Nanostructure directed interfaces created from nanoparticle island sites deposited to microporous arrays and forming sensor platforms

Abstract

Novel nanostructured island sites are made to decorate a microporous/nanoporous array. These island sites are formed from a variety of easily produced nanostructured metal oxides deposited from solution. Sensor platforms are distinct from and do not require film-based coating. The nanostructure directing acidic metal oxide sites which vary in their Lewis acidity decorate micropores and control the electron transduction process. The interaction of analytes with these island sites varies in a predictable manner and can be modified through in-situ functionalization of their Lewis acidity. The microporous structure allows rapid Fickian diffusion of analytes to the active nanostructure island sites whose reversible interaction dominates the sensor response as it requires low energy consumption. Highly accurate repeat depositions are not required. We require that the island sites are deposited at sufficiently low concentration so as not to interact electronically with each other. The response time of these interfaces is more rapid than film-based depositions, which require a more lengthy diffusion time. The sensors are reversible. The nanoporous structure prevents sintering of these island centers at elevated temperatures. The concentration of detection centers can be made to produce an optimum matrix of enhanced sensor responses, force a dominant distinct analyte-interface physisorption (rather than chemisorption). The produced semiconductor interface is easily functionalized to create an enhanced range of nanoparticle semiconductor sites. The matrix provides a sensitive means of transferring electrons that are easily detected. The sensors operate at room temperature as well as elevated temperatures. Low energy magnetic field signal enhancement can be achieved with transition metals. Contaminated sensors can be readily rejuvenated. Pulsed mode operation ensures low analyte consumption and high analyte selectivity and further provides the ability to rapidly assess false positive signals using Fast Fourier Transfer techniques, Solar pumped sensors requiring low light levels (≤ 1 Watt) have been demonstrated. Water vapor contamination can be greatly if not entirely reduced. The modelling of sensor response with a new Fermi energy distribution -based response isotherm is found to be superior to other isotherms. Sensors operate can be made to operate efficiently for two gases simultaneously. Modes of extending these studies to multiple gas arrays are considered.