An official website of the United States government
Two-photon polymerization (TPP) has emerged as a favored advanced manufacturing tool for creating complex 3D structures in the sub-micron regime. However, the widescale implementation of this technique is limited partly due to the cost of a high-power femtosecond laser. In this work, a method is proposed to reduce the femtosecond laser 3D printing power by as much as 50% using a combination of two-photon absorption from an 800 nm femtosecond laser and single photon absorption from a 532 nm nanosecond laser. The underlying photochemical process is explained with modeling of the photopolymerization reaction. The results show that incorporating single-photon absorption from a visible wavelength laser efficiently reduces inhibitor concentration, resulting in a decreased requirement for femtosecond laser power. The radical to macroradical conversion is dominated by the reduction in oxygen concentration, while the reduction in photoinitiator concentration limits the threshold power reduction of the femtosecond laser.
more »
« less
Simulation and Analysis of 3D Optical Devices through the use of Additive Manufacturing
The utilization of silicon photonics and integrated optics provide a transformative solution to many technological challenges presented today. The manufacturing and testing of these devices and their interconnects has historically been performed in a cleanroom environment using advanced semiconductor technologies, hence requiring costly infrastructure and an advanced workforce. Advances in additive manufacturing have yielded the two-photon polymerization method, among whose various intended applications is the fabrication of optical devices. In this work, through the use of the two-photon polymerization method and FDTD simulations, optical passive components are simulated and fabricated to demonstrate the capability of this effective new additive manufacturing method.
more »
« less
- Award ID(s):
- 2018853
- PAR ID:
- 10476421
- Publisher / Repository:
- ERAU
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Two-photon polymerization (TPP) uses nonlinear light interactions in photo-cross-linkable precursors to create high-resolution (∼100 nm) structures and high dimensional fidelity. Using a near-infrared light source in TPP results in less scattering and a higher penetration depth, making it attractive for creating biological models and tissue scaffolds. Due to unmatched flexibility and spatial resolution, they range from microvascular constructs to microneedles and stents. This review reviews the working principles and current inks used for TPP-printed constructs. We discuss the advantages of TPP over conventional additive manufacturing methods for tissue engineering, vascularized models, and other biomedical applications. This review provides a short recipe for selecting inks and photoinitiators for a desired structure.more » « less
-
Abstract Precise patterning of quantum dot (QD) layers is an important prerequisite for fabricating QD light‐emitting diode (QLED) displays and other optoelectronic devices. However, conventional patterning methods cannot simultaneously meet the stringent requirements of resolution, throughput, and uniformity of the pattern profile while maintaining a high photoluminescence quantum yield (PLQY) of the patterned QD layers. Here, a specially designed nanocrystal ink is introduced, “photopatternable emissive nanocrystals” (PENs), which satisfies these requirements. Photoacid generators in the PEN inks allow photoresist‐free, high‐resolution optical patterning of QDs through photochemical reactions and in situ ligand exchange in QD films. Various fluorescence and electroluminescence patterns with a feature size down to ≈1.5 µm are demonstrated using red, green, and blue PEN inks. The patterned QD films maintain ≈75% of original PLQY and the electroluminescence characteristics of the patterned QLEDs are comparable to thopse of non‐patterned control devices. The patterning mechanism is elucidated by in‐depth investigation of the photochemical transformations of the photoacid generators and changes in the optical properties of the QDs at each patterning step. This advanced patterning method provides a new way for additive manufacturing of integrated optoelectronic devices using colloidal QDs.more » « less
-
Abstract Nature provides us with a large number of functional material systems consisting of hierarchical structures, where significant variations in dimensions are present. Such hierarchical structures are difficult to build by traditional manufacturing processes due to manufacturing limitations. Nowadays, three-dimensional (3D) objects with complex structures can be built by gradually accumulating in a layer-based additive manufacturing (AM); however, the hierarchical structure measured from macroscale to nanoscale sizes still raises significant challenges to the AM processes, whose manufacturing capability is intrinsically specified within a certain scope. It is desired to develop a multiscale AM process to narrow this gap between scales of feature in hierarchical structures. This research aims to investigate an integration approach to fabricating hierarchical objects that have macro-, micro-, and nano-scales features in an object. Firstly, the process setup and the integrated process of two-photon polymerization (TPP), immersed surface accumulation (ISA), and mask image projection-based stereolithography (MIP-SL) were introduced to address the multiscale fabrication challenge. Then, special hierarchical design and process planning toward integrating multiple printing processes are demonstrated. Lastly, we present two test cases built by our hierarchical printing method to validate the feasibility and efficiency of the proposed multiscale hierarchical printing approach. The results demonstrated the capability of the developed multiscale 3D printing process and showed its future potential in various novel applications, such as optics, microfluidics, cell culture, as well as interface technology.more » « less
-
Cationic polymerization is a powerful strategy for the production of well-defined polymers and advanced materials. In particular, the emergence of living cationic polymerization has enabled pathways to complex polymer architectures inaccessible before. The use of light and electricity as external stimuli to regulate cationic polymerization represents another advance with increasing applications in surface fabrication and patterning, additive manufacturing, and other advanced material engineering. The past decade also witnessed vigorous progress in stereoselective cationic polymerizations, allowing for the dual control of both the tacticity and the molecular weight of vinyl polymers towards precision polymers. In addition, in addressing the plastics pollution crisis and achieving a circular materials economy, cationic polymerization offers unique advantages for generating chemically recyclable polymers, such as polyacetals, polysaccharides, polyvinyl ethers, and polyethers. In this review, we provide an overview of recent developments in regulating cationic polymerization, including emerging control systems, spatiotemporally controlled polymerization (light and electricity), stereoselective polymerization, and chemically recyclable/degradable polymers. Hopefully, these discussions will help to stimulate new ideas for the further development of cationic polymerization for researchers in the field of polymer science and beyond.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Workshop Report:
- The DOI is not currently available.
