Scalable Fabrication of Paper Analytical Devices for Chemical Education and Pharmaceutical Screening

Microfluidic paper analytical devices (µPADs) promise to provide an ideal platform for point-of-use tests because of their low cost, user-friendliness, rapidity, and portability. Few µPADs, however, successfully move beyond the proof-of-concept stage to become viable commercial or clinical products, largely due to the lack of scalable fabrication methods. Wax printing was once hailed as the method of choice for µPAD fabrication, but with the growing scarcity of wax printers, alternative methods are needed. Here, I present the air-gap PAD, a low-cost paper device that can be produced with roll-to-roll manufacturing. I successfully adapted two devices previously made with wax printing—a paper-based titration device used for chemical education and a multi-lane PAD used for pharmaceutical quality control and illicit drug checking—to an air-gap format, and partnered with a commercial manufacturer to produce these devices at scale. I developed a reproducible, semi-automated method for depositing colorimetric reagents on the PADs, designed devices to apply both liquid and solid drug samples to the PAD with no need for sample preparation, and collaborated to test a mobile application to read, interpret, and catalog the PAD’s colorimetric pharmaceutical screening results. These advances in µPAD manufacturability, quantitative usefulness, and user-friendliness will make µPADs a more viable platform for point-of-use testing in low-resource settings.