Localized 3D acoustic streaming in microdroplets using high‐frequency micro‐beam IDTs

Acoustic streaming enables non‐contact fluid manipulation in micro‐sized droplets, with applications in lab‐on‐chip diagnostics and biochemical processing. One important existing challenge is that conventional approaches rely on interdigitated transducers (IDTs) with apertures larger than the droplet, limiting the spatial resolution of flow control. In this work, we introduce an acoustic microbeam IDT with an aperture of , significantly smaller than the droplet diameter, operating at a high frequency of 160 MHz. This miniaturized actuator enables precise, localized acoustic excitation at the droplet base. This miniaturization step facilitates the generation of complex streaming patterns and tuneable particle aggregation. By positioning the micro‐IDT inside the droplet, we demonstrate three‐dimensional flow structures not achievable with conventional IDTs. This micro‐sized acoustic generator enables high‐resolution acoustic actuation with broad potential in biosensing, point‐of‐care diagnostics, and targeted drug screening.