The OneFerm single-use pH sensors mimics the offering provided by standard, reusable process pH sensors. There are products that output traditional analog (millivolt) pH signals as well as, provide Arc intelligent sensor technology. The purpose of this article is to help differentiate between products based on your application.
Traditional OneFerm pH Sensors
Traditional OneFerm sensors with the K8 electrical connector as seen above offer a millivolt output signal that works with most bioreactors and transmitters. This sensor has no temperature compensation thus the input device must rely upon a secondary dedicated temperature input or have a manual temperature setting that can be input by the user.
These products are well suited for existing bioreactor controllers that are being adapted for single-use processing. Hamilton offers a variety of adapter cables to interface with different devices.
Traditional OneFerm pH Sensors with Temperature Compensation
Traditional OneFerm sensors are also available with integral temperature compensation. Temperature elements include both PT100 and PT1000 options. Both forms of temperature elements are two-wire RTDs. Due to the additional connections required for temperature compensation and the millivolt signal, a VP6 electrical connector is used.
The addition of temperature compensation makes these sensors well suited for direct wiring into transmitters or whenever a separate, temperature element cannot be easily used for compensation of the pH measurement.
Arc OneFerm pH Sensors
Arc OneFerm pH sensors are designed to work in combination with the Arc Single-Use pH Module (Ref 243233) as shown above. The product functions similar to a reusable Arc pH sensor with the key difference being the detachable electronics module. The module functions similar to a transmitter. It is fully reusable and stays with the bioreactor. The pH sensor is pre-installed and pre-sterilized with the bag. Once module and sensor are mated up, sensor calibration data must be scanned into the module using the ArcAir software.
Arc OneFerm single-use pH sensors look similar to traditional sensors with the VP connector; but are identified by the NTC temperature compensation element (see label on the sensor body). These products are most commonly found on newer bioreactors that allow for either 4 to 20mA or Modbus digital protocol signals directly into the controller.
Please consult with your single-use bag or bioreactor vendor to learn which options are available for your application.