Ultrasound medicine is an interdisciplinary field that integrates ultrasonics and medicine, encompassing the applications of ultrasound in medical diagnosis, therapy, and basic research. While classical acoustic theories and technologies have reached a developmental bottleneck, their convergence with physics, artificial intelligence (AI), and related advanced technologies has spawned a dynamic research landscape defined by ultra-microscale precision and extreme interdisciplinarity. This paper presents a comprehensive systematic review of sound field modulation theories and their cutting-edge advances in ultra-microscale and highly interdisciplinary biological research. Leveraging acoustic metamaterials, microbubble dynamics, and acoustic streaming coupling effects, breakthroughs have been achieved in deep subwavelength diffraction imaging and precise nanoscale/microscale manipulation at extreme deep subwavelength resolutions. These innovations are fueling biophysical revolutions—including mechanical loading of biomolecules and regulation of ion channel proteins—while enabling breakthroughs in emerging technologies such as sonogenetics and non-invasive ultrasound-based brain-computer interfaces (BCIs). In the future, acoustics is poised to generate disruptive technologies in areas such as artificial structures and devices, non-invasive BCIs, cell and molecular regulation, micro- and nano-imaging/manipulation, and targeted drug delivery. Its unique characteristics—wavelength tunability and cross-scale integration—will continue to drive the deep fusion of physics, biology, and information science, fostering unexploited interdisciplinary synergy.

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.