A Tip Optofluidic Immunoassay System for COVID-19 Immuno-protection Evaluation Using Fingertip Blood

Infectious diseases such as COVID-19 continue posing significant global health challenges, with recurrent re-infections contributing to long-term symptoms such as cardiac issues and anosmia. Effective management of re-infections relies heavily on maintaining high levels of circulating binding and neutralizing antibodies. Traditional methods for antibody quantification, such as ELISA, face significant challenges, including narrow dynamic ranges and complex sample preparation procedures, which hinder their applications in rapid and routine diagnosis. This study introduces a novel optofluidic biosensing technology, tip optofluidic immunoassay (TOI), that addresses these limitations by enabling the quantitative analysis of binding IgG against multiple SARS-CoV-2 strains from only 1 L of fingertip blood. The proposed TOI system, featuring industrial-grade micro-fabricated immuno-reactors and a portable chemiluminescent imaging station, can provide test results within 12 minutes. For IgG binding assays, TOI possesses a lower limit of detection of 0.1 ng/mL, a dynamic range of 3-4 orders of magnitude, along with a high signal-to-noise ratio (approximately 10,000). This technology not only simplifies the antibody quantification process but also enhances patient compliance and facilitates decentralized testing, which is crucial for infectious disease management. By enabling precise and rapid antibody assessment, this system can support the optimization of vaccination strategies and broader public health responses to COVID-19 and other infectious diseases.