Fig. 3: Navigation and retention properties of the IngRI.

A Schematic (left) and optical image (right) of the in vitro setup for simulating in vivo navigation of the IngRI using an external hand-held neodymium magnet. B The minimum actuation distance of the IngRI when manipulated by a hand-held neodymium magnet under different orientations and wetness conditions obtained from setup in (A). Each data point is an average from n = 3 samples. Data are presented as mean ± SD. C, D Demonstrations of in vivo navigating and flipping ability of the IngRI. Pictures are captured from Supplementary Movies 1 and 2. E Schematics of the bio-inspired hydrogel adhesive for enhancing gastric retention of the IngRI. Briefly, the mechanism relies on a bilayer of soft silicone disk and lyophilized hydrogel, which together provide a combination of physical and chemical adhesion to overcome the challenging gastric environment. F Averaged peeling forces of the IngRI with (disk+) and without (disk−) the soft silicone disk at day 0. G Averaged peeling forces of the IngRI with (gel+) and without (gel−) lyophilized hydrogel at day 0. H Averaged peeling forces of IngRI with (gel+) and without (gel−) the bio-inspired hydrogel adhesive at day 7. For (F) and (G), each data point is an average from n = 3 or 5 samples. I Radiographs at day 0, day 2, and day 5, respectively, tracking the gastric retention of devices with the bio-inspired hydrogel adhesive in the porcine stomach. 5 out of 7 devices are intact after 48 h of ingestion. Error bars in all plots indicate standard deviations (SD).