**3.2 Inorganic nanostructured materials**

Conventional silicon-based semiconductor devices are essential elements for real-time data processing and data transmission, but these silicon-based semiconductor devices are mostly composed on rigid chips. To solve this problem, the electronic component can be bonded on a rigid chip through micro- or macroscopic structural changes of materials, then, a wearable device can be manufactured through this approach [62].

Kaltenbrunner et al. developed a sensing system that enables to electronics of virtually unbreakable and imperceptible behaviors with ultrathin materials [63]. A sensing device of 2 mm thick layer was very light, reducing electronic waste, and this device was able to be applied to curves and dynamic surfaces (i.e., plastic wrap) (**Figure 8A**). Organic TFTs using ultra-high-density oxide gate dielectrics several nanometers thick at room temperature enable sophisticated large-area electronic foils with unprecedented mechanical and environmental stability. It can be crumpled like paper, with a radius of less than 5mm, which is repeatedly bent, providing an elongation rate of up to 230% in a pre-modified elastomer.

Silver nanoparticles from ultra-thin silver powder can be applied to the electronics sector due to their high conductivity [54]. Typically, the diameter of Ag nanoparticles is of hundreds of nanometers, but the shape of those particles is uneven [64–67].

On the other hand, silver nanowires (Ag NWs) are widely investigated over a long time due to their versatile electrical, chemical, and biological properties. Peng et al. demonstrated a triboelectric nanogenerator (TENG)-based e-skin which is highly conformal and stretchable, enough to attach on human skin. They have used nanofiber for breathability, biodegradability, sensitivity and Ag NWs for antibacterial activity [68]. The developed devices have been designed for the detection of physiological characteristics and movement states of the whole body (**Figure 8B**). A 3D nano-porous structure was formed by combining PLGA Tribune layer and PVA substrate and nanofiber.
