AlN Lamb Wave Resonators on a Flexible Substrate

We report on Lamb wave resonators (LWRs) on a flexible substrate made of polyethylene terephthalate (PET) by transferring method. LWRs with three different topologies were fabricated on the same silicon wafer and then were transferred simultaneously to a flexible substrate with air cavities using a polydimethylsiloxane stamp. The resonators were aligned accurately with the air cavities on the PET, and presented equivalent performance to those on the silicon wafer. The flexible resonator implementing thickness field excitation exhibited a quality factor of 1294 and a coupling coefficient of 2.2%. The flexible two-port resonator presented a low insertion loss of 3.8 dB. The resonator demonstrated excellent mechanical stability under a series of deformations. These results pave the way for flexible electronic filters and oscillators in future wearable electronic systems.