Microwaves (frequencies of 300 MHz–300 GHz with wavelengths of 1 m–1 mm) lie between radio waves and infrared frequencies in the electromagnetic spectrum (Fig. 4a). The most effective way to produce MW is from a magnetron source, but they can also beproduced from klystrons,power
grid tubes, traveling wave tubes and gyrotrons [56]. MW can be reflected, transmitted and / or absorbed when applied on a particular material. The absorbed MW energy is converted into heat within the material, resulting in an increase in temperature. Indeed, gases, liquids and solids can interact with MW to be heated. Under certain conditions, gases can be excited by
MW to form plasmas that also can be useful for processing [57]. In many cases, materials processing using MW technology have numerous advantages compared to traditional materials processing techniques. These anticipated benefits include more precise and controlled volumetric heating, faster ramp-up to temperature, lower energy consumption, and enhanced
quality and properties of the processed materials [58,59]. In addition, MW is convenient and economic method thus expected to be optimized for mass production [19,60] although the known limitations of penetration depth of MW [13]. Hence, MW assisted materials synthesis has become an appealing synthetic tool,even though the use of MW radiation in biomaterials science is still limited, with an apparent growing interest to be used in biomaterials synthesis for the
next decade [21].