**8. Conclusions**

Metamaterials are the advanced engineered materials which offer the naturally unobtainable properties. Due to their unique behaviour the metamaterials gained considerable attention in various fields including sensors, energy harvesting, photonics, and so on. Graphene based metamaterials efficiently can control absorption/transmission/reflection of electromagnetic waves. The graphene assisted THz metamaterial sensing platform is suitable for biological sensing applications. Even though, massive research is going on to search new kind of tunable metamaterials with improved performance, significant challenges remain. The star shaped dielectric resonator antenna (SDRA) achieves the WLAN bandwidth requirements (5.15–5.35 GHz and 5.725–5.825 GHz). This is useful in communication, like aeronautical and meteorological radio navigation and satellite navigation systems (c-band). However, in comparison with the normal materials the metamaterials exhibit superior properties. The electrical energy generated by energy harvesting metamaterial can be used in low power consuming devices and to power up the wireless sensor network. Lead zirconate titanate transducer and double layered acoustic energy harvester exhibits the maximum power of 73.1 nW at the incident wave frequency of 318 Hz and pressure of 2 Pa. Metamaterial-based absorbers have increased for electromagnetic signal harvesting and absorbing applications in microwave region. The image of chimera states of SQUID metamaterials is prominent applicants for verifying the theoretical findings. Finally, with the rapid advancement of relevant science and technology in recent years,

metamaterials have been developed in the direction of a standard technology platform to accomplish basic tunability and advanced application of metamaterial devices.

**Author Contributions:** Conceptualization, N.S.K. and K.C.B.N.; methodology, N.S.K.; validation, N.S.K., K.C.B.N., P.B. and T.A.B.; resources, B.V.S.R.; data curation, T.A.B.; writing—original draft preparation, N.S.K.; writing—review and editing, K.C.B.N.; visualization, B.V.S.R.; supervision, N.S.K.; project administration, K.C.B.N.; funding acquisition, P.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** One of us P. Banerjee received UGC, India start-up grant no F.30-457/2018 (BSR).

**Institutional Review Board Statement:** Not applicable for studies not involving humans or animals.

**Informed Consent Statement:** Not applicable for studies not involving humans or animals.

**Data Availability Statement:** The data will be made immediately available based on the request.

**Acknowledgments:** The authors express thankfulness to P. Sreeramulu, (English), GITAM, Bangalore for providing English language editing services to this manuscript.

**Conflicts of Interest:** The authors declare that we have no conflicts of interest.
