pH Sensor Design
The first commercially available glass membrane pH sensors were launched to the marketplace in the mid-1930s. The sensors of today still rely on the same design principles as these first products.
A Basic pH Measurement System Consists of:
- The Measurement Electrode
- The Reference Electrode
- A High Impedance Voltmeter
This series of articles will explore the millivolt output signal as well as each physical component of the pH sensor measurement chain. Understanding the design of the sensor is a basis for learning why pH sensors have different features based on the application they are used in.
The Measurement Electrode
The measurement electrode is one half of the pH sensor measurement system used to determine a pH value in an aqueous solution. This article will focus on the pH sensitive glass membrane electrode and how it works.
The pH Reference Electrode
The pH reference electrode is the other half of the pH sensor measurement system. It provides a stable reference voltage and electrical path through the liquid junction. This article discusses how the reference electrode works.
The Combination pH Electrode
This article dives into modern pH sensor design with a brief description of the combination electrode and an overview of various reference electrolyte improvements to solve different user applications.
The Liquid Junction (Diaphragm)
The diaphragm is a porous liquid junction that allows reference electrolyte to contact the process liquid. This provides an electrical pathway to complete the pH measurement circuit.
pH Sensor Types
pH sensors come in many different shapes and designs to comply with different applications found in the laboratory and process measurements. This article provides some brief descriptions and illustrations of each design.
The Measurement of Potential Difference
The pH measurement is based on a voltage potential summed up from the pH measurement chain. This article provides a brief introduction to the concept of the potential voltage difference as well as glass membrane impedance.
Download Our pH Measurement Guide
Get a better understanding of pH measurement in Hamilton’s comprehensive pH Measurement Guide.