Wireless sEMG System with a Microneedle-Based High-Density Electrode Array on a Flexible Substrate

Surface electromyography (sEMG) signals reflect muscle contraction and hence, can provide information regarding a user's movement intention. High-density sEMG systems have been proposed to measure muscle activity in small areas and to estimate complex motion using spatial patterns. However, conventional systems based on wet electrodes have several limitations. For example, the electrolyte enclosed in wet electrodes restricts spatial resolution, and these conventional bulky systems limit natural movements. In this paper, a microneedle-based high-density electrode array on a circuit integrated flexible substrate for sEMG is proposed. Microneedles allow for high spatial resolution without requiring conductive substances, and flexible substrates guarantee stable skin-electrode contact. Moreover, a compact signal processing system is integrated with the electrode array. Therefore, sEMG measurements are comfortable to the user and do not interfere with the movement. The system performance was demonstrated by testing its operation and estimating motion using a Gaussian mixture model-based, simplified 2D spatial pattern.111Ysciescopu

Cell density-dependent differential proliferation of neural stem cells on omnidirectional nanopore-arrayed surface

112Ysciescopu

Simple and Biodegradable Polymer Microneedle Array Fabrication for Transdermal Drug Delivery with Various Aspect Ratio and Arrangement

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Physically microstriped-nanoengineered polystyrene surface (PMS-NPS) for regulating cell attachment and alignment fabricated by nano-injection molding

In the present study, we developed a physically microstriped-nanoengineered polystyrene surface (PMS-NPS) to control cell attachment and alignment. The PMS-NPS was mass replicated by nano-injection molding with a rigid metallic nano-mold insert, which was cost-effectively manufactured by two-step anodization process, UV-photolithography, and electroforming process. In our previous result, attachment of MG-63 cells was found to be enhanced on the nanoengineered polystyrene surface (NPS) without any biochemical treatments. In this study, the PMS-NPS was proposed to control the cell attachment and alignment by biophysical cue without biochemical cue. Throughout this study, we were able to observe the enhanced MG-63 cell attachment and alignment on PMS-NPS compared to flat PS. (C) 2016 Elsevier B.V. All rights reserved.1132sciescopu

Development of contaminant-free and effective micro-mixing methods based on non-contact dispensing system

This paper presents the development and characterization of two different types of effective micro-mixing methods with small volumes of liquids, both of which are based on simple non-contact dispensing systems to avoid the contamination between mixing-target liquids, thereby preventing undesirable crosstalk in biochemical assays. The principle of micro-mixing methods is to control the trajectory and volume of dispensing droplets. The first micro-mixing method induces mixing by smashing two different droplets in the air by dispensing the droplets simultaneously (called, a simultaneous micro-mixing method, SMM). The second method is to dispense two different droplets into a well in a controlled alternating manner (namely, an alternating micro-mixing method, AMM). In the dispensing system developed in this study for the micro-mixing, pressurized air transfers a liquid from a reservoir to a nozzle via a high-speed-solenoid valve, thus injecting liquid droplets with volume ranging from several ten nanoliters to several microliters, depending on the viscosity of the liquid. The droplet volumes of mixing-target liquids dispensed from the dispensing system were measured under various dispensing conditions by changing operating pressure and opening time of high-speed-solenoid valve. Sodium hydroxide (NaOH) ethanol solution and phenolphthalein ethanol solution added with glycerol were used as the mixing-target liquids to quantitatively characterize the mixing performances. The mixing performances were evaluated according to the different volumes of dispensing droplets and micro-mixing methods. The SMM exhibited a higher mixing performance compared to the AMM. However, both micro-mixing methods achieved the improved mixing performances compared with conventional mixing methods, such as micro-stirrer and micro-well shaking. The present methods could be useful in the automated micro-mixing system for clinical applications. (C) 2013 Elsevier B.V. All rights reserved.X111sciescopu

Simple and Cost-effective Fabrication of Solid Biodegradable Polymer Microneedle Arrays with Adjustable Aspect Ratio for Transdermal Drug Delivery Using Acupuncture Microneedles

Polymer microneedle arrays (MNAs) have received much attention for their use in transdermal drug delivery and microneedle therapy systems due to the advantages they offer, such as low cost, good mechanical properties, and a versatile choice of materials. Here, we present a simple and cost-effective method for the fabrication of a biodegradable polymer MNA in which the aspect ratio of each microneedle is adjustable using commercially available acupuncture microneedles. In our process, a master template with acupuncture microneedles, whose shape will be the final MNA, was carefully prepared by fixing them onto a plastic substrate with selectively drilled holes which, in turn, determine the aspect ratios of the microneedles. A polylactic acid (PLA; a biodegradable polymer) MNA was fabricated by a micromolding process with a polydimethylsiloxane (PDMS) mold containing the cavity of the microneedles, which was obtained by the PDMS replica molding against the master template. The mechanical force and degradation behavior of the replicated PLA MNA were characterized with the help of a compression test and an accelerated degradation test, respectively. Finally, the transdermal drug delivery performance of the PLA MNA was successfully simulated by two different methods of penetration and staining, using the skin of a pig cadaver. These results indicated that the proposed method can be effectively used for the fabrication of polymer MNAs which can be used in various microneedle applications.X111112sciescopu