High-Performance Acoustofluidic Platform for Hematocrit Determination and Particle Separation Using Lateral Plate Transducer Modes

Acoustofluidics enables contact-free manipulation of particles in fluids using acoustic forces, making it ideal for handling biological samples without labeling or surface modification. While bulk acoustic wave (BAW) devices typically rely on transducer thickness modes, this work demonstrates high-performance particle manipulation using lateral width modes. Our silicon-glass-based microfluidic device, coupled to a piezoelectric transducer in an antisymmetric lateral mode, achieves acoustic energy densities up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{3000 J/m}^{\text{3}}$</tex-math></inline-formula>—comparable to leading thickness-mode systems. This work demonstrates the two key applications, first, direct hematocrit determination by focusing red blood cells in whole blood, enabling optical analysis without centrifugation, and second, flow-through separation of particles and cells at rates up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{9 mL/min}$</tex-math></inline-formula>. The efficient particle focusing and separation performance confirm that lateral transducer modes are a powerful alternative in acoustofluidics. This approach broadens the design space for lab-on-chip systems targeting label-free diagnostics and sample preparation.