Intraocular pressure (IOP) is an essential indicator of the diagnosis and treatment of glaucoma. IOP has an apparent physiological rhythm, and it often reaches its peak value at night. To avoid missing the peak value at night and sample the entire rhythm cycle, the continuous monitoring of IOP is urgently needed. A wearable contact lens IOP sensor based on a platinum (Pt) strain gauge is fabricated by the micro-electro-mechanical (MEMS) process. The structure and parameters of the strain gauge are optimized to improve the sensitivity and temperature stability. Tests on an eyeball model indicate that the IOP sensor has a high sensitivity of 289.5 μV/mmHg and excellent dynamic cycling performance at different speeds of IOP variation. The temperature drift coefficient of the sensor is 33.4 μV/°C. The non-invasive IOP sensor proposed in this report exhibits high sensitivity and satisfactory stability, promising a potential in continuous IOP monitoring.

As the second leading cause of blindness in the world, glaucoma is mainly caused by persistent high intraocular pressure (IOP) that compresses the optic nerve and causes permanent damage. Noninvasive continuous monitoring of IOP is an essential method for the diagnosis and treatment of glaucoma. In this paper, we propose a new strain gauge material based on graphene nanowalls (GNWs) for continuous monitoring of IOP with high sensitivity in a wide range. By simulation, we studied the relationship between the strain of the cornea and contact lens and IOP. The structure and the location of the GNWs in the contact lens are optimized. A method for transferring GNWs on contact lenses with the assistance of a gold film is proposed. The simulated tests on porcine eyes in vitro show that the resistance response of the device to normal IOP fluctuation reaches 1.014 kΩ mmHg⁻¹. Its normal sensitivity of 42 250 ppm mmHg⁻¹ and the response range of 0–75 mmHg are far more than those of most noninvasive methods reported before. This study shows the enormous potential of GNWs for continuous IOP monitoring with high sensitivity and low power consumption.