2)2) were designed and synthesized. Their crystal structures, photophysical properties and air stabilities were characterized and discussed. It is found that the introduction of the bulky phenyl group not only increases the air stability by sterically hindering the central Eu2+ ions, but also tunes the maximum emission wavelength by influencing the ligand field. This work provides rules for regulating the luminescence properties of Eu(II) complexes as well as design basis for achieving stable and efficient Eu(II) complexes.

Gear involute artefact (GIA) is a kind of measurement standard for calibrating the gear involute measuring instrument. To reduce the profile form deviations and the difference of the profile slope deviations between the opposite flanks (left and right flank) of GIA, the effect of installation eccentricity on the profile deviations is analysed, and an adjustment method for profile deviations of GIA by the eccentric installation is proposed. The difference of profile slope deviations between the opposite flanks of GIA with designed base circle radius r b = 100 mm changes from 0.31 μm to 0.1 μm after the adjustment through the eccentricity of the mandrel. The difference of profile slope deviations between the opposite flanks of GIA with designed base circle radius r b = 60cos20° mm changes from 0.77 μm to 0.12 μm after the adjustment through a kind of rotary stroke bearing with eccentricity, meanwhile, the profile form deviations are reduced from 0.53 μm to 0.34 μm (right flank) and 0.89 μm to 0.46 μm (left flank). This adjustment method could improve the used accuracy of GIA without improving the machining accuracy of the involute and changing the measurement process of the measurement standard of GIA.

Quasi-2D (Q-2D) perovskites are promising materials applied in light-emitting diodes (LEDs) due to their high exciton binding energy and quantum confinement effects. However, Q-2D perovskites feature a multiphase structure with abundant grain boundaries and interfaces, leading to nonradiative loss during the energy-transfer process. Here, a more efficient energy transfer in Q-2D perovskites is achieved by manipulating the crystallization kinetics of different-n phases. A series of alkali-metal bromides is utilized to manipulate the nucleation and growth of Q-2D perovskites, which is likely associated with the Coulomb interaction between alkali-metal ions and the negatively charged PbBr64– frames. The incorporation of K+ is found to restrict the nucleation of high-n phases and allows the subsequent growth of low-n phases, contributing to a spatially more homogeneous distribution of different-n phases and promoted energy transfer. As a result, highly efficient green Q-2D perovskites LEDs with a champion EQE of 18.15% and a maximum brightness of 25 800 cd m–2 are achieved. The findings affirm a novel method to optimize the performance of Q-2D perovskite LEDs.

Polymer metallization is widely used in a variety of micro and nano system technologies, and magnetron sputtering of a metal film is one of the essential processes of polymer metallization. However, some defects are likely generated in sputtered metal films on a polymer substrate. In this work, the defect generation mechanism in the sputtered Au film on a polymethylmethacrylate (PMMA) substrate was investigated for the first time. The characteristics of defects on the PMMA surface and in the Au film were examined by an optical microscope, a scanning electron microscope (SEM) and a confocal microscope. Detailed characterization results indicate that the ejected Au atoms bombard the PMMA substrate and cause snowflake-like defects on the PMMA surface because of the low hardness of PMMA, then Au atoms nucleate and grow at PMMA defect sites and form a partially suspended metal film, subsequently dropping the photoresist makes the suspended metal film conformally adhere to the PMMA defect, and the snowflake-like morphology is replicated to the metal film. The effects of sputtering parameters on the defects were studied, and the amount of defects in the Au film reduced with the decrease of the sputtering power or the sputtering pressure.

To eliminate the interference effect of ascorbic acid (AA) and reduced nicotinamide adenine dinucleotide (NADH) on electrochemical detection of uric acid (UA), a non-enzymatic approach for electrochemical detection of UA was developed using the Nafion-modified screen-printed carbon electrode strip (SPCEs). Electrodeposition was utilized to control the thickness of Nafion film. With Nafion-modified SPCEs, the selectivity of UA from AA and NADH was investigated. The Nafion-modified SPCEs exhibits high selectivity of UA, good linearity, and reasonable detection limit in neutral pH environment. The interference effect can be evidently reduced. The advantages are no requirements of enzyme reagents, acid environment, and complicated preparation of the electrodes.

