Hierarchical 3D-printing of Integrated Multifunctional Structures

Intellectual Merit
Incorporating multifunctional capabilities in 3D objects has been the new frontier of additive manufacturing. Fundamental challenges in depositing different classes of materials, poor interface quality between materials that do not bond together, and the difficult control over wetting dynamics impede the realization of multifunctional 3D-printed structures. This year, we lift these limitations by introducing a new ink paradigm of a metal-insulator-semiconductor 3D-microstructured filament ink that enables the quick formation of fully-integrated customizable functional structures. Key to the construction of a spatial light-emitting 3D structure is the generation of in-fiber capillary breakup microspheres that act as pixel sites. Here, we demonstrate that conductive microspheres can be programmably laser-written in desired positions to form connective interfaces of high resolution -- a feat not possible with current multimaterial printing systems. This approach is useful not only in 3D printing and fiber systems but generally in the field of microelectronics.

Figures a-c. Programmable laser-induced capillary formation of discrete BiSn pixel-spheres. Printing 3D-microstructured filaments creates 3D macrostructures capable of electrically-activated (Figure d) spatial light-emission and (Figure e) light-detection.


Broader Impact
Having this ability to print a diverse set of 3D-microstructured filament-inks offers opportunities towards the formation of 3D objects with a multitude of different functionalities. For instance, utilizing micro-shaped optoelectronic filaments as the print ink, high-resolution spatial light-emitting (Figure a-c) and light detecting capabilities (Figure d-h) can be equipped into customizable printed objects, rendering applications in optics and internet-of things. Looking ahead, our print approach can also be implemented on a whole host of designable 3D-structured multimaterial filaments such as those with touch-sensing or actuating functionalities which can be printed into useful products for robotics.


Figure a. A meter-long filament with pixelated light emitters inside; a cylinder printed from this filament. Figures b,c. Light emitted around the printed cylinder. Figure d. A complex printed pattern with fully-connected microscale sensing elements, allowing light detection through measurement of photocurrent from the current-voltage curves in Figure  e. Figure  f. A closed sphere capable of omni-directionally and locally detecting light impinged at any point of its surface (Figure  g) through only 2 photocurrent measurements (i1 and i2). Figure h Corresponding reconstruction of both the 3D sphere and detected light locations

Loke, G., Yuan, M. Rein, R., Jain, Y., Joannopoulos, J.D., and Fink, Y. "Hierarchical 3D-printing of multifunctional integrated systems by designable 3D-microstructured filaments, " in preparation.