Highly stretchable and customizable microneedle electrode arrays for intramuscular electromyography.

Stretchable three-dimensional (3D) penetrating microelectrode arrays have potential utility in various fields, including neuroscience, tissue engineering, and wearable bioelectronics. These 3D microelectrode arrays can penetrate and conform to dynamically deforming tissues, thereby facilitating targeted sensing and stimulation of interior regions in a minimally invasive manner. However, fabricating custom stretchable 3D microelectrode arrays presents material integration and patterning challenges. In this study, we present the design, fabrication, and applications of stretchable microneedle electrode arrays (SMNEAs) for sensing local intramuscular electromyography signals ex vivo. We use a unique hybrid fabrication scheme based on laser micromachining, microfabrication, and transfer printing to enable scalable fabrication of individually addressable SMNEA with high device stretchability (60 to 90%). The electrode geometries and recording regions, impedance, array layout, and length distribution are highly customizable. We demonstrate the use of SMNEAs as bioelectronic interfaces in recording intramuscular electromyography from various muscle groups in the buccal mass of Aplysia.

Mechanically Guided Hierarchical Assembly of 3D Mesostructures.

3D, hierarchical micro/nanostructures formed with advanced functional materials are of growing interest due to their broad potential utility in electronics, robotics, battery technology, and biomedical engineering. Among various strategies in 3D micro/nanofabrication, a set of methods based on compressive buckling offers wide-ranging material compatibility, fabrication scalability, and precise process control. Previously reports on this type of approach rely on a single, planar prestretched elastomeric platform to transform thin-film precursors with 2D layouts into 3D architectures. The simple planar configuration of bonding sites between these precursors and their assembly substrates prevents the realization of certain types of complex 3D geometries. In this paper, a set of hierarchical assembly concepts is reported that leverage multiple layers of prestretched elastomeric substrates to induce not only compressive buckling of 2D precursors bonded to them but also of themselves, thereby creating 3D mesostructures mounted at multiple levels of 3D frameworks with complex, elaborate configurations. Control over strains used in these processes provides reversible access to multiple different 3D layouts in a given structure. Examples to demonstrate these ideas through both experimental and computational results span vertically aligned helices to closed 3D cages, selected for their relevance to 3D conformal bio-interfaces and multifunctional microsystems.

Simultaneous determination of trace Cd(II), Pb(II) and Cu(II) by differential pulse anodic stripping voltammetry using a reduced graphene oxide-chitosan/poly-l-lysine nanocomposite modified glassy carbon electrode.

The reduced graphene oxide (RGO) and Chitosan (CS) hybrid matrix RGO-CS were coated onto the glassy carbon electrode (GCE) surface, then, poly-l-lysine films (PLL) were prepared by electropolymerization with cyclic voltammetry (CV) method to prepare RGO-CS/PLL modified glassy carbon electrode (RGO-CS/PLL/GCE) for the simultaneous electrochemical determination of heavy metal ions Cd(II), Pb(II) and Cu(II). Combining the advantageous features of RGO and CS, RGO and CS are used together because the positively charged CS can interact with the negatively changed RGO to prevent their aggregation. Furthermore, CS has many amino groups along its macromolecular chains and possessed strongly reactive with metal ions. Moreover, PLL modified electrodes have good stability, excellent permselectivity, more active sites and strong adherence to electrode surface, which enhanced electrocatalytic activity. The RGO-CS/PLL/GCE was characterized voltammetrically using redox couples (Fe(CN)63-/4-), complemented with electrochemical impedance spectroscopy (EIS). Differential pulse anodic stripping voltammetry (DPASV) has been used for the detection of Cd(II), Pb(II) and Cu(II). The detection limit of RGO-CS/PLL/GCE toward Cd(II), Pb(II) and Cu(II) is 0.01µgL-1, 0.02µgL-1 and 0.02µgL-1, respectively. The electrochemical parameters that exert influence on deposition and stripping of metal ions, such as supporting electrolytes, pH value, deposition potential, and deposition time, were carefully studied.