A novel multi-frequency energy harvester has been designed and fabricated, which consists of three permanent magnets, three sets of two-layer copper coils and a supported beam of acrylic, while these coils are made of thin fire resistant 4 (FR4) substrates using a standard printed circuit board. The energy under the first, second and third resonant modes can be harvested, corresponding to the resonant frequencies of 369 Hz, 938 Hz and 1184 Hz, respectively. The maximum output voltage and power of the first and second vibration modes are 1.38 mV, 0.6 μW and 3.2 mV, 3.2 μW for a 14 μm exciting vibration amplitude and a 0.4 mm gap between the magnet and coils, respectively. The feasibility study results are in good agreement with the theoretical calculations and show promising application potentials.

High-quality monolayer graphene was synthesized on high-κ dielectric single crystal SrTiO3 (STO) substrates by a facile metal-catalyst-free chemical vapor deposition process. The as-grown graphene sample was suitable for fabricating a high performance field-effect transistor (FET), followed by a far lower operation voltage compared to that of a SiO2-gated FET and carrier motilities of approximately 870-1050 cm(2)·V(-1)·s(-1) in air at rt. The directly grown high-quality graphene on STO makes it a perfect candidate for designing transfer-free, energy-saving, and batch production of FET arrays.

Materials showing reversible resistance switching between high-resistance state and low-resistance state at room temperature are attractive for today’s semiconductor technology. In this letter, the reproducible hysteresis and resistive switching characteristics of metal-CuxO-metal (M-CuxO-M) heterostructures driven by low voltages are demonstrated. The fabrication of the M-CuxO-M heterostructures is fully compatible with the standard complementary metal-oxide semiconductor process. The hysteresis and resistive switching behavior are discussed. The good retention characteristics are exhibited in the M-CuxO-M heterostructures by the accurate controlling of the preparation parameters.

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