A Flexible Film Bulk Acoustic Resonator Radio Frequency Sensor Based on Pb_1.2(Zr_0.52Ti_0.48)O₃/Polymer Thin Films

A flexible radio frequency (RF) sensor based on Pb1.2(Zr0.52Ti0.48)O3/polymer thin films is proposed. The RF sensor is a film bulk acoustic resonator (FBAR) type sensor with sand-witched Pb1.2(Zr0.52Ti0.48)O3 film. Experimental results show that at 255 MHz, the sensor exhibits high sensitivity to both bending and pressure while being insensitive to temperature, its pressure and bending sensitivities can reach −2966.01 kHz<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>kPa<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}}$ </tex-math></inline-formula> and −61.1 kHz<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot \mu $ </tex-math></inline-formula>m<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}}$ </tex-math></inline-formula>, respectively, while it is almost temperature insensitive, with only 0.472% frequency drift between <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$24~^{\circ }$ </tex-math></inline-formula>C and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50~^{\circ }$ </tex-math></inline-formula>C. This type of sensor can operate in a passive and wireless way. Additionally, it possesses the other inherent advantages of high sensitivity, flexible and wearable adaptability, and excellent stability and reliability. The sensor holds promising potential for practical applications in intelligent skin, robotic arms, and vital signal detection.