Disposable Na+-ion-sensing Device for Research on Salt-tolerant Plants

Abstract

A disposable microfabricated Na+-ion-sensing device was developed for the direct on-site measurement of the Na+-ion concentration in live plants. To conduct reliable measurements, silver chloride (AgCl) in thin-film Ag/AgCl electrodes within the ion-selective electrode (ISE) and the reference electrode (RE) was regenerated prior to measurements using platinum electrodes formed in the containers of the electrolyte solutions. Distinct responses were observed, and the relationship between the potential of the ISE and Na+-ion concentration agreed with that expected from the Nernst equation. Welsh onion (Allium fistulosum) was used as a model plant, and the internal Na+-ion concentration was measured using the ISE. The tendency observed using the device agreed well with those obtained using conventional glasscapillary ISE and RE.