A microfluidic platform for implementing molecular logic gate with fluorescent chemosensors

In this research, we report a micropump-actuated microfluidic device based on pneumatically-controlled valves implement molecular logic gates of fluorescent chemosensors which shows different intensities responding to different pH and ion conditions. The polydimethylsiloxane (PDMS) microfluidic device was fabricated by multilayer soft lithography. Logic mixing is achieved in a circulating loop by a pneumatic rotary micropump connected to a computer running LABVIEW program. The loop diameter is 1.6 mm and the channel dimensions are 100 µm wide by 10 µm high. This microfluidic system provides fixed-volume control and five chambers for two-factor logic gate conditioned mixing and efficient chemistry reactions on chip to obtain molecular logic gate of these fluorescent chemosensors. As results, INH and NOR two-input logic gates were attained after logic mixing on chip following changes in the intensity of fluorescent chemosensors. An integrated OR logic gate was achieved with two chemosensors which can behave separately XOR and AND logic gates. We also applied transferrin, a copper-binding protein, to copper chemosensor logic mixing and implemented a biological NOT(INH) logic gate. These results show that molecular logic gates which have been known to work only in solution can be implemented in an electronically controlled microfluidic device. This also suggests that our molecular logic gate platform will be further utilized in developing a wet microprocessor in the future.