Room temperature processed high mobility W-doped In2O3 electrodes coated via in-line arc plasma ion plating for flexible OLEDs and quantum dots LEDs.

We fabricated W-doped In2O3 (IWO) films at room temperature on a flexible PET substrate using an in-line arc plasma ion plating system for application as flexible transparent conducting electrodes (FTCEs) in flexible organic light emitting diodes (OLEDs) and quantum dots light emitting diodes (QDLEDs). Due to the high-energy flux of the sublimated ions generated from the plasma region, the IWO films showed a well-developed crystalline structure with a low sheet resistance of 36.39 Ohm/square and an optical transmittance of 94.6% even though they were prepared at room temperature. The low sheet resistance of the IWO film processed at room temperature is attributed to the high mobility (59 cm2/V-s) in the well-developed crystalline structure of the ion-plated IWO film and screening effect of W dopants. In addition, the better adhesion of the ion-plated IWO film on the PET substrate led to small critical outer and inner bending radii of 6 and 3 mm, respectively, against substrate bending. Due to the low sheet resistance, high optical transmittance, better crystallinity, better adhesion, and outstanding flexibility of the ion-plated IWO films, the flexible OLEDs and QDLEDs with the IWO electrodes showed better performances than flexible OLEDs and QDLEDs with sputtered flexible ITO anodes. This indicates that in-line arc plasma ion plating is a promising large area coating technique to realize room temperature processed high-quality FTCEs for flexible OLEDs and QDLEDs.

Reliability of the intelligent stretching device for ankle stiffness measurements in healthy individuals.

BACKGROUND: A number of devices have been developed to measure joint stiffness. This study investigated the reliability of the Intelligent (Intel) stretch device to measure bilateral ankle joint stiffness during passive range of motion (ROM). METHODS: The reliability of the device was investigated based on torque and angle by establishing the consistency of measurements between examiners on different testing days. In addition, demographic variables were analyzed to investigate the degree of stiffness. Forty-six gender-matched subjects completed the test. RESULTS: The reliability ICC2(,)1 coefficient of ankle stiffness between-day for both examiners was 0.77 for the right ankle and 0.76 for the left ankle with a 0.05 standard error of measurement (SEM) for ankle stiffness for the right side and 0.04 for the left side. The ICC values of the two examiners were also high based on Chronbach's alpha (0.87 and 0.86). Among the demographic variables, gender (F=35.25, p=0.001) and body weight (F=23.55, p=0.001) were the most important factors in determining ankle joint stiffness. DISCUSSION: The results of this study indicated that dorsiflexion and plantarflexion measurements obtained by the Intel stretch device are reproducible and consistent. In addition, ankle stiffness was significantly different based on gender and body weight to develop and/or maintain ankle function. These results may help to identify ankle stiffness factors that will lead to more efficient rehabilitation programs and injury prevention strategies.

Kinematic analyses of trunk stability in one leg standing for individuals with recurrent low back pain.

This prospective study examined normalized stability differences based on dominance side and visual feedback. Subjects with low back pain (LBP) (n=26; 9 men, 17 women) and without LBP (n=28; 11 men, 17 women) participated in this study. All subjects were asked to maintain single leg standing balance with the contralateral hip flexed 90° for 25s. The outcome measures included normalized holding duration and stability. The combined rotation (R(xyz)) was also calculated to compare the upper and lower thorax and lumbar axes relative to the core spine axis. The holding duration was significantly different between groups (T=-2.21, p=0.03). The subjects without recurrent LBP (control group) demonstrated longer hold duration times (24.60±4.2s) than the subjects with recurrent LBP (21.2±7.1s). For the normalized hold duration, there was a significant difference between groups based on visual input (F=7.13, p=0.009). There was also a significant difference in standing stability based on visual input (F=93.93, p=0.0001) and trunk area (F=101.51, p=0.0001). In addition, the normalized stability was significantly different based on dominance and visual input (F=11.28, p=0.002). Therefore, trunk stability could prompt an uncoordinated bracing effect with poor proprioception from injury to passive structures or due to interference of pain during central processing of information in subjects with recurrent LBP.

Dielectrophoretic technique for measurement of chemical and biological interactions.

We present a novel dielectrophoretic technique that can be used to characterize molecular interactions inside a microfluidic device. Our approach allows functionalized beads which are initially at rest on a functionalized surface to be pulled away from the surface by the dielectrophoretic force acting on the beads. As a result, the interaction between the molecules on the surface and the beads can be quantitatively examined. We report detailed experimental results and validate the results with a model to show that the technique can be used to measure forces of interaction between molecules under various experimental conditions.

Hydrophilic electrospun polyurethane nanofiber matrices for hMSC culture in a microfluidic cell chip.

Mimicking cellular microenvironments by MEMS technology is one of the emerging research areas. Integrated biomimetic systems with nanofiber polymer networks and microfluidic chips were fabricated and cellular behaviors were observed by changing surface characteristics of nanofibers and flow rates of microchannels. Modification of polyurethane nanofiber surfaces were achieved by grafting acrylic acid with plasma treatment and these nanofiber matrices were employed in a poly(dimethylsiloxane) based microfluidic chip. The surface characteristics of both electrospun nanofiber matrices was evaluated by measuring contact angle, porosity, and chemical structure using attenuated total reflection-Fourier transform infrared spectrometry. After modification, a terminal carboxyl group formed on the nanofiber surface and the wettability increased significantly. Human MSCs were seeded on the nanofiber matrices and a morphological investigation with actin filament staining and scanning electron microscopy was performed. A proliferation test by WST-1 and Live/Dead assay were performed to investigate the cell culture environment. It was observed that the cells on the AA-grafted nanofibers spread and proliferate compared to untreated nanofibers. It has also shown that flow rates in the microchannels played an important role for cell proliferation (Sim et al., Lab Chip 2007;7:1775-1782). Integration of nanofiber matrices into the microchannels provides the useful tools for mimicking cellular microenvironments and elucidating basic questions of cell and ECM assembly and interactions.

Soft material-based microculture system having air permeable cover sheet for the protoplast culture of Nicotiana tabacum.

In plant cell culture, the delivery of nutrition and gas (mainly oxygen) to the cells is the most important factor for viability. In this paper, we propose a polydimethylsiloxane (PDMS)-based microculture system that is designed to have good aeration. PDMS is known to have excellent air permeability, and through the experimental method, we investigated the relation between the degree of air delivery and the thickness of the PDMS sheet covering the culture chamber. We determined the proper thickness of the cover sheet, and cultured protoplasts of Nicotiana tabacum in a culture chamber covered with a PDMS sheet having thickness of 400 microm. The cells were successfully divided, and lived well inside the culture chamber for 10 days. In addition, protoplasts were cultured inside the culture chambers covered with the cover glass and the PDMS sheet, respectively, and the microcolonies were formed well inside the PDMS covered chamber after 10 days.