A bristle-bot or vibrobot is a multi-legged robot made of bristles and an oscillating actuator that generates vibrations. This work presents the first demonstration of a microbristle-bot, with 3D-printed legs, fabricated by two-photon polymerization (TPP) lithography. The presented miniaturized bristle-bot has a weight of only 5 mg, in the size of 2 mm × 1.87 mm × 0.8 mm, and can achieve a speed up to 4 times the body length per second. A base structure with six legs is fabricated by TPP direct laser writing in a single fabrication step, allowing for rapid prototyping of various leg designs. The base is attached to a 0.3 mm thick lead zirconate titanite (PZT) actuator block. The vibrational energy is provided by an external piezoelectric shaker in this work, which mimics the ocillatory behavior of the on-board PZT block. This work demonstrates the locomotion of micro-bristle-bots with various leg designs that utilizes the resonant bending mode shape at small excitation voltages applied to the external piezoelectric shaker. The presented micro-bristle-bots show a resonant frequency around 6.3 kHz, which can be tailored based on their geometry. This feature allows for addressing individual micro-bristle-bots with various geometries based on their unique resonance frequency.

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Molecular beam epitaxy is used for growth of structures with ScAlN for radio frequency filter applications. The nitride layers are grown directly on Si substrates for surface acoustic wave resonators, Lamb acoustic wave resonators, and on an epitaxial Mo on Er2O3 buffer layer on Si for film bulk acoustic resonators (FBARs). The crystal structure of the ScAlN layer is defined by Sc concentration. It can vary from wurtzite to hexagonal. Good crystal quality of the Mo layer results in low sheet resistance which is very close to that of the bulk material. Enhanced electroacoustic performance is achieved in fabricated acoustic devices. A Lamb acoustic wave resonator with ScAlN grown directly on Si demonstrates a high coupling factor (4.8%) and figure of merit (Q × kt2) (9.1) at a resonance frequency of 9.02 GHz. A fundamental resonance frequency 4.32 GHz is achieved for an FBAR device fabricated using the structure with the nitride layer on an epitaxial metal electrode. At the 4.32 GHz resonance frequency, the extracted figure of merit of the resonator is 10.6.

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