Columnar growth of transparent semiconducting films: Learning from nature

A two-dimensional array of a large number of identical densely-packed indium-oxide nano-columns was prepared by pulsed laser deposition. The structure closely mimics tubular structure of the under-cap layer of tubular mushrooms. The growth was initiated by a dense array of gold or silver nanodots. The resulting structure forms a transparent semiconducting layer whose resistance is highly sensitive to composition of gases in atmosphere. A simple device based on the array of nano-columns is able to accurately monitor gas balance in an open or closed-space environment. The simplicity of the device, its compactness and a well-established process of deposition would allow incorporating it in various equipment of general or personal use. The application of the sensor could range from health monitoring during the exhale to the check of the car exhaust or gas content in homes, offices, workplaces or in the dangerous and threatening environment.