Every organ contains nerves that regulate the organ’s function. New medical devices are under development that modulate signals on such nerves to treat disease1,2 (e.g., inflammatory3, hypertension4, diabetes5, obesity6, and gastrointestinal disorders7,8). However, nerve stimulation strategies using permanently implanted electrodes3,9,10, transcutaneous electro-magnetic fields11,12, or adapted brain stimulation technologies13–16 are limited to stimulating large nerves that can be accessed by an...