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.