Figure 2. Reliability of the microfluidic immunosensing chip for repeated immunoassays.

Surface passivation was achieved using BSA and Tween-20 to block compartments of the microfluidic immunosensing chip. (a) Brightfield (left) and fluorescent (right) images showing the imaging chamber array before (top) and after (bottom) being filled with Omnibead solutions (5 mg mL⁻¹). (b) Representative plot of fluorescent signal detected from one imaging chamber before and after three Omnibead solution filling and cleaning cycles. (c) Bar plot of fluorescent signals collected simultaneously from all eight chambers of one imaging chamber array, where three Omnibead solution fillings followed by three chamber cleanings were carried out. The error bar for each chamber represents the range, and n = 2. The mean fluorescent signal (yellow line) ± one standard deviation (S.D.; orange area) from all Omnibead solution filled chambers were calculated and included in the plot.