An Extended Gate Field Effect Transistor-based (EGFET-based) Urea Microbiosensor Based on Polypyrrole

Here, an extended – gate field effect transistor (EGFET) urea microsensor based on modified polypyrrole (PPy) is reported for the quantitative detection of urea in aqueous solution. the EGFET urea sensor was made by integrating a small and cheap metal oxide semiconductor field - effect transistor (MOSFET) with a Au microelectrode modified with urease and pH sensitive PPy. First, the urease was added to a pyrrole solution and then pyrrole/urease solution was electropolymerized on the surface of gold microelectrode in galvostanic mode to produce a urea sensitive microelectrode. The microsensor was imaged using a stereo microscope to confirm the polymerization of pyrrole/urease. The EGFET urea microsensor was tested in deionized water containing various concentrations of urea. The electrode showed a linear response for a wide concentration range of urea from 10⁻⁹ to 10⁻⁵ M with a sensitivity of 35.5 mV/decade urea.