Single fibre enables acoustic fabrics via nanometre-scale vibrations

Fabrics, byvirtue of their composition and structure, have traditionally been used as acoustic absorbers(1,2). Here, inspired bythe auditory system(3), we introduce a fabric that operates as a sensitive audible microphone while retaining the traditional qualities of fabrics, such as machine washability and draping. The fabric medium is composed of high-Young's modulus textile yarns in the weft of a cotton warp, convertingtenuous 10(-7)-atmosphere pressure waves at audible frequencies into lower-order mechanical vibration modes. Woven into the fabric is a thermally drawn composite piezoelectric fibre that conforms to the fabric and converts the mechanical vibrations into electrical signals. Keyto the fibre sensitivity is an elastomeric cladding that concentrates the mechanical stress in a piezocomposite layer with a high piezoelectric charge coefficient of approximately 46 picocoulombs per newton, a result of the thermal drawing process. Concurrent measurements of electric output and spatial vibration patterns in response to audible acoustic excitation reveal that fabric vibrational modes with nanometre amplitude displacement are the source of the electrical output of the fibre. With the fibre subsuming lessthan 0.1% of the fabric byvolume, a single fibre draw enables tens of square metres of fabric microphone. Three different applications exemplify the usefulness of this study: a woven shirt with dual acoustic fibres measuresthe precise direction of an acoustic impulse, bidirectional communications are established between two fabrics working as sound emitters and receivers, and a shirt auscultates cardiac sound signals.

Automated summary

Inspired by the auditory system, this study introduces a fabric that functions as a sensitive microphone while retaining the traditional qualities of fabrics. The fabric utilizes high-Young's modulus textile yarns and thermally drawn composite piezoelectric fibers to convert tenuous pressure waves at audible frequencies into electrical signals. The results show that nanometer-level vibrational modes in the fabric are responsible for the electrical output of the fibers. Applications of this study include measuring the direction of acoustic impulses, establishing bidirectional communication between fabrics, and auscultating cardiac sound signals.