(a) Schematic representation of the localization and retention of the micromotors in the stomach and GI tract. (b) ICP-MS analysis of the number of micromotors with different enteric coating thickness retained in the stomach, duodenum, jejunum, and ileum 6 hours post oral administration. The samples include (i) bare Mg micromotors without enteric coating, (ii) EMgMs with thin polymer coating, (iii) EMgMs with medium polymer coating, and (iv) EMgMs with thick polymer coating (n = 6 mice per group; estimation of number of the motors in each administration can be found in Supporting Note). (c) Superimposed fluorescent images of mouse GI tracts at 6 hours and 12 hours post-administration of EMgMs loaded with the dye Rhodamine 6G and covered with medium polymer coating. PBS was used as a control.