Microcavity-assisted microfluidic physical sensors: materials, structures, and multifunctional applications.

Microfluidic sensing has long been dominated by chemical approaches that usually rely on fluorescent labels or specific reagents to achieve high specificity. However, these methods often require complex preparation and suffer from limited real-time capability, challenges that become more pronounced in wearable and portable platforms. In contrast, physical sensing offers a complementary route by detecting variations in mechanical, acoustic, optical, or thermal properties directly, enabling label-free, faster, and more robust operation. Under this background, microcavity architectures stand out as one promising option among various physical sensing designs. By spatially confining and enhancing physical signals at the miniature scale, microcavities can sharpen detection resolution and extend dynamic range. These gains are further elevated through the use of tailored materials and are reinforced by fabrication strategies that deliver precise geometry control and adaptable functionality. Harnessing such features, microcavity-based systems have been leveraged in fields ranging from high-resolution tactile sensing in soft robotics to wearable healthcare and human-machine interaction. This review surveys recent progress in materials, fabrication methods, and sensing mechanisms for microcavity-assisted microfluidic physical sensors, and discusses future directions toward broader adoption and scalable deployment.