3D Printing of Multimaterial Contact Lenses

Abstract

3D printing of multimaterial objects is an emerging field with promising applications. The layer-by-layer material addition technique used in 3D printing enables incorporation of distinct functionalized materials into the specialized devices. However, very few studies have been performed on the usage of multimaterial 3D printing for printable photonic and wearable devices. Here, we employ vat photopolymerization-based 3D printing to produce multimaterial contact lenses, offering enhanced multiband optical filtration, which can be valuable for tackling ocular conditions such as color blindness. A combination of hydroxyethyl methacrylate (HEMA) and polyethylene glycol diacrylate (PEGDA) was used as the base hydrogel for 3D printing. Atto565 and Atto488 dyes were added to the hydrogel for wavelength filtering, each dye suitable for a different type of color blindness. Multimaterial disks and contact lenses, with separate sections containing distinct dyes, were 3D-printed, and their optical properties were studied. The characteristics of multimaterial printing were analyzed, focusing on the formation of a uniform multimaterial interface. In addition, a novel technique was developed for printing multiple dyed materials in complex lateral geometrical patterns, by employing suitable variations in CAD models and the UV curing time. It was observed that the multimaterial printing process does not negatively affect the optical properties of the contact lenses. The printed multimaterial contact lenses offered a combined multi-band color blindness correction due to the two dyes used. The resulting optical spectrum was a close match to the commercially available color blindness correction glasses.

Keywords: contact lenses; hydrogel; multimaterial 3D printing; vat photopolymerization; wavelength filtering.

Figure 1

(a) Multimaterial 3D printing process used for producing discs and contact lenses with multiple embedded dyes achieving multiband optical filtering properties. (b) CAD models of optical disks used in this study, with 14 mm diameters and thicknesses of 1 mm and 0.5 mm. (c) CAD models used for printing single and multimaterial contact lenses. (d) CAD model modification for printing complex multimaterial patterns.

Figure 2

Transmission spectra from liquid resin tinted with (a) Atto565 and (b) Atto488 dyes. Inset shows the images of the liquid resin. Transmission spectra of 3D-printed disks with (c) Atto565 dye and 1 mm thickness; (d) Atto488 dye and 1 mm thickness; (e) Atto565 and 0.5 mm thickness; and (f) Atto488 dye and 0.5 mm thickness. The inset shows the surface and cross-sectional images of the 3D-printed samples.

Figure 3

(a) Transmission spectra of liquid resin with both Atto565 and Atto488 mixed. Inset shows the images of liquid resins. Transmission spectra of 3D-printed disks (1 mm thick) made of (b) Atto565 and Atto488 mixed together, and (c) multimaterial samples having Atto565 and Atto488 in 0.5 mm thick separate sections. Inset shows the 3D-printed samples and the cross-sectional images. (d) Comparison of transmission spectra for multimaterial, mixed, and single composition samples of the same concentration (1.25%). The inset shows the 3D-printed samples. Cross-sections of printed disks made of (e) mixed Atto 565 + Atto 488 resin and (f) multimaterial Atto565 and Atto488, both of concentration 2.5%.

Figure 4

Comparison of transmission spectra from 3D-printed single-material disks (thickness 0.5 mm) with multimaterial disks (thickness 1 mm) having combination (a) clear:Atto565 and (b) clear:Atto488. (c) Cross-sections of clear:Atto565 and clear:Atto488 disks having concentration 2.5%. (d) Multimaterial contact lenses printed with clear resin and resins containing Atto565 and Atto488. (e) Transmission spectra and (f) absorption spectra of commercial color blindness glasses compared with 3D-printed multimaterial samples.

Figure 5

Highly magnified images of the cross-section of multimaterial disk obtained using optical microscopy and SEM.

Figure 6

Multimaterial interface boundary, visible on the outermost surfaces of the 3D-printed samples. (a) Multimaterial interface boundary for same material (clear resin) under different cure times and pause conditions. (b) Boundary effect for multimaterial printed samples at cure time 25 s and with pausing, cleaning, and material change in between.

Figure 7

(a) Water absorption of dry 3D-printed samples, immersed in DI water. (b) Light absorption peaks of multimaterial samples immersed in DI water for extended periods for studying dye leakage and (c) images of respective samples.

Figure 8

(a) Multimaterial disks (made of clear, Atto565, and Atto488 resins) printed in two complex patterns. (b) Process used to print these complex patterns. (c) Cross-sections of these patterned disks. (d) Cross-section showing Atto488 surrounded by clear resin on all sides, which is not possible to produce through the normal DLP printing process.