Potentiometers

Electrode Test Station

A pH electrode manufacturer wanted a system to improve their quality control testing of pH and reference electrodes. The system needed to be capable of testing batches of electrodes by a number of standard methods at different temperatures, to produce statistical and traceability data, whilst reducing their labour by automating the system. It also needed to be able to produce validation certificates, to be included with the product and manufacturing process control charts.

The system delivered was a custom microprocessor controlled 8-channel high input impedance potentiometer designed to operate with a PC with bespoke software, and a temperature controlled water bath. Each input was +/- 2V with 16-bit resolution. The system allowed up to 8 pH electrodes to be tested at one time.
The PC software included a set standard methods for testing the electrodes to determine their performance. Appropriate pass/fail limits could be automatically set. This produced data that was used to create Statistical Process Control charts to monitor batch-to-batch variability and the manufacturing process. Each electrode was individually numbered to ensure traceability. The data could be output in either excel or text formats.
The company greatly benefited by reducing their labour costs used to test electrodes as many electrodes could be tested in the time previously used to set up and test a single electrode. They were able to monitor the Statistical Process Control of the batches of electrodes to identify any changes in the manufacturing process that could then be addressed. Each electrode was individually numbered and a summary of the data was included in the box of each electrode, therefore traceability was ensured. With PC software controlling the method used, all tests were more reproducible than before as there was a consistency regardless of the operator of the test.

Micro Potentiometer

An academic customer required a robust potentiometer to interface with ion selective electrodes to measure water samples at a remote location. A micro three channel potentiometer with one reference electrode was supplied. The potentiometer was enclosed in a waterproof enclosure and was battery operated. It could be left at remote locations collecting data to be downloaded at a later date to a pc via USB connection. PC software was supplied that allowed measurement parameters, such as sample interval to be set and data downloaded for analysis.