Screen-printed carbon electrode (SPCE) has been widely used in electrochemical (EC) field. Nevertheless, compared with some metal electrodes, SPCE is not sensitive to small amounts of reagent owing to its relatively low electron transfer rate. In this paper, the UV/ozone modification was proposed to treat SPCE to improve its electron transfer rate and EC performance. The changes of SPCE morphology and composition induced by UV/ozone modification were investigated in detail. The results show that the improved electron transfer rate can be mainly attributed to the increase of oxygen functional groups. To clarify the essential EC characterization, potentiodynamic polarization and electrochemical impedance spectroscopy of K3[Fe(CN)6] was studied. Furthermore, to demonstrate the improved EC effect, two typical samples: small-molecule K3[Fe(CN)6] and macro-molecule nicotinamide adenine dinucleotide (NADH), were measured by cyclic voltammetry. After UV/ozone modification, the oxidation potential and peak current responses to K3[Fe(CN)6] and NADH were obviously improved in both original and CNT-modified SPCEs. Whereas, the original SPCE is more suitable to measure macromolecule NADH rather than CNT-modified one as the oxidative products of NADH are more likely to adsorb on rough surface.

Gear involute artefact (GIA) is a kind of measurement standard used to calibrate involute measuring instruments. To measure the profile deviation of GIA more accurately, the effect on the measurement of a gear involute profile caused by the error of the probe position is considered, the value of profile deviations would be affected and the measurement curve of profile deviations would be compressed or stretched along the roll path length, caused by the error of the probe position. Moreover, about 60% of the measurement errors are concentrated within the involute root of roll path length ρ= 0–5 mm. Based on the above research, an adjustment method for the probe position with a double roller-guide involute measuring instrument is proposed and measurement experiments are carried out using probes with probe radius ro = 0.5 mm, 1.5 mm and 2.5 mm. As the error of probe position e > 0, the curve of profile deviations at the root of the involute is biased towards the body. As the error of probe position e < 0, the profile deviation curve at the root of the involute except for the vicinity of base circle is biased towards the body, while the profile deviation curve near the base circle is biased out of the body caused by the interference of the transition surface, and the measurement curve of profile deviations at the root of the involute is significantly compressed. These errors decrease as the probe radius increases and the error of the probe position decreases. The difference of profile slope deviations and profile form deviations measured by the three probes after adjustment is 0.11 μm and 0.04 μm respectively, which indicates the feasibility of the probe adjustment method described above. The research supports the machining and measurement of a high-precision gear involute artefact.

Grating rulers are high-precision linear displacement sensors used in the servo control system of CNC machine tools. Due to the long lifetime of these rulers, evaluating their reliability level by using traditional methods takes huge amounts of time and resources. Meanwhile, some incomplete data are observed in the failure data, which will cause inaccurate evaluation results. In this study, an accelerated life reliability evaluation method of a grating ruler based on a competing risk model and incomplete data is proposed. Firstly, according to the characteristics of the grating ruler, the life distribution model based on competitive risk is established. The representation and conversion methods of failure data, considering incomplete data, are also proposed. Secondly, the accelerated life test (ALT) system is set up, and the 4500 h step stress ALT is conducted. Results indicate that the reliability level of the grating ruler is MTBFt = 8864.12 h, and that of each subsystem is MTBFt(MS) = 13,351.98 h, MTBFt(OS) = 14,283.48 h and MTBFt(ES) = 17,038.65 h. The advantages of the proposed method are that it is helpful in determining the subsystem with the highest failure rate in each stage and puts forward targeted suggestions for subsequent improvement designs.

Divalent europium 5d-4f transition has aroused great attention in many fields, in a way of doping Eu2+ ions into inorganic solids. However, molecular Eu2+ complexes with 5d-4f transition are thought to be too air-unstable to explore their applications. In this work, we synthesized four Eu2+-containing azacryptates EuX2-Nn (X = Br, I, n = 4, 8) and systematically studied the photophysical properties in crystalline samples and solutions. Intriguingly, the EuX2-N8 complexes exhibit near-unity photoluminescence quantum yield, good air-/thermal-stability and mechanochromic property (X = I). Furthermore, we proved the application of Eu2+ complexes in organic light-emitting diodes (OLEDs) with high efficiency and luminance. The optimized device employing EuI2-N8 as emitter has the best performance as the maximum luminance, current efficiency, and external quantum efficiency up to 25470 cd m−2, 62.4 cd A−1, and 17.7%, respectively. Our work deepens the understanding of structure-property relationship in molecular Eu2+ complexes and could inspire further research on application in OLEDs., Though divalent-europium-based complexes are promising materials for next-generation light-emitting devices, their poor air stability limits their applicability. Here, the authors report the design of air stable divalent-europium-based complexes for efficient organic light-emitting diodes.

