Electronic instruments mimicking the mammalian olfactory system are often referred to as “electronic noses” (E-noses). Thanks to recent nanotechnology breakthroughs the fabrication of mesoscopic and even nanoscopic E-noses is now feasible in the size domain where miniaturization of the microanalytical systems encounters principal limitations. Here we describe probably the simplest and yet fully functioning E-nose made of an individual single-crystal metal oxide quasi-1D nanobelt. The nanobelt was indexed with a number of electrodes in a way that each segment of the nanobelt between two electrodes defines an individual sensing elemental “receptor” of the array. The required diversity of the sensing elements is “encoded” in the nanobelt morphology via longitudinal width variations of the nanobelt realized during its growth and via functionalization of some of the segments with Pd catalyst. The proposed approach represents the combined bottom-up/top-down technologically viable route to develop robust and sensitive analytical systems scalable down to submicrometer dimensions.
Kolmakov notes that the potential applications for this sensor device are are numerous and include stand alone truly microscopic detectors and analyzers which can be part of RFID tags (radio-frequency identification devices), smart phones, military devices (micro vehicles), medicine etc.
The researchers’ vision is to be able to grow ‘smart’ sand – imbed a battery, simple circuitry and reporter all on to the same nanostructure.