Additive Manufacturing (AM) has been recognized as a disruptive manufacturing technology for its capability of fabricating 3D objects with unprecedented geometric complexity and multiple functionalities. Also, AM enables revolutionary new designs by using complex 3D structures, heterogeneous materials, and programmable properties. Our research focuses on Next Generation Additive Manufacturing (NGAM), which includes the following aspects:
Novel AM processes and machine development
AI-assisted process planning and control methodologies
AI-driven design methods for AM-empowered applications
Programmable materials, soft materials, and functional composites
Hopping Light Vat Photopolymerization for Multiscale Fabrication
3D objects with features spanning from microscale to macroscale have various applications. However, the fabrication of such multiscale structures challenges current photopolymer-based additive manufacturing (AM) processes due to the tradeoffs among manufacturable feature resolution, maximum building area, and printing speed. This work presents a digital light processing (DLP)-based AM process called Hopping Light Vat Photopolymerization (HL-VPP) to solve this critical barrier. The key idea is to synchronize scanning projection with galvo mirror rotation.
Publication in Small:
Hybrid Vat Photopolymerization
Vat photopolymerization (VPP) has difficulties in achieving multi-material fabrication due to material contamination issues and suffers from limited material options such as photopolymers. The hybrid VPP integrates a laser-scanning-based VPP module with multiple Direct Ink Writing (DIW) printer heads. The proposed hybrid process can realize efficient multi-material AM as well as broaden material options by incorporating non-photocurable materials. This will benefit various applications including soft robotics and wearable electronics.
Publication in Small:
In-situ Transfer Vat Photopolymerization for Transparent Microfluidic Device Fabrication
Vat photopolymerization (VPP) has difficulty achieving micrometer-sized channels in the layer building direction. The considerable light penetration depth of transparent resin leads to over-curing that inevitably cures the residual resin inside flow channels, causing clogs. The proposed In-situ Transfer VPP is low-cost but features 10-20x higher resolution (within 10 μm level, can be even smaller) than other AM processes and has no additional constraints such as reduced fabrication speed and resin transparency.
Publication in Nature Communications:
Reusable Support for Additive Manufacturing
AM processes such as material extrusion and VPP require support to fabricate parts with overhang features. These 3D-printed supports waste material and lower printing efficiency for nozzle-based material extrusion processes. The presented reusable support and compatible optimization algorithm can reduce fabrication time and material waste by 40% on average.
Publication in Additive Manufacturing:
Direct Droplet Writing-A Novel Droplet-punching Capillary-splitting 3D Printing Method for Viscous Materials
Material jetting can define objects’ property voxel by voxel but suffers from low-viscosity restriction. The filament-based Direct Ink Writing can print with highly viscous materials. The new printer head called Direct Droplet Writing (DDW) inherits both methods’ advantages. DDW enables the printing materials to have a viscosity up to 190,000 mPa·s (can be higher) without common issues in jetting approaches such as satellites and deflection.
Publication in Procedia Manufacturing:
A Vibration-assisted Separation Method for Constrained-surface-based Stereolithography
Excessive separation force in large-area VPP will cause print failure. A new design of vibration-assisted separation method using piezoelectric actuator was developed to reduce separation force by 75% on average.
Publication in Journal of Manufacturing Science and Engineering (JMSE):
Multichannel Piezo-Ultrasound Implant with Hybrid Waterborne Acoustic Metastructure for Selective Wireless Energy Transfer at Megahertz Frequencies
A multichannel piezo-ultrasound implant (MC-PUI) is presented that integrates a hybrid waterborne acoustic meta-structure (HWAM), multiple piezo-harvesters, and a miniaturized circuit with electronic components for selective wireless control via ultrasound frequency switching. The HWAM that utilizes both a 3D-printed air-diffraction matrix and a half-lambda Fabry–Perot resonator is optimized to provide the advantage of ultrasound selectivity at megahertz frequencies.
Publication in Advanced Materials: