# Electrospun Nanofibers for Integrated Sensing, Storage, and Computing Applications
## 2 Different Types of Electrospun Nanofiber Process and Structures  
As one of the most convenient and efficient ways to prepare nanofiber in today's scientific research, the electrospinningning technique emerged in the experiment of German scientist [PERSON] in the 1930s, and it was originally used to prepare artificial silk-like fibers [7]. This ancient nanotechnology has been rediscovered for modern demands by [PERSON]'s group, who officially introduced the professional term \"electrospinning\" in the 1990s [8]. Today, blowout research has made this technique one of the most important methods for the multi-functional, large-scale, and low-cost preparation of continuous nanofibers with diameters as small as nanometers. Generally, the composition of this technology is very simple, mainly including a high-voltage power source, a syringe pump, a spinneret, and a conductive collector (Figure 1) [9]. In the electrospinningning process, the droplets ejected by the spinneret generate jets, which are then stretched into nanofibers with the help of the electric field and deposited on the collector. These systems can be easily assembled to realize a spinning system in any laboratory. Electrospun nanofibers have a cross-linked ultra-fine fiber structure, which gives the material the characteristics of large specific surface area, light weight, high porosity, excellent thermal stability, and mechanical flexibility [10; 11; 12; 13]. They have broad applications in filtration membranes, catalytic supports, energy storage, biomedical research, and photonic and electronic devices [14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24]. At present, the applications of electrospinningning have not only been studied in the laboratory, but have also made some achievements in the field of commercialization. The first commercial product based on electrospun nanofibers, namely the air filtration technology Ultra-Web\({}^{\oplus}\), appeared in 1981 with the work of the Donaldson company [25]. Recently, the international market for electrospun fiber-based applications has been brisk, and the total value reached 927 million dollars in 2018 [26]. It is believed that in the future, the 1D nanomaterials prepared by electrospinningning will continue to be developed and this will give full play to their potential to be used in various industries. Electrospinning was originally used to spin polymer solutions into polymeric nanofibers. Organic polymers can be directly applied to electrospinningning as long as they can be dissolved in appropriate solvents to obtain a viscous solution. Combined with sol-gel chemistry, electrospinningning is enabled to prepare composite and ceramic nanofibers [27]. At present, a variety of organic polymers and metal oxides, such as TiO\({}_{2}\), SnO\({}_{2}\), ZnO, and CeO\({}_{2}\)[28; 29; 30; 31], can be prepared by electrospinningning. One typical process of electrospinningning includes the following three steps: (i) preparation of spinning solution from a sol-gel precursor, a polymer, and a solvent, (ii) fabrication of primary nanofibers by electrospinningning under appropriate conditions, and (iii) calcination of the primary nanofiber at high temperature to remove organic components and obtain ceramic nanofibers. It was demonstrated that a cross-linked InTiO nanofiber network can be obtained using the InTiO precursor solution, composed of indium chloride tetrahydrate (InCl\({}_{3}\cdot\)4H\({}_{2}\)O), titanium tetrachloride (TiCl\({}_{4}\)), and N, N-Dimethylformamide (DMF), by electrospinningning [32]. The diameter of the nanofiber was around 220 nm and its randomly oriented distribution on the substrate was caused by the bending instability of the whipping process. Figure 2 is the SEM image of the above nanofiber prepared by the electrospinningning. This approach is usually in the far-field mode with the use of a hollow needle as the spinneret to achieve solid unordered nanofibers.