A micro-patterned transient UV photodetector enabled by solvent-free microfabrication.

Transient electronics, which can be controllably broken down with zero environmental impact, hold significant potential in implantable devices, hardware security, and disposable sensors. While miniaturization is essential for enhancing device performance, increasing integration density, and enabling new applications, degradable materials often face challenges with conventional microfabrication processes like lithography due to their sensitivity to heat and solvents. In this paper, we present a UV photodetector (PD) with micro-scale patterning, fabricated using a novel solvent-free material patterning method. The PD, consisting of molybdenum (Mo) as the electrode, zinc oxide (ZnO) as the photoactive material, and polyvinyl alcohol (PVA) as the substrate, can be dissolved in deionized (DI) water, leaving behind non-toxic byproducts. The device exhibits high responsivity over 50 A/W and an obvious response to varying sunlight intensities, demonstrating its potential for temporary, eco-friendly UV sensing applications. Additionally, we demonstrated that the photoresist used in the solvent-free material patterning method can be reused for subsequent fabrication while maintaining good registration, enhancing efficiency and reducing material waste. This approach provides a scalable and high-efficiency microfabrication strategy for integrating functional materials into unconventional platforms, offering broader applicability in next-generation transient, biodegradable, and flexible sensor technologies.