3D Printing Contact Lenses, Optics, and Visualization

Category: Blog,From Academia
blank blank Apr 09, 2021

In this issue of “From Academia”, we included four recent research publications related to “seeing”, including articles focusing on how to create smart contact lenses, cornea, glass optics, and microscope leveraging 3D printing technologies. In the first article, researchers presented a way to create hydrogel-based contact lenses that can have biosensing capabilities, including sensing eye blinking (peristaltic pressure), PH, and Na+ level, adding another tool to the future wearable market. In the second article, researchers demonstrated how additive manufacturing of gradient index (GRIN) silica-titania glass via direct ink writing method could potentially create a variety of conventional and unconventional optical functions in a flat glass component with no surface curvature. In the third article, the researchers described a way to create a 3D corneal stroma using an orthogonally oriented pure electro-compacted collagen (EC). The researchers believe this technique could potentially be used to create a future full-thickness corneal replacement. In the final article, the authors presented UC2 (You. See. Too.), a low-cost, 3D-printed, open-source, modular microscopy toolbox. The authors demonstrate its versatility by realizing a complete microscope development cycle from concept to experimental phase and aim to develop an open standard in optics to facilitate interfacing with various complementary platforms. “From Academia” features recent, relevant, close to commercialization academic publications. Subjects include but not limited to healthcare 3D printing, 3D bioprinting, and related emerging technologies.

Email: Rance Tino (tino.rance@gmail.com) if you want to share relevant academic publications with us.

Microengineered poly(HEMA) hydrogels for wearable contact lens biosensing

Authored by Yihang Chen, Shiming Zhang, Qingyu Cui, Jiahua Ni, Xiaochen Wang, Xuanbing Cheng, Halima Alem, Peyton Tebon, Chun Xu, Changliang Guo,  Rohollah Nasiri, Rosalia Moreddu, Ali K. Yetisen, Samad Ahadian, Nureddin Ashammakhi, Sam Emaminejad, Vadim Jucaud,   Mehmet R. Dokmeci  and  Ali Khademhosseini. Lab on a Chip. 13 October 2020

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Fig. 2 Microfabrication of microchannels in the poly(HEMA) hydrogel. (A) Process flow of fabricating encapsulated microchannels in a poly(HEMA) hydrogel with the combination of 3D printing and replication. It includes: 1) 3D printing of a reverse mold; 2) deposition of a 2 μm-thick parylene layer on the mold to ease future removal; 3) casting the poly(HEMA) precursor on the mold; 4) removal of the poly(HEMA) hydrogel; 5)flattening of the micromachined poly(HEMA) hydrogel; 6) encapsulation of the poly(HEMA) microchannels with a thin poly(HEMA) capping layer. (Band C) Straight poly(HEMA) microchannels with a width and depth of 200 μm and poly(HEMA)reservoirs with a depth of 500 μm; (D) cross-section of the poly(HEMA) microchannel (100 μm in width and depth) connecting to a reservoir with a depth of 1 mm; (E) encapsulation of poly(HEMA)
microchannels (bottom) with a poly(HEMA) capping layer (top) via plasma-assisted bonding (details in the Materials and methods section); (F and G)serpentine-shaped poly(HEMA) microchannels with a channel width of 200 μm; (H) poly(HEMA) microchannels with a reservoir connecting four branches in different directions; (I and J) cross-sectional images of the encapsulated poly(HEMA) microchannels (200 μm in depth). The demonstrated microchannels were obtained by 3D printing and plasma-assisted bonding (I) and laser ablation and poly(HEMA) precursor-assisted bonding (J), respectively.

Abstract: 

Microchannels in hydrogels play an essential role in enabling a smart contact lens. However, microchannels have rarely been created in commercial hydrogel contact lenses due to their sensitivity to conventional microfabrication techniques.

Here, we report the fabrication of microchannels in poly(2-hydroxyethyl methacrylate) (poly(HEMA)) hydrogels that are used in commercial contact lenses with three-dimensional (3D) printed mold.

We investigated the corresponding capillary flow behaviors in these microchannels. We observed different capillary flow regimes in these microchannels, depending on their hydration level.

In particular, we found that a peristaltic pressure could reinstate flow in a dehydrated channel, indicating that the motion of eye-blinking may help tears flow in a microchannel-containing contact lens.

