Dual functionalization of aligned silicon nanowires by APTES and nano-Ag to achieve high response to rarefied acetone at high ambient humidity

摘要

Silicon nanowires (SiNWs) array is a promising gas sensitive material featured as room-temperature response and compatibility of modern semiconductor technology. Towards breath diagnosis applications, a dual-functionalized SiNWs-based sensor (APTES&Ag@SiNWs) capable of rarefied acetone detection at high humidity level was developed based on the co-modification of 3-aminopropyl-triethoxylsilane (APTES) and nanoparticles of Ag. The SiNWs array was fabricated via metal assistant chemical etching (MACE) process and Ag nanoparticles modification was one-step achieved conveniently from MACE-produced Ag dendrites during SiNWs etching. In the APTE-S&Ag@SiNWs sensor, molecular functionalization of APTES could achieve obvious response promotion due to the active terminal amino groups of APTES for acetone molecule adsorption, while the modified Ag nanoparticles serve as wet centers to gather the adsorbed water molecules and then weaken the adverse effect of water adsorption on gas adsorption and response at high humidity. Resultantly, the on-chip sensor based on the dual-functionalized APTES&Ag@SiNWs array is revealed highly effective for acetone-sensing at room temperature and high humidity ambient (up to 85%RH). In particular, the as-developed APTES&Ag@SiNWs sensor shows linear response with the acetone concentration increasing from 1 to 4 ppm at 80%RH. The unique sensing characteristic makes the co-modified sensor promising in noninvasive diagnosis of diabetes via breath sensing. Finally, the moisture resistance analysis of the modified Ag is preformed based on first-principles calculations and meanwhile the contribution of APTES molecular functionalization on response enhancement is clarified.