A Piezoelectric Microspeaker with a High-Quality PMN-PT Single-Crystal Membrane

Abstract

We have designed and fabricated a piezoelectric microspeaker with a lead magnesium niobatelead titanate (PMN-PT) single-crystal membrane. The PMN-PT piezoelectric membranes were designed with inter-digitated electrodes (IDEs) to obtain a higher sound output from the speakers. The PMN-PT microspeakers were successfully fabricated using silicon-based microelectromechanical systems (MEMS) technology and had a thickness of just 0.5 mm and an area of just 1.5 1.5 cm2. The areas of the 10m-thick PMN-PT active regions were just 1.2 1.2 cm2. The measured output sound pressure levels (SPL) of the microspeakers were about 85 dB SPL between 800 Hz and 7 kHz with an input drive of 14 Vp k at a distance of 1 cm, which produces a competitive output compared to other commercial microspeakers. Also, the displacements at the center of the PMN-PT membrane (with an input voltage of 1 Vp k) were measured to be 2.5 m and 4.1 m at the 1st resonant frequency of 840 Hz and the 2nd resonant frequency of 2.3 kHz, respectively.