Scientists in the United Kingdom discovered graphene, in 2004. The commercial and industrial uses for graphene have been in solar cells, computer chips, and sensors and graphene oxide has superior antibacterial properties. Scientists have made sheets of paper from graphene oxide, and then grown bacteria on it. it can be mass-produced and easily processed to make freestanding and flexible paper with low-cost. This thinnest possible sheets of carbon with the built-in ability to fight disease-causing bacteria could have applications that range from anti-bacterial bandages to food packaging that keeps food fresher longer to shoes that ward off foot odor. This carbon nanomaterial may find important environmental and clinical applications.
Graphene for self-Powered sensors
Petroleum exploration is an expensive process involving drilling deep down in the earth and detecting the presence of oil or natural gas. A number of micro scale or nanoscale sensors are used into new and existing drill wells into the network of cracks that exist underneath the well to collect data on the presence of hydrocarbons. Nowadays to power these sensors convention power sources have to be used which becomes cumbersome. To overcome this problem researchers at Rensselaer Polytechnic Institute have shown that flow of water over surfaces coated with graphene which is a single-atom-thick sheet of carbon atoms which are arranged like a chain-link fence could generate small amounts of electricity to the tune of 0.2 W/sq.m, which could be sufficient to power them. A large numbers of micro scale or nanoscale sensors can be sent into new and existing drill wells to travel laterally through the earth, carried by pressurized water pumped into these wells.
This energy may be sufficient to power tiny sensors that are introduced into water or other fluids and pumped down into a potential oil well. As the injected water moves through naturally occurring cracks and crevices deep in the earth, the devices detect the presence of hydrocarbons and can help uncover hidden pockets of oil and natural gas.
As long as water is flowing over the graphene-coated devices, they should be able to provide a reliable source of power. This power is necessary for the sensors to relay collected data and information back to the surface.
The discovery is a potential solution for a key challenge to realizing these autonomous micro sensors, which will need to be self-powered. By covering the micro sensors with a graphene coating, the sensors can harvest energy as water flows over the coating. Oil companies would no longer be limited to vertical exploration, and the data collected from the sensors would arm these firms with more information for deciding the best locations to drill.
Principle
As water flows over the graphene, the friction force between the water flow and the layer of adsorbed chloride ions present in the water stick to the surface of graphene causing the ions to drift along the flow direction. The motion of these ions drags the free charges present in graphene along the flow direction and creates an internal current.
This means the graphene coating requires ions to be present in water to function properly. Therefore, oil exploration companies would need to add chemicals to the water that is injected into the well.
Uses
Energy harvested from water flowing over a film of graphene is an inexpensive solution. By using graphene the energy generation and performance was superior compared to even the nanotube. Future applications of this technology could be for self-powered micro robots or micro submarines and getting power from a graphene coating on the underside of a boat.