Magnetomechanic triggering of payload release from miniaturized devices

A carrier device and methods of use are described. The device and methods are directed toward implanting in biological tissue and for releasing a medical payload or functional material in biological tissue according to a remote magnetic trigger. The carrier device has a cavity with an opening through an external surface of the device. The carrier device includes at least one moveable, magnetic element sensitive to a magnetic field gradient. When a magnetic field gradient, rotating magnetic field, or uniform magnetic field, or a combination of thereof is applied to the tissue, the moveable magnetic element provides release of the medical payload or functional material through the cavity opening. In some embodiments, payload release can be started, stopped, and restarted at a later time or place. In addition to payload release, devices of this invention are equipped with a propelling element, the propelling element is responsive to external stimuli that enables propulsion and navigation of the device.