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The solution process and vacuum evaporation, both fabrication methods for conventional organic light-emitting diodes (OLEDs), are intrinsically restricted with regard to their ability to enhance pattern resolutions and film stability outcomes. Here, we introduce a novel approach of the solution process followed by intense pulsed light (IPL) evaporation for producing high-resolution line patterns of OLEDs. Through control of the wettability between the banks and microchannels via a mask-free selective surface treatment, we successfully deposited phosphorescent green and red inks only into the microchannels. Then, high-resolution patterns of an emitting layer (EML) layer were uniformly evaporated onto the device substrate using IPL evaporation. Ultimately, we fabricated green and red phosphorescent OLED devices with a high pixel density of a line-patterned EML with a width of 6 μm and a pitch of 13.6 μm. In addition, we demonstrated that the IPL-evaporated films have many advantages compared to those fabricated by the conventional solution process. We also showed that the IPL evaporation process can be less sensitive to problems related to the aggregation of organic molecules during a drying or annealing process. Hence, the device performance and lifetime of the IPL-evaporated OLEDs were enhanced compared to those of the spin-coated OLEDs.

The rapid development of portable and wearable electronic devices has led researchers to actively study triboelectric nanogenerators (TENGs) that can provide self-powering capabilities. In this study, we propose a highly flexible and stretchable sponge-type TENG, named flexible conductive sponge triboelectric nanogenerator (FCS-TENG), which consists of a porous structure manufactured by inserting carbon nanotubes (CNTs) into silicon rubber using sugar particles. Nanocomposite fabrication processes, such as template-directed CVD and ice freeze casting methods for fabricating porous structures, are very complex and costly. However, the nanocomposite manufacturing process of flexible conductive sponge triboelectric nanogenerators is simple and inexpensive. In the tribo-negative CNT/silicone rubber nanocomposite, the CNTs act as electrodes, increasing the contact area between the two triboelectric materials, increasing the charge density, and improving charge transfer between the two phases. Measurements of the performance of flexible conductive sponge triboelectric nanogenerators using an oscilloscope and a linear motor, under a driving force of 2–7 N, show that it generates an output voltage of up to 1120 V and a current of 25.6 µA. In addition, by using different weight percentages of carbon nanotubes (CNTs), it is shown that the output power increases with the weight percentage of carbon nanotubes (CNTs). The flexible conductive sponge triboelectric nanogenerator not only exhibits good performance and mechanical robustness but can also be directly used in light-emitting diodes connected in series. Furthermore, its output remains extremely stable even after 1000 bending cycles in an ambient environment. In sum, the results demonstrate that flexible conductive sponge triboelectric nanogenerators can effectively power small electronics and contribute to large-scale energy harvesting.

Wind and solar energy are recognized as environmentally friendly energies. Wind energy is generated from the surface of the earth by solar energy. While wind energy can be regarded as "free" energy, generating it entails high installation cost as well as a large land footprint and noise, which is deemed to be a nuisance. In addition, maintenance costs are high. In this study, we propose a novel tree-wrapped wind energy harvester, which is inexpensive and easy to manufacture. Triboelectric generators follow simple principles and can be of various generator types. Triboelectric generators running on wind energy have been studied by many researchers. Our design comprises light and flexible tree-wrapped triboelectric generator modules. Multiple generator modules can be connected in parallel to harvest electrical energy. We show that the proposed generator can potentially harvest sufficient wind energy and can even be used in an urban environment by mounting them on trees in cities.

International audience; We demonstrate the electrical properties of nano energy harvesters (NEHs) with various textiles for smart textiles that can be applied to the next generation wearable electronics. Output voltages and currents of NEHs with various fabrics, such as a cotton, rayon and wool that have different triboelectricity were measured. Cotton, rayon and wool shows the maximum output voltages of 1.250, 3.313 and 4.063 V, respectively. In addition, output currents of those textiles were 0.75, 4.4, 1.063 lA, respectively. Wool, in particular, which has the highest triboelectricity of 350 V exhibits the highest output voltage.

Many studies have looked at the chemical mechanical polishing (CMP) process of sapphire substrates. However, the research on the processing mechanism of the sapphire substrate is insufficient compared with semiconductor CMP processing. This paper focuses on the effect of the slurry pH on the removal rate of sapphire substrate in CMP. When the pH of the slurry is changed, the possible factors that can influence removal rate of sapphire include the zeta potential, abrasive agglomeration, and hydration reaction layers. The colloidal silica slurry used in this study did not show aggregation at any pH value. However, the zeta potential between the abrasive and the substrate changed remarkably at acidic and basic pH. The attractive force between the abrasive and substrate in acidic conditions is higher than that in basic conditions due to the relative surface charge. A higher attractive force caused by opposite charges makes more of the abrasive participate in the polishing process, which increases the removal rate in acidic conditions. However, the removal rate in basic conditions is higher than that in acidic conditions despite the repulsive relative charges. The reason for the higher removal rate in basic conditions seems to be the easier formation of a hydration layer, which is caused by the higher concentration of [OH]− in basic conditions. If the hydration effect is negligible, then the removal rate strongly depends on the magnitude of relative surface charges, which can be defined by the product of the zeta potentials of the abrasives and the substrate. If the product of the potentials is large, the probability of contact between the abrasives and the substrate is increased. Thus, the removal rate is increased. However, if the hydration layer forms, it plays a dominant role in determining the removal rate.

