Due to their amazing capabilities and expanding array of applications, wireless sensor networks have attracted a lot of interest from general public and scientific groups. A specialised transducer that is part of WSN brings sensing capabilities to IoT. Low battery and resource capacity of this equipment poses numerous difficulties for both academia and business. Many current WSN routing protocols have been improved to solve certain LEACH protocol problems. The goal of suggested approach is to prolong network longevity while maintaining good scalability because LEACH's performance rapidly degrades with growing networks. The fuzzy logic-based Stable Election Protocol (FI-SEP) is described in this work. suggested approach aims to increase network longevity in spite of network size growth. In this study, the network performance of the FI-SEP and I-SEP routing protocols are compared. According to simulation results, FI-SEP performs better in terms of energy efficiency on large-scale WSNs than the benchmarked protocol. Keywords: WSNs, Clustering, IoT, Routing, I-SEP, Energy efficiency, Fuzzy logic