A novel electrochemical cell design in a vertically stacked configuration is presented. Through a layered structure using a top macroporous working electrode, a polyelectrolyte, and a bottom metallic conductor a standalone electrochemical cell with an internal reference electrode is built. This sensor allows monitoring an electrochemical property of an external solution with only one electrode in direct contact with the sample. Using paper-based platinum electrode for the porous top electrode and Nafion as polyelectrolyte material, the self-powered detection of hydrogen peroxide is performed. The system can be operated in multiple modes. In a capacitive way, the open circuit potential is measured. Alternatively, in a self-powered current mode, the system emulates a fuel cell. Additionally, a potential-current switched mode is also demonstrated. Because of this unique design and operational features this sensor is considered as an electrochemical pixel. To further demonstrate the advantages of this device, the detection of glucose is performed by building an array of sensors using a single back (reference) electrode and multiple working electrodes. These results lay the groundwork for the development of a new generation of simple and low cost biochemical sensors and electrochemical sensing arrays.
Keywords: Capacitive biosensors; Mixed potential; Polyelectrolyte membranes; Pseudo-capacitors; Solid-state sensors.
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