On-chip phased interdigital metamaterials enable versatile manipulation of surface acoustic waves, microfluids, and micro/nano-objects

Surface acoustic waves (SAWs) offer great potential for quantum information processing, optomechanics, acoustofludics, and acoustic tweezers. However, existing SAW chips lack the ability to control SAWs in a manner similar to current metamaterials, which can achieve versatile subwavelength-resolution manipulation of bulk acoustic waves. This study presents on-chip phased interdigital metamaterials (PIMs) featuring customized interdigital electrodes whose geometries are encoded with deep-subwavelength-resolution phase profiles, enabling versatile transformation of SAWs and manipulation of fluids and micro/nano-objects. Our on-chip PIMs can transform forward SAWs into waves with desired wavefronts and energy patterns, such as SAWs propagating in a specified direction, a SAW jet with energy confined in a wavelength, and twin jets. They also enable "diode-like" SAW transmission, allowing for routing the information carried by SAWs along a forward pathway while blocking backward communication. Additionally, SAWs generated by PIMs exhibit unique energy patterns, allowing for versatile active control of fluid streaming and micro/nano-object distributions.