Flexible and disposable paper and plastic based gel micropads for nematode handling, imaging, and chemical testing

Zach Njus, Taejoon Kong, Upender Kalwa, Christopher Legner, Matthew Weinstein, Shawn Flanigan, Jenifer Saldanha, Santosh Pandey

Today, the area of point-of-care diagnostics is synonymous with paper microfluidics where cheap, disposable, and on-the-spot detection toolkits are being developed for a variety of chemical tests. In this work, we present a novel application of microfluidic paper-based analytical devices (microPADs) to study the behavior of a small model nematode, Caenorhabditis elegans. We describe schemes of microPAD fabrication on paper and plastic substrates where membranes are created in agarose and Pluronic gel. Methods are demonstrated for loading, visualizing, and transferring single and multiple nematodes. Using an anthelmintic drug, levamisole, we show that chemical testing on C. elegans is easily performed because of the open device structure. A custom program is written to automatically recognize individual worms on the microPADs and extract locomotion parameters in real-time. The combination of microPADs and the nematode tracking program provides a relatively low-cost, simple-to-fabricate imaging and screening assay (compared to standard agarose plates or polymeric microfluidic devices) for non-microfluidic, nematode laboratories.