Teppei Araki

Transparent electrodes made of silver nanowires (AgNWs) exhibit higher flexibility when compared to those made of tin doped indium oxide (ITO) and are expected to be applied in plastic electronics. However, these transparent electrodes composed of AgNWs show high haze because the wires cause strong light scattering in the visible range. Reduction of the wire diameter has been proposed as a way to weaken light scattering, although there have seldom been any studies focusing on the haze because of

Smart textiles such as wearable computers and health-care sensors on everyday clothing will be realized likely in the near future. Here, we report that highly electrical conductors were fabricated by filling half of the volume of a polyurethane elastomer with microsized silver flakes under a low temperature of 70 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C. Given the high affinity of polyurethane with silver flakes and substrates, high

Mechanically and visually imperceptible sensor sheets integrated with lightweight wireless loggers are employed in ultimate flexible hybrid electronics (FHE) to reduce vital stress/nervousness and monitor natural biosignal responses. The key technologies and applications for conceptual sensor system fabrication are reported, as exemplified by the use of a stretchable sensor sheet completely conforming to an individual's body surface to realize a low-noise wireless monitoring system (<1 µV) that

We formulate copper salt (copper formate/acetate/oleate) precursor inks for photonic sintering using high-intensity pulsed light (HIPL) based on the ink's light absorption ability. The inks can be developed through controllable crystal field splitting states (i.e., the ligand weights and their coordination around the metal centers). The inks' light absorption properties are extremely sensitive to the carbon chain lengths of the ligands, and the ink colors can drastically change. From the relatio

Silver nanowires (AgNWs) are excellent candidate electrode materials in next-generation wearable devices due to their high flexibility and high conductivity. In particular, patterning techniques for AgNWs electrode manufacture are very important in the roll-to-roll printing process to achieve high throughput and special performance production. It is also essential to realize a non-contact mode patterning for devices in order to keep the pre-patterned components away from mechanical damages. Here

Optical transparency is highly desirable in bioelectronic sensors because it enables multimodal optical assessment during electronic sensing. Ultrathin (<5 µm) organic electrochemical transistors (OECTs) can be potentially used as a highly efficient bioelectronic transducer because they demonstrate high transconductance during low-voltage operation and close conformability to biological tissues. However, the fabrication of fully transparent ultrathin OECTs remains a challenge owing to the harsh

The anomaly of a discrete symmetry is defined as the Jacobian of the path-integral measure. Assuming that the anomaly at low energies is cancelled by the Green-Schwarz (GS) mechanism at a fundamental scale, we investigate possible Kac-Moody levels for anomalous discrete family symmetries. As the first example, we consider discrete abelian baryon number and lepton number symmetries in the minimal supersymmetric standard model with the see-saw mechanism, and we find that the ordinary unification o

Neural interfaces that directly measure brain activity are increasingly employed to elucidate large-scale brain networks and treat intractable neurological disorders. Considering the softness of brain tissue, current efforts to study chronic disorders aim to minimize invasiveness. We discuss recent progress on flexible neural interfaces with high durability under bending and stretching achieved by using organic materials. Multichannel microelectrodes are usually fabricated on thin polymer substr

Non-contact printing of high-viscosity silver precursor inks was achieved to provide highly conductive lines by a laser-induced forward transfer technique.

Abstract The growing demand for efficient home healthcare applications for brain disorder diagnostics and treatment has inspired the development of wearable devices for monitoring brain activity. However, flexible probes that have improved biocompatibility for wearable devices are markedly affected by noise due to contact interface issues. In this study, a stretchable (≤1500% strain) and transparent (over 85% transmittance) biocompatible electrode that steadily adheres to skin is developed to fa

Flexible and transparent electrodes are highly useful in wearable optoelectronic systems for healthcare and biosensing applications for conducting multimodal assessments with electrophysiological and optical measures. In such systems, the electrodes should exhibit a low sheet resistance, high visible transmittance, and small feature size, for reliable electrical sensing, optical observation of attached objects, and integration of devices for mapping local biology events, respectively. Herein, fi

Abstract A centrifugal countercurrent type chromatography (Centrifugal Partition Chromatography) was applied to separations of lighter rare earth metal ions (LaCl3, CeCl3, PrCl3, NdCl3, SmCl3 and EuCl3) first time. The results obtained by using di-(2-ethylhexyl)phosphate (D2EHPA) showed that this technique is successfully usable for the laboratory-scale separations, though the numbers of theoretical plate calculated from the chromatograms were considerably lower than expected. The values of sepa

Abstract On‐skin electronics, which offers an interface for extracting electrophysiological signals from skin, is intensively investigated using electrodes mounted on flexible substrates. Despite numerous efforts toward substrate design to optimize user comfort, substrates with skin‐adhesion, skin‐breathability, skin‐compatibility, mechanical endurance, sterilizability, sustainability, and biodegradability remain desirable candidates for human‐ and environment‐friendly on‐skin electronics. To th

Silver flakes/polyurethane composites have been reported as promising materials for stretchable conductors that can be easily fabricated by wet spinning or printing and yet have low electrical resistance. However, it is also important to control the effects of strain on electrical resistance: for example, stable electrical resistance over a range of strains would be useful for flexible displays or solar cells, whereas a positive or negative correlation between electrical resistance and strain wo

Abstract Wearable devices with excellent mechanical stretchability, comparable to that of human skin, are highly desirable for preventing discomfort and dermatitis. Composite material systems that use metal particles and elastomers are promising for realizing intrinsic stretchable electrodes with high conductivity and enhancing mechanical flexibility of wearable devices. However, it is challenging to achieve stable device performance under mechanical deformation using stretchable electrodes. In