Micro and nano materials and processing techniques for printed biodegradable electronics

Biodegradable electronics can disintegrate and dissolve in liquids, leading to promising applications in healthcare and consumer electronics. However, biodegradable electronics are typically achieved by modified complementary metal-oxide-semiconductor (CMOS) processes with special requirements for low processing temperature and anhydrous fabrication procedures, leading to a complex and time-consuming process. In contrast, printing technology allows the direct generation of complex planar and spatial structures on flat and curved surfaces with improved yield and throughput, leading to promising use of this technology in rapid prototyping and mass fabricating biodegradable electronics. However, a fully printed biodegradable system with complex electronic components has seldom been achieved. The underlying reasons demand in-depth analysis. From a standpoint of necessary components in constructing a fully printing biodegradable system, this article summarizes both the state-of-the-art techniques in printing biodegradable electronic devices and potentially techniques that may be used in developing printing biodegradable electronics. Fundamental principles and general guidelines in developing biodegradable inks and pastes suitable for printing have also been presented, followed by our perspectives on challenges and future trends in printing biodegradable electronics. This article may inspire the effort in developing printed biodegradable electronic systems by utilizing mature techniques and well-established concepts in conventional printable electronics. Both the manufacturing and recycling of the printing biodegradable electronics accommodate the needs for low energy consumption and low carbon emission, leading to sustainable development of industry and consumer electronics.