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

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 PININ-PT microspeakers were successfully fabricated rising silicon-based microelectromechanical systems (MEMS) technology and had a thickness of just 0.5 mm and an area of just 1.5 x 1.5 cm(2) The areas of the 10-mu-thick PMN-PT active regions were just 1.2 x 1.2 cm(2). The measured output sound pressure levels (SPL) of the microspeakers were about 85 dB SPL between 800 Hz and 7 kHz with air 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 mu m and 4.1 mu m at the 1st resonant frequency of 840 Hz arid the 2nd resonant frequency of 2.3 kHz, respectively.