2. Design and fabrication of the microfluidic chip
The chips utilize a filter in a channel that traps the sensor bacteria while the sample is free to flow in-between
them. As depicted in Fig.1a, the filter can first be loaded with bacteria in the lab and next be perfused with an
aqueous sample. The fabrication process (using two masks) is depicted in Fig.1b. The channels were defined with 5
μm thick SU-8 while the filter gaps were made with 0.5 μm thick sacrificial patches of sputtered amorphous silicon
under the SU-8 layer. As substrate we used double-side polished borosilicate glass.