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

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

Enhanced osteogenic fate and function of MC3T3-E1 cells on nanoengineered polystyrene surfaces with nanopillar and nanopore arrays

During in vitro culture, cell fate and function, including cell adhesion, morphology, proliferation and differentiation, are affected by surface characteristics, such as geometry, wettability, hardness, chemistry and charge. This study replicated two different types of nanoengineered polystyrene surfaces (NPS) containing nanopillar (NPS-Pi) or nanopore (NPS-Po) arrays by hot embossing and investigated their topographical effects on cell behavior using osteoblast-like MC3T3-E1 cells. To mass-replicate NPS, rigid metal nano-stamps were manufactured by nickel electroforming onto two different nano-templates: (1) a nanopore-arrayed anodic aluminum oxide nano-template using two-step electrochemical oxidation and (2) a nanopillar-arrayed polymer using hot embossing process. The physical and mechanical properties of the NPS, including geometry, wettability, hardness and elastic modulus, were evaluated with the help of field emission-scanning electron microscopy, a contact angle meter, and a nanoindenter. The nanotopography maintained the bulk property, while drastically changing the surface properties. In vitro the NPS had significant effects on MC3T3-E1 cell morphology, attachment, proliferation and osteogenic differentiation compared to a flat substrate due to the altered physical and mechanical surface properties of the nanoengineered surface. Interestingly, the NPS-Po was more effective at enhancing cell proliferation and osteogenesis differentiation. One potential explanation for these results may be that the subcellular binding sites induced by the nanostructures changed the cell morphology and promoted contractile cytoskeletons, thereby enhancing osteogenic differentiation. This, which allows for the cost-effective replication of NPS and the control of cell behavior, has various applications with respect to biomedical and cell surface interaction studies, in addition to enhanced osteogenic cell fate and function.X112322sciescopu