At Zimmer and Peacock, we ensure that only sensors which display acceptable calibration profiles are used in any field trials or lab testing through a thorough OQC (Outgoing Quality Control) procedure. This procedure is set up so that farmers and other beta testers receive sensors of the highest quality, a practice in line with our ISO 13485 certification.
Sensor manufacture and activation of the ion selective membrane is completed in the lab before the sensor is secured into a protective housing which we call the sensor module. Fixing the sensors inside the sensor module is a cost effective way to test and calibrate them, but also provides the advantage of being safe for use in liquid based applications such as hydroponics and vertical farming.
The calibration itself consists of a three step process with three concentrations of Nitrate Solution, with each concentration increasing by a factor of ten. The process begins with the weakest concentration first, through to the strongest. Between steps, the sensor itself is rinsed with de-ionised water and dried thoroughly to ensure that we get the truest response as to the concentration of the solution.
Sensors displaying positive results will then be used in the manufacture of our Nitrate Rods. When the nitrate rods have been built with the sensor modules attached, a second round of the same calibration is performed. This is to ensure that the same result is seen and that there has been no damage to the sensor during the process of manufacturing the rod.
Using all of these discussed methods, we ensure that the final product is of a high standard and only quality products are dispatched to any testers. We have the OQC process in place to ensure that our testers and future clients are satisfied with the final product we deliver to them. Finally, to ensure we keep accountability of the sensors and can correlate the field results to the correct calibration profile, our manufacturing database is regularly updated to keep a log of every sensor and it's location.