A thin-film piezoelectric microactuator using a novel combination of active vertical translational scanning and passive resonant rotational scanning is presented. Thin-film lead-zirconate-titanate unimorph bending beams surrounding a central platform provide nearly 200-μm displacement at 18 V with bandwidth greater than 200 Hz. Inside the platform, a mirror mount, or mirror surface, supported by silicon dioxide spring beams can be excited to resonance by low-voltage; high-frequency excitation of the outer PZT beams. Over ±5.5° mechanical resonance is obtained at 3.8 kHz and ±2 V. The combination of large translational vertical displacements and high-speed rotational scanning is intended to support real-time cross-sectional imaging in a dual axes confocal endomicroscope.

Inspired by the human cochlea, we propose a directional sound sensor using a resonator array to overcome the limitations of existing directional microphones. The proposed sensor consists of multiple cantilevers that respond to different resonance frequencies and separately acquire signals to then combine them for sound sensing. The directionality of the cantilevers is bipolar (figure -of-8) because a signal proportional to the input sound's pressure gradient is generated. We adopt multimode resonance to cover the wide frequency range of 100-8,000 Hz using few resonators. A wide-bandwidth (low-quality-factor) trenched cantilever is used to obtain a flat frequency response. Bidirectional sound sensors are tapered to achieve acoustic beamforming by simple signal processing. The directional characteristics can be easily changed according to the weighted sum of the signals acquired from a pair of sensors. We demonstrate that ambient noise can be effectively suppressed through beamforming to acquire the desired signal using the proposed sensor.

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