Fully Non-Invasive Liquid Level Detection

The Fully Non-Invasive Liquid Level Detection system operates by utilizing the XKC-Y25 NPN capacitive sensor to monitor fluid presence through the wall of a container without ever making direct physical contact with the liquid. Capacitive sensors work by detecting changes in electrostatic capacitance in their surrounding environment. When liquid inside a non-metallic container reaches the height of the sensor mounted on the exterior wall, the dielectric constant changes due to the presence of the fluid compared to air. This triggers the XKC-Y25 sensor, changing its NPN digital output state, which is then monitored by the Arduino UNO R3 via a designated digital input pin. The Arduino continuously reads the signal state from the sensor. When the sensor indicates that liquid has been detected, the Arduino executes its programmed logic to activate the connected buzzer (B1), providing an audible alert. Conversely, when the liquid level drops below the sensor threshold, the output state reverts, and the buzzer is turned off. The entire circuit is wired on a standard breadboard using jumper wires to connect the sensor power, ground, and signal lines to the Arduino UNO R3, while the software sketch compiled and uploaded via the Arduino IDE manages the real-time polling and audio feedback.