Towards high-performance, low-cost quartz sensors with high-density, well-separated, vertically aligned ZnO nanowires by low-temperature, seed-less, single-step, double-sided growth
Towards high-performance, low-cost quartz sensors with high-density, well-separated, vertically aligned ZnO nanowires by low-temperature, seed-less, single-step, double-sided growth
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DOI：
10.1088/0957-4484/24/35/355503
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发表时间：
2013-09
期刊：
影响因子：
3.5
通讯作者：
A. Orsini;P. Medaglia;D. Scarpellini;R. Pizzoferrato;C. Falconi
中科院分区：
文献类型：
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作者：
A. Orsini;P. Medaglia;D. Scarpellini;R. Pizzoferrato;C. Falconi
由于潜在的传感面积非常大，具有纳米结构表面的谐振传感器长期以来一直被认为是高灵敏度转换的新兴平台。然而，到目前为止，仅描述了复杂、耗时、昂贵且次优的制造程序；事实上，特别是在液体应用方面，报道的设备很少。在这里，我们首先证明，通过将带有未抛光银电极的标准超低成本石英谐振器浸入传统的硝酸锌/HMTA等摩尔营养液中，金属封装的轻微污染允许在高密度（高达10μm−2）和分离良好（根部无融合）ZnO纳米线阵列的电极上直接生长，无需任何种子层或热退火。高密度和良好分离的结合非常适合增加感应面积；此外，这种独特简单的单步工艺适用于传统、超低成本和高频石英，并产生已经封装并可供使用的设备。另一个优点是，可以通过测量生长前后的石英导纳来有效优化工艺参数。作为初步测试，我们表明，高频（即高灵敏度）石英对液体特性的敏感性可以进一步提高近一个数量级，从而显示出有史以来报告的最高的导纳共振响应浸入乙醇和水中的频移。
Resonant sensors with nanostructured surfaces have long been considered as an emergent platform for high-sensitivity transduction because of the potentially very large sensing areas. Nevertheless, until now only complex, time-consuming, expensive and sub-optimal fabrication procedures have been described; in fact, especially with reference to in-liquid applications, very few devices have been reported. Here, we first demonstrate that, by immersing standard, ultra-low-cost quartz resonators with un-polished silver electrodes in a conventional zinc nitrate/HMTA equimolar nutrient solution, the gentle contamination from the metallic package allows direct growth on the electrodes of arrays of high-density (up to 10 μm−2) and well-separated (no fusion at the roots) ZnO nanowires without any seed layer or thermal annealing. The combination of high-density and good separation is ideal for increasing the sensing area; moreover, this uniquely simple, single-step process is suitable for conventional, ultra-low-cost and high-frequency quartzes, and results in devices that are already packaged and ready to use. As an additional advantage, the process parameters can be effectively optimized by measuring the quartz admittance before and after growth. As a preliminary test, we show that the sensitivity to the liquid properties of high-frequency (i.e. high sensitivity) quartzes can be further increased by nearly one order of magnitude and thus show the highest ever reported frequency shifts of an admittance resonance in response to immersion in both ethanol and water.