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B. A. Parviz, T. T. Shen, H. Ho; Functional Contact Lens With Integrated Inorganic Microstructures. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4783. doi: https://doi.org/.
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Conventional contact lenses are homogeneous polymer structures primarily used for the correction of vision. We present a set of microfabrication techniques that allow for integration of inorganic microstructures and functional micro-devices onto a contact lens. The integration of function into the structure of a contact lens opens a number of intriguing venues such as inclusion of a bio-sensor directly on the surface of cornea.
Basic inorganic structures, such as metal connection lines are incorporated into the lens structure by solid-state fabrication. The lenses are build on 100 micron thin polyethylene terephthalate substrates. The features are made by photopatterning of resist on flat substrates, metal evaporation or sputtering in vacuum, followed by lift-off. A second polymer layer (SU8) is patterned and cross-linked to make dielectric bridges on the template. Functional devices such as light emitting diodes can be independently fabricated and consequently self-assembled on the substrate. In order to self-assemble such components, binding sites with shapes corresponding to the one of the components are positioned on the substrate and capillary forces are used to trap the components in the correct location on the lens. Upon the completion of the microfabrication and assembly process, the structure can by encapsulated in polymethyl methacrylate and molded to the proper three-dimensional shape.
We have been able to incorporate micron-scale metal structures such as connectors, bridges, and antennas on contacts lenses. We have been able to verify the high conductivity of the connector lines made of gold and aluminum and have demonstrated radio frequency power transmission to the lens at the 2.4 GHz carrier frequency. We have also been able to develop a process to batch microfabricate red AlGaAs compound semiconductor light emitting diodes that can participate in a self-assembly process and have demonstrated their incorporation in the structure of a contact lens via the self-assembly process described above.
We have demonstrated a set of processes that enable the incorporation of inorganic structures into the structure of a contact lens. This ability enables the incorporation of a variety of new functions, hitherto deemed unfeasible, into a wearable lens structure. Candidate functions include radio frequency power transmission to a contact lens and bio-sensing.
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