Wearable devices present a minimally invasive way to examine health in real time. They can continuously and instantaneously measure physical and chemical quantities such as heart rate, blood pressure, glucose level, and concentration of biomarkers associated with serious illnesses.

As one such example, intraocular pressure monitors are crucial for glaucoma management. Chen et al. developed a reliable and inexpensive manufacturing process to produce titanium microstructures for pressure sensing on curved hydrogel surfaces. They identified important processing conditions and used their method to deposit the structures on contact lenses.

Few techniques have reported direct fabrication on contact lenses because of challenges related to their hydrogel composition and curved surface. Using a shadow-mask-assisted flattening and deposition (SFD) method, the team temporarily flattened the lens then deposited titanium with a shadow mask. They created square arrays and concentric rings while minimizing distortion.

“We also experimentally and theoretically studied three key factors for obtaining a good yield and fidelity for the resultant titanium patterns on such hydrogel substrates: the surface smoothness of the 3D-printed sample holder, the shrinkage of the hydrogel material during dehydration-hydration cycles, and the geometric changes of the curved hydrogel substrates during the fabrication course,” said author Xiaogan Liang.

The researchers tested the intraocular pressure sensor on a silicon eye model. The contact lenses are biocompatible, and the center is left intentionally black in the pupil region to avoid vision obstruction.

“We will continue to optimize the design of functional devices fabricated on contact lenses, and ultimately, we will commercialize this type of smart contact lens for diagnosing and treating different eye diseases,” said author Long Que.

Source: “Fabrication of microstructures on curved hydrogel substrates,” by M. Chen, X. Ding, L. Que, and X. Liang, Journal of Vacuum Science & Technology B (2022). The article can be accessed at https://doi.org/10.1116/6.0002071.

This paper is part of the Papers from the 65th International Conference on Electron, Ion, And Photon Beam Technology and Nanofabrication (EIPBN 2022) Collection, learn more here.