A paradigm shift in sensing methods and principles is required to meet the legislative demands for detecting hazardous substances in the molecular world. This will encompass the development of new sensing technologies capable of performing very selective and sensitive measurements at an acceptable cost, developed by multidisciplinary teams of chemists, engineers and computer scientists to harvest information from a multitude of molecular targets in health, food and the environment. In this study we present the successful implementation of a low-cost, wireless chemical sensing system that employs a minimum set of components for eective operation. Specically, our eorts resulted in a wireless, tri-electrode, ISE pH sensor for use in environmental monitoring. Sensor calibration and validated in-situ eld trials have been carried out and are presented in this paper.

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A third RF system was commissioned and the existing two systems were modified. Included in the revisions were a new 100 kW, 50 MHz power amplifier, an infra-red heat sensor monitoring the accelerating cavity temperature to compensate for water film coefficient thermal loss, and the isolation of vacuum-RF seals on the accelerating cavity. The results of these changes will be detailed.

A mechanically driven loop tuner in addition to water temperature variation is used to compensate f o r the reactive detuning of the 5 2 . 8 MHz RF accelerating cavity at a 1 ampere circulating current. This combination avoids the higher order resonances that occur with a single mechanical tune. System description and operating results will be detailed.