2026 Volume 47 Issue 2 Pages 132-141
This study investigates strategies to enhance the loading and dispensing capabilities of a droplet in ultrasonic levitation systems through acoustic field optimization. Using a 28.58 kHz transducer, two approaches were evaluated: (1) horizontal standing waves with a 5° angled reflector at first- to third-order resonances, and (2) inclined standing waves at different angles (first-order resonance) under a fixed surface vibration velocity of 0.8 m/s. Results show that the horizontal configurations with the angled reflector required up to 112.5% higher surface vibration velocity to reach comparable levitation performance to that of parallel reflectors, revealing inefficiencies in reflector-angle adjustments. In contrast, tilting the standing wave angle to 45° significantly enhanced stability, enabling reliable levitation of an averaged 1.0 μL droplet with reduced energy input. The inclined-wave method outperformed reflector-angle modifications, achieving precise droplet insertion and dispensing while minimizing acoustic energy consumption.
