Scalable and parallelized biochemical assays in paper devices integrated with a programmable binary valve matrix

The integration of simple fabricated paper devices with a multiplexing fluid control technology are the keys for extending traditional microfluidic applications to paper-based devices. However, paper devices to date have lacked a method for addressing the integration of complex fluid manipulations. By featuring a scalable and programmable mechanical valve matrix that is actuated by push-pull solenoids, we present a paper microfluidic multiplexing technology for performing biochemical assays in a high degree of autonomy. The technology allows every channel of a paper network to be autonomously addressed and isolated while uses a minimal number of control elements, efficiently reducing its complexity. The technology is implemented in an integrated portable system including a multiplexor controller, a relay matrix, a paper device, on-chip temperature control unit and an image analyzer. Biochemical reaction signals can be acquired and automatically interpreted via a self-built mobile App. A prototype that consists of 8 independent valve lines was demonstrated, allowing multiplexed control of a paper device with 16 operating channels. After thoroughly studying the behaviour of fluid transport in the paper device using both numerical simulation and experimentations, multiplex colorimetric assays of heavy metal samples and glucose in common soft drinks and artificial saliva samples were analyzed. To the best of our knowledge, this is the first demonstration of a simple fabricated paper device integrated with a valve multiplexing technology. The scalability of this integration makes the technology ideally suited for high throughput analysis and holds great potential for progressing large scale integration of paper microfluidics.