The Nanophone: Sensing Sound with Nanoscale Spider Silk

October 5, 2018
Ronald Miles | Binghamton University

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.

Speaker Details

Distinguished Professor Ron Miles serves as chair of the Department of Mechanical Engineering. His research involves the diverse fields of mechanics, acoustics, vibrations, MEMS, neurobiology, and control systems to create advanced micro acoustic sensors. These devices have applications in consumer electronics, laboratory instrumentation, automotive, hearing aids and other healthcare applications. He currently serves as Associate Editor for the ASME Journal of Vibration and Acoustics. Prof. Ron Miles received his BS in Electrical Engineering from the University of California at Berkeley in 1976, and his MS and PhD in mechanical engineering from the University of Washington. He had worked at Boeing for eight years and was also a faculty fellow in the Structural Acoustics Branch at NASA Langley. Dr. Miles has published over one hundred scholarly articles and presented over seventy invited lectures.