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High-precision printing machines are essential for the fabrication of more sophisticated printed electronics. In particular, roll-to-roll printing with flexible substrates and nonideal rolls, which exhibit cylindricity, misalignment, and run-outs, produces nonlinear effects that are hard to manage with conventional control systems. For instance, printing rolls with cylindricity and run-outs cause large perturbations in the printing forces. In this paper, we propose a hybrid printing force control system that provides uniform printing conditions in the regions where printing occurs. The unique parallel arrangement of two force components provides excellent regulation of the printing force; this system also consumes less power. Our experimental results verify that the force control performance of the hybrid force control system is better than that of a conventional system. We also report the results of in situ printing quality tests with a pressure-sensitive film that confirm the effectiveness of the proposed system. [ABSTRACT FROM PUBLISHER]

The visible quality assessment of images is important to evaluate the performance of image processing methods such as image correction, compressing, and enhancement. The structural similarity is widely used to determine the visible quality; however, existing structural similarity metrics cannot correctly assess the perceived human visibility of images that have been slightly geometrically transformed or images that have undergone significant regional distortion. We propose an improved structural similarity metric that is more close to human visible evaluation. Compared with the existing metrics, the proposed method can more correctly evaluate the similarity between an original image and various distorted images. [ABSTRACT FROM AUTHOR]

As the demand for soft and flexible devices steadily increases, the ionic applications demonstrated with gel materials have come under the spotlight. Here, stretchable and wearable ionic diodes (SIDs) made from polyelectrolyte hydrogels are introduced. Polyelectrolyte hydrogels are mechanically modified using methacrylated polysaccharides while preserving the ion‐permselectivity of poly(sulfopropyl acrylate) potassium salt (PSPA) and poly([acrylamidopropyl]trimethylammonium chloride) (PDMAPAA‐Q), forming ionic copolymers. Then, SIDs composed of polyelectrolyte copolymer hydrogels are fabricated in VHB substrates as a stretchable and transparent insulating layer which is engraved by a laser. The SIDs show rectifying behaviors beyond the stretch of 3 with the aid of perfect adhesion between hydrogels and elastomeric substrates, and preserve their rectifications over hundreds of cycles. The operation of the SID is visualized by a wearable ionic circuit which rectifies ionic currents and lightens the LED under the forward bias during finger movements. A stretchable ionic diode is demonstrated from polyelectrolyte hydrogels. Polyelectrolyte gels are mechanically modified with maintaining their own ion‐selective properties to generate a P–N junction. With the aid of perfect adhesion between the hydrogel materials and an elastomeric substrate, ionic diodes can rectify ionic currents under the applied stretch beyond 3. [ABSTRACT FROM AUTHOR]