ZnO Thin Films and Nanostructures for Acoustic Wave-Based Microfluidic and Sensing Applications

Progress in ZnO thin films and nanostructures for the acoustic wave microfluidic and sensing applications are reviewed in this chapter. ZnO thin films with good piezoelectric properties possess large electromechanical coupling coefficients and can be fabricated for the surface acoustic wave (SAW) and film-bulk acoustic resonator (FBAR) devices with a good acoustic performance. The SAWs can be excited to mix, stream, pump, eject, and atomize the liquid, and precision sensing can be performed using SAWs and FBARs. Therefore, the ZnO SAW devices are attractive to be integrated into a lab-on-chip system where the SAWs can transport bio-fluids to the desired area, mix the extracted DNA or proteins, and detect the changes of the signals using SAWs or FBARs. The ZnO SAW and FBAR devices in combination with different sensing layers could also be used to successfully detect gas, UV light, and biochemicals with remarkable sensitivities.