3D printed self-propelled composite floaters

Abstract

Abstract This article presents a method for fabricating millimeter scale self-propelled floaters that move under their own power in random trajectories. The floaters are fabricated using fused deposition modeling of ABS scaffolds that are encapsulated in, and subsequently dissolved from, polydimethylsiloxane. The evacuated millifluidic channels left by dissolving acrylonitrile butadiene styrene (ABS) scaffolds are filled in with an ethanol-infused polyethylene glycol diacrylate hydrogel that serves as the fuel to drive propulsion in a fluid. We examine the motion of four different shapes, finding that shapes with two open ends exhibited pulsation in their trajectory, while shapes with a single open end featured trajectories that directed it to move in circles. The mean square displacement (MSD) was constructed from these trajectories to measure the mean position variance and average velocity. The floater design with a single open end was measured to have a higher mean variance per unit time (2.9 mm2 s−1) and average velocity (4.4 mm s−1). These parameters were nearly twice as high in comparison to the slowest floater design, which had an mean variance per unit time and average velocity of 1.7 mm2 s−1 and 1.5 mm s−1, respectively. In order to show that the motion behaved in a manner that is similar to Brownian motion, we simulated the trajectories using a Langevin dynamic simulation. The result of these simulations showed excellent agreement between the measured and simulation MSD. To show the utility of these structures for mixing applications, we designed a floating spinner that completely mixes a mixture of dye and water within 12 s. Ultimately, the design process illustrated here may find use in variety of platforms that require sample mixing, cargo transport and sensing.