Nanosensor

A nanosensor is a device that makes use of the unique properties of nanomaterials and nanoparticles to detect and measure parameters such as chemical compounds in concentrations as low as one part per billion, or the presence of different infectious agents such as virus or harmful bacteria.

Nanosensors can be classified as i) Physical nanosensors which work on the properties of nanotube and nanoribbon used to measure magnitudes such as mass, pressure, force, or displacement. Example of these is pressure nanosensors, force nanosensors or displacement nanosensors, ii) Chemical nanosensors which are mostly working based on the changes of electronic properties of Carbon Nano Tubes (CNTs) and Graphene Nano Ribbon (GNRs) change and iii) Biological nanosensors which is composed of (a) a biological recognition system or bioreceptor, (b) a transduction mechanism (electrochemical detector, optical transducer, or amperometric, voltaic or magnetic detector). These are used to monitor biomolecular processes such as antibody/antigen interactions, DNA interactions, enzymatic interactions or cellular communication processes.

For the fabrication of an individual ZnO nanowire (50 nm in diameter) based nanosensor, the ZnO nanowires are released from the initial substrate by sonication in ethanol. Then, they are transferred to a cleaned SiO2-coated Si substrate. The separated ZnO nanowires are transferred via direct contact with a clean substrate with predeposited Cr/Au external electrodes. Focused Ion Beam (FIB) is used to pattern metal electrodes that contacted both ends of a single ZnO nanowire.

ZnO nanorod-based hydrogen gas nanosensor

Nanogenerators have no mechanical moving parts and are built with arrays of as many as 20,000 zinc oxide nanowires capable of producing up to 1.2 volts of output voltage. They are fabricated with a chemical process designed to facilitate low-cost manufacture on flexible substrates. Tests done with nearly one thousand which showed that they can be operated over time without loss of generating capacity.

Sensing devices

By combining a new generation of piezoelectric nanogenerators with two types of nanowire sensors, researchers have created self-powered nanometer-scale sensing devices that draw power from the conversion of mechanical energy. These devices can measure the pH of liquids or detect the presence of ultraviolet light using electrical current produced from mechanical energy in the environment.

The new generator and nanoscale sensors open new possibilities for very small sensing devices that can operate without batteries, powered by mechanical energy harvested from the environment. Energy sources could include the motion of tides, sonic waves, and mechanical vibration, the flapping of a flag in the wind, pressure from shoes of a hiker or the movement of clothing.