TEER measurement
The TEER measurement was based on commercial EVOM3 instrument (World
Precision Instruments, America) and a simple device compatible with our
chip for measuring TEER was designed (Fig. S2) . Four platinum
wires were fixed on the PC cover after being cleaned several times with
Piranha solution (A mixture of concentrated sulfuric acid and 30%
hydrogen peroxide (3:1)), acetone, ethanol, and water, directly
inserting into the solution as electrodes after sterilization by wiping
with 70% ethanol. Washed the cell by PBS buffer once and the
measurement was carried out in the PBS after the electrode was soaked in
PBS for half an hour before use. The blank channel of the chip was
measured in PBS before inoculating cells as blank control.