From Mosfet to MOSFET: Our system can convert the external fluctuation signals into simple 0 and 1 signals to realize the function of analog-to-digital converter. At the same time, as a result of the introduction of recombinases, our system will theoretically be more accurate as a biological switch, with lower leakage, less signal expression affected by the concentration signal of external inducers. Due to the characteristics of recombinases, the engineered cells of our subject can change the signals of different concentrations from the outside into two kinds of simple outputs, and the threshold can be changed by changing type of the promoter and the recombinase. Based on these considerations above, our engineering cells can be used in the following situations