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The inkjet printing of metal electrodes on polymer films is a desirable manufacturing process due to its simplicity but is limited by the lack of thermal stability and serious delaminating flaws in various aqueous and organic solutions. Kapton, adopted worldwide due to its superior thermal durability, allows the high-temperature sintering of nanoparticle-based metal inks. By carefully selecting inks (Ag and Au) and Kapton substrates (Kapton HN films with a thickness of 135 μm and a thermal resistance of up to 400 °C) with optimal printing parameters and simplified post-treatments (sintering), outstanding film integrity, thermal stability, and antidelaminating features were obtained in both aqueous and organic solutions without any pretreatment strategy (surface modification). These films were applied in four novel devices: a solid-state ion-selective (IS) nitrate (NO 3 − ) sensor, a single-stranded DNA (ssDNA)-based mercury (Hg 2+ ) aptasensor, a low-cost protein printed circuit board (PCB) sensor, and a long-lasting organic thin-film transistor (OTFT). The IS NO 3 − sensor displayed a linear sensitivity range between 10 −4.5 and 10 −1 M (r 2 = 0.9912), with a limit of detection of 2 ppm for NO 3 − . The Hg 2+ sensor exhibited a linear correlation (r 2 = 0.8806) between the change in the transfer resistance (R CT ) and the increasing concentration of Hg 2+ . The protein PCB sensor provided a label-free method for protein detection. Finally, the OTFT demonstrated stable performance, with mobility values in the linear (μ lin ) and saturation (μ sat ) regimes of 0.0083 ± 0.0026 and 0.0237 ± 0.0079 cm 2 V −1 S −1 , respectively, and a threshold voltage (V th ) of −6.75 ± 3.89 V.

Previous studies have shown that metallic coatings can be successfully cold sprayed onto several polymer substrates. However, the electrical performance of the cold-sprayed polymers is not generally enough to utilize them as an electronic device. In this study, an environment-friendly metallization technique has been proposed to achieve highly electrically conductive metal patterns onto polymer substrates using cold spray deposition and subsequent electroless copper plating (ECP). Copper feedstock powder was cold sprayed onto the surface of the acrylonitrile-butadiene-styrene (ABS) parts. The as-cold sprayed powders then served as the activating agent for the selective ECP to modify the surface of the polymers to be electrically conductive. A series of characterizations were conducted to investigate the morphology, analyze the surface chemistry, evaluate the electrical performance, mechanical adhesion, and mechanical strength performance of the fabricated coatings. Moreover, simple electrical circuits were presented for the ABS parts through the described method. Findings demonstrated that low-pressure cold spray (LPCS) copper deposition followed by the ECP processes could be used as an environmental-friendly manufacturing method of electrically conductive patterns on ABS polymer.

In recent years, the metallization of polymers has been intensely studied as it takes advantage of both plastics and metals. Laser direct writing (LDW) is one of the most widely used technologies to obtain metal patterns on polymer substrates. In LDW technology, different methods including injection-molding, drop-casting, dip coating, and spin coating are utilized for surface preparation of polymer materials prior to the laser activation process. In this study, an atomization based dual regime spray coating system is introduced as a novel method to prepare the surface of the materials for LDW of metal patterns. Copper micropatterns on the polymer surface were achieved with a minimum feature size of 30 μm, having a strong adhesion and excellent conductivity. The results show that the dual regime spray deposition system can be potentially used to obtain uniform thin film coating with relatively less material consumption on the substrates for surface preparation of laser direct metallization of polymers.

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