Colorimetric pH and electrochemical Na+ sensing capabilities were demonstrated in these microchannels. This work paves the way for the development of micro-engineered poly(HEMA) hydrogels for various biomedical applications such as eye care and wearable biosensing.

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Fig. 5 Colorimetric contact lens biosensor in microchannel-containing poly(HEMA) contact lens. A) The flow administration in the microchannel containing poly(HEMA) contact lens. B) The concept of the poly(HEMA) microchannel-based contact lens biosensor. The bottom images show the real color response of the pH colorimetric sensor to acid and base solutions. C) RGB triplet of the biosensor at different pH values ranging from 5.0 to 9.0 with a step of 0.5 in aqueous solutions (N = 8). Inset shows the displayed color in the test chamber that was filled with target solutions.

3D printed gradient index glass optics

Authored by Rebecca Dylla-Spears, Timothy D. Yee, Koroush Sasan, Du T. Nguyen, Nikola A. Dudukovic, Jason M. Ortega, Michael A. Johnson, Oscar D. Herrera, Frederick J. Ryerson and Lana L. Wong, Science Advances. 18 November 2020 

Process of additive manufacturing of gradient index (GRIN) silica-titania glass via DIW. (A) Two silica-based inks with different titania dopant concentrations are mixed under active shear in a microfluidic nozzle. The composition is dictated by the respective flow rates of the two inks. (B) The 3D printed green body is thermally treated to remove all organic components and densify to glass, and then polished flat. The pink color in the first image is the result of an organic dye added to one ink for visualization. (C) The addition of titania to the silica glass increases the refractive index (41, 42); as a result, the 3D printed glass contains spatial variation in refractive index prescribed by the compositional gradient. wt %, weight %; ppm, parts per million. (D) GRIN glass optics with a variety of shapes, sizes, and optical functions can be designed and produced. Grid pitch in all images is 1 mm. Photo credit: Nikola Dudukovic, Lawrence Livermore National Laboratory. Copyright Science Advances
Process of additive manufacturing of gradient index (GRIN) silica-titania glass via DIW. (A) Two silica-based inks with different titania dopant concentrations are mixed under active shear in a microfluidic nozzle. The composition is dictated by the respective flow rates of the two inks. (B) The 3D printed green body is thermally treated to remove all organic components and densify to glass, and then polished flat. The pink color in the first image is the result of an organic dye added to one ink for visualization. (C) The addition of titania to the silica glass increases the refractive index (41, 42); as a result, the 3D printed glass contains spatial variation in refractive index prescribed by the compositional gradient. wt %, weight %; ppm, parts per million. (D) GRIN glass optics with a variety of shapes, sizes, and optical functions can be designed and produced. Grid pitch in all images is 1 mm. Photo credit: Nikola Dudukovic, Lawrence Livermore National Laboratory. Copyright Science Advances

Abstract: 

We demonstrate an additive manufacturing approach to produce gradient refractive index glass optics. Using direct ink writing with an active inline micromixer, we three-dimensional print multi-material green bodies with compositional gradients, consisting primarily of silica nanoparticles and varying concentrations of titania as the index-modifying dopant.

The green bodies are then consolidated into glass and polished, resulting in optics with tailored spatial profiles of the refractive index. We show that this approach can be used to achieve a variety of conventional and unconventional optical functions in a flat glass component with no surface curvature.

CFD and experimental results for mixing efficiency in the active mixing geometry. (A) Comparison of composition at outlet cross section from simulations and experiments shows good qualitative agreement. (B) Calculated COV values indicate that the best mixing is achieved at active mixer rotational speeds >100 rpm. The deviation in the calculated COV at high mixing speeds stems from imaging inconsistencies and pixelation of the experimental data.. Copyright Science Advances
CFD and experimental results for mixing efficiency in the active mixing geometry. (A) Comparison of composition at outlet cross-section from simulations and experiments shows good qualitative agreement. (B) Calculated COV values indicate that the best mixing is achieved at active mixer rotational speeds >100 rpm. The deviation in the calculated COV at high mixing speeds stems from imaging inconsistencies and pixelation of the experimental data.. Copyright Science Advances

Biomimetic corneal stroma using electro-compacted collagen

– Authored by Zhi Chen, Xiao Liu, Jingjing You, Yihui Song, Eva Tomaskovic-Crook, Gerard Sutton, Jeremy M.Crook, Gordon G.Wallace. Acta Biomaterialia, 1 September 2020 

Copyright. Acta Biomaterialia
Copyright. Acta Biomaterialia

Abstract: 

Engineering substantia propria (or stroma of cornea) that mimics the function and anatomy of natural tissue is vital for in vitro modeling and in vivo regeneration. There are, however, few examples of the bioengineered biomimetic corneal stroma.

