Stretchable Oxide TFT for Wearable Electronics

Abstract

St retchable electronics can enable innovative applications such as electronic textiles, wearable displays, and sensors. One of the key challenges of this technology is to design a device/system that tolerates high levels of strain (>>1 percent) without degradation of performance. This challenge entails numerous research issues covering a broad range of fields, including materials, device architectures, mechanics, and fabrication methods. 1 A stretchable thin-film transistor (TFT) is a basic building block for electronic circuits, displays, and sensors. Table 1 presents a brief summary of stretchable TFTs reported in the literature. Although mechanically robust materials and components have been improved recently, fabrication processes with high yield and device stability under mechanical strain remain challenging issues in terms of commer-cialization. [2][3][4][5][6] Of note are some efforts in ruggedization of devices that show excellent performance but less "softness." Wavy, coiled, net-shaped, or spring-like structures have also been used to accommodate large mechanical deformations. 7-10 In addition, active devices on stiff islands that are interconnected with stretchable conductors have proven successful in achieving highly stretchable electronics. [10][11][12][13][14] Stretchable Oxide TFT for Wearable ElectronicsOxide thin-film transistors (TFTs) in a neutral plane are shown to be robust under mechanical bending and thus can also be suitable for TFT backplanes for stretchable electronics. The oxide TFTs when built on a PI substrate can then be transferred onto a PDMS substrate and applied to stretchable electronics. The PDMS regions on the TFT parts are UV/O 3 treated for stiff PDMS and then the TFTs are transferred onto this region. This substrate with TFTs applied can then be stretched up to 50 percent without significant performance degradation. Therefore, stretchable oxide TFT arrays can be used for stretchable displays and sensors.

A Review of the Progress of Thin-Film Transistors and Their Technologies for Flexible Electronics

“…The application of metal oxide TFTs has been reported mostly for bendable/paper displays [80,81], wearable sensors [82], flexible memories [83,84], and energy storage [85]. While the maximum reported mobility for oxides surpasses 150 cm 2 /Vs, it is commonly in the range of 1 to 100 cm 2 /Vs [86].…”

Robust Oxide Thin-Film Transistors With Embedded CNT Buried Layer for Stretchable Electronics

“…Many approaches have been taken for various design innovations to improve mechanical stability such as wavy, coiled, net-shaped, spring-like structures [12]- [15]. In addition, active devices on stiff islands and interconnected with stretchable conductors are also proved to achieve highly stretchable electronics [13], [16]- [18]. Although mechanical robustness of the materials, components, and structures have been improved in recent years, the fabrication process with high yield and the device stability under mechanical strain or stretching remain challenging issues.…”

“…In our previous reports, we demonstrated highly stretchable neutral plane (NP) oxide TFTs for wearable electronics that can be stretched up to 50 % elongation with negligible electrical performance degradation [16]- [18]. The NP oxide TFTs were integrated onto selectively modified polydimethylsiloxane (PDMS) substrate by UV/O 3 treatment [16]. Due to the integration of stiff islands on stretchable PDMS substrate and NP architecture, prolonged repetitive mechanical stretching was possible for the fabricated TFTs.…”