State Key Laboratory for Strength and Vibration of Mechanical Structures, International Center for Applied Mechanics and School of Aerospace, Collaborative Innovation Center of Suzhou Nano Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln 68588-0526, Nebraska, USA.
Nat Commun. 2016 Aug 24;7:12316. doi: 10.1038/ncomms12316.
Exploring the abundant resources in the ocean requires underwater acoustic detectors with a high-sensitivity reception of low-frequency sound from greater distances and zero reflections. Here we address both challenges by integrating an easily deformable network of metal nanoparticles in a hydrogel matrix for use as a cavity-free microphone. Since metal nanoparticles can be densely implanted as inclusions, and can even be arranged in coherent arrays, this microphone can detect static loads and air breezes from different angles, as well as underwater acoustic signals from 20 Hz to 3 kHz at amplitudes as low as 4 Pa. Unlike dielectric capacitors or cavity-based microphones that respond to stimuli by deforming the device in thickness directions, this hydrogel device responds with a transient modulation of electric double layers, resulting in an extraordinary sensitivity (217 nF kPa(-1) or 24 μC N(-1) at a bias of 1.0 V) without using any signal amplification tools.
探索海洋中的丰富资源需要水下声学探测器，该探测器能够从更远的距离接收低频声音，并且具有零反射的高灵敏度。在这里，我们通过在水凝胶基质中集成易于变形的金属纳米粒子网络来解决这两个挑战，将其用作无腔麦克风。由于金属纳米粒子可以像包含物一样密集地植入，甚至可以排列成相干阵列，因此该麦克风可以从不同角度检测静态负载和空气微风，以及从 20 Hz 到 3 kHz 的水下声信号，其幅度低至 4 Pa。与通过在厚度方向上变形器件来响应刺激的介电电容器或基于腔的麦克风不同，这种水凝胶器件通过双电层的瞬态调制来响应，从而在不使用任何信号放大工具的情况下实现了非凡的灵敏度（在 1.0 V 的偏置下为 217 nF kPa(-1) 或 24 μC N(-1)）。
