Fabrication and Optimization of Fiber-Based Lithium Sensor: A Step toward Wearable Sensors for Lithium Drug Monitoring in Interstitial Fluid.

A miniaturized, flexible fiber-based lithium sensor was fabricated from low-cost cotton using a simple, repeatable dip-coating technique. This lithium sensor is highly suited for ready-to-use wearable applications and can be used directly without the preconditioning steps normally required with traditional ion-selective electrodes. The sensor has a stable, rapid, and accurate response over a wide Li concentration range that spans over the clinically effective and the toxic concentration limits for lithium in human serum. The sensor is selective to Li in human plasma even in the presence of a high concentration of Na ions. This novel sensor concept represents a significant advance in wearable sensor technology which will target lithium drug monitoring from under the skin.