Redox-potential sensor array based on extended-gate field-effect transistors with ω-ferrocenylalkanethiol-modified gold electrodes

► 32×32 array of FET-based chemical sensors for detecting redox reactions. ► Consistent output from sensors throughout the array. ► Linear response to hexacyanoferrate(II)/hexacyanoferrate(III) redox reaction. ► Detect glucose in enzyme-catalyzed reaction with detection limit of 50μM. ► Detect glucose in human serum. A chip was developed with a 32×32 array of extended-gate field-effect transistor (FET)-based redox-potential sensors, each with a gold electrode modified with 11-ferrocenylundecane-1-thiol (11-FUT). The potential of the sensors was stable to within 0.5mV/h. Overall, for the 32×32 sensor cells, 80% showed potentials that were within ±5mV of the median and 92% were within ±1mV of the median. The sensor array detected the redox reaction of hexacyanoferrate(II) and hexacyanoferrate(III) as a change in the electric potential of the 11-FUT-modified electrode with a Nernstian response, at a slope of −58.0mV/decade at room temperature, and a dynamic range of more than five orders of magnitude. Two-dimensional and real-time visualization were made possible by imaging of the sensor array. With an enzyme-catalyzed redox reaction, the FET-based sensor array showed a slope of −59.5mV/decade for logarithmic concentrations of glucose in the range 0.1–2mM, and it successfully detected glucose levels from 22.5 to 360mg/dL. The limit of detection of glucose was 50μM. Finally, the FET-based enzyme sensor array successfully detected glucose levels in samples of human serum from 100.1 to 264.3mg/dL.