A Simple Way to Fabricate Novel Paper-Based Valves Using Plastic Comb Binding Spines.

A novel strategy for fabricating the paper-based valves on microfluidic paper-based analytical devices (µPADs) was described to control fluid in a user-friendly way. Initial prototypes of 3D µPADs manipulate the spatial distribution of fluid within the device. The movable paper channel in different layer could be achieved the channel's connection or disconnection to realize the valve function using plastic comb binding spines (PCBS). The entire valve manipulation process was similar to a desk calendar that can be flipped over and turned back. It is notable that this kind of PCBS valve can control fluid in a simple and easy way without the timing setting or any trigger, and this advantage makes it user-friendly for untrained users to carry out the complex and high throughput operations. The reusable plastic comb binding spines greatly reduce the cost of fabricating paper-based valves. To prove the performance, the actual samples of Fe (II) and nitrite were successfully analyzed. We hope this method will open a new approach to the fabrication of paper-based valves on µPADs in the future.