Soft Contact Lens With Embedded Moiré Patterns-Based Intraocular Pressure Sensors

Soft contact lenses with built-in sensors have shown great potential for real-time monitoring of intraocular pressure (IOP). This paper reports a contact lens IOP sensor based on the moiré patterns. One concentric ring grating (G1) is fabricated on a commercial contact lens, the other line grating (G2) is stored in a computer. Images of G1 are captured using a smartphone camera. Then moiré patterns are generated by superimposing the images of the two gratings in a computer. The central angle $\theta $ formed between two innermost adjacent moiré patterns is extracted as the IOP transducing signals. The performance of the sensor has been evaluated using a home-made hollow hemispherical silicone model eye. The sensitivity of the contact lens IOP sensor is ~0.15°/mmHg with high repeatability. Additionally, the sensor sensitivity is essentially independent of the initial IOP exerted on the contact lens. Furthermore, the virtual G2 provides great flexibility for the design and fabrication of the sensor, the fabrication of G1 directly on commercial contact lenses paves the way for clinic use. All these results indicate the suitability of this type of sensor for monitoring IOP. [2022-0111]