Various dielectric materials were mixed with biodegradable polymers such as PLA for electronic devices. PLA/TiO2 was reported for the humidity sensor . It can be used for the detection of humidity in the range of 20-90% . PLA/barium titanate (BaTiO3) nanowires (NWs) produce printable energy harvesters that can proceed using the 3D printing method . BaTiO3 nanowires can be well aligned, offering 273% higher power generation capacity than conventional cast nanocomposites with randomly oriented nanowires. Al2O3 improved the dielectric properties of cellulose acetate . 3D printing was also reported for PLA/NiTi nanowires . PLA/NiTi nanowires were reported as a sensor for measuring temperature and strain simultaneously . Electrospinning of PLA/boron dye was reported to detect oxygen in real-time for tissue scaffold applications . PLA/boron dye sensor can determine the low level of dissolved oxygen (< 15 ppm) in the scaffold . Other materials, including cellulose nanocrystals (CNC) , clays , ZnO , SnO2 , cobalt ferrites , nitride nanosheets /copper calcium titanate , gold nanoparticles , or PbS were also reported to improve the dielectric properties of polymers. There are several mechanism for the dielectric improvement using these nanoparticles including the decrease in energy band gap .