Lab-on-a-Contact Lens Platforms Fabricated by Multi-Axis Femtosecond Laser Ablation

Contact lens sensing platforms have drawn interest in the last decade for the possibility of providing a sterile, fully integrated ocular screening technology. However, designing scalable and rapid contact lens processing methods while keeping a high resolution is still an unsolved challenge. In this article, femtosecond laser writing is employed as a rapid and precise procedure to engrave microfluidic networks into commercial contact lenses. Functional microfluidic components such as flow valves, resistors, multi-inlet geometries, and splitters are produced using a bespoke seven-axis femtosecond laser system, yielding a resolution of 80 mu m. The ablation process and the tear flow within microfluidic structures is evaluated both experimentally and computationally using finite element modeling. Flow velocity drops of the 8.3%, 20.8%, and 29% were observed in valves with enlargements of the 100%, 200%, and 300%, respectively. Resistors yielded flow rate drops of 20.8%, 33%, and 50% in the small, medium, and large configurations, respectively. Two applications were introduced, namely a tear volume sensor and a tear uric acid sensor (sensitivity 16 mg L-1), which are both painless alternatives to current methods and provide reduced contamination risks of tear samples.

Automated summary

In this article, femtosecond laser writing is used to engrave microfluidic networks into commercial contact lenses, achieving rapid and precise processing. The ablation process and tear flow within microfluidic structures are evaluated experimentally and computationally. Functional microfluidic components such as flow valves, resistors, and two applications, a tear volume sensor and a tear uric acid sensor, are introduced, providing painless alternatives with reduced contamination risks.