Search for: All records

The emergence of soft robots has presented new challenges associated with controlling the underlying fluidics of such systems. Here, we introduce a strategy for additively manufacturing unified soft robots comprising fully integrated fluidic circuitry in a single print run via PolyJet three-dimensional (3D) printing. We explore the efficacy of this approach for soft robots designed to leverage novel 3D fluidic circuit elements—e.g., fluidic diodes, “normally closed” transistors, and “normally open” transistors with geometrically tunable pressure-gain functionalities—to operate in response to fluidic analogs of conventional electronic signals, including constant-flow [“direct current (DC)”], “alternating current (AC)”–inspired, and preprogrammed aperiodic (“variable current”) input conditions. By enabling fully integrated soft robotic entities (composed of soft actuators, fluidic circuitry, and body features) to be rapidly disseminated, modified on demand, and 3D-printed in a single run, the presented design and additive manufacturing strategy offers unique promise to catalyze new classes of soft robots. 

In situ direct laser writing ( is DLW) strategies that facilitate the printing of three-dimensional (3D) nanostructured components directly inside of, and fully sealed to, enclosed microchannels are uniquely suited for manufacturing geometrically complex microfluidic technologies. Recent efforts have demonstrated the benefits of using micromolding and bonding protocols for is DLW; however, the reliance on polydimethylsiloxane (PDMS) leads to limited fluidic sealing ( e.g. , operational pressures <50–75 kPa) and poor compatibility with standard organic solvent-based developers. To bypass these issues, here we explore the use of cyclic olefin polymer (COP) as an enabling microchannel material for is DLW by investigating three fundamental classes of microfluidic systems corresponding to increasing degrees of sophistication: (i) “2.5D” functionally static fluidic barriers (10–100 μm in height), which supported uncompromised structure-to-channel sealing under applied input pressures of up to 500 kPa; (ii) 3D static interwoven microvessel-inspired structures (inner diameters < 10 μm) that exhibited effective isolation of distinct fluorescently labelled microfluidic flow streams; and (iii) 3D dynamically actuated microfluidic transistors, which comprised bellowed sealing elements (wall thickness = 500 nm) that could be actively deformed via an applied gate pressure to fully obstruct source-to-drain fluid flow. In combination, these results suggest that COP-based is DLW offers a promising pathway to wide-ranging fluidic applications that demand significant architectural versatility at submicron scales with invariable sealing integrity, such as for biomimetic organ-on-a-chip systems and integrated microfluidic circuits. 

Abstract Direct laser writing (DLW) is a three-dimensional (3D) manufacturing technology that offers significant geometric versatility at submicron length scales. Although these characteristics hold promise for fields including organ modeling and microfluidic processing, difficulties associated with facilitating the macro-to-micro interfaces required for fluid delivery have limited the utility of DLW for such applications. To overcome this issue, here we report anin-situDLW (isDLW) strategy for creating 3D nanostructured features directly inside of—and notably, fully sealed to—sol-gel-coated elastomeric microchannels. In particular, we investigate the role of microchannel geometry (e.g., cross-sectional shape and size) in the sealing performance ofisDLW-printed structures. Experiments revealed that increasing the outward tapering of microchannel sidewalls improved fluidic sealing integrity for channel heights ranging from 10μm to 100μm, which suggests that conventional microchannel fabrication approaches are poorly suited forisDLW. As a demonstrative example, we employedisDLW to 3D print a microfluidic helical coil spring diode and observed improved flow rectification performance at higher pressures—an indication of effective structure-to-channel sealing. We envision that the ability to readily integrate 3D nanostructured fluidic motifs with the entire luminal surface of elastomeric channels will open new avenues for emerging applications in areas such as soft microrobotics and biofluidic microsystems.