Biodegradable electronics have great potential to reduce the environmental footprint of electronic devices and to avoid secondary removal of implantable health monitors and therapeutic electronics. Benefiting from the intensive innovation on biodegradable nanomaterials, current transient electronics can realize full components’ degradability. However, design of materials with tissue-comparable flexibility, desired dielectric properties, suitable biocompatibility and programmable biodegradability will always be a challenge to explore the subtle trade-offs between these parameters. In this review, we firstly discuss the general chemical structure and degradation behavior of polymeric biodegradable materials that have been widely studied for various applications. Then, specific properties of different degradable polymer materials such as biocompatibility, biodegradability, and flexibility were compared and evaluated for real-life applications. Complex biodegradable electronics and related strategies with enhanced functionality aimed for different components including substrates, insulators, conductors and semiconductors in complex biodegradable electronics are further researched and discussed. Finally, typical applications of biodegradable electronics in sensing, therapeutic drug delivery, energy storage and integrated electronic systems are highlighted. This paper critically reviews the significant progress made in the field and highlights the future prospects.

Excessive or burst production of reactive oxygen species (ROS) brings oxidative stress that leads to various vital diseases such as cancers, Parkinson’s disease and Ischemia-reperfusion damage, etc. However, traditional biological analysis of ROS based on separate procedure of capturing, labelling, and spectrometrically detecting is complicated and time-consuming, the accuracy of which was severely affected by the short lifespan (microseconds to milliseconds) of ROS, and thus, a fast and effective approach that allows for a real-time detection is highly desired. In this work, we have developed a printable CeO2 − x-CNTs-nanocomposite-based paste and fabricated an integrated flexible ROS sensor (IFRS) by directly printing the paste on a flexible polyethylene terephthalate (PET) substrate as both working electrode and sensing material. This IFRS device demonstrated the fast and real-time response to the hydrogen dioxide in lab as well as to total ROS in sweat of an adult, showing excellent current response to hydrogen oxide in the wide range of 0.01 to 10 mM with a limit of detection (LOD) reaching 1.85 µM. The superior sensitivity of the device to hydrogen oxide was found to be 136.59 \(\text{μA∙}{\text{mM}}^{\text{-1}}\text{∙}{\text{cm}}^{\text{-2}}\), 1.5 to 10 times higher than previously reported sensors. This IFRS device distinguished the instant ROS in the sweat of adult men in vitro, with amperometric response increased 8 times after half an hour strenuous exercise, exhibiting good selectivity and excellent stability together with confirmed high biosafety. Overall, our designed IFRS provides an applicable and translational feasibility toward the simple, rapid and real-time detection of ROS in the near future.