An additively manufactured flexible millimeter-wave Doppler radar: Towards fully printed high-frequency multilayer flexible hybrid electronics

Abstract

Abstract Flexible hybrid electronics (FHE) is an emerging technology enabled through the integration of semiconductor devices and 3D printing technology. It unlocks tremendous market potential by realizing low-cost flexible circuits and systems that can be conformally integrated into various applications. However, the operating frequencies of most reported FHE systems are relatively low. It is also worth noting that reported FHE systems have been limited to simple design concepts since complex systems will impose challenges in aspects such as multilayer interconnections, printing materials, and notably, bonding layers. Here, we report an additively manufactured flexible four-layer millimeter-wave Doppler radar (i.e., a millimeter-wave FHE system). The sensing performance and flexibility of the printed radar are characterized and validated by general laboratory tests, field tests, and on-object tests. Our results demonstrate the feasibility of developing additively manufactured high-frequency multilayer FHE, which can be conformally and seamlessly integrated into irregular surfaces for applications such as vehicle radars.