Convection and mass transfer enhanced rapid capacitive serum immunoassay

The mechanism of conventional serum immunoassay typically relies on the nature of diffusion of the target analytes, which can cause slow specific binding and long detection times. This work presents a rapid capacitive immunoassay which enhances analyte transport by integrating the AC electrothermal (ACET) flow stirring and capacitive biosensing. The ACET flow conveys target molecules towards the probecoated electrode surface, and leads to rapid preconcentration of target analytes and an instant capacitance change at the electrode-fluid interface. Numerical simulation of ACET convection and mass transfer is provided to analyze how the ACET flow affects the target molecule flux and binding with immobilized receptors. Bovine progesterone diagnosis is demonstrated as an experimental validation. Pregnancy positive and negative serum can be distinguished in 60 seconds. This rapid, sensitive label-free immunoassay can be readily integrated into many microsystems for the detection of many other immunoglobulins.