An infrared based sensor system for the detection of ethylene for the discrimination of fruit ripening

摘要

Highlights ? A compact IR thermal ethylene sensor is developed for screening fruit ripening. ? A customized IR thermal source is tuned for emitting 10.6μm thermal waves. ? Silicon temperature detector of high accuracy is used for capturing thermal waves. ? The sensor exhibits a sensitivity of 3.3% with detection range as low as 5ppm. ? This compact IR ethylene sensor system can be used for ensuring food safety. Abstract We report the fabrication and testing of a prototype ethylene sensing device for use in fruit ripening applications. A sensor based on infrared (IR) thermal emission was developed and used to detect the ethylene level released during the fruit ripening process. An IR thermal source tuned to the 10.6μm wavelength was linked to a high-sensitivity silicon temperature detector. When introduced into the wave path between the IR source and temperature detector, ethylene absorbs the 10.6μm IR waves and decreases the surface temperature of the detector. The output is then converted to an electrical signal (in mV), which gives a direct measurement of the ethylene level. Using this sensor, ethylene concentration measured from a fruit sample continuously decreased from 59 to 5ppm during the natural ripening process. The sensor exhibited a sensitivity of 3.3±0.2% (change in detector output (mV)/ppm×100) and could measure concentrations as low as 5ppm with rise and recovery times of 1 and 3s, respectively. The system demonstrated good reproducibility. Devices employing this sensor system may be used for fruit ripening applications on site and in the field and for screening artificially ripened fruits, therefore contributing to ensure food safety. ]]>