Sensitivity Study of Cancer Antigens (CA-125) Detection Using Interdigitated Electrodes Under Microfluidic Flow Condition

Abstract

The integrated module of microfluidics with the biosensor is of great research interest with the increasing trend of lab-on-the-chip and point-of-care devices. Though there are numerous studies performed on associating the microfluidics to the biosensing mechanisms, the study of the sensitivity variation due to microfluidic flow is very much limited. In this paper, a study of the sensitivity variation while detecting the CA-125 antigen using interdigitated electrodes, with static drop and with microfluidic flow of biofluid sample (CA-125 antigens with phosphate buffer saline solution), was performed. When the biofluid sample was passed on the CA-125 antibodies that are immobilized on the gold interdigitated electrodes, the capacitance variation of the sensing circuit was caused due to the antigen–antibody interaction. However, the capacitance measured during CA-125 antigen–antibody interaction with the microfluidic flow condition (270.34 pF) was lower than static drop condition (296.09 pF) due to the instability of the immobilized antibodies on the sensing surface that was caused by the shear stress on the sensing surface during the microfluidic flow. This study helps to understand the capacitive sensitivity issues in the biosensing mechanisms with microfluidic platform.