Inkjet printing for flexible and wearable electronics

Flexible and wearable electronic devices are emerging as the novel platform for portable health monitoring, human–machine interaction, and some other electronic/optic applications. Future development of human-friendly smart electronics relies on efficient manufacturing and processing of advanced functional materials on flexible/stretchable substrates with effective device integration. Inkjet printing, known as a highly efficient solution-based printing and patterning technology with low-cost, high-quality, and high-throughput advantages, suits large-scale fabrication of flexible and wearable electronics. Over the years, researchers focused on high pattern resolution and uniformity on flexible substrates for advanced electrical/optical performances by various inkjet printing techniques. Different ink materials that can realize multiple functions have been fully investigated for achieving favorable printability and desired interactions with the substrates. Here, the most recently reported inkjet printing strategies, functional ink materials, and diverse inkjet-printed wearable electronic devices for practical applications (e.g., sensors, displays, transistors, and energy storage devices) are summarized. An outlook on future challenges as well as opportunities of inkjet-printed flexible and wearable electronics for research development and industrial commercialization is also presented.