Thermally induced ultrasonic: emission from porous silicon
Thermally induced ultrasonic: emission from porous silicon
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DOI：
10.1038/23664
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发表时间：
1999-08-26
期刊：
影响因子：
64.8
通讯作者：
Koshida, N
中科院分区：
文献类型：
--
作者：
Shinoda, H;Nakajima, T;Koshida, N
用于在空气中产生超声波的最常见的机制（1）是经由压电换能器，由此电信号被直接转换成机械振动。但是这样产生的声压通常被限制为小于10 Pa，大多数压电陶瓷的频率带宽很窄，并且难以将这种换能器组装成没有串扰的精细尺度相控阵列（2，3），使用微机械静电隔膜的替代策略显示出一些前景（4，5），但是所需的高电压和隔膜的机械弱点对于应用来说可能是有问题的。在这里，我们表明，简单的热传导从多孔硅到空气的结果在高强度的超声，而不需要任何机械振动系统。我们的非优化器件在1 W cm（-2）的功耗下产生0.1 Pa的声压，并在高达至少100 kHz的频率下表现出平坦的频率响应。我们期望效率的实质性改进应该是可能的。此外，由于这种材料适合于与常规电子电路集成，因此开发这些设备的精细结构的相控阵应该是相对简单的，这将控制声发射的波前。
The most common mechanism(1) for generating ultrasound in air is via a piezoelectric transducer, whereby an electrical signal is converted directly into a mechanical vibration. But the acoustic pressure so generated is usually limited to less than 10 Pa, the frequency bandwidth of most piezoelectric ceramics is narrow and it is difficult to assemble such transducers into a fine-scale phase array with no crosstalk(2,3), An alternative strategy using micromachined electrostatic diaphragms is showing some promise(4,5), but the high voltages required and the mechanical weakness of the diaphragms may prow problematic for applications. Here we show that simple heat conduction from porous silicon to air results in high-intensity ultrasound without the need for any mechanical vibrational system. Our non-optimized device generates an acoustic pressure of 0.1 Pa at a power consumption of 1 W cm(-2), and exhibits a flat frequency response up to at least 100 kHz. We expect that substantial improvements in efficiency should be possible, Moreover, as this material lends itself to integration with conventional electronic circuitry it should be relatively straightforward to develop finely structured phase arrays of these devices, which would give control over the wavefront of the acoustic emissions.