Multianalyte Electrochemical Sensors on a Monolith Electrode By Optically Probing the Electrical Double Layer

Electrochemical sensors are arguably the most successful chemical sensing devices primarily because of their high sensitivity at low cost. The key advantage of electrochemical devices is the active signal due to chemical reaction allowing specific recognition of the chemical with a low incidence of false positives. However, only one redox reaction per electrode is possible to measure. An opto-electrochemical method, called Scanning Electrometer for Electrical Double-layer (SEED), to quantitatively detect multiple, individual redox reactions on a monolith electrode will be described. SEED optically measure the charging/discharging of the electrical double layer to quantify the local redox current. By scanning a laser beam, local redox current density distribution can be quantitatively mapped to detect multiple analytes on a monolith (working) electrode. SEED is responsive to (redox) reactions of 0.1 atto-mole of molecules. The local redox current is measured as the change in the charge in the electrical double-layer which significantly changes due to redox reaction. SEED signal enhances as the sensing area reduces in size. Characteristics of SEED and application to chemical and biochemical sensing, and genomics will be described.