Direct Pen Writing of Adhesive Particle-Free Ultrahigh Silver Salt-Loaded Composite Ink for Stretchable Circuits

In this article, we describe a writable particle-free ink for fast fabrication of highly conductive stretchable circuits. The composite ink mainly consists of soluble silver salt and adhesive rubber. Low toxic ketone was employed as the main solvent. Attributed to ultrahigh solubility of silver salt in short-chain ketone and salt-assisted dissolution of rubber, the ink can be prepared into particle-free transparent solution. As-prepared ink has a good chemical stability and can be directly filled into ballpoint pens and use to write on different substrates to form well adhesive silver salt-based composite written traces as needed. As a result of high silver salt loading, the trace can be converted into highly conductive silver nanoparticle-based composites after <i>in situ</i> reduction. Because of the introduction of adhesive elastomeric rubber, the as-formed conductive composite written trace can not only maintain good adhesion to various substrates but also show good conductivity under various deformations. The conductivity of written traces can be enhanced by repeated writing-reduction cycles. Different patterns can be fabricated by either direct handwriting or hand-copying. As proof-of-concept demonstrations, a typical handwriting heart-like circuit was fabricated to show its capability to work under different deformations, and a pressure-sensitive switch was also manufactured to present pressure-dependent change of resistance

Data_Sheet_1_Application of 3D Printed Porous Copper Anode in Microbial Fuel Cells.docx

<p>In this study, 3D printing technique was utilized to fabricate three-dimensional porous electrodes for microbial fuel cells with UV curable resin, followed by copper electroless plating. A maximum voltage of 62.9 ± 2.5 mV and a power density of 6.45 ± 0.5 mWm⁻² were achieved for MFCs with 3D printed porous copper (3D-PPC) anodes, which were 8.3- and 12.3-fold higher than copper mesh electrodes, respectively. This illustrated the great advantage of 3D porous anodes in MFCs compared to flat anode structures. Besides, the biocompatibility of the copper anode with Shewanella oneidensis MR-1 was examined by comparing with carbon cloth, which produced a 3-fold larger maximum voltage and a ~10-fold higher power density vs. 3D-PPC anodes and thus indicated the possible copper corrosion during MFC operation. ICP-MS analysis of MFC solution revealed the high concentration of 732 ± 27.1 μg/L copper ions detected in the MFC effluent. This result, coupled with EDX showing the lower copper content on the 3D-PPC anode surface after >15 days of MFC operation, confirmed the copper dissolving behavior in MFC. MR-1 biofilm formation under copper suppression was finally characterized by SEM and less biofilm was observed on copper anodes, illustrating their poor biocompatibility, even though 3D printing technology and porous structures were quite promising for future scale-up.</p