Several critical parameters affect the polymer's conductivity (Figure ). The size of polymers determines the polymer conductivity. When the volume fraction of polymers increases to a specific critical value, there is a significant increase in the conductivity of the polymer, i.e., conversion of insulator materials to the conductor. The conductivity of biodegradable polymers can be improved by adding conductive nanofillers. It can be improved by adding a small volume fraction of high conductivity materials. The conjugated polymers exhibit electrical conductivity in the range of 10 -10 to 10 -5 S•cm -1 . The electrical conductivity can be improved via several methods, including doping with molecules such as salt ions that can improve the polymer's electrical conductivity to 10 4 S•cm -1 . As a rule of thumb, the critical value (defined as the percolation threshold) of the conductive material in the composites offers a significant increase of several orders of magnitude in conductivity. The critical value of the conductivity materials in polymer composite converts an insulator to a conductor. Above this threshold, the relation between the concentration and the conductivity (σ) or electrical resistivity (ρ) can be described by a scaling law :