The increase in the diabetes population makes glucose monitoring a pressing demand for clinical and continuous use. Non-invasive sensing would allow a painless, convenient solution compared to traditional skin-piercing glucose meters. Among various body fluids, tear fluid, which is correlated to the glucose concentration in blood , is directly accessible on the eye and can provide a unique opportunity to develop an interface between a sensor and the human body. The current technique is to collect tear fluid samples in capillary tubes and assay the samples for glucose ex situusing standard laboratory instrumentation. Integrating sensors into a contact lens would provide a way to continuously and reliably sense metabolites in tear fluids.