本研究中利用五種不同的『單層有機分子膜包覆的奈米金簇(Monolayer Protected Gold Nano-Cluster，MPC)』做為感測材料，將MPC塗佈於阻抗式(Chemiresistor，CR)及質量式(Quartz Crystal Microbalance，QCM)感測器上，對於十種揮發性有機氣體(Volatility Organic Compound，VOC)做偵測，藉以探究奈米金殼層結構與氣體吸附反應機構間的關係；另一方面，對於奈米金粒子作一系列的材料鑑定，分別有UV-Visible spectrum、TEM、SEM、EDS，用以觀察材料之粒徑大小、表面情況，此外利用電化學交流阻抗分析法(electrochemical impedance spectroscopy，EIS)，加強奈米金感測材料的純化鑑定。而氣體感測主要分為兩部分探討，首先評估材料AuTBT、AuEBT、AuPEM，它們於阻抗式感測器的靈敏度差，CR/QCM數值0.074 (AuTBT─butylacetate)~1.187(AuPEM─octane)，在質量式感測器中靈敏度最高可達11.544(AuTBT─butylacetate)，可知材料AuTBT有極好的氣體吸附效果。第二部分中針對AuTBT、AuC8及AuC8mixTBT探討，當AuC8mixTBT(10:1)同時具有AuC8飽和碳鏈伸縮性及AuTBT對於氣體吸附效果，兩種官能基同時存在對於氣體感測靈敏度CR/QCM提升至9.192(butanol)~67.116(octane)，置換前後的感測表現為探討重點。

In this study, we synthesized a series of Monolayer Protected Gold Nano-Cluster (MPC) that were capped by various thiolate functional groups and investigated their vapor sensing mechanisms on chemiresistor (CR) and quartz crystal microbalance (QCM) by detecting 10 volatile organic compounds (VOCs). The thiolate functional groups capped on nano-gold core are 1-octanethiol (C8), 4-tert-butylbenzenethiol (TBT), 4-ethylbenzenethiol (EBT), 2-phenylethanethiol (PET) , and mixed 1-octanethiol and 4-tert-butylbenzenethiol. The completeness of MPC purification by detecting the residual of tetra-n-octylammonium bromide (TOAB) using electrochemical impedance spectrometry were proposed and tested. The discussion of vapor sensing mechanism were divided into two sections. First, material AuEBT, AuPEM, and AuTBT has similar structure and short carbon chain. The sensitivities of MPC coated on QCM are better than those of CR sensors coated with this series of material. The average CR/QCM ratios are ranged from 0.321 for AuTBT to 0.562 for AuPET. AuTBT is an extreme example of high absorption mass with very low resistive changes. Second, material AuTBT, AuC8 and AuC8mixTBT are different in the degree of sorptive quantity and interparticle shell overlaps. That causes material AuC8mixTBT has the most superior sensitivity performance in CR. The CR/QCM amplification factors are range from 9.192 for butanol to 67.116 for octane. The correlation between the response sensitivity and the interparticle structure properties revealed not only a clear dependence of the sensitivity on ligand overlap but also the occurrence of a change of the competitive effect in permittivity and interparticle relaxation. The findings in this research reflects that interparticle flexibility and sorptive quantity of MPCs have a profound impact on the response characteristics of such sensing materials on different platform.

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