Biomedical soft contact-lens sensor for in situ ocular biomonitoring of tear contents

A soft contact-lens biosensor (SCL-biosensor) for novel non-invasive biomonitoring of tear fluids was fabricated and tested. Wearing a biosensor on eye enabled the in situ monitoring of tear contents. The biosensor has an enzyme immobilized electrode on the surface of a polydimethyl siloxane (PDMS) contact lens. The SCL-biosensor was fabricated using microfabrication techniques for functional polymers (PDMS and 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer). In investigation of in vitro characterization, the SCL-biosensor showed excellent relationship between the output current and glucose concentration from 0.03 to 5.0 mmol·L-1, with a correlation coefficient of 0.994. The calibration range covered the reported tear glucose concentrations (0.14 mmol·L-1). Based on the result, ocular biomonitoring with the SCL-biosensor was carried out. The SCL-biosensor well worked both in the static state and the dynamic state. The tear glucose level of rabbit was estimated to 0.12 mmol·L-1 at first and then the tear turnover was successfully calculated to be 29.6 ± 8.42% min-1. The result indicated that SCL-biosensor is useful for advanced biomonitoring on eye.