Over the last decade, flexible analytical devices have received considerable attention in both academia and industry. Compared to conventional analytical devices which are generally made from rigid materials, such as silicon, glass, and plastics, flexible devices offer several unique advantages, such as simplified fabrication, lower costs, enhanced portability and disposability, and compliance to curved or deforming surfaces. For these reasons, flexible analytical devices are well suited for many diagnostic applications, including wearable and in vivo sensing, and point-of-care testing for disease detection and health monitoring. This special issue showcases a comprehensive review and exciting original research on topics ranging from wearable sensors for human motion monitoring and disease diagnosis, flexible electrochemical sensor arrays for human cell culture monitoring, paper-based sensors and immunoassays for diagnostic testing, a paper-based biological solar cell for power generation and storage, and a 3D printing strategy for rapid prototyping of flexible microfluidic devices.  Link to journal articles: http://journals.sagepub.com/toc/jlad/25/1