Printed skin-like large-area flexible sensors and actuators

AbstractIn ambient electronics in the next generation, multiple electronic objects are scattered on walls, ceilings or in imaginative locations and interact each other to enhance safety, security and convenience. For implementation of many electronic objects in our daily life, large-area sheet-type flexible devices are expected to play an important role. In this paper, we review recent progress and future prospects of printed skin-like large-area flexible sensors and actuators. Moreover, the issues and the future prospect of flexible devices such as printed plastic MEMS devices and organic transistors will be addressed from the view point of ambient electronics

Facile fabrication of stretchable Ag nanowire/polyurethane electrodes using high intensity pulsed light

Silver nanowires (AgNWs) have emerged as a promising nanomaterial for next generation stretchable electronics. However, until now, the fabrication of AgNW-based components has been hampered by complex and time-consuming steps. Here, we introduce a facile, fast, and one-step methodology for the fabrication of highly conductive and stretchable AgNW/polyurethane (PU) composite electrodes based on a high-intensity pulsed light (HIPL) technique. HIPL simultaneously improved wire-wire junction conductivity and wire-substrate adhesion at room temperature and in air within 50 mu s, omitting the complex transfer-curing-implanting process. Owing to the localized deformation of PU at interfaces with AgNWs, embedding of the nanowires was rapidly carried out without substantial substrate damage. The resulting electrode retained a low sheet resistance (high electrical conductivity) of <10 Omega/sq even under 100% strain, or after 1,000 continuous stretching-relaxation cycles, with a peak strain of 60%. The fabricated electrode has found immediate application as a sensor for motion detection. Furthermore, based on our electrode, a light emitting diode (LED) driven by integrated stretchable AgNW conductors has been fabricated. In conclusion, our present fabrication approach is fast, simple, scalable, and cost-efficient, making it a good candidate for a future roll-to-roll process

Ultraflexible Wireless Imager Integrated with Organic Circuits for Broadband Infrared Thermal Analysis

Kawabata R., Li K., Araki T., et al. Ultraflexible Wireless Imager Integrated with Organic Circuits for Broadband Infrared Thermal Analysis. Advanced Materials 36, 2309864 (2024); https://doi.org/10.1002/adma.202309864.Flexible imagers are currently under intensive development as versatile optical sensor arrays, designed to capture images of surfaces and internals, irrespective of their shape. A significant challenge in developing flexible imagers is extending their detection capabilities to encompass a broad spectrum of infrared light, particularly terahertz (THz) light at room temperature. This advancement is crucial for thermal and biochemical applications. In this study, a flexible infrared imager is designed using uncooled carbon nanotube (CNT) sensors and organic circuits. The CNT sensors, fabricated on ultrathin 2.4 µm substrates, demonstrate enhanced sensitivity across a wide infrared range, spanning from near-infrared to THz wavelengths. Moreover, they retain their characteristics under bending and crumpling. The design incorporates light-shielded organic transistors and circuits, functioning reliably under light irradiation, and amplifies THz detection signals by a factor of 10. The integration of both CNT sensors and shielded organic transistors into an 8 × 8 active-sensor matrix within the imager enables sequential infrared imaging and nondestructive assessment for heat sources and in-liquid chemicals through wireless communication systems. The proposed imager, offering unique functionality, shows promise for applications in biochemical analysis and soft robotics

Kondo effect in underdoped n-type superconductors

We present high-field magnetotransport properties of high-quality single-crystalline thin films of heavily underdoped nonsuperconducting (La,Ce)2CuO4, (Pr,Ce)2CuO4, and (Nd,Ce)2CuO4. All three materials show identical behavior. They are metallic at high temperatures and show an insulating upturn at low temperatures. The insulating upturn has a log T dependence, but saturates toward the lowest temperatures. Notably, the insulating upturn tends to be suppressed by applying magnetic fields. This negative magnetoresistance has a log B dependence, and its anisotropy shows non simple behavior. We discuss these findings from the viewpoints of Kondo scattering and also two-dimensional weak localization, and demonstrate Kondo scattering as a more plausible explanation. The Kondo scatters are identified as Cu2+ spins in the CuO2 planes.Comment: 17 pages, 6 figures, submitted to Phys. Rev. Let

Study Of Organic Thin-Film Transistors Under Electrostatic Discharge Stresses

Low-voltage pentacene-based organic thin-film transistors (OTFTs) are characterized for the first time under the electrostatic discharge (ESD) stresses. The measurements are conducted using the transmission line pulsing (TLP) tester which generates the human body model equivalent pulses. The ESD behaviors and tolerances of OTFTs having different dimensions and gate biasing conditions are investigated. OTFT\u27s failure mechanism and dc performance degradation due to the ESD stresses are also studied. © 2011 IEEE

Investigation Of Organic Thin-Film Transistors For Electrostatic Discharge Applications

Low-voltage, pentacene-based organic thin-film transistors (OTFTs) are characterized under the electrostatic discharge (ESD) stresses. The measurements are conducted using the transmission line pulsing (TLP) tester which generates the human body model (HBM) equivalent pulses. The ESD performances and tolerances of OTFTs having different gate biasing conditions and dimensions are investigated. A HBM-ESD robustness of 702V can be achieved by gate-grounded OTFT with a width of 3.8 cm and multi-finger drain/source layout. OTFT\u27s failure mechanism and DC performance degradation due to the ESD stresses are also studied by post-stress DC characterization and microscopy observation. © 2011 IEEE

Organic transistors manufactured using inkjet technology with subfemtoliter accuracy

A major obstacle to the development of organic transistors for large-area sensor, display, and circuit applications is the fundamental compromise between manufacturing efficiency, transistor performance, and power consumption. In the past, improving the manufacturing efficiency through the use of printing techniques has inevitably resulted in significantly lower performance and increased power consumption, while attempts to improve performance or reduce power have led to higher process temperatures and increased manufacturing cost. Here, we lift this fundamental limitation by demonstrating subfemtoliter inkjet printing to define metal contacts with single-micrometer resolution on the surface of high-mobility organic semiconductors to create high-performance p-channel and n-channel transistors and low-power complementary circuits. The transistors employ an ultrathin low-temperature gate dielectric based on a self-assembled monolayer that allows transistors and circuits on rigid and flexible substrates to operate with very low voltages