A Flexible Printed Potentiometric Sensor for Potassium Ion Sensing

In this work, a flexible printed potassium ion (K
⁺
) sensor with good sensitivity is developed. The sensor is a two-electrode structure potentiometric sensor. It is fabricated by printing the working and reference electrode on a flexible Kapton film, followed by drop casting of an ion-sensitive membrane (ISM) on the working electrode. For the ISM, ion exchangers are deliberately doped into ionophores to obtain a stable and reproducible response and reduce the effects of interfering ions. The sensor has achieved a sensitivity of 50.0mV/log[K
⁺
] with an accuracy of 0.19 log[K
⁺
] and resolution of 0.17 log[K
⁺
] over 10
^-5
to 1 M K
⁺
concentration range. The interfering ions over the range present in saliva do not significantly affect the sensor’s measurement. The sensor can be used to detect the concentration of K
⁺
accurately from the human saliva in order to achieve quick and non-invasive health diagnostics.