Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba, Ibaraki 305-8565, Japan.
Department of Chemistry, Massachusetts Institute of Technology (MIT) , Cambridge, Massachusetts 02139, United States.
ACS Appl Mater Interfaces. 2017 Nov 1;9(43):38062-38067. doi: 10.1021/acsami.7b12992. Epub 2017 Oct 23.
As-synthesized single-walled carbon nanotubes (SWCNTs) are a mixture of metallic and semiconducting tubes, and separation is essential to improve the performances of SWCNT-based electric devices. Our chemical sensor monitors the conductivity of an SWCNT network, wherein each tube is wrapped by an insulating metallosupramolecular polymer (MSP). Vapors of strong electrophiles such as diethyl chlorophosphate (DECP), a nerve agent simulant, can trigger the disassembly of MSPs, resulting in conductive SWCNT pathways. Herein, we report that separated SWCNTs have a large impact on the sensitivity and selectivity of chemical sensors. Semiconducting SWCNT (S-SWCNT) sensors are the most sensitive to DECP (up to 10000% increase in conductivity). By contrast, the responses of metallic SWCNT (M-SWCNT) sensors were smaller but less susceptible to interfering signals. For saturated water vapor, increasing and decreasing conductivities were observed for S- and M-SWCNT sensors, respectively. Mixtures of M- and S-SWCNTs revealed reduced responses to saturated water vapor as a result of canceling effects. Our results reveal that S- and M-SWCNTs compensate sensitivity and selectivity, and the combined use of separated SWCNTs, either in arrays or in single sensors, offers advantages in sensing systems.
合成的单壁碳纳米管（SWCNTs）是金属和半导体管的混合物，为了提高基于 SWCNT 的电子设备的性能，必须进行分离。我们的化学传感器监测 SWCNT 网络的电导率，其中每个管都被绝缘的金属超分子聚合物（MSP）包裹。强亲电子试剂（如神经毒剂模拟物二乙基膦酰氯（DECP））的蒸气可以触发 MSP 的拆卸，从而形成导电的 SWCNT 通路。在这里，我们报告说，分离的 SWCNT 对化学传感器的灵敏度和选择性有很大影响。半导体 SWCNT（S-SWCNT）传感器对 DECP 最敏感（电导率增加高达 10000%）。相比之下，金属 SWCNT（M-SWCNT）传感器的响应较小，但对干扰信号的敏感性较低。对于饱和水蒸气，S-和 M-SWCNT 传感器的电导率分别增加和降低。由于抵消效应，M-和 S-SWCNT 的混合物对饱和水蒸气的响应降低。我们的结果表明，S-和 M-SWCNT 补偿了灵敏度和选择性，并且分离的 SWCNT 的组合使用，无论是在阵列中还是在单个传感器中，都为传感系统提供了优势。
