Infectious diseases such as coronavirus disease 2019 (COVID-19) continue to pose significant global health challenges. Effective management of reinfection risks depends on sustained levels of binding and neutralizing antibodies. However, conventional methods—such as enzyme-linked immunosorbent assays (ELISA) and virus neutralization tests (VNT)—are limited by complex workflows, long assay durations, and high sample volume requirements, making them less suitable for routine, decentralized, or time-sensitive surveillance. This study presents a custom-developed tip optofluidic immunoassay (TOI) platform that enables rapid, multiplexed antibody profiling using only 1 μL of fingertip blood. The system integrates batch-fabricated microfluidic immunoreactors with a portable chemiluminescent imaging station, completing both binding and neutralization capability assessments within 40 min. TOI achieves a broad dynamic range (3–4 orders of magnitude), high signal-to-noise ratio (~10,000), and excellent sensitivity for immunoglobulin G (IgG) detection. A renovated version of the rapid in vitro inhibition assay (RIVIA) is incorporated to evaluate neutralizing antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with greater speed and cost-efficiency. In clinical studies, TOI successfully quantified antibody protection against multiple variants, identifying individuals with broad-spectrum immunity to both wild-type and XBB strains. With its high-precision, rapid turnaround, and minimal sample requirement, TOI offers a valuable tool for decentralized immune surveillance and personalized immunization strategy development.

Due to the stimulated emission amplification, lasers with excellent characteristics, including the high energy density, ultra-narrow spectral linewidth, and high directionality, are extremely favorable for sensing, detection, and imaging. Bringing these merits into the micro/nano scale, micro/nano lasers with miniaturized device sizes further enable outstanding spatial and temporal confinement, greatly boosting the light-matter interaction and bridging the size mismatch between light and biomolecules. Thanks to these advantages, micro/nano lasers have drawn widespread attention and opened new opportunities for a variety of biomedical and biochemical applications. In this paper, we review recent developments in biomolecular sensing and cellular analysis based on micro/nano lasers. We first describe the fundamental building blocks of micro/nano lasers, with discussions on gain material considerations, cavity structures, and pumping. We then review recent applications using micro/nano lasers as biosensors and bioprobes, including biomolecule (mainly proteins and DNAs) sensing, wavelength-multiplexed cell labeling/tracking/probing, and high-resolution cellular/tissue bioimaging. Finally, an outlook of the challenges and potential developments of micro/nano lasers for biological sensing and clinical applications is provided.