Case study: optical gas sensor
Background
With increasingly severe regulations imposed by bodies such as the FDA; being able to measure and control the production processes for products requiring sterilisation is critical. Many gas sterilisation processes require monitoring to ensure that the gas concentration is sufficiently high. Whilst it is usually possible to buy sensors off-the-shelf for use in industrial environments, these solutions are frequently expensive and not sufficiently robust.
The opportunity
For this development Sentec was approached by a manufacturer of sterile process equipment with the requirement of reducing sensor cost from those on the market by a factor of 10, without any reduction in the sensor’s range or sensitivity. Sentec successfully developed several prototype devices for the client embodying more than one technology solution.
The requirements were demanding against a tight deadline:
- Develop a novel sensor to measure concentration of sterilising gas
- Reduce cost of sensor such that a single production machine could incorporate several at reasonable cost
- Each sensor should cost less than 10% of the market price of an off-the-shelf product
- Sensor must function at temperatures of up to 150oC
Our approach
Brainstorm to determine appropriate methods for target gas detection
Review of relevant patents and commercially available solutions
Characterise spectral features of target gas and other gas species present from UV-C to mid- infrared
Preliminary BoM constructed
Detailed evaluation and design including mechanical (space restriction), electronic (sampling times) and fundamental science (prediction of accuracy, relative spectral feature intensity)
Prototype creation including intial testing and calibration
Testing at client's site
Results
In a demanding timescale, Sentec constructed a prototype gas sensor for testing in the client's process. The sensor was built with low cost long lifetime components which, coupled with a robust construction, gave a durable device for high temperature environments. It exhibited good resistance to oxidation and accuracy comparable to off the shelf, more expensive systems.
Development is ongoing.
