Displacement and acoustic vibration sensor based on gold nanobipyramids doped PDMS micro-fiber. 
We propose and demonstrate a novel flexible and elastic vibration-displacement fiber sensor with a doped polydimethylsiloxane (PDMS) micro-fiber based on model interference.  High resolution three-dimensional displacement measurement is achieved through monitoring the output pattern and variation of power.  The sensor with a length of about 200 μm reveals frequency range from 50 Hz to 14 kHz, covering all the human voice frequency, with greatly enhanced high signal to noise ratio (SNR) reaching up to 66 dB. This work suggests a simple structure, small size and low cost fiber-based convenient way to achieve a multifunctional sensing applications including human motion detection.