pH is one of the most fundamental properties in all of nature and is a critical parameter in virtually everything we touch, consume, or even stand next to on a daily basis;
- Human Health
- Plant and animal physiology
- Drinking water
- Rivers, lakes and oceans
- Crop science
- Production and processing of dairy products, food and beverages
- Pharmaceutical research and production
In the 1930s, Arnold Beckman revolutionized pH measurement with the invention of the acidimeter, a product that launched Beckman Instruments and evolved into the ubiquitous pH meter. His acidimeter was based on multi-chamber hand blown glass electrodes connected to a voltmeter requiring well trained technicians to carefully expose the glass electrode to multiple samples of precisely known pH, in order to create a calibration curve prior to each use. 80 years later, pH measurement is still relegated to the same fragile glass pH electrodes that require frequent calibration, suffer from fouling and signal drift, and require tedious maintenance and storage protocols.
Senova Systems has developed the pHit smart sensor platform which has the capability and versatility to revolutionize pH measurement in virtually any environment imaginable. The pHit sensor utilizes a carbon substrate containing proprietary analyte sensing molecules or ASMs. These ASMs are reduction oxidation (redox) active compounds which reversibly bind protons (hydronium ions) when subjected to a voltage sweep or scan.
The animation below demonstrates the pHit sensor’s surface as it undergoes a scan. The ASMs are shown graphically on the exposed carbon surface.
The pHit sensor works by applying a voltage scan across the sensor, which causes the ASMs to gain or lose electrons. The voltage at which this redox reaction occurs is dependent on the concentration of hydrogen ions in solution. As show in the animation, when there is a high concentration of hydrogen ions present (corresponding to low pH), the reaction occurs at a lower voltage and the reaction is detected as a spike in current flow as indicated in the graphic below. On the other hand, when the hydrogen ion concentration is low (corresponding to high pH), the redox reaction requires a higher voltage as seen in the graphic below.
The figure below demonstrates that the chemical reaction between the ASMs on the sensor surface and the hydronium ions in solution is quite linear over a broad pH range.
The relationship between the voltage scan and the redox reaction is constant and validated so this data is stored in memory as an internal calibration. Thus no user calibration is required. The signal from the sensor module is processed by the electronics in the cartridge and can then be transmitted to a local display or to a PC, tablet computer, or process controller.