For commercial shellfish farmers and recreational hunters alike, marine biotoxins pose a significant threat to health and welfare. With this project, we aim to create an inexpensive and easy-to-use test kit for the detection of the small molecules auxin and theophylline using engineered yeast strains and DNA aptamers on a paper device. We hope that this project paves the way for a new class of biosensors capable of detecting a wide range of molecules, including the shellfish toxin okadaic acid.