Contact lens sensing platforms have drawn interests in the last decade for the possibility of providing a sterile, fully integrated ocular screening method. However, designing scalable and convenient processing methods while keeping a high resolution is still an unsolved challenge. In this article, femtosecond laser writing was employed as a rapid and precise method to engrave microfluidic networks into commercial contact lenses. Functional microfluidic components such as flow valves, resistors, multi-inlet geometries, and splitters were produced using a bespoke 7-axis femtosecond laser system, yielding a resolution of 80 µm. The ablation process and the tear flow within microfluidic structures was 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 mgL-1), which are both painless alternatives to current methods and provide reduced contamination risks of tear samples.
Bibliographical noteFunding in fomation: The authors would like to acknowledge the support of LASEA SA, Belgium, within the framework of the ESIF project “Smart Factory Hub” (SmartFub). R.M. acknowledges the University of Birmingham, UK, for funding. A.K.Y. thanks the Engineering and Physical Sciences Research Council (EPSRC) for a New Investigator Award (EP/T/).
- Contact lenses
- Femtosecond Laser Ablation
- Wearable Sensors