A monitoring system comprising a monitor is disclosed that utilizes a vibration sensor to monitor the occurrence and properties of an event. The monitor does not require disassembly of the device to be monitored, or interfere with the operation of the device to be monitored, because the monitor is affixed to the exterior of a device to be monitored or a component thereof, or is integrated into the design of the device to be monitored. In a preferred embodiment, the device to be monitored is a drug delivery device, most preferably an inhaler or autoinjector. The monitoring system includes a display device such as a smartphone or tablet computer for analyzing data related to the device to be monitored usage and displaying information to a user, patient and/or caregiver before, during, and after a usage event. Preferred embodiment monitor the inhalation flow rate through an inhaler, and the dose delivered by an injector.
