Light to electric conversion photochemical effect can be achieved by using biocompatible material, polycrystalline TiO₂ nano-fibers (poly-TiO₂ NFs). With versatility and low cost advantages, electrospinning process had been explored recently as means for preparing a wide variety of polycrystalline nanofiber materials for potential applications, for example, in tissue engineering, membranes, solar cells, and chemical and biological sensors. Cell division and antibacterial issues were widely explored in recent research. However, as a large bandgap n type semiconductor, single crystalline TiO₂ materials has the attribute of responding UV light (400 nm). Due to the defect-rich structure, polycrystalline TiO₂ NFs can respond not only to UV light but also to visible light (wavelength between 400~550 nm). The photochemical effect hugely can be hugely enhanced by using specific power hydrogen plasma treatment because plasma treatment can tune the barrier height between grains, surface potential and defect level. The soft energy light (long wavelength light, such as the red light (region wavelength between 620~730 nm)) can also be used in bio research (such as stimulating the cell growth or antibacterial growth). Antibacterial observation or the cell growth process always incubates in solution. The photo responses of our device are different between low and high humidity environment.

Recently, there are considerable interests in electrospun-titanium dioxide nanofibers (TiO₂ NFs) as antibacterial agents owing to their large grain to grain surface and the formation of reactive hydroxyl radicals (which can react with bacteria, cell membranes, and cellular proteins, leading to cell death). However, the photocatalytic effects of TiO₂ NFs are relatively low due to the rich defect states. With H₂ plasma treatment passivation, the surface potential of polycrystalline TiO₂ nanofibers were in was smoothened for electrons to transport. Consequently, the H₂ plasma treated TiO₂ nanofibers remained showed greater numbers of hydroxyl radicals and significantly enhanced visible light photocatalytic antibacterial activity. Based on these defect and interface engineering, poly-TiO₂ NFs with hydrogen plasma treatment is a potential candidate for bio application.