Standards for sensors in sterile environments
Sterile medicinal products and medical devices must be packaged free from contamination, as required by the EU GMP Directive. The updated Annex 1 effective from the end of August 2024 means this now applies not only to parts that come into direct or indirect contact with products, but also to all components that may disrupt “first air,” such as sensors positioned above sterile components. Different challenges and opportunities arise for the use of sensors in pharmaceutical production and packaging depending on their type.
Figure 1: Previously, decontamination was considered sufficient for sensors and reflectors installed in a way that interrupted first air. Annex 1 “Manufacture of Sterile Medicinal Products Guideline” requires that these components also be treated with validated, penetrative sterilization methods (e.g., autoclaving).
The new Annex 1 requirements make the careful selection and integration of sensor technology essential. Hygienic, flexibly mountable stainless-steel sensors from Leuze help you to comply with the requirements safely and efficiently. Our experts will be happy to advise you and work with you to find the right solution for maximum process reliability and compliance.
Significance for the sensor technology used
The position and type of sensors and reflectors play a key role in complying with the new Annex 1 requirements. Sensors or reflectors mounted above the product are considered contact parts that interrupt first air. They must be sterilized by SIP (sterilization in place) or autoclaving. In practice, ultrasonic sensors for filling level measurement and retro-reflective photoelectric sensors with reflectors above the product have often been used because they offer the necessary operating ranges. It is precisely these solutions that are now critical: reflectors and ultrasonic sensors often cannot withstand the high temperatures and conditions of sterilization. Even if they were technically suitable for sterilization, this would involve considerable additional work and costs – the sensors and reflectors would have to be removed for autoclaving.
Figure 2: Annex 1 compliant solution: ToF sensors mounted on the side or underneath the product reliably detect it without entering the first-air area, so the sensors do not need to be sterilized.
Hygienic time-of-flight sensors in response to Annex 1
Modern optical sensors based on ToF (time of flight) such as the ODT55CL1-2M from Leuze provide significant advantages in relation to Annex 1: Thanks to their long operating range, they can be mounted at the side or underneath the product and at a considerable distance. As a result, they have no direct, indirect or first-air interrupting contact with the sterile product they detect – for example a stopper plug – and therefore do not need to be sterilized. The compact design, as offered by the 53C and 55C sensor series in a stainless-steel housing, is also an advantage, as space is often limited in pharmaceutical plants. Where sensors enable the evaluation of measurement values via IO-Link, system operators also benefit from additional process data. This makes control and verification in accordance with Annex 1 easier.
Summary
The new Annex 1 requirements make the careful selection and integration of sensor technology essential. Hygienic, flexibly mountable stainless-steel sensors from Leuze help you to implement the specifications safely and efficiently. Our experts will be happy to advise you and work with you to find the right solution for maximum process reliability and compliance.
