Im Jisun, Sterner Elizabeth S, Swager Timothy M
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Sensors (Basel). 2016 Feb 2;16(2):183. doi: 10.3390/s16020183.
An integrated cellulose polymer concentrator/single-walled carbon nanotube (SWCNT) sensing system is demonstrated to detect benzene, toluene, and xylenes (BTX) vapors. The sensing system consists of functionalized cellulose as a selective concentrator disposed directly on top of a conductive SWCNT sensing layer. Functionalized cellulose concentrator (top layer) selectively adsorbs the target analyte and delivers the concentrated analyte as near as possible to the SWCNT sensing layer (bottom layer), which enables the simultaneous concentrating and sensing within a few seconds. The selectivity can be achieved by functionalizing cellulose acetate with a pentafluorophenylacetyl selector that interacts strongly with the target BTX analytes. A new design of the integrated cellulose concentrator/SWCNT sensing system allows high sensitivity with limits of detection for benzene, toluene, and m-xylene vapors of 55 ppm, 19 ppm, and 14 ppm, respectively, selectivity, and fast responses (<10 s to reach equilibrium), exhibiting the potential ability for on-site, real-time sensing applications. The sensing mechanism involves the selective adsorption of analytes in the concentrator film, which in turn mediates changes in the electronic potentials at the polymer-SWCNT interface and potentially changes in the tunneling barriers between nanotubes.
一种集成纤维素聚合物浓缩器/单壁碳纳米管（SWCNT）传感系统被证明可用于检测苯、甲苯和二甲苯（BTX）蒸气。该传感系统由功能化纤维素作为选择性浓缩器组成，直接设置在导电SWCNT传感层的顶部。功能化纤维素浓缩器（顶层）选择性吸附目标分析物，并将浓缩后的分析物尽可能靠近SWCNT传感层（底层）输送，这使得在几秒钟内能够同时进行浓缩和传感。通过用与目标BTX分析物强烈相互作用的五氟苯基乙酰基选择剂对醋酸纤维素进行功能化，可以实现选择性。集成纤维素浓缩器/SWCNT传感系统的新设计具有高灵敏度，苯、甲苯和间二甲苯蒸气的检测限分别为55 ppm、19 ppm和14 ppm，具有选择性且响应快速（<10 s达到平衡），展现了现场实时传感应用的潜在能力。传感机制涉及分析物在浓缩器薄膜中的选择性吸附，这反过来介导了聚合物-SWCNT界面处电子电位的变化以及纳米管之间隧穿势垒的潜在变化。
