Design and Implementation of a Plug-And-Play Power-Based Safety System for Detecting Unattended Children in Vehicles

Abstract

Leaving children unattended in parked vehicles poses a serious safety risk, particularly in hot climates, where cabin temperatures can rise rapidly. This paper presents the design and functional demonstration of a plug-and-play IoT-based safety prototype using an ESP32 microcontroller, DHT22 temperature sensor, passive infrared (PIR) motion sensor, and MQ-2 environmental gas sensor. The PIR sensor provides occupancy-related motion input, while the DHT22 and MQ-2 provide environmental inputs. The MQ-2 serves as an auxiliary indicator of combustible-gas or smoke-related conditions and is not treated as a direct measure of human presence or respiration. When PIR-detected motion coincides with either the temperature threshold or the programmed MQ-2 threshold, the system activates audible and visual alarms, sends a Telegram notification, and logs the event in Google Sheets. The power architecture uses the vehicle supply while the vehicle is running and a rechargeable lithium-ion battery to maintain monitoring after the vehicle supply is switched off. Selected development-stage observations from the cloud log demonstrated the operation of the sensing, classification, logging, and alert pathways. However, because the demonstration did not use a predefined ground-truthed trial protocol, these observations are not presented as accuracy or reliability dataset. The prototype is therefore presented as a functional proof of concept that requires further controlled performance evaluation and testing under automotive-environment conditions.