Hamilton Releases ‘VisiFerm mA,’ the Next Generation of Optical Dissolved Oxygen Sensors

Longer cap life and fewer calibrations significantly reduce maintenance efforts and costs

VisiFerm mA, an Optical Dissolved Oxygen Sensor
Designed especially for production environments, the new VisiFerm mA is a simple 2-wire 4-20 mA (HART) installation with ATEX approval


Hamilton Process Analytics released the next  generation of its popular VisiFerm optical dissolved oxygen (oDO) sensors, which greatly reduce calibration frequency and the risk of deviation while increasing the overall sensor lifetime at the same time.

“VisiFerm mA” is based on the proven VisiFerm sensor family which features the optical measurement principle, first introduced by Hamilton in 2007 and now state-of-the-art and preferred dissolved oxygen measuring method in most biological production processes.

“A significantly increased cap lifetime and reduced signal drift over time make our new VisiFerm sensors unique”, explains Jahir Kololli, Senior Product Manager at Hamilton Process Analytics. “It reduces the need for calibration by 80%, lowering maintenance efforts and costs significantly”.

Currently, the standard optical dissolved oxygen best practice is to recalibrate the sensors after every run to prevent costly measurement deviations which occur from batch to batch. However, each application is unique and individual factors on site, such as sensor aging, chemical attack, temperature and physical damage all contribute to a measurement’s relative error. Algorithms to compensate for aging and temperature errors have therefore limited utility. During the development of this next generation of VisiFerm sensors, Hamilton engineers looked at ways to overcome the influence of SIP/CIP and photobleaching  in order to reduce the frequency of calibration and  unnecessary deviation reports. This required innovations in both sensor and cap design. “Both key components have been enhanced for the most robust VisiFerm ever on the market”, concludes Jahir Kololli.

Additional benefit of the VisiFerm family is the proven integrated micro transmitter which eliminates signal noise and enables predictive estimates of sensor and cap life, calibration and troubleshooting.  This can be conducted in a controlled lab or at line and documentation is simplified with automatic report generation.

The VisiFerm is available in various configurations to meet the needs for most applications in GMP environments. The core measurement principle is consistent across all models with various electrical connections, sensor caps, firmware versions and ATEX and FDA, USP Class VI certifications to ensure consistent performance and reliability across different applications.

Detailed information about the sensor are available on Hamilton’s website under


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