## Static there are various methods to generate

Static electricity is caused by an imbalance of electric charges inside or on the surface of a material. All physical objects are made up of atoms which contain protons, neutrons and electrons. Protons are positively charged, electrons are negatively charged while neutrons are neutral. Like charges repel and unlike charges attracts.  When two objects of different materials come into contact with each other and then separated, some electrons may be transferred over to achieve a neutral charge equilibrium. As a result, the atoms in one of the said materials will have an excess in electrons (negatively charged) whilst leaving the other with a deficit in electrons (positively charged).  In general, most matter are electrically neutral. This implies that the number of protons in the atoms and molecules is the same as the number of electrons. When a material gains a surplus in electrons by any means, it will then have a negative charge. Subsequently, when this material is brought into contact with another material which is electrically neutral or positive, this will generate static electricity via the release of excess electrons from the negatively charged material. The electric field generated will produce effects of attraction, repulsion or even a spark.  As there are various methods to generate static electricity, for the purposes of this project, we will be focusing on triboelectricity – generation of static electricity by friction. Triboelectric effect is one way of generating static electricity where certain materials become electrically charged when they are rubbed vigorously against other various materials. This can cause excess electrical charges to be created on their surfaces. As a result, triboelectricity is formed.  The amount of static electricity created is determined by the triboelectric series, as shown in Figure 1. A material towards the bottom of the series, when touched with a material near the top of the series, will acquire a more negative charge. The farther away two materials are from each other on the series, the greater the charge transferred. As this project is on the generation of electricity due to friction, we will be talking about the various devices and applications that makes use of triboelectric effect to generate electricity.  A device that is able to generate electricity through friction is called a triboelectric generator. It is fabricated by stacking two polymer sheets made of materials having very different triboelectric characteristics such as hair and teflon. Two metal films then sandwich these polymer sheets. Figure 2 shows a simple illustration of this arrangement.Once subjected to mechanical deformation, owing to the nano-scale roughness, friction between the two films would generate equal amount but opposite signs of charges at two sides. This causes a formation of a triboelectric potential layer at the interface region, serving as a charge “pump” for driving the flow of electrons in the external load if there is a variation in the capacitance of the system