Printing has emerged as a technically feasible and economically viable approach to fabricate antennas on a wide range of rigid and flexible substrates. Printing offers several advantages such as rapid prototyping, minimal number of processing steps and minimal equipment needs relative to conventional microfabrication and other antenna manufacturing techniques, versatility in the choice of substrates and low cost. Here we use a plasma-based printing approach to print self-sintered copper and silver antennas. The morphology of the printed films is continuous with nanoparticles agglomerated and fused together under the influence of the plasma. The printed antennas exhibit a reflection coefficient of about −20 dB or lower and bandwidth over 10% at a resonant frequency around 2.4 GHz. The results show the feasibility of printing high performance antennas on flexible substrates such as polyimide using plasma printing technology.
Abstract Printing of metallic, semiconducting and other materials is a key step in printed and flexible electronics. Plasma jet printing is emerging as an alternative to inkjet, aerosol and other competing printing techniques since it is a single step process that does not require post-thermal annealing to obtain consolidated printed films with good adhesion. Here, we provide results for printing metallic films and patterns from flight tests with varying gravity from 0 to 2 G. The conductivity of the as-printed silver film without any post-sintering was 12% of the bulk value for silver. As expected, the absence of gravity has no adverse impact on the print quality since the ink content along with the plasma is forcefully ejected by the applied electric field towards the substrate, while the successful flight test itself attests to the robustness of the printer and the printing technique.
This paper reports a scalable prototype supercapacitor using metal oxides and graphene oxide and an ionic liquid electrolyte. Our novel approach to combining pseudocapacitance and electric double layer capacitance in a tri-layered composite, promises to increase the energy density of the device, without sacrificing the high power density attributed to it. Solutions of KOH, Acetonitrile and 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMIm-BF4) are used in manufacturing our devices, with more focus on the ionic liquid. These room temperature molten salts are predicted to function better as an electrolyte under extremely low temperatures. This paper presents the scalable synthesis of composites of reduced graphene oxide on MnO2 nanowires and Co3O4 nanorods. We assemble the devices with different electrolytes and employ a modified electrophoretic deposition process which produces uniform layers of rGO on semiconductors, metals and flexible substrates.
Abstract The proliferation of electronic devices has made electromagnetic interference (EMI) shielding an exponentially growing business. Regulatory requirements change constantly as new technologies continue to emerge. Innovations in materials and new advances in shielding implementation techniques are needed to pass regulatory compliance tests at an affordable cost. Here, we print various EMI shielding materials such as copper, silver and a composite of copper with Fe 3 O 4 using plasma jet printing. Printing enables shields only a few microns thick capable of high shielding effectiveness. Copper’s EMI shielding performance is primarily contributed by reflection mechanism, as expected and this is known to cause secondary pollution. A Green Index for EMI shielding, given by the ratio of absorption and reflection contributions to shielding, indicates values lower than 0.1 for printed copper films.
Diamond with nitrogen, silicon and other group IV vacancies have been receiving attention as single-photon sources for various quantum applications. Typically, diamond is prepared by epitaxial methods and the desired vacancies are incorporated by in situ doping or ion implantation. Here we prepare diamond by plasma jet printing from nanodiamond ink and incorporate silicon also by printing using a nanoparticle ink. Printed diamond films exhibit all the characteristic Raman, X-ray diffraction and photoluminescence (PL) features commonly seen in epitaxially-grown films. Printed silicon films are crystalline and when printed on diamond, silicon incorporation shows the characteristic silicon vacancy PL peak.
Great focus has been directed towards double-layer capacitance and Faradic, redox reactions because of their long device lifetimes and their high power densities, respectively. Our novel approach to combining these mechanisms in a tri-layered composite electrode promises to increase the energy densities of the device, without sacrificing the supercapacitance and the high power densities attributed with it. Initial analysis of the interfacial interactions of graphene oxide (GO) and manganese oxide (MnO2) were promising. This paper aims to further demonstrate the tri-layered composite by forming a layer of reduced graphene oxide (rGO) on MnO2 nanowires and cobalt oxide nanorods. We have successfully created the first of a kind supercapacitor electrode material as a scalable device. In this paper, in addition to analysis of the composite electrode, we present modifications to the traditional electrophoretic deposition process and optimizations to the thermal reduction of GO in order to create rGO surfaces on substrates that are normally difficult to adhere it to.
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