The FTFs are reviewed exhausting thus several internet websites such as Google Scholar

The FTFs are reviewed exhausting thus several internet websites such as Google Scholar, Scopus, AIP, ACS journals, US patent, IEEE, Science direct, Elsewhere, some other online international journals and conference papers. The detailed research work done has been tabulated in Table S1, period wise detailed conclusions have been listed as follows. We are classified this whole research work into five periods according to their achievements and enhancements in preparation and applications of spinel-type of ferrite materials.
i) Start-up of FTFs fabrication (1967) and innovative advances up to 2000 : The several research groups have been concentrated on the preparation of FTFs as well as design and fabrication of FTFs have been tested for different kind of applications viz. FTF inductor, multilayer chip inductors, microwave, high-density recording for read/write characteristics, pressure and photosensors and the MIC sub-assemblies. In this period, a number of research groups have been examining the different kind of new technique to prepare the FTFs and their respective applications. However, the main outlook to develop the durability of FTF is to use a spinel-type of ferrite materials, which has been described by many research groups 1, 3, 47.
ii) Developments of FTFs with screen printing technology (2001-2005): In this period, several research groups have been prepared ferrite powders by chemical co-precipitation, ceramic, and sol-gel/auto-combustion method. Moreover, thick films have been fabricated by screen printing, doctor blade and thermal spray techniques and studied in the field of magnetic, microwave, gas sensor, planar transformer, DC-DC converters and LTCC. It concludes that the a few researcher to find out the better way of synthesis techniques FTFs and it is useful for practical applications.
iii) Fabrication of new FTF sensor technology (2006 to 2010): In this period, many research groups have been concentrated on the LTCC, gas sensor, microwave, patch antenna, high-frequency applications. In another approach an innovative method to develop low cost, simple processing techniques are exploring and studied. The FTFs are improving for adding different kind of (organic and inorganic) binders, achieve good adhesive and adhesion properties of FTFs. Moreover, to examine the new kind of binders for fabricating thick films. The main role of pre-sintering and sintering of powders to enhanced the crystallite size and grain size has been studied in these period. Therefore, the FTFs size and shape has been mainly depends upon the different applications such as patch antenna, nano-size circuit design and etc. Furthermore, the FTFs applications have mainly depends upon the method of preparation, sintering, pre-sintering, organic binder, inorganic binder, crystallite size and grain size, method of deposition, substrate and final sintering temperature have been studied in details with next section.
iv) Microwave, Inductor and Smartphones in FTF technology (2011 to 2015): In this period, the gas sensor and selective of FTFs have been examined and improved. A number of research groups have been reported the FTFs with the structural, electrical, optoelectronics, magnetic properties, planar inductor, high-frequency, DC-DC converters, gas sensor, microwave and smartphones have been studied. A few of research groups have been changed their (FTFs) substrates like alumina, FR4, ZnO, and MgO with improving FTFs properties. It concludes that some influenced parameters of FTFs improved their preparation methods and applications. The FTFs are applicable for many applications.
v) Humidity and Gas sensing FTFs technology (2016 to 2018): in this period, the FTFs have been studied in application of gas sensor, humidity sensor, patch antenna, electrical, magnetic and microwave properties. A number of research groups have been trying to endeavoring better results for FTFs with flexibility, portability, disposability and recyclability. Inappropriately, the importance of FTF is somewhat inadequate, mostly due to the absence of highly active materials with highly stable materials.