  Surface assays such as ELISA are pervasive in clinics and research and
predominantly standardized in microtiter plates (MTP). MTPs provide many
advantages but are often detrimental to surface assay efficiency due to
inherent mass transport limitations. Microscale flows can overcome these and
largely improve assay kinetics. However, the disruptive nature of microfluidics
with existing labware and protocols has narrowed its transformative potential.
We present WellProbe, a novel microfluidic concept compatible with MTPs. With
it, we show that immunoassays become more sensitive at low concentrations (up
to 9-fold signal improvement in 12-fold less time), richer in information with
3-4 different kinetic conditions, and can be used to estimate kinetic
parameters, minimize washing steps and non-specific binding, and identify
compromised results. We further multiplex single-well assays combining
WellProbes kinetic regions with tailored microarrays. Finally, we demonstrate
our system in a context of immunoglobulin subclass evaluation, increasingly
regarded as clinically relevant.
