Self‐cavity lasing from organic crystalline wires of a thiophene/phenylene co‐oligomer (BP3T), which is clearly evident in the inset spectrum (see picture), is reported. The BP3T crystalline wires show self‐waveguided photoluminescence with a high internal quantum efficiency of photoluminescence. The efficiency at 300 K is estimated to be 0.8. The crystalline wires are epitaxially grown on KCl substrates using an improved growth technique.

We fabricate a wearable blood leakage sensor on a cotton textile by combining two newly developed techniques. First, we employ a screen-offset printing technique that avoids blurring, short circuiting between adjacent conductive patterns, and electrode fracturing to form an interdigitated electrode structure for the sensor on a textile. Furthermore, we develop a scheme to distinguish blood from other substances by utilizing the specific dielectric dispersion of blood observed in the sub-megahertz frequency range. The sensor can detect blood volumes as low as 15 μL, which is significantly lower than those of commercially available products (which can detect approximately 1 mL of blood) and comparable to a recently reported value of approximately 10 μL. In this study, we merge two technologies to develop a more practical skin-friendly sensor that can be applied for safe, stress-free blood leakage monitoring during hemodialysis.

In this study, we investigate the static and dynamic aspects of the nip formed during roll-to-sheet-type reverse offset printing. First, we show that several modes of roof collapses (bottom contact defects) could be formed depending on the poly(dimethylsiloxane) (PDMS) blanket thickness and pattern size. We regulate the manifestation of the defect modes driven by the local pile-up of the incompressible PDMS, as modelled by the contact mechanics formulation, together with a complementary numerical simulation. In dynamics, we first differentiate between the static nip and dynamic nip during printing, where the width is extended by the kinetically controlled adhesion of the blanket PDMS. Further, we observe that depending on the pattern structure, there was spatial deviation of the microscopic contact and subsequent separation behaviours of the cliché from a macroscopically recognizable nip, and consequently, local detachment rates were heterogeneous in the pattern-generation process of the reverse offset printing, even with a constant machine speed. In addition, we found that the parts of a pattern where the ink transfer fails in a high-speed patterning condition corresponded to the region of the locally enhanced detachment rates found during direct observation.

We have successfully demonstrated a significant fluorescence property in an organic crystal made of a thiophene/phenylene co-oligomer called AC5. The crystal showed no non radiative transition, meaning it has 100% internal fluorescent quantum efficiency. The crystal also showed high quantum efficiency of photoluminescence of 23 AE 1%. Furthermore, it showed an amplified spontaneous emission at a threshold energy of 21.3 mJ/cm 2 and subsequently showed a quite high optical gain of 52.3 cm À1 . These features are attractive in many areas in the organic optics field such as organic light emitting diodes, organic lasers, and so on.

We investigated the shape integrity of silver nanoparticle ink patterns formed by reverse offset printing, focusing particularly on the proximity effect of neighbouring patterns due to the local deformation of a polydimethylsiloxane (PDMS) blanket during contact with a hard cliché. We performed printing tests using a cliché having circular patterns with smaller neighbouring circles located at various distances (2–20 µm), and the results revealed that as we decrease the thickness of PDMS and the inter-pattern gap distance, and as we increase the printing indentations, the shape integrity of the printed pattern was worsened. A complementary numerical simulation of PDMS deformations suggested that the pattern distortion during the contact with clichés was caused by the horizontal deformation of PDMS during the printing, which becomes a significant burden when the uplifted region of PDMS is closer to the gap distance of each pattern. Our analysis further indicates that during printing, there is slipping of the ink at the PDMS interface. In addition, we examined the effects of a synchronization mismatch in a roll-to-sheet printing on the pattern size tolerance. The magnitude of the size distortions was severely influenced not only by the mismatch ratio but also by the nip width. This result verifies the scraping of the ink accompanied by the slipping of the PDMS during the printing process, and thereby determines the size tolerance of printed patterns in reverse offset printing. Finally, we discuss the optimization of process parameters to ensure the size integrity of reverse offset printing.

The relationship between thiophene sequences and organic thin-film transistor (OTFT) characteristics was studied to determine their effect on ionization potential, molecular orientation, and air stability. Two types of molecular structures were used: continuous sequence and divided sequence thiophenes. The length of thiophene sequence did not affect FET characteristics but did affect ionic potential and air stability.Furthermore, materials with divided thiophene sequences showed no change in OTFT characteristics when exposed to air. These results suggest that separation of thiophene sequences can improve air stability, which is a problem of thiophene-based materials.

We present a novel process for manufacturing cantilever structures by the additive stacking of ink layers. The three-dimensional transfer of printed mechanical parts was achieved by optimizing the ink-sintering conditions to guarantee the structural integrity of the printed parts and provide adequate differences in adhesion strengths between the receiver and donor interfaces. A metal–insulator–metal cantilever structure with a bottom electrode, air insulator, and cantilevered top electrode was fabricated on a flexible film, forming a successful capacitive bending sensor for use on human bodies. This process allows highly efficient device fabrication in the MEMS field.

In this paper, an improved transfer process to fabricate a cantilever structure with a precise air gap is reported. For this fabrication, a planar imprinting method was used and the drying conditions of the cantilever precursor ink were controlled. The air gap between the cantilevered top and bottom electrodes was formed with an estimated error of less than 3%. An operational force gauge with a changeable capacitance was obtained by applying a force to the cantilevered top electrode. This process can facilitate the eco-friendly fabrication of micro-devices with three-dimensional structures.