Low-Voltage Organic Transistor Memory Fiber with a Nanograined Organic Ferroelectric Film

Abstract

Wearable technology offers new ways to be more proactive about our health and surroundings in real time. For next-generation wearable systems, robust storage and recording media are required to monitor and process the essential electrical signals generated under various unpredictable strain conditions. Here, we report the first fibriform organic transistor memory integrated on a thin and flexible metal wire. A capillary tube coating system allows the formation of a thin and nanograined organic ferroelectric film on the wire. The uniform morphology imparts excellent switching stability (∼100 cycles), quasi-permanent retention (over 5 × 10 4 s), and low-voltage operation (below 5 V) to the fibershaped memory devices. When sewn in a stretchable textile fabric, the memory fiber achieves long retention time of more than 10 4 s with negligible degradation of memory window even under a constant diagonal strain of 100% that exhibits reliable data storage under tough environments. These results illustrate the possibility of the practical, wearable fiber memory for recording electronic signals in smart garment applications.

One-dimensional organic artificial multi-synapses enabling electronic textile neural network for wearable neuromorphic applications

“…Figure 1A shows the fabrication process for 1D artificial multisynapses implemented by substrate-free ferroelectric organic transistors on a thin Ag wire (diameter of 100 m). An organic ferroelectric P(VDF-TrFE) film, which functioned as a common gating dielectric layer, was uniformly and directly coated onto the whole surface of the Ag wire via the dip-coating method using a capillary tube equipped with a printing speed controller (15,25). After annealing at 140°C for 1 hour in an air convection oven to crystallize the coated film, 50-nm-thick pentacene as an active semiconductor channel was thermally deposited on the upper semicircle of the P(VDF-TrFE)/Ag wire.…”

“…Although this thickness is enough to prevent an undesired gate leakage current (fig. S2) and the electrical short, it would lead to a high operating voltage at the same time (25). Therefore, it is important to find optimal conditions between the operating voltage [or the thickness of P(VDF-TrFE)] and device performance/stability depending on the target applications.…”

Chip on a fiber toward the e-textile computing platform

“…A transistor, a capacitor, an inverter, and a ring oscillator based on an indium gallium zinc oxide (IGZO) metal oxide semiconductor are placed on the top surface of the ber while the temperature sensor is built onto the side of the ber. To demonstrate the whole device, we exploited both a capillary tube-assisted coating (CTAC) method and high-resolution maskless photolithography, which are able to fabricate precisely patterned metal electrodes onto the thin and narrow mono lament ber substrate 17,18 . The CTAC process has the potential to be compatible with a reel-to-reel coating process, which is an e cient way to minimize material waste and allows ne control of photoresist (PR) lm thickness and uniformity by adjusting the coating speed and solution concentration 17 .…”

“…To demonstrate the whole device, we exploited both a capillary tube-assisted coating (CTAC) method and high-resolution maskless photolithography, which are able to fabricate precisely patterned metal electrodes onto the thin and narrow mono lament ber substrate 17,18 . The CTAC process has the potential to be compatible with a reel-to-reel coating process, which is an e cient way to minimize material waste and allows ne control of photoresist (PR) lm thickness and uniformity by adjusting the coating speed and solution concentration 17 . Cross-sectional scanning electron microscope (SEM) images indicate that the CTACprocessed PR lm uniformly covered the entire outer surface of the ber, and the thickness of the PR layer is estimated to be approximately 2 μm (Supplementary Figure S1).…”

Integration of multiple electronic components on a microfibre towards an emerging electronic textile platform

“…1a ). By using high-resolution maskless photolithography with a capillary tube-assisted coating method 20 , multiple miniaturized device units are integrated onto a very narrow and thin fibre surface. As a proof-of-concept demonstration, basic electronic devices (field-effect transistors, inverters, and ring oscillators) and sensors (photodetectors, signal transducer, and distributed temperature sensors consisting of thermocouples) are fabricated onto the two different sides of the rectangular fibre.…”