Immunoassay is a powerful technique to identify and quantify biological molecules, which base on the specificity and selectivity of antigen-antibody interaction. Impedance-based immunosensor has recently shown a great potential to provide rapid and label-free detections. However, the conventional impedance-based immunosensors rely on dedicated electrochemical measurement interface which involves expensive fabrication procedures such as gold deposition and photolithography. In this work, we propose an ultra-low-cost and high processing efficiency platform for impedance-based immunosensing. With effortless operations of direct-laser-writing, an impedance-based immunoassay can be fabricated within 5 min in standard laboratories. The as-fabricated devices have shown great stability and a high device-to-device uniformity. In order to further validate impedance sensing system's performance, finite element analysis and impedance equivalent model analysis were performed. The measured data was consistent with the simulation results. With the standard gold electrodes surface bio-functionalization procedures, the disposable immunoassay can detect anti-IgG down to 10 ng/ml.
Keywords: Direct laser writing; Disposable immunosensor; Impedance sensor; Label-free immunoassay.
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