Imagine that gastrointestinal disorders could be diagnosed and cured, and that the role of the microbiome could be elucidated by simply taking an autonomous tablet. We wish to do just that by combinations of local i) sensing, ii) sampling and iii) drug delivery. To achieve this, we need minimally invasive and compact energy sources to be able to e.g. drive sensors and trigger events. Here, energy materials and energy harvesting in the gul will play a crucial role.