An inventory management device (102, 202, 402) to monitor an amount of a material in a container (104, 304), the device (102, 202, 402) comprising: a capacitive level sensor to measure a first capacitance value and a second capacitance value, wherein the capacitive level sensor measures the first capacitance value when the amount of the material in the container (104, 304) is greater than a threshold amount of material in the container (104, 304) and the second capacitance value when the amount of the material in the container (104, 304) is less than or equal to the threshold amount of material in the container (104, 304); a vibration sensor in electronic communication with the capacitive level sensor to generate a vibration signal that corresponds to a vibration of the container (104, 304); 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 battery to power the capacitive level sensor, vibration sensor, storage unit, controller, and transmitter; characterized in that the inventory management device (102, 202, 402) has a thickness less than 1 mm and is flexible, reusable and removably attachable to a container (104, 304) holding a material, and comprises a flexible printed circuit board or printed electronics and a flexible battery, wherein the inventory management device (102, 202, 402) is configured to allow users to customize a reorder point by adjusting the position of the inventory management device (102, 202, 402) at the desired minimum material amount, wherein the reorder point is the amount of material that triggers an action to replenish that particular material. a capacitive level sensor to measure a first capacitance value and a second capacitance value, wherein the capacitive level sensor measures the first capacitance value when the amount of the material in the container (104, 304) is greater than a threshold amount of material in the container (104, 304) and the second capacitance value when the amount of the material in the container (104, 304) is less than or equal to the threshold amount of material in the container (104, 304); a vibration sensor in electronic communication with the capacitive level sensor to generate a vibration signal that corresponds to a vibration of the container (104, 304); 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 battery to power the capacitive level sensor, vibration sensor, storage unit, controller, and transmitter; characterized in that the inventory management device (102, 202, 402) has a thickness less than 1 mm and is flexible, reusable and removably attachable to a container (104, 304) holding a material, and comprises a flexible printed circuit board or printed electronics and a flexible battery, wherein the inventory management device (102, 202, 402) is configured to allow users to customize a reorder point by adjusting the position of the inventory management device (102, 202, 402) at the desired minimum material amount, wherein the reorder point is the amount of material that triggers an action to replenish that particular material.