Highlights  Modeling of mechanical behavior for the material-jet printed polymers  Validation of the material models by comparing the finite element analysis and physical tensile test with multi-material printed specimens  The result proves that it is possible to create a desired strain field by locally changing the ratio of the digital materials without changing the overall shape

Development of polymer based mid-wavelength infrared (MWIR) optics has been limited mainly due to high optical loss of organic polymers used in general optical components. In this study, a MWIR polarization grating based on a sulfuric polymer poly(sulfur-random-(1,3-diisopropenylbenzene)) with a low loss in the MWIR range was fabricated using a simple two-step process: imprint and metal deposition. Fourier-transform infrared (FTIR) spectroscopy measurement showed that this polymeric MWIR polarizer selectively transmitted the polarized IR in transverse magnetic (TM) mode over the transverse electric (TE) mode at normal incidence. The measured extinction ratios ( = The ratio of transmissions in TM and TE) were 208, 176, and 212 at the wavelength of 3, 4, and 5 µm, respectively.The computational simulation and analytical model confirmed that the enhanced TM transmission efficiency and followed a Fabry-Pérot (FP) resonance mode within the created sulfuric polymer film. This polymeric MWIR polarizer demonstrated a great potential for broader applications in IR photonics to realize low-cost and durable optical components.

Growth of printed electronics has increased the interest in the nanoparticle inks. Research on flexible electronics has expanded not only due to inherent benefits of producing flexible products but also for its high-throughput manufacturability, such as roll-to-toll (R2R) process. Conventional sintering methods cause microcracks and voids in the sintered nanoink film, which lead to subpar performance, and are not suitable for the high-throughput R2R production. Furthermore, these methods are incompatible with many polymer substrates used in flexible electronics due to their low thermal budget. In this study, we present an alternative method utilizing an intense pulsed light (IPL) with a xenon flash lamp to sinter silver nanoink on a polymer substrate. The IPL method is capable of selectively sintering the silver nanoink in milliseconds without damaging the polymer substrates. The silver nanoink was stencil printed on a polydimethylsiloxane (PDMS) specimen. Samples were prepared using five different sintering conditions and tested under uniaxial strain. Three IPL sintering conditions were compared against a non-sintered (NS) and an oven-sintered (OS) conditions. The IPL-sintered samples show a significant improvement in tensile test over NS and OS samples. Samples sintered at 20 J/cm 2 of flash energy density and 10 ms of duration were stretched up to 27% strain before losing electrical conductivity. Scanning electron microscopy (SEM) confirms these results showing a reduction in porosity of the sintered nanoink as compared to NS and OS samples.

We have demonstrated a three-dimensional composite structure of graphene and carbon nanotubes as electrodes for super-capacitors. The goal of this study is to fabricate and test the vertically grown carbon nanotubes on the graphene layer acting as a spacer to avoid self-aggregation of the graphene layers while realizing high active surface area for high energy density, specific capacitance, and power density. A vertical array of carbon nanotubes on silicon substrates was grown by a low-pressure chemical vapor deposition process using anodized aluminum oxide nanoporous template fabricated on silicon substrates. Subsequently, a graphene layer was grown by another low-pressure chemical vapor deposition process on top of a vertical array of carbon nanotubes. The Raman spectra confirmed the successful growth of carbon nanotubes followed by the growth of high-quality graphene. The average measured capacitance of the three-dimensional composite structure of graphene-carbon nanotube was 780 µFcm−2 at 100 mVs−1.