Polymer-based surface acoustic wave device operating in ultra-high frequency

The high cost of conventional surface acoustic wave (SAW) devices limits its widespread use as micro-sensor and actuator for lab-on-a-chip applications. Solution-processed, inexpensive SAW device based on poly[(vinylidenefluoride-co-trifluoroethylene] [P(VDF-TrFE)], a ferroelectric polymer, is an alternative route to address this issue. However, incompatibility of P(VDF-TrFE) films with photoresist strippers and temperature intensive steps, often used in the optical lithography process, impede the development of efficient SAW device. This paper describes suitability of methanol as an alternative photoresist stripper without compromising the ferroelectric property of P(VDF-TrFE). Furthermore, a novel Bilayer-IDT architecture based SAW device is presented, which can be easily poled after temperature intensive fabrication steps to restore its ferroelectric property prior to SAW characterization. The SAW device, presented here, shows resonant frequency in the ultra-high frequency (UHF) range (≈451 MHz), which is quite superior to the highest reported value for P(VDF-TrFE) based SAW. The result is in good agreement with FEM simulations.