A High Dynamic Range Protein Sensing Platform for Low-Volume Magneto Immunoassay Automation

Immunoassays have been employed in diagnosing numerous diseases. Typically, these tests require a large volume of biofluid samples and overnight reaction. In this article, a high dynamic range (DR) microfluidic protein sensing platform is presented. This platform reduces the required sample volume, expedites the reactions, and automatically controls the sample processing procedures. The platform includes a high-performance potentiostat circuit for redox signal acquisition and eight-channel polydimethylsiloxane (PDMS) microfluidic device for automatic sample processing. The sensing circuit employs a capacitive transimpedance amplifier (CTIA) architecture, which achieves low current noise (15.8 pA), wide (116 dB) DR, and good linearity. The linearity of the whole platform is verified with electrochemical measurements using potassium ferricyanide (K3[Fe(CN)6]). The immunoassays are performed with patients’ serum samples and horseradish peroxidase (HRP)/3,3’,5,5’-tetramethylbenzidine (TMB) substrate-based assays. The limit-of-detection (LoD) of the whole system is 7 pg/mL.