Single-crystalline halide perovskites with regular morphology
are
of great significance for laser applications because they can be used
to fabricate a natural whispering-gallery-mode resonator. Although
enormous efforts have been put to synthesize single-crystalline perovskites,
controlling the lateral size and thickness of the crystal, particularly
at the nanoscale, is still challenging. Here, we report a facile and
high-throughput strategy to selectively one-step create micro/nanoscale
size-controlled all-inorganic perovskite single-crystal arrays by
surface-tension-confined evaporative assembly. Our method can be used
to easily tune the single crystal size and selectively position the
single crystal, with versatility in fabricating perovskite single-crystal
arrays in a wafer scale. When the patterned size increases from 2
to 25 μm, the width of the CsPbClBr2 perovskite microplates
increased from 150 nm to 4.2 μm. Fixing the width of the microplates
at 1.6 μm, with the increase of the sliding speed from 50 to
250 mm/min, we could significantly control the thicknesses from 270
to 430 nm. Additionally, our present study provides a characterization
of lasers based on different three-dimensional structures, confirming
their width-dependent lasing mode and thickness-dependent lasing threshold
characteristic, which is beneficial for the tunability of a high-performance
microlaser.
Polycyclic aromatic hydrocarbons (PAHs) are always regarded as contaminants originating from the incomplete combustion of organic compounds. Benzo[a]pyrene (B[a]P) can be adopted as a marker for the overall PAH mixture due to its ultratoxic property, which can cause cancer of the lungs, skin, and prostate. It is necessary to monitor the B[a]P contamination levels in a water environment. In this article, an in-line fiber optofluidic sensor for the detection of B[a]P in water by using an antiresonant reflecting optical waveguide is proposed and experimentally demonstrated. One air hole in the cladding of the hollow-core fiber was fabricated as an in-line fiber optofluidic combined with two inlet and outlet microchannels fabricated by using femtosecond laser micromachining. The B[a]P molecule can be detected through the antiresonant reflecting optical waveguide due to the immunoreaction between the antibody and the target B[a]P. The experimental results show that a sensitivity of up to 23 pm/pM is achieved. The proposed fiber sensor appears to have potential applications in research on environmental contamination, food safety, human health, etc.
Highly conductive multilayer graphene nanosheet films are self-assembled for tattoo dry electrodes and strain sensors, which can be used for detecting human electrocardiogram, electromyogram, wrist pulse and breath.
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