A fully roll-to-roll gravure-printed carbon nanotube-based active matrix for multi-touch sensors.

Wookyu Lee,Younchang Choi,Gyoujin Cho,Ali Javey,Jinsoo Noh,Kevin Chen,Kye-Si Kwon,Hyunmo Koo,Junfeng Sun,Chiseon Yeom

doi:10.1038/srep17707

Abstract

Roll-to-roll (R2R) printing has been pursued as a commercially viable high-throughput technology to manufacture flexible, disposable, and inexpensive printed electronic devices. However, in recent years, pessimism has prevailed because of the barriers faced when attempting to fabricate and integrate thin film transistors (TFTs) using an R2R printing method. In this paper, we report 20 × 20 active matrices (AMs) based on single-walled carbon nanotubes (SWCNTs) with a resolution of 9.3 points per inch (ppi) resolution, obtained using a fully R2R gravure printing process. By using SWCNTs as the semiconducting layer and poly(ethylene terephthalate) (PET) as the substrate, we have obtained a device yield above 98%, and extracted the key scalability factors required for a feasible R2R gravure manufacturing process. Multi-touch sensor arrays were achieved by laminating a pressure sensitive rubber onto the SWCNT-TFT AM. This R2R gravure printing system overcomes the barriers associated with the registration accuracy of printing each layer and the variation of the threshold voltage (Vth). By overcoming these barriers, the R2R gravure printing method can be viable as an advanced manufacturing technology, thus enabling the high-throughput production of flexible, disposable, and human-interactive cutting-edge electronic devices based on SWCNT-TFT AMs.

Highlights

Since its first appearance in 19061, roll-to-roll (R2R) gravure has evolved and is currently the highest throughput printing technique with the highest resolution for printing magazines and packaging[2]
The R2R gravure printing setup is as follows: a 15 × 0.25 m2 poly(ethylene terephthalate) (PET) roll with a thickness of 100 μ m as the web, a printing speed of 8 m/min, an impression roller pressure of 6 kgf, a web tension of 5 kgf, a 40° contact angle between the blade and gravure cylinder, and pyramidal engraved cell structures on the gravure cylinder (10–35 μ m in depth and 55–130 μ m in width as illustrated in Supplementary Fig. S1)
The engraved cell structures are selected based on our previous results from R2R gravure-printed single-walled carbon nanotube (SWCNT)-thin film transistor (TFT) on a 150 m PET roll[17]

Summary

Introduction

Since its first appearance in 19061, roll-to-roll (R2R) gravure has evolved and is currently the highest throughput printing technique with the highest resolution for printing magazines and packaging[2]. The OPRA of our R2R gravure, which represents an output value that includes the results of R2R web handling, can reach up to ±20 μ m at a poly(ethylene terephthalate) (PET) web transfer speed of 8 m/min To satisfy this R2R gravure printing speed, the three different types of inks used to print the interconnects and source/drain electrodes, dielectric layers, and active layers should show the required printability on an inexpensive substrate, such as PET or paper, while maintaining the minimum electrical properties to operate the R2R-printed TFT-based electronic devices www.nature.com/scientificreports/. The resultant fully R2R gravure-printed AM is demonstrated as a pressure sensor matrix for potential applications in multi-touch sensor arrays by laminating a pressure-sensitive rubber sheet

Methods

Results

Conclusion