An origami microfluidic battery: A low-cost activity

Abstract

Paper microfluidic technologies are emerging as a promising disruptive technology for low-cost sensing and detection. Researchers have developed a number of sensing and actuating devices that allow the design and creation of microfluidic devices using standard office software and equipment. These devices can be easily designed and produced in a first- or second-year engineering laboratory. This paper will discuss a novel design of a folded, paper microfluidic battery based on the work of N. Thom et al. that can power a surface-mounted light-emitting diode. This origami design, named for the Japanese art of folding paper called origami, allows one to print and assemble postage-stamp sized paper batteries for an initial equipment investment of under $1000 (a wax printer and micropipettes). Although the start-up cost of supplies is a few hundred dollars, the approximate cost per postage-stamp sized battery is on the order of $0.10. The design presented here has a folded footprint of 1 cm2 and outputs an open circuit voltage of 2.5 V for over 15 minutes. Once printed, the dosing of electrolytes and the salt bridge, assembly and testing can be done in about 2 hours. Like standard batteries, the voltage output reflects the chemical potential difference of the electrode metals and the flow of current happens through ion transport in the electrolytes and salt bridge. This origami paper microfluidic battery is a low-cost activity that deepens the understanding of capillary action, chemical potential, and charge transport in batteries. It also represents a hands-on way to introduce students to the emerging technology of paper microfluidics.