Flexible, planar, and stable electrolyte-gated carbon nanotube field-effect transistor-based sensor for ammonium detection in sweat

In this work, a flexible and planar electrolyte-gated carbon nanotube field-effect transistor-based sensor for ammonium detection is reported. The active layer was manufactured by means of a spray-deposited semiconducting single-walled carbon nanotube (SWCNT) thin film. The device was functionalized with an ion-selective membrane, based on the nonactin ionophore. The characterization was carried out by means of transfer and output curves, to test the response of the devices towards different concentrations of ammonium. The calibration curve of the fabricated sensors showed a linear detection range for ammonium from 0.01 to 10 mM, which covers the entire range of physiological concentrations of interest, with average sensitivities of 0.346 µA/decade and 94.35% coefficient of determination.