Capacitive pressure sensors based on porous structures have been extensively explored for various applications because their sensing performance is superior to that of conventional polymer sensors. However, it is challenging to develop sufficiently sensitive pressure sensors with linearity over a wide pressure range owing to the trade-off between linearity and sensitivity. This study demonstrates a novel strategy for the fabrication of a pressure sensor consisting of stacked carbon nanotubes (CNTs) and polydimethylsiloxane. With the addition of carbon nanotubes, the structure is linearly compressed due to the reinforced mechanical properties, thereby resulting in high linearity. Additionally, the percolation effect is boosted by the CNTs having a high dielectric constant, thus improving the sensitivity. The pressure sensor exhibits linear sensitivity (R2 = 0.991) in the medium-pressure range (10-100 kPa). Furthermore, it delivers excellent performance with a fast response time (∼60 ms), in conjunction with high repeatability, reproducibility, and reliability (5 and 50 kPa/1000 cycles). The fabricated sensors are applied in wearable devices to monitor finger bending and detect finger motions in real time with high precision. The large-area sensor is integrated with a neural network to accurately recognize the sitting posture on a plane, thereby demonstrating the wide-range detection performance.

Highly flexible and compressible porous polyurethane (PU) structures have effectively been applied in capacitive pressure sensors because of the good elastic properties of the PU structures. However, PU porous structure-based pressure sensors have been limited in practical applications owing to their low durability during pressure cycling. Herein, we report a flexible pressure sensor based on a three-dimensional porous structure with notable durability at a compressive pressure of 500 kPa facilitated by the use of a shape memory polymer (SMP). The SMP porous structure was fabricated using a sugar templating process and capillary effect. The use of the SMP resulted in the maintenance of the sensing performance for 100 cycles at 500 kPa, the SMP can restore its original shape within 30 s of heating at 80 °C. The pressure sensor based on the SMP exhibited a higher sensitivity of 0.0223 kPa−1 than a typical PU-based sensor and displayed excellent sensing performance in terms of stability, response time, and hysteresis. Additionally, the proposed sensor was used to detect shoe insole pressures in real time and exhibited remarkable durability and motion differentiation.

In recent times, polymer-based flexible pressure sensors have been attracting a lot of attention because of their various applications. A highly sensitive and flexible sensor is suggested, capable of being attached to the human body, based on a three-dimensional dielectric elastomeric structure of polydimethylsiloxane (PDMS) and microsphere composite. This sensor has maximal porosity due to macropores created by sacrificial layer grains and micropores generated by microspheres pre-mixed with PDMS, allowing it to operate at a wider pressure range (~150 kPa) while maintaining a sensitivity (of 0.124 kPa&minus, 1 in a range of 0~ 15 kPa) better than in previous studies. The maximized pores can cause deformation in the structure, allowing for the detection of small changes in pressure. In addition to exhibiting a fast rise time (~167 ms) and fall time (~117 ms), as well as excellent reproducibility, the fabricated pressure sensor exhibits reliability in its response to repeated mechanical stimuli (2.5 kPa, 1,000 cycles). As an application, we develop a wearable device for monitoring repeated tiny motions, such as the pulse on the human neck and swallowing at the Adam&rsquo, s apple. This sensory device is also used to detect movements in the index finger and to monitor an insole system in real-time.

Oxytetracycline (OTC) is a member of the broad-spectrum tetracycline (TC) group of antibiotics and TCs are widely used to prevent bacterial infections in livestock and increase their growth rate. Hence a large percentage of the antibiotics is either accumulated in tissues or excreted and released into the environment that leads to serious health implications such as antibiotic resistance. Thus, simple, fast and easy to use methods are needed for OTC detection. Here a simple and highly sensitive aptamer-based single walled carbon nanotube (SWCNT) biosensor containing probe-DNA immobilized on functionalized SWCNTs was developed for fast and specific OTC detection. We employed a newly developed flexible biosensor device which was fabricated by a high-rate nanoscale offset printing process using directed assembly and transfer of SWCNTs. Employing a simple directed assembly and non-covalent functionalization process these fabricated probe DNA-based SWCNT biosensors were designed with two electrode terminals to allow continuous resistance response monitoring for antibiotics detection. The developed environmental sensor had a detection range of 10 μg L−1 to 75 μg L−1 (20–325 nM), with a detection limit of 1.125 μg L−1 (2.5 nM). When compared to other biosensors such as colorimetric, electrical or cantilever-based biosensor systems, the biosensor developed here is simpler and faster (less than 10 minutes, including pre-incubation, measurement and regeneration) with a lower detection limit. And the portable platform also allows for potential on-site or real-time measurements. The biosensor could be regenerated and reused over 20 times with good stability with signal decrease less than 15%. In addition, its inherent miniature size makes this biosensor potentially useful for a simple portable model for environmental and industrial applications.

