Telemetric electrochemical sensor.

A telemetric system was designed and constructed to sense pH and ethanol variation in aqueous solutions. The measured signals were transferred by software digitally and transmitted wirelessly by the telemeter, personal digital assistant (PDA), through the General Packet Radio Service (GPRS) protocol. The pH sensing electrode was designed to measure a chemical potential induced by a proton concentration gradient on the electrode's surface which exhibits internal Donnon diffusion behavior, and a linear relationship between the electrical potential and pH was found. The result shows that the wireless sensing system allowed not only long-term usage and long-distance transmission but also with high accuracy (e.g. S.D. less than +/-2%). The telemetric system can also be modified to measure ethanol concentration in aqueous solution amperometrically. It was found that the sensitivity of that ex situ measurements matched those of in field measurements with negligible deviation, less than 4%.