Chemostat-like microfluidic platform for highly sensitive detection of heavy metal ions using microbial biosensors

Reporter-gene-based microbial biosensors have high potential for detecting small molecules, including heavy metal ions (HMIs). However, the sensitivity and dynamic range of microbial biosensors are largely limited by the conventional culture environments that rely on the batch-type addition of the small molecules in nutrients and the subsequent genetic induction. In this work, we report a chemostat-like microfluidic platform that can continuously supply both nutrients and inducers (e.g. Pb²⁺ and Cd²⁺) with microbial biosensors. We employed a mixing microchannel network integrated with microfabricated ratchet structures so that fresh and constant culture environments were conserved for microbial biosensors. Such chemostat-like microfluidic platform enabled sensitive and selective detection of HMIs by enhancing cell growth rates on a chip and even in a high throughput manner.