The Nanophone: Sensing Sound with Nanoscale Spider Silk

Опубликовано 24 октября 2018, 13:22

Hundreds of millions of years of evolution resulted in hair-based flow sensors in terrestrial arthropods that stand out among the most sensitive biological sensors known. These tiny sensory hairs can move with a velocity close to that of the surrounding air at frequencies near their mechanical resonance, in spite of the low viscosity and low density of air. No man-made technology to date demonstrates comparable efficiency. Here we show that nanodimensional spider silk captures fluctuating airflow with maximum physical efficiency (Vsilk/Vair≈1) from 1Hz to 50kHz, providing an unparalleled means for miniaturized flow sensing. Our mathematical model shows excellent agreement with experimental results for silk with various diameters: 500nm, 1.6µm, 3µm. When a fiber is sufficiently thin, it can move with the medium flow perfectly due to the domination of forces applied to it by the medium over those associated with its mechanical properties. By modifying a strand of spider silk to be conductive and transducing its motion using electromagnetic induction, we demonstrate a miniature, directional, broadband, passive, low cost approach to detect airflow with full fidelity over a frequency bandwidth of 1 Hz to 50 kHz. This easily spans the full range of human hearing, as well as other mammals, birds, amphibians, and reptiles.

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