Transfer printing is an emerging assembly technique for flexible and stretchable electronics. Although a variety of transfer printing methods have been developed, transferring patterns with nanometer resolution remains challenging. We report a sacrificial layer-assisted nanoscale transfer printing method. A sacrificial layer is deposited on a donor substrate, and ink is prepared on and transferred with the sacrificial layer. Introducing the sacrificial layer into the transfer printing process eliminates the effect of the contact area on the energy release rate (ERR) and ensures that the ERR for the stamp/ink-sacrificial layer interface is greater than that for the sacrificial layer/donor interface even at a slow peel speed (5 mm s−1). Hence, large-area nanoscale patterns can be successfully transferred with a yield of 100%, such as Au nanoline arrays (100 nm thick, 4 mm long and 47 nm wide) fabricated by photolithography techniques and PZT nanowires (10 mm long and 63 nm wide) fabricated by electrohydrodynamic jet printing, using only a blank stamp and without the assistance of any interfacial chemistries. Moreover, the presence of the sacrificial layer also enables the ink to move close to the mechanical neutral plane of the multilayer peel-off sheet, remarkably decreasing the bending stress and obviating cracks or fractures in the ink during transfer printing. Transfer printing is an emerging assembly technique for flexible and stretchable electronics, and a breakthrough method has been developed that allows transfer printing at the nanoscale by means of a weak-adhesion intermediate (sacrificial) layer. Although transfer printing has gained considerable attention for transferring various classes of materials with a wide range of geometries and configurations from one substrate to another, very few methods have allowed such printing at the nanoscale; those methods demand very elaborate processing. However, a team headed by Junshan Liu at Dalian University of Technology, China developed a simple, versatile transfer printing technique utilizing a sacrificial layer that for the first time permitted the successful transfer of large-area nanoscale patterns with a 100% yield. The authors intend to further investigate the possibilities of their innovative system and its application in various nanotechnologies.

Compared to red and green organic light-emitting diodes (OLEDs), blue OLEDs are still the bottleneck due to the lack of efficient emitters with simultaneous high exciton utilization efficiency (EUE) and short excited-state lifetime. Different from the fluorescence, phosphorescence, thermally activated delayed fluorescence (TADF), and organic radical materials traditionally used in OLEDs, we demonstrate herein a new type of emitter, cerium(III) complex Ce-1 with spin-allowed and parity-allowed d–f transition of the centre Ce3+ ion. The compound exhibits a high EUE up to 100% in OLEDs and a short excited-state lifetime of 42 ns, which is considerably faster than that achieved in efficient phosphorescence and TADF emitters. The optimized OLEDs show an average maximum external quantum efficiency (EQE) of 12.4% and Commission Internationale de L’Eclairage (CIE) coordinates of (0.146, 0.078)., OLEDs: deep blue emission from cerium(III) complex A luminescent cerium(III) complex could be promising for realizing efficient and stable deep-blue organic-LEDs required for display and lighting applications, arising from its theoretical high exciton utilization efficiency and short excited-state lifetime. Liding Wang, Zifeng Zhao, and coworkers from China have shown that a new cerium (III) complex called Ce-1, which supports a d-f energy level transition, can efficiently emit blue light with a high photoluminescence quantum yield up to 93% and a short excited-state lifetime of 42 ns. OLEDs fabricated from the complex offered a maximum external quantum efficiency of 12.4% and a luminance of about 1000 cd m−2, and their emission is characterized as being deep blue with CIE colour coordinates of (0.146, 0.078).

In the field of RGB diodes, development of a blue organic light-emitting diode (OLED) is a challenge because of the lack of an emitter which simultaneously has a short excited state lifetime and a high theoretical external quantum efficiency (EQE). We demonstrate herein a blue emissive rare earth cerium(III) complex Ce-2 showing a high photoluminescence quantum yield of 95% and a short excited state lifetime of 52.0 ns in doped film, which is considerably faster than that achieved in typical efficient phosphorescence or thermally activated delayed fluorescence emitters (typical lifetimes >1 μs). The corresponding OLED shows a maximum EQE up to 20.8% and a still high EQE of 18.2% at 1000 cd m−2, as well as an operation lifetime 70 times longer than that of a classic phosphorescence OLED. The excellent performance indicates that cerium(III) complex could be a candidate for efficient and stable blue OLEDs because of its spin- and parity-allowed d−f transition from the Ce3+ ion., Unlike traditional emitters in organic light-emitting diodes (OLEDs), lanthanide cerium(III) complexes with d–f transition show simultaneously advantages of theoretical high efficiency, short excited state lifetime, adjustable emission color, and low cost.

