Printing technologies to produce conductive films and electronic devices are well established and employ only inexpensive materials and devices as well as rapid post-processing methods. In this work, silver nanoparticle and copper-oxide nanoparticle ink was printed using a consumer inkjet printer on a large variety of commercially available substrates. The print quality was assessed by various methods. Self-sintering of the silver ink led to sheet resistances of less than 400 mΩ □⁻¹. Photonic sintering reduced the sheet resistance down to 55 mΩ □⁻¹ within a few milliseconds, equivalent to 2.4 times that of bulk silver. Copper oxide ink was reduced by intense pulsed light and a sheet resistance of 335 mΩ □⁻¹, or 4.5 times that of bulk copper, was obtained. The parameters for sintering were optimized for both inks to achieve low resistivities within a few seconds without damaging the substrates. The production process can be reduced to a few minutes and is fully roll-to-roll compatible, thus providing a quick and ultra-low-cost manufacturing method to produce conductive patterns for wiring, printed circuit boards, antennas, sensor electrodes, light emitting diodes, and solar cells.

This work presents a detailed study of the photothermal ablation of Kapton^® polyimide by a laser diode targeting its electrical conductivity enhancement. Laser-treated samples were structurally characterized using Scanning Electron Microscopy (SEM), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS), as well as Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy. The results show that the laser-assisted ablation constitutes a simple one-step and environmental friendly method to induce graphene-derived structures on the surface of polyimide films. The laser-modified surface was also electrically characterized through the Transmission Line Method (TLM) aiming at the improvement of the conductivity of the samples by tuning the laser power and the extraction of the contact resistance of the electrodes. Once the laser-ablation process is optimized, the samples increase their conductivity up to six orders of magnitude, being comparable to that of graphene obtained by chemical vapor deposition or by the reduction of graphene-oxide. Additionally, we show that the contact resistance can be decreased down to promising values of ∼2 $\mathsf{\Omega }$ when using silver-based electrodes.

The advent of mobile communication has made antennas omnipresent. Conventional methods of antenna manufacturing cannot address the growing demands for novel applications requiring transparent and flexible antennas. In this paper, transparent silver nanowire films are studied with respect to their high‐frequency properties. Transparent silver nanowire (AgNW)‐based antennas that are screen printed onto flexible polyethylene terephthalate (PET) substrate are reported. Transparent films with a low sheet resistance of 8.5 Ω sq⁻¹ and a high transmittance of 85%, at a wavelength of 550 nm, are characterized as bowtie antennas with a radiation efficiency of 52%. This combination of efficiency and transmittance rivals the ones that are commonly reported for conductive‐oxide based transparent antennas and paves their use for any automobile window, liquid crystal display, or organic‐light‐emitting‐diode display.

In this work, we report on a fabrication protocol to produce fully inkjet-printed temperature sensors on a bendable polyethylene terephthalate (PET) substrate. The sensing layer is made of polymer-based Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) ink that is electrically contacted by an underlying interdigitated electrode (IDE) structure based on a silver nanoparticle (AgNP) ink. Both inks are available commercially, and no further ink processing is needed to print them using a cost-effective consumer printer with standard cartridges. The fabricated sensor modules are tested for different IDE dimensions and post-deposition treatments of the AgNP film for their response to a temperature range of 20 to 70 °C and moisture range of 20 to 90% RH (relative humidity). Attributed to the higher initial resistance, sensor modules with a larger electrode spacing of 200 µm show a higher thermal sensitivity that is increased by a factor of 1.8 to 2.2 when compared to sensor modules with a 150 µm-spacing. In all cases, the sensors exhibit high linearity towards temperature and a response comparable to state of the art.

We present a capacitive force sensor based on a polydimethylsiloxane (PDMS) film integrated into a printed circuit board (PCB) on a flexible substrate whose layout is defined by inkjet printing. The influence of the dielectric thickness on the sensor behavior is presented. The thinner PDMS film of about 45 μm shows a sensitivity of up to 3 pF/N but poorer dynamic response. The dielectrics with thicknesses above 200 μm show a significantly reduced sensitivity. The best compromise between sensitivity and dynamic response is found for PDMS film of about 100 μm, showing about 1.1 pF/N and less than 15 s of recovery time. This film is integrated into a flexible PCBS including a microcontroller capable of evaluating the sensor. Interconnects of the circuit are defined by silver nanoparticles deposited by inkjet printing. The working principle of the circuit is demonstrated, proving that this simple approach can be used for artificial skin applications.

A chipless wireless sensor for temperature monitoring is described in this work. The sensor is fabricated by screen printing of an RLC circuit on a flexible substrate. The sensing element is a resistive carbon paste with positive temperature coefficient placed in a small area in the interconnection between the inductor and the capacitor. This sensing layer modifies the resonance frequency of the circuit when the temperature varies. We also show the influence of the sensor sensitivity with respect to the reading distance.