| Summary: | We present a reference-electrode free sensor able to measure both pH and conductivity<br />based on impedance spectroscopy. The electrode is made of a layer of indium-tin-oxide (ITO). The<br />impedance of this electrode at low frequencies depends on its double layer capacity, which varies<br />with pH due to modification of oxide groups at the ITO surface. At high frequencies, the impedance<br />is determined by the resistance in the system, which corresponds to the inverse conductivity of the<br />solution. Because no reference electrode is needed for this technique, miniaturization of the pH<br />sensor is simple. We demonstrate a proof-of-principle experiment of the sensor for human plasma<br />pH measurements.
|
|---|
