Development of a source-drain electrode coated with an insulation layer for detecting concentration changes in a nitrate ion solution
Development of a source-drain electrode coated with an insulation layer for detecting concentration changes in a nitrate ion solution
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DOI：
10.1016/j.snb.2006.10.029
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发表时间：
2007-05
影响因子：
8.4
通讯作者：
Takaaki Isoda;H. Makimoto;H. Imanaga;R. Imamura;J. Pawłat;T. Ueda
中科院分区：
文献类型：
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作者：
Takaaki Isoda;H. Makimoto;H. Imanaga;R. Imamura;J. Pawłat;T. Ueda
研究了涂有绝缘层的芯片源漏电极在浓硝酸根离子溶液中的监测能力。将电极表面暴露在高浓度硝酸根离子溶液中会导致检测电压升高，而弱浓度硝酸根离子溶液会导致检测电压下降。用光刻技术在玻璃芯片上制备了厚度为1/0.1μm的Au/Cr膜，构成了半圆形微电极。使用酚醛树脂或氟烯烃乙烯基醚共聚物作为源漏电极上绝缘层的前驱体。将1×10−6~1 0moll−1(1μL)的NaNO3溶液涂在绝缘电极上，通过测量检测电压来评价其化学灵敏度。研究了厚度、绝缘层类型、溶液和传感器材料对化学灵敏度的影响。对于厚度为<；2.5μm的酚醛树脂绝缘层，传感器电压非常不稳定，而较厚的绝缘层(>；5μm)导致传感器电压与NaNO_3浓度在1.0×10~(-6)~1.0×10~(-3)−~(-1)范围内呈线性关系。传感器的响应随绝缘层厚度的增加而提高。因此，如果要实现有效的传感器，绝缘子厚度的优化是必要的。传感器的检测还受溶液种类和电极材料的影响。在绝缘子表面放置液滴，在界面处形成双电层。在这里，绝缘体内的分子变得极化，并在液体和固体之间的边界表面和绝缘体的反面形成电荷。在这种情况下，源漏电极电流和传感器电压之间的关系遵循欧姆定律。基于这一原理，源漏电极响应绝缘层的极化引起的电流变化而产生信号。
A chip-mounted source–drain electrode coated with an insulator layer was investigated with respect to its ability for monitoring in a concentrated nitrate ion solution. Exposing the electrode surface to highly concentrated nitrate ion solutions resulted in an increase in the detection voltage, while weakly concentrated solutions caused the detection voltage to decrease. Semi-circular shaped microelectrodes consisted of an Au/Cr film of 1/0.1μm thickness on a glass chip, constructed using photolithography. A novolac resin or fluoro-olefin vinyl ether copolymer was used as the precursor of an insulator layer on the source–drain electrode. NaNO3solutions of 1.0×10−6to 1.0moll−1(1μl) were applied to the insulated electrode, and the chemical sensitivity was evaluated by measuring the detection voltage. The effects of thickness, insulator type, solution, and sensor material, on the chemical sensitivity were investigated. For a novolac resin insulator layer of thickness <2.5μm, the sensor voltage was noticeably unstable, whereas a thicker insulator layer (>5μm) resulted in a sensor voltage that showed a linear response depending on the NaNO3concentration in the range of 1.0×10−6to 1.0×10−3moll−1. The responsiveness of the sensor was improved with increasing insulator layer thickness. Optimization of the insulator thickness is therefore necessary if an effective sensor is to be realized. Sensor detection was also effected by the kind of solution and electrode material. The placing of a liquid droplet on the insulator surface resulted in the formation of an electric double layer at the boundary surface. Here, the molecules within the insulator become polarized, and a charge is formed at the boundary surface between the liquid and solid, and on the reverse side of the insulator. In this case, the relationship between the source–drain electrode current and the sensor voltage follows Ohm's law. Based on this principle, a source–drain electrode produces a signal in response to changes in current originating from polarization of the insulator layer.