Extending lifetime of gas-phase odor biosensor using liquid thickness control and liquid exchange

In recent few years, researchers utilized cell expressing olfactory receptor for vapor detection under various sensing mechanisms. Those olfactory systems, however, have relatively short lifetime due to the dry out of aqueous solution covering the cell. In this paper, we came up with a feedback control structure composed of an impedance measurement circuit, a microcontroller and two syringe pumps for maintaining thin liquid layer above cell. Cell lifetime was improved from less than 40 min to longer than 75 min when liquid film control was introduced. However, the biosensor lifetime remained similar between with or without liquid thickness control. Then, we added liquid exchange to further extend the lifetime of our odor biosensor. Minimal liquid exchange speed was able to significantly extend the biosensor lifetime. Meanwhile, faster liquid exchange speed resulted in better sensor responses. Furthermore, the enhancement acquired from intermittent liquid exchange was compared with continuous one. In this study, the lifetime of odor biosensor was extended to more than 3 h whereas it was less than half an hour without liquid thickness control. We believe the methodology we established in this paper will facilitate gas phase odor biosensor in continuous monitoring of target substances.