Magnetospirillum magneticum can do directional movement along the geomagnetic field due to the magnetosome. In our whole project, we aslo need to kown whether our engineering bacteria can produce the magnetosome or not, but what should we do? We utilize the characteristics that the Magnetospirillum magneticum has magnetism to build the mathematical model reflecting the relationship between the bacterial number and magnetic field intensity. However, how to do it? We design the microfluidic chip according our need. Through the design drawing, we can kown that the microfluidic chip is divided into three different channels. And in order to differentiate, we respectively marked them as channel 1 and channel 2 and channel 3. The channel 1 is a narrow channel. And bacterial broth slowly flows through this channel. Next, the bacteria enters into the channel 2. The channel 2 is a relatively wide area, we also call itthe magnetic deflection area, bacterial will deflect under the action of magnetic field which we apply. And then after the bacteria deflected in the magnetic field, the bacteria will go into the channel 3. The channel 3 is divided into fiftysmaller channels that every channel has a filter and the bacteria will stay inside under the effect of the filter.After a certain amount of time, we count the bacteria in the small channel under microscope, and finally build the model according the relationship between bacterial number and magnetic field intensity.