Morphologically Reconfigurable Magnetic Micropillar Arrays using Acoustic Streaming for Particle Capture and Droplet Manipulation

The accurate and efficient manipulation of particles and droplets is crucial for the fields of disease diagnosis, target drug delivery, and sample purification, specific microstructure-based particle and droplet manipulation have been widely utilized in bioassays. However, current techniques are mainly based on the fixed microstructures, which is extremely difficult to achieve dynamic modulation by adjusting microstructure morphology and excitation conditions. Herein, we present a novel particle capture and droplet manipulation methodology by using morphologically reconfigurable magnetic micropillar arrays incorporate with acoustic streaming effects, which enables reconfigurable particle capturing, cargo transportation, and droplet manipulation. The mechanism is to assemble NdFeB magnetic powders by magnetic gradient fields to form morphologically variable magnetic micropillar arrays with porous surfaces, and the localized acoustic streaming effects generated by surface acoustic waves (SAWs) enable micropillar arrays to capture nearby particles onto the surfaces or to drive perturbations in droplets in the vicinity. To demonstrate the capabilities of this technology, we have achieved the high-volume acoustofluidic particle capture and loading (0.214 MCF), targeted complex maze navigation, efficient droplets manipulation (≤ 3.96mm/s), and acoustofluidic mixing acceleration (≤ 2.5s). Therefore, this technique enables reconfigurable and versatile manipulation of particles and droplets in biomedical applications.