An inventory management device to monitor a volume of a material in a container may generally include a capacitive level sensor to measure a first capacitance value and a second capacitance value; a vibration sensor in electronic communication with the capacitive level sensor to generate a vibration signal that corresponds to a vibration of the container; a storage unit in electronic communication with the capacitive level sensor to store the first capacitance value; a controller in electronic communication with the capacitive level sensor and storage unit to measure a change in the capacitance between the first capacitance value and second capacitance value; a transmitter in electronic communication with the controller to transmit an output signal when the controller measures the change in capacitance; and a flexible battery to power the capacitive level sensor, vibration sensor, storage unit, controller, and transmitter.