This miniature device is the smallest discrete pH sensor yet built by WPI. Included in each sensor tip is a reference electrode. The Mini Combo pH Electrode exhibits Nernstian response over a pH range of 2 to 12. It can be used for a quick reference in most aqueous fluids, in as little as 5 microlitres of sample fluid. (Not suitable for long-term studies.).
Drift: 0.1mV/min 0.01 pH/min

Electrode tip combines a pH sensing surface and reference electrode.
 

ZBEECAL is a battery operated level shifting device to shift the pH/millivolt curve of the electrode so as to be compatible with virtually any standard pH meter.