A Microcontroller-Based Wireless Patient-to-Clinician Alert System: Prototype Documentation and IoMT Reappraisal

In large hospitals, delays between a patient’s request for help and a clinician’s response remain a recognised contributor to adverse outcomes, particularly in patients in wards that are physically distant from staff stations. This paper revisits a low-cost wireless patient-to-clinician alert system originally prototyped in 2017. The original design used an 8051-family microcontroller (AT89S52) at both ends of a simplex link, an HT12E/HT12D encoder–decoder pair, and a 433/434 MHz amplitude-shift-keyed (ASK) radio module; on a bedside button press, the transmitter encoded the originating ward and bed identifier and relayed it to a receiver, where it was rendered on a character LCD at the staff station, over a line-of-sight range of approximately 100 metres (m), consistent with the operating characteristics of the RF modules used. We first document this prototype accurately, including its block-level architecture, the encoder/decoder signalling chain, and the regulated 5 V power subsystem. We then provide a critical reappraisal of the design in light of developments between 2017 and 2026, reinterpreting the device as an early edge node within a layered cyber-physical healthcare system. We analyse how it could be migrated from a fixed point-to-point RF link to an IoMT edge node built around a Wi-Fi/Bluetooth-capable system-on-chip (e.g., ESP32) or a Raspberry Pi Pico W, communicating via MQTT, Bluetooth Low Energy (BLE), or a Low-Power Wide-Area Network (LPWAN) such as LoRaWAN. We discuss three engineering requirements that are now non-negotiable for clinical deployment but were absent from the original scope: transport- and payload-layer security (TLS with AES, and lightweight cryptography for resource-constrained nodes); energy optimisation through deep-sleep duty cycling for battery-powered wearable nodes; and message-delivery reliability through quality-of-service controls, acknowledgements, and store-and-forward fail-safes against packet loss. The contribution of this paper is therefore twofold: a faithful record of a working undergraduate prototype, and a structured analysis that situates it within contemporary smart-hospital practice.