Ethylene is a plant hormone and an indicator for the ripeness of various fruits and vegetables. Measuring the ethylene concