Mechanism and optimization of pH sensing using SnO2 nanobelt field effect transistors.
Mechanism and optimization of pH sensing using SnO2 nanobelt field effect transistors.
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DOI：
10.1021/nl801696b
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发表时间：
2008-12
期刊：
影响因子：
10.8
通讯作者：
Wang ZL
中科院分区：
文献类型：
--
作者：
Cheng Y;Xiong P;Yun CS;Strouse GF;Zheng JP;Yang RS;Wang ZL
我们报告了一个系统的调查的pH值传感机制，使用二氧化锡纳米带场效应晶体管（FET）。基于单个SnO 2纳米带的FET是通道受限的，并且具有适当的接触钝化;通过集成微流体用磷酸钠溶液进行pH传感。在不同的栅压下测量了FET沟道电导对pH的响应：在线性传输“开”状态下观察到线性pH依赖性，而在亚阈值状态下观察到指数依赖性。在相同的pH值，但不同的离子浓度的测量表明，FET的pH值的灵敏度随离子浓度的递减。通过比较具有和不具有表面改性的相同装置的pH响应来评估APTES官能化的效果。APTES功能化导致pH灵敏度的轻微增强和噪声水平的大抑制，导致信噪比的显著改善。结果表明，pH传感是基于场效应管的筛选场效应响应的表面质子化/去质子化的纳米带上。这项研究提供了几个有用的指导方针，优化传感器的性能，化学和生物分子检测。
We report a systematic investigation about the mechanism of pH sensing using SnO2 nanobelt field effect transistors (FETs). The FETs, based on single SnO2 nanobelts, are channel-limited and with proper contact passivation; the pH sensing was conducted with sodium phosphate solutions through integrated microfluidics. The responses of the FET channel conductance to pH were measured at different gate voltages: a linear pH dependence was observed in the linear transport “on” state, while an exponential dependence was observed in the subthreshold regime. Measurements at the same pH but different ion concentrations demonstrated that the FET's pH sensitivity decreases logarithmically with the ion concentration. The effect of APTES-functionalization was evaluated by comparing the pH responses of the same device with and without the surface modification. The APTES functionalization results in a slight enhancement of the pH sensitivity and a large suppression of the noise level, leading to marked improvement in the signal-to-noise ratio. The results indicate that the pH sensing is based on a screened field-effect response of the FETs to the surface protonation/deprotonation on the nanobelt. This study provides several useful guidelines for optimizing the sensor performance for chemical and biomolecular detection.
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