The wireless system developed by Stanford University Assistant Professor Ada Poon uses the same power as a cell phone to safely transmit energy to chips the size of a grain of rice.
The technology paves the way for new "electroceutical" devices to treat illness or alleviate pain.
The discoveries culminate years of efforts by Poon, assistant professor of electrical engineering, to eliminate the bulky batteries and clumsy recharging systems that prevent medical devices from being more widely used.
The technology could provide a path towards a new type of medicine that allows physicians to treat diseases with electronics rather than drugs, researchers said.
"We need to make these devices as small as possible to more easily implant them deep in the body and create new ways to treat illness and alleviate pain," said Poon.
Poon's team built an electronic device smaller than a grain of rice that acts as a pacemaker. It can be powered or recharged wirelessly by holding a power source about the size of a credit card above the device, outside the body.
The central discovery is an engineering breakthrough that creates a new type of wireless power transfer using roughly the same power as a cell phone that can safely penetrate deep inside the body, said researchers.
An independent laboratory that tests cell phones found that her system fell well below the danger exposure levels for human safety.
Her lab has tested this wireless charging system in a pig and used it to power a tiny pacemaker in a rabbit. She is currently preparing the system for testing in humans.
Poon believes this discovery will spawn a new generation of programmable microimplants sensors to monitor vital functions deep inside the body; electrostimulators to change neural signals in the brain; and drug delivery systems to apply medicines directly to affected areas.
The finding was published in the journal PNAS.