**5.2. Medical applications**

has been revealed. Specifically, we know little about its mechanical properties including tensile strength, tearing strength, and bursting strength. The combination of electrospun non-woven fabrics with traditional non-woven fabrics or textiles should also be tested since the bonding

Electrospun non-woven fabrics have been used in several fields including high-efficiency filtration, battery separation, biological medicine, sensors, and functional nanofiber textiles, because of their high specific surface area, small pores, and special physical and chemical properties like high conductivity, heat insulating ability, electromagnetic shielding, and

**Figure 6.** Overview of the number of publications featuring nanofibers used in various applications [70].

In the air filtration field, electrospun non-woven fabrics are taking the place of traditional filter media like activated carbon and fiberglass, because of their excellent performance in filter efficiency and pressure loss. It has been demonstrated by various authors [71] that electrospun nanofibers can remove the volatile organic compounds (VOC) in the air, with some samples filtering faster than conventional activated carbon. Scientists have found that the slip flow mechanism becomes dominant due to the ability of the smaller fiber to disturb the air flow instead of non-slip flow in traditional filters [72]. Surface loading of dust particles takes place on non-woven fabrics coating conventional filters. In one work, Heikkila et al. [73] optimized the coating thickness of polyamide nanofibers required to improve filtration efficiency and

of nanofiber to thick fiber-based substrate seems difficult.

biocompatibility [70].

44 Non-woven Fabrics

**5.1. Filtration**

**5. Applications of electrospun non-woven fabrics**

Biopolymers including polysaccharides (cellulose, chitin, chitosan, and dextrose), proteins (collagen, gelatin, silk, etc.), and DNA [81], as well as some biopolymer derivatives and composites, have been successfully electrospun into non-woven fabrics [82]. Applications of these as-spun fabrics have been carried out in many medical fields like tissue engineering, drug delivery, and wound dressing.

Using electrospun non-woven fabrics or partially aligned fabrics as cell scaffold in tissue engineering is one promising application. Scientists found that alignment of fiber in scaffold would be beneficial. Cell elongation and proliferation have been demonstrated to occur along the direction of these nanofibers, which could improve tissue engineering applications [83]. In some other examples, it was found that the number of anchoring points for cells, wettingproperties, and degradation rates can all be varied by adjusting the porosity of as-spun fabrics [84]. However, in most cases, the pores in solution electrospun fabrics were too small for cells to pass through and influenced both cellular and enzymatic behavior [85]. Thus, a lot of measures were adopted to enlarge the diameter of the pores between as-spun fibers including multilayering and mixing electrospinning techniques [86] and combination of electrospun fiber and traditional microscale fiber [81, 87]. A more effective solution was to use the melt electrospinning method and its meshed fabrics as scaffolds, which, had large spaces for cell penetration and tailored aliment for effective cell proliferation [88].

Drug delivery alleviating medical conditions is another application of electrospun fabrics because nanofiber can be controlled to deliver drugs efficiently to a specific area at a controlled release rate via a dissoluble starting material [89]. Most cases focused on drug delivery materials specially applied in tissue engineering scaffold such as bioactive growth factors or factors to prevent infection while repair and regeneration occur [90], other samples used these non-woven fabrics as a targeted drug carrier for oral medicine [91].

However, electrospinning is still an emerging technology, which requires further theoretical and experimental study. Consideration should be given to the design of a patient-compliant dosage form, material choice, and process controlling. Scaling-up and commercial production are other challenges which need to be overcome for biopolymer composites.