Shape memory polymer (SMP) is a polymer based on PU that has the property of restoring to its original shape at a specific temperature like a shape memory alloy. This ability could improve durability of sensors in cyclic loading. We fabricate a porous structured sensor having a self-recovery ability. This sensor shows good durability and sensitivity than other polyurethane porous structure. Also, the developed sensor is rapidly restored in 30 seconds in a 70 °C oven. We propose a self-recovering capacitive pressure sensor which has excellent durability. Furthermore, it works in the wide pressure range (∼400kPa) with good linearity.

International audience; A comparative study of the electrical performance of triboelectric nanogenerators (TENGs) with plain-and 2/1 twill-woven cotton textiles was conducted. Furthermore, the microstructures of the cotton fiber surfaces were examined to understand the fundamental mechanical interaction among the cotton fibers in the TENGs. The TENG with 2/1 twill-woven cotton textiles exhibited higher output voltages compared to that with plain-woven cotton textiles. The difference in the output voltage between the two types of TENGs resulted from the difference in triboelectric charge generation between the constituent cotton textiles. The higher output voltage of the TENG with 2/1 twill-woven cotton textiles was attributed to the higher density in triboelectric interactions among the cotton fiber molecules.

Energy harvesting, especially for powering low-power internet-of-things (IoT) devices, is gaining attention in recent years. Triboelectric nanogenerators have been studied to improve the output by applying a structure that can concentrate electrons on the surface of the generator materials. For enhancing the triboelectrification output, we herein focused on the power output line. A method for increasing the amount of electrons on the power lead by potential difference and their acceleration was studied. A rod was shaken by external vibrations, the accumulated charges were discharged in a manner similar to that of a lightning rod. Micro plasma was generated when the rod made contact with the mating micro-cracked surface innumerable times. The micro-cracked surface was fabricated with a diamond tip moving horizontally to the surface. As the resistance of the micro plasma was close to zero, the amount of electron movement was instantaneously accelerated. This type of triboelectric generator can be fabricated in the form of an electric box. By using this triboelectric power amplifier, voltage can be amplified 2 to 3 times, and the current can be amplified 10 to 15 times, thus, enhanced energy harvesting efficiency is attained.

High-rate nanoscale offset printing using a newly developed reusable template enables the assembly of nanomaterials into nanostructures followed by their transfer onto a flexible substrate in a few minutes. The developed template can potentially be reused more than 100 times in the offset printing process without any additional functionalization. This approach provides a new way for the printing of flexible devices with nanoscale patterns.

Copper (Cu) had been attractive material due to its superior properties comparing to other metals such as aluminum or tungsten and considered as the best metal which can replace them as an interconnect metal in integrated circuits. CMP (Chemical Mechanical Polishing) technology enabled the production of excellent local and global planarization of microelectronic materials, which allow high resolution of photolithography process. Cu CMP is a complex removal process performed by chemical reaction and mechanical abrasion, which can make defects of its own such as a scratch, particle and dishing. The abrasive particles remain on the Cu surface, and become contaminations to make device yield and performance deteriorate. To remove the particle, buffing cleaning method used in post-CMP cleaning and buffing is the one of the most effective physical cleaning process. AE(Acoustic Emission) sensor was used to detect dynamic friction during the buffing process. When polishing is started, the sensor starts to be loaded and produces an electrical charge that is directly proportional to the applied force. Cleaning efficiency of Cu surface were measured by FE-SEM and AFM during the buffing process. The experimental result showed that particles removed with buffing process, it is possible to detect the particle removal efficiency through obtained signal by the AE sensor.

High roughness and a greater number of defects were created by lithium niobate (LN; LiNbO 3 ) processes such as traditional grinding and mechanical polishing (MP), should be decreased for manufacturing LN device. Therefore, an alternative process for gaining defect-free and smooth surface is needed. Chemical mechanical planarization (CMP) is suitable method in the LN process because it uses a combination approach consisting of chemical and mechanical effects. First of all, we investigated the LN CMP process using commercial slurry by changing various process conditions such as down pressure and relative velocity. However, the LN CMP process time using commercial slurry was long to gain a smooth surface because of lower material removal rate (MRR). So, to improve the material removal rate (MRR), the effects of additives such as oxidizer (hydrogen peroxide; H 2 O 2 ) and complexing agent (citric acid; C 6 H 8 O 7 ) in a potassium hydroxide (KOH) based slurry, were investigated. The manufactured slurry consisting of H 2 O 2 –citric acid in the KOH based slurry shows that the MRR of the H 2 O 2 at 2 wt% and the citric acid at 0.06 M was higher than the MRR for other conditions.