Here we describe the construction of an orthogonally oriented 3D corneal stroma model (3D-CSM) using pure electro-compacted collagen (EC). EC films comprise aligned collagen fibrils and support primary human corneal stromal cells (hCSCs). Cell-laden constructs are analogous to the anatomical structure of the native human cornea.

The hCSCs are guided by the topographical cues provided by the aligned collagen fibrils of the EC films. Importantly, the 3D-CSM are biodegradable, highly transparent, glucose-permeable, and comprise quiescent hCSCs. Gene expression analysis indicated the presence of aligned collagen fibrils is strongly coupled to downregulation of active fibroblast/myofibroblast markers α-SMA and Thy-1, with a concomitant upregulation of the dormant keratocyte marker ALDH3. The 3D-CSM represents the first example of an optimally robust biomimetic engineered corneal stroma that is constructed from pure electro-compacted collagen for cell and tissue support. The 3D-CSM is a significant advance for synthetic corneal stroma engineering, with the potential to be used for full-thickness and functional cornea replacement, as well as informing in vivo tissue regeneration.

A versatile and customizable low-cost 3D-printed open standard for microscopic imaging

Authored by Benedict Diederich, René Lachmann, Swen Carlstedt, Barbora Marsikova, Haoran Wang, Xavier Uwurukundo, Alexander S. Mosig & Rainer Heintzmann. Nature Communications. 25 November 2020

Optical Setup using UC2 Optical Building Blocks. a The 4f-system divides Fourier-optical arrangements into functional units, where f′ corresponds to the focal-lengths. BFP corresponds to the back focal plane (i.e. pupil plane). b The unit element (cube) acts as a base framework for any component which fits inside (lens, camera, Z-autofocusing mechanism, etc.). b A magnetic snap-fit mechanism connects the optical building blocks to a skeleton to realize mechanical stability and rapid-prototyping of a given optical setup. c An exemplary setup of a microscope for an ordinary smartphone (not shown) and an inexpensive objective as a combination of available modules. The cubes fit on the baseplate grid at 50 × 50 mm2 design pitch (see Supplementary Notes 3) .Copyright Nature Communications
Optical Setup using UC2 Optical Building Blocks. a The 4f-system divides Fourier-optical arrangements into functional units, where f′ corresponds to the focal-lengths. BFP corresponds to the back focal plane (i.e. pupil plane). b The unit element (cube) acts as a base framework for any component which fits inside (lens, camera, Z-autofocusing mechanism, etc.). b A magnetic snap-fit mechanism connects the optical building blocks to a skeleton to realize mechanical stability and rapid-prototyping of a given optical setup. c An exemplary setup of a microscope for an ordinary smartphone (not shown) and an inexpensive objective as a combination of available modules. The cubes fit on the baseplate grid at 50 × 50 mm2 design pitch (see Supplementary Notes 3) .Copyright Nature Communications

Abstract: 

Modern microscopes used for biological imaging often present themselves as black boxes whose precise operating principle remains unknown, and whose optical resolution and price seem to be in inverse proportion to each other.

With UC2 (You. See. Too.) we present a low-cost, 3D-printed, open-source, modular microscopy toolbox and demonstrate its versatility by realizing a complete microscope development cycle from concept to experimental phase. The self-contained incubator-enclosed brightfield microscope monitors monocyte to macrophage cell differentiation for seven days at cellular resolution level (e.g. 2 μm). Furthermore, by including very few additional components, the geometry is transferred into a 400 Euro light-sheet fluorescence microscope for volumetric observations of a transgenic zebrafish expressing green fluorescent protein (GFP).

With this, we aim to establish an open standard in optics to facilitate interfacing with various complementary platforms. By making the content and comprehensive documentation publicly available, the systems presented here lend themselves to easy and straightforward replications, modifications, and extensions.

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From Academia: 3D Bioprined Dendritic Vascular Networks, Cornea, Alternative Drug Delivery

Product Liability : Biocompatible Materials in 3D Printed Products

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