Organic electrochemical transistors (OECTs) are useful as biological sensors because they are made of biocompatible materials and require relatively low voltage to operate. A typical OECT consists of three electrodes (gate, source, drain), an organic semiconductor linking the source and the drain, and an electrolyte connecting the semiconductor and the gate. This summer, I demonstrated that an OECT device utilizing CPE-K, a conductive polymer synthesized by the Nguyen research group, can detect a change in glucose concentration in a physiologically buffered solution. To fabricate the OECT device, I first established a functionalizing procedure of the gate electrode with an enzyme. Glucose in the electrolyte of the OECT is oxidized by the enzyme, which begins a cascade of reactions that ultimately change the current measured through the conductive polymer, CPE-K. The detection of glucose is based on the correlation between glucose concentration and the read-out current. By successfully building a working proof-of-concept, my project demonstrates that CPE-K can potentially be useful in sensing the concentration of biological metabolites, such as glucose, in biological systems.