Forum on Wearable and Biodegradable Sensors

A modern sensor is a device that responds to a physical stimulus (e.g., heat, light, sound, etc.) or chemical and sends a signal/information, typically, to other electronics for processing or display.Recently, the growing social interest in health care has encouraged many researchers to develop a variety of wearable and implantable sensors.Nonetheless, it is challenging for these types of devices to be applied practically.They require a marginal gap between the device and skin, and the long-term operational stability in contact with the body fluid.In parallel, the minimization of skin irritation, in vivo toxicity, or immune responses should be considered seriously.Furthermore, from the perspective of a user or a patient, wearing rigid/heavy sensors all day long or having surgery for implanted device removal would be preferentially avoided.To satisfy all these requirements, it is necessary to develop wearable sensors with decent flexibility and partial stretchability and transient devices based on not only biocompatibility but also biodegradable/bioresorbable materials.Owing to the interdisciplinary efforts by many researchers, it is expected that certain types of wearable and biodegradable sensors will show up in markets or hospitals in the near future.Considering both aspects of electronics and biomaterials in such a rapidly growing research field, this joint Forum of ACS Applied Electronic Materials and ACS Applied Bio Materials covers wearable and biodegradable sensors, focusing on flexible/biodegradable electronics and biomaterials for patient-centric diagnostic, health-monitoring, and therapeutic systems that are very close to commercialization.The purpose of this forum is to suggest various research approaches for developing practical bioelectronics in terms of novel functional materials, fabrication/integration processes, and device architectures.In particular, the recent advancement in the field of flexible and biodegradable bioelectronics technology is discussed, for instance, transistor-based biosensors, paper bioelectronics, patterning techniques, wearable biomedical devices, contactless battery-free biosignal recorders, temperature sensors, etc.For the issue of ACS Applied Electronic Materials, four reviews and three research articles are contributed by outstanding researchers in the field of flexible and biodegradable bioelectronics, as briefly summarized in the following.Feng Yan and co-workers reviewed the recent progress in flexible electrochemical biosensor-based detection techniques.Particularly, they focused on amperometry and potentiometry with a brief review on other related technologies.Additionally, transistor-based biosensing was highlighted.Muhammad M. Hussain and co-workers reviewed paper-type biosensors employing cellulose-based materials.They are categorized into paper for substrates and paper for active sensing materials.