[Physical Review Letters] Huygens-Fresnel acoustic interference and the development of robust time-a
The periodic pattern generation using time-averaged acoustic forces conventionally requires the intersection of counter-propagating wave fields, where suspended micro-objects in a microfluidic system collect along force potential minimising nodal/antinodal lines. Whereas this effect typically requires either multiple transducer elements or whole channel resonance, we report the generation of scalable periodic patterning positions without either of these conditions. A single propagating surface acoustic wave interacts with the proximal channel wall to produce a knife-edge effect according to the Huygens-Fresnel principle, where these cylindrically propagating waves interfere with classical wavefronts emanating from the substrate. We simulate these conditions and describe a model that accurately predicts the lateral spacing of these positions in a robust and novel approach to acoustic patterning.
Phys. Rev. Lett.
Citsabehsan Devendran, David J. Collins, Ye Ai, and Adrian Neild