Annealing Effect on Structural, Functional, and Device Properties of Flexible ZnO Acoustic Wave Sensors Based on Commercially Available Al Foil

Abstract

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Bimorph material/structure designs for high sensitivity flexible surface acoustic wave temperature sensors

“…There is an increasing trend with the increase of thickness of Al foils. The TCF values for the 50 μm Al foil sample are quite large, but are supported by our previously reported values of ZnO/Al foil SAW devices 25 .…”

“… Comparison of TCF readings between ZnO/Al SAWs in this study and ZnO based SAWs on other commonly used substrates reported in literature 16 , 22 , 23 , 25 , 33 – 39 . …”

“…This could dramatically increase the thermal expansion of the devices during heating/cooling and result in significant variations in the wave velocities with temperature.

Figure 5 Comparison of TCF readings between ZnO/Al SAWs in this study and ZnO based SAWs on other commonly used substrates reported in literature 16 , 22 , 23 , 25 , 33 – 39 .

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“…Al foil or thin Al plates, on the other hand, could be used as an alternative substrate for flexible or bendable SAW devices, reducing the problem of acoustic wave damping and, most importantly, also showing very high TCF values, which were reported by Liu et al . 25 . Therefore, it is promising to use Al foils or thin plates to generate high TCF values for flexible temperature sensing applications.…”

Stability studies of ZnO and AlN thin film acoustic wave devices in acid and alkali harsh environments

“…The Raman peak around 1150 cm À1 is also observed, which is corresponding to the optical overtone of the ZnO. 17 There is a slight decrease for Raman peaks during the corrosion, due to the deteriorated ZnO crystal quality in the acid/alkali harsh environments, although the changes are not so signicant. The reason may be attributed to that the intensity of Raman peaks reects the nature of crystal bonding quality, which does not change signicantly during the corrosion of ZnO lms.…”