Fig. 4: Characterization of the edible aquatic robot.

a Fluidic actuator design and fuel expulsion process. (i) Fluidic actuator with injected fuel photograph, blue food dye was added to the fuel for visualization. The fluidic actuator’s shape and size parameters were illustrated with additional black lines. (ii–iv) Illustration of the exhaustion of the fuel reservoir by time (\({t}_{1} < {t}_{2} < {t}_{3}\)). The fuel expulsion is triggered by water and driven by the gas pressure generated from the chemical reaction. b Sample trajectory of an edible aquatic robot captured during motion tests. c Nutritional profile of the edible aquatic robot based on the material composition of the boat-shaped body and of the fluidic actuator. d Triggering time and expulsion duration of 12 fluidic actuator samples, where L1–L6 represent the 6 samples of type L, R1–R6 represent the six samples of type R. e Asymmetric trend of turning direction of the edible aquatic robots with the two types of samples, likely caused by the asymmetricity of the design. f Comparison of motion velocity and duration predicted by the model with those measured in experiments. Blue and orange data points represent edible aquatic robot samples that contain 10 mg and 20 mg ethylcellulose powder in their reaction chambers, respectively.