Flexible Dual-Wave Mode AlN-Based Surface Acoustic Wave Device on Polymeric Substrate

In the last decade, the development of new flexible electronics is producing pervasive technologies for the Internet of Things (IoT), robotics and wearables transducers, pushing towards the demonstration of highly compliant low cost components on disposable or recyclable substrates. In recent years, there was a marked improvement in these technologies using organic or inorganic transistors. However, the lack of a high-performance passive-wireless devices in flexible electronics is one of the key bottlenecks for compliant IoT and wearables sensing nodes. One of the main building blocks for sorting this issue out is the development of flexible, bendable and stretchable acoustic-based devices, controllable via wireless antenna. In this work, a flexion characterization of a polymeric-based surface acoustic wave (SAW) device is presented. The flexible SAW is fabricated on polyethylene naphthalate (PEN), employing the high performance of the aluminum nitride (AlN) as a piezoelectric layer. The dual-wave modes, Rayleigh and Lamb, have been characterized. The Lamb waves show better results, in terms of strain sensitivity (1.81E-04 ε) and responsivity (1.156 kHz/με), as compared to the Rayleigh wave (4.29E-04 ε and 0.577 kHz/με, respectively). This polymeric flexiblebased SAW device could pave the way for the development of a passive wireless strain sensor.