Advances of paper-based microfluidics for diagnostics: The original motivation and current status

Paper has shown potential as a ubiquitous material for fabricating micro analytical devices for diagnostic and drinking water screening applications for resource-limited regions; paper-based sensing technology has become a hot research field since 2007. Intensive research in the past decade has accumulated a large number of scientific publications. However, commercialization of microfluidic paper-based analytical devices (μPADs) for real applications is noticeably lagging behind. The "ASSURED" criteria (i.e., Affordable, Sensitive, Specific, User-friendly, Rapid and robust, Equipment-free, Deliver to the users who need them), set by the World Health Organization, specified the whole spectrum of requirements for a low-cost sensor designed for use in developing countries; they define the technical capabilities (i.e., "ASSR") and user acceptance (i.e., "UED") of low-cost sensing technology. While ASSR should be taken as the basic requirements of any sensor, UED determines whether or not the sensor could potentially be commercialized and gain user acceptance. This Perspective presents these two critical aspects of paper-based diagnostics by revisiting the original motivation of the paper-based analytical platform. It is our opinion that UED are important requirements that deserve more research to increase the commercialization of paper-based analytical devices.