Cleaning is required following CMP (chemical mechanical planarization) to remove particles. The minimization of particle residue is required with each successive technology generation, and the cleaning of wafers becomes more complicated. In copper damascene process for interconnection structure, it utilizes 2-step CMP consists of Cu and barrier CMP. Such a 2-steps CMP process leaves a lot of abrasive particles on the wafer surface, cleaning is required to remove abrasive particles. In this study, the chemical mechanical cleaning(CMC) is performed various conditions as a cleaning process. The CMC process combined mechanical cleaning by friction between a wafer and a pad and chemical cleaning by CMC solution consists of tetramethyl ammonium hydroxide (TMAH) / benzotriazole (BTA). This paper studies the removal of abrasive on the Cu wafer and the cleaning efficiency of CMC process.

PVA (polyvinyl alcohol) brush cleaning method is a typical cleaning method for semiconductor cleaning process especially post-CMP cleaning. PVA brush contacts with the wafer surface and abrasive particle, generating the contact rotational torque of the brush, which is the removal mechanism. The brush rotational torque can overcome theoretically the adhesion force generated between the abrasive particle and wafer by zeta potential. However, after CMP (chemical mechanical polishing) process, many particles remained on the wafer because the brush was contaminated in previous post-CMP cleaning step. The abrasive particle on the brush redeposits to the wafer. The level of the brush contamination increased according to the cleaning run time. After cleaning the brush, the level of wafer contamination dramatically decreased. Therefore, the brush cleanliness effect on the cleaning performance and it is important for the brush to be maintained clearly.

Cu (copper) has been widely used for interconnection structure in integrated circuits because of its properties such as a low resistivity and high resistance to electromigration when compared with aluminum [1, 2]. Damascene process for the interconnection structure utilizes 2-steps CMP (chemical mechanical polishing). After 2-steps CMP process, many abrasive particles leave on the wafer surface, which should be removed in post-Cu CMP cleaning process. Cleaning efficiency affects directly on the subsequent process and device yield [3]. Therefore, cleaning of abrasive particles is the critical issue in semiconductor manufacturing.

There are many factors to affect polishing performance normally in chemical mechanical polishing (CMP) process. One of the factors is a pad profile. A pad profile has not been considered as a significant factor. However, a pad profile is easily changed by conditioning process in CMP, and then changed pad profile affects polishing performance. Therefore, understanding how the pad profile is changed by conditioning process is very important. In this paper, through the simulation based on kinematic analysis, the variation of the pad profile was described in accordance with difference condition of conditioning process. A swing-arm type conditioner was applied in this simulation. A swing-arm type conditioner plays a role of generating asperities on pad surface. The conditions of conditioing process to get uniform removal were also investigated by comparing the simulation with the experiment.

Lithium niobate (LN, LiNbO3) is a kind of artificial crystal with piezoelectricity, pyroelectricity and ferroelectricity, which has been widely used in electron components. The large difference in thermal expansion coefficients between Si and LN causes a serious thermal stress during the thermal-pressure bonding process. Therefore room temperature bonding would be the best candidate to make strong and stress-free interface between Si and LN. However, room temperature bonding requires lower surface roughness (Ra

Although the laser shockwave cleaning process offers a promising alternative to conventional dry-cleaning processes for nanoscale particle removal, its difficulty in removing organic particles has been an unexplained problem. This work elucidates the physics underlying the ineffectiveness of removing organic particles using laser shock cleaning utilizing polystyrene latex particles on silicon substrates. It is found that the shockwave pressure is high enough to deform the particles, increasing the contact radius and consequently the particle adhesion force. The particle deformation has been verified by high-angle scanning electron microscopy. The Maugis-Pollock theory has been applied to predict the contact radius, showing good agreement with the experiment.

We report a nanolithography technique for the high aspect-ratio nanostructure manufacturing using DODE (double oxide deposition and etching) process. Conventional microfabrication processes are integrated to manufacture nanostructure arrays with sub-100 nm of linewidth. This lithography method is developed to overcome resolution limits of photolithography. High aspect-ratio nanostructures with sub-100 nm of lindewidth were fabricated on wafer-scale substrate without nanolithography techniques. The DODE lithography process presented enabled to pave a way to overcome limitations of nanolithography processes and allowed to manufacture large-scale nanostructures using photolithography and thin film deposition and dry etching processes.