2.7. Functional integration and payload transportation
The ability to integrate modular components and payloads can functionalize ingestible magnetic crawler robots with advanced sensing, actuation, and drug delivery capabilities that can ultimately enable a broad range of surgical-free diagnostic and treatment strategies. Here we show that the centralized compartment in MR-LF enables the integration of modular electronic components (Figure \ref{570124}A, Movie S4) which are otherwise challenging to integrate into soft robots due to their rigid and planar architectures. The MR-LF compartment also facilitates the incorporation of payloads such as medications for drug delivery (Figure \ref{570124}C, Movie S5) and can potentially provide storage space for tissue and fluid samples acquired by the robot. In the experiment shown in Figure \ref{570124}C and Movie S5, the medication release is triggered by the temperature of the water environment. The compartment in MR-LF readily enables the integration of alternative triggerable release mechanisms \cite{Kong2019,Timko_2010} for drug delivery at a specific target location. Further, though not the focus of this study, we also show that multiple robots can be assembled, similar to a previous study by Abbott et al. \cite{Pham2020}, by conjoining two MR-LFs with feet with opposite polarity. Such capability suggests that the functionality is not limited to a single dosage form, as multiple pills can be taken to further increase functionality and payload (Figure \ref{570124}B, Movie S6).