**1.1. Low power consumption**

conceived by Lord Rayleigh [2] in the late 19th century. In 1902, Morton [3] and Cooley [4] disclosed a patent using the electrospinning process via a composite solution. This patent was issued for the production of fibers from a solution jet using an electric field. From 1934 to 1944, Formhals published a series of patents [5-9], describing an experimental setup for the produc‐ tion of polymer filaments using an electrostatic force. Since then, electrospinning truly

emerged as a feasible technique for spinning fibers with small diameters.

**Figure 1.** Diagram showing the principle of the electrospinning process.

fabric.

34 Non-woven Fabrics

A formal electrospinning process can be defined as below [10]: a polymer solution or melt is held at the end of a capillary tube and is subjected to a high static electric field (commonly 1-6\*106 V/m); the charges are then induced on the liquid surface; the mutual charge repulsion causes a force directly opposite to the surface tension; as the intensity of the electric field increases, the hemispherical surface of the solution or melt elongates to form a conical shape known as a Taylor cone; when the static electric field surpasses a critical value, the repulsive electrical forces overcome surface tension forces, resulting in a charged jet ejected from the tip of the Taylor cone. The route and thinning of this jet can be controlled by the electric field. At the same time, the solvent either evaporates or the polymer melt solidifies, leaving behind a charged polymer fiber. Continuous fibers are finally collected in the form of a non-woven

In the electrospinning process, the driving force during jet thinning is the electrostatic force. Usually, in electrospinning the current carried by a typical jet is around 0.1-1µA [11].This means that one jet in the electrospinning process consumes less than 0.1 W/h (power per hour). In other words, a mobile phone battery can drive more than 5-10 electrospinning jets for more than ten hours. Consequently, it is easy to develop handheld electrospinning equipment [12].
