GENERAL DESCRIPTION OF BIOMETRIC DOOR SYSTEMS WITH IoT AND THE ESP8266 MICROCONTROLLER

Abstract

The security of residential, commercial, and institutional buildings remains a key engineering challenge. Conventional mechanical locks, digital password locks, and RFID access control systems all have known vulnerabilities, such as key duplication, credential leaks, and susceptibility to data theft. Biometric authentication, particularly fingerprint recognition, offers an attractive alternative due to its uniqueness, durability, and ease of use. This article provides a comprehensive overview of biometric and IoT-enabled door locking systems, with a focus on ESP8266/Nicodemus-based systems. This review examines architectures that combine an optical fingerprint sensor, a relay-controlled magnetic lock, and Wi-Fi connectivity for remote monitoring and access logging. It investigates techniques for securing resource-constrained biometric hardware templates, field studies of low-cost fingerprint modules, documented attack vectors against commercial smart locks, and various ESP8266/ESP32/NodeMCU prototypes described in the current literature. A representative block diagram of the system hardware and a flowchart of the fingerprint authentication and locking process are presented, along with comparative tables summarizing access control technologies, vulnerability-free authentication methods , and the key contributions of the reviewed studies. The article concludes that hybrid designs—combining on-device biometric matching with secure, resource-efficient IoT communication and clear failover/alert mechanisms—offer the best balance of cost, security, and usability for the cost-effective deployment of smart locks. At the same time, template security, firmware integrity, and network reliability are identified as the most significant open challenges.