Luminescent Eu

In contact dispensing process including the extruding, stretching, and liquid-bridge breakup, the initial distance d n − s i n i between the needle tip and the substrate has great influence on the dispensed adhesive volume. Herein, the effect of d n − s i n i on the dispensing process in nano-liter level is studied for high-viscosity adhesive. Complete contact dispensing process is simulated using computational fluid dynamic technique. Moreover, the experimental platform including heating device, dispenser, and imaging unit etc. is built up to investigate the dispensing process. According to the results, with the increase of d n − s i n i , the variation of extruded adhesive volume can be divided into three regimes that are respectively dominated by different factors. As d n − s i n i is in the range of 45–75 μm, due to the spatial flow resistance decreasing, the extruded volume sharply increases. Then, when d n − s i n i is in the range of 75–115 μm, owing to the contact area sa-s between the extruded adhesive and the substrate continuing to decrease, the increase of extruded volume becomes slow. Once d n − s i n i reaches 115 μm, comparing to the decrease of sa-s, the contribution of spatial flow resistance can be neglected, thus the extruded volume will decrease until sa-s approaches to zero. Additionally, the following transfer process based on the liquid-bridge breakup is studied too. The variation of absolute transferred volume is consistent with that of the extruded volume. However, since sa-s continuously decreases with the increasing of d n − s i n i , the transfer ratio gradually decreases. The presented results can improve the precise contact dispensing process and other related techniques.

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.

A high triplet energy level (ET) and balanced carrier mobility are critical factors for host materials in efficient blue phosphorescent organic light-emitting diodes (PHOLEDs). Herein, we report a facile synthesis of four compounds, dicarbazolylphenylphosphine (DCPP), dicarbazolylphenylphosphine oxide (DCPPO), tricarbazolylphosphine (TCP), and tricarbazolylphosphine oxide (TCPO), and their application as host materials in a classic blue phosphorescent emitter bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III) (FIrpic). The four compounds show a high ET of up to 3.0 eV and tunable mobilities. We fabricated four OLEDs with a device structure of ITO/MoO3 (1 nm)/N,N′-dicarbazolyl-3,5-benzene (mCP):MoO3 (20 wt%, 10 nm)/mCP (30 nm)/Host:FIrpic (7 wt%, 20 nm)/1,3,5-tri(m-pyrid-3-yl-phenyl) benzene (TmPyPB, 40 nm)/LiF (1 nm)/Al (100 nm), all of which display maximum external quantum efficiencies (EQEs) exceeding 20%. The DCPPO-based device reaches the highest EQE of 27.5%, the maximum luminance of 14 070 cd m−2, and the lowest efficiency roll-off of 22.2% from 1 to 10 mA cm−2, which is among the best-performing FIrpic-based PHOLEDs without using any light extraction method.

The dispensing resolution of high-viscosity liquid is essential for adhesive micro-bonding. In comparison with the injection technique, the transfer printing method appears to be promising. Herein, an analytical model was developed to describe the dynamic mechanism of squeezing-and-deforming a viscous droplet between plates in a transfer printing process: as the distance between plates decreases, the main constituents of contact force between the droplet and substrate can be divided into three stages: surface tension force, surface tension force and viscous force, and viscous force. According to the above analysis, the transfer printing method was built up to dispense high-viscosity adhesives, which replaced the geometric parameters, utilized the critical contact force to monitor the adhesive droplet status, and served as the criterion to trigger the liquid-bridge stretching stage. With a home-made device and a simple needle-stamp, the minimum dispensed amount of 0.05 nL (93.93 Pa&middot, s) was achieved. Moreover, both the volume and the contact area of adhesive droplet on the substrate were approximately linear to the critical contact force. The revealed mechanism and proposed method have great potential in micro-assembly and other applications of viscous microfluidics.

Polymer metallization is extensively used in a variety of micro- and nanosystem technologies. However, the deposited metal film exhibits poor adhesion to polymer substrates, which may cause difficulties in many applications. In this work, ultraviolet (UV)-ozone surface modification is for the first time put forward to enhance the adhesion between metal films and polymer substrates. The adhesion of sputtered Cu films on UV-ozone modified poly(methyl methacrylate) (PMMA) substrates is enhanced by a factor of 6, and that of Au films is improved by a factor of 10. Moreover, metal films on the modified PMMA substrates can withstand a long-time liquid immersion. To understand the mechanism for the adhesion enhancement, the surface modification is studied with contact angle measurements, attenuated total reflection Fourier-transform infrared spectrometry (ATR-FTIR) and atomic force microscopy (AFM). Detailed characterization results indicate that the significant adhesion enhancement is attributed to the increases of both the surface wettability by generating some polar functional groups and the roughness of the surface in nanoscale. To demonstrate this novel polymer metallization method, a 6-in. PMMA chip with arrays of three-electrode electrochemical microsensors is designed and fabricated, and the microsensor exhibits excellent reproducibility, uniformity, and long-term stability.

Microelectroforming is a metal fabrication process that is indispensable in producing many microstructures in microelectromechanical systems. The relation of oxygen content to current density at the interface of nickel electroformed layer and copper substrate was explored in order to enhance the bonding strength of microstructures. The oxygen content was investigated with deep etching and X-ray photoelectron spectroscopy from the surface of electroformed layer to substrate vertically. A scratch tester was utilized to acquire the bonding strength between electroformed layer and substrate. The results reveal that the oxide film upon the substrate surface can be reduced while current density ranges from 0.3 A/dm2 to 1.0 A/dm2 at the initial stage of electroformed nickel upon the copper substrate. The decrease of oxygen content at the interface results in electrochemical activation upon the surface of substrate. The bonding performance of the electroformed layer to the copper substrate is improved. Wh...

In wireless sensor networks, sensors are usually equipped with limited lifetime batteries. To face the short lifetime, some sensor nodes have the option to connect an extra battery, or to use smart battery-packs with multiple cells. In these cases, a major technique to save the energy is to schedule the batteries or battery cells through the properties of the batteries. This study presents a scheduling algorithm to decide which batteries have to work based on the remaining energy. Hence, the energy consumption model of node based on ZigBee protocol was proposed. The parameters, including working current, working voltage, time duration of data sending and receiving, and so on are used to establish energy consumption model of node. Experiment based on JN5148 shows that the energy consumption model is feasible. Using the kinetic battery model and configuring relevant parameters can accurately express battery's energy consumption curve. On the basis of the above work, MATLAB simulation results show that the proposed battery scheduling strategy is superior to best-of-two scheduling.

Three novel highly efficient blue bicyclometalated iridium(III) complexes (Ir1–Ir3) were designed and synthesized with 4-(2, 6-difluoropyridin-3-yl)-6-mesitylpyrimidine as primary ligands. The alternation of ancillary ligands had precisely regulated their emitting peaks from sky-blue to deep-blue. These complexes exhibit unimodal emission with PLQYs higher than 90% and lifetimes shorter than 1.1 μs. These complexes also show good thermal stability with Td > 320 °C. The OLED using complex Ir3 as emitter in 13 wt% exhibited a maximum luminous efficiency of 16.9 cd A−1 with a high EQE of 13.0%. The CIE coordinates of this device are (0.15, 0.16), which are close to the standard blue color region.

A novel method based on plasma etching was proposed for monolithically integrating planar nanochannels and microelectrodes on a poly (methyl methacrylate) (PMMA) plate, and complete PMMA nanofluidic electrochemical chips with integrated microelectrodes were constructed by bonding with another PMMA plate containing microchannels. The fabrication sequences of nanochannels and microelectrodes were optimized. The oxygen plasma etching rate of PMMA nanochannels was studied, and the average rate was 15 nm/min under optimal conditions. An UV-ozone assisted thermal bonding method was developed to realize a low-temperature chip bonding, and the variations in width and depth of nanochannels before and after bonding were 2% and 5%, respectively. As a demonstration, a nanoparticle crystal (NPC)-based nanofluidic biosensor with integrated Ag microelectrodes was designed and fabricated. Sub-microchannel arrays with a depth of 400 nm and a width of 30 μm on the biosensor functioned as filters, and trapped 540 nm silica nanoparticles modified with streptavidin inside the connected microchannel to assemble the NPC. The interspaces in the NPC formed a three-dimensional nanochannel network with an equivalent diameter of 81 nm. By measuring the conductance across the NPC, a high quality nanofluidic sensing of biotin was achieved. The limit of detection was 1 aM, and the detection range was from 1 aM to 0.1 nM.