pHsensorer

pHsensorer are analytical devices used to measure the acidity or basicity of aqueous solutions by determining hydrogen ion activity, reported as pH. They are essential in laboratories, environmental monitoring, food and beverage production, medicine, and industrial processes.

Most common pHsensorer combine a pH-sensitive glass electrode with a reference electrode to produce a voltage that depends on pH. The measured potential follows a Nernstian relation, E = E0 - S·pH, where the slope S is about 59 mV per pH at 25°C. Temperature changes alter the response, which is mitigated by automatic temperature compensation or by reporting pH at a known temperature. Other designs include solid-state ion-sensitive field-effect transistor (ISFET) sensors and optical colorimetric sensors.

A typical setup includes a sensing electrode, a reference electrode, and a meter or readout with calibration buffers (commonly pH 4, 7, and 10). Regular calibration improves accuracy, and temperature compensation ensures stability. Clean storage and proper rinsing between samples extend electrode life.

pHsensorer vary in form from portable handheld meters to benchtop meters and inline probes for process control. Glass-electrode sensors offer wide pH range and accuracy but can be fragile; ISFET and optical sensors are more robust and suitable for miniaturized or waterproof designs. Calibration and maintenance are crucial for reliable measurements.

Common challenges include electrode drift with age, fouling by organic matter, interference from high concentrations of salts, and color or turbidity of samples that affect optical sensors. Advances include solid-state and nano-structured pH sensors, longer-lasting reference membranes, and integration with wireless data systems.