Printed electronics integrated with paper-based microfluidics: new methodologies for next-generation health care

Paper-based microfluidics combined with printed electronics has the potential to yield exceptionally powerful point-of-care diagnostic devices at extremely low cost. To achieve such devices, new manufacturing methodologies must be developed to allow scalable, low-cost production whilst maintaining good reproducibility and performance. In this paper, we discuss the use of high-resolution inkjet printing of various advanced materials as a means to achieve the production of such devices. We present preliminary examples of printing techniques to produce both paper-based microfluidic devices and printed electronic components, which could be further developed into highly integrated, powerful, yet single-use, diagnostic devices. High-resolution inkjet printing of PDMS hydrophobic barriers on nitrocellulose membranes is demonstrated as a means to generate precise (~60-μm-wide) microfluidic circuits allowing low sample volume consumption. To our knowledge, these are the narrowest features produced in paper-based analytical devices via non-lithographic methods. In addition, a novel printing technique based upon agarose gel is demonstrated as a means to directly print microfluidic circuits in paper that may reduce fabrication time and costs as well allow deposition of agarose gel for electrophoresis applications. Printing methods are also used to deposit silver nanoparticle ink electrodes on nitrocellulose with good conductivity, and an all-printed, organic field-effect transistor on a silicon substrate is further presented. These examples serve to highlight the potential application of advanced printing techniques to the production of low-cost, highly functional diagnostic devices.