A low-cost ion detecting device with paper-based disposal sensor

We present a simple low-cost paper-based ion-sensing device based on a salt bridge. An electrochemical activity was monitored through the Ag/AgCl electrodes between wax-defined two zones. An inexpensive disposable sensor showed a linear response for detecting the chloride ions at the range of 10-1000 mM including the clinical relevant range of 98-109 mM Cl- in blood serum. Therefore, this device is likely to be suitable for point-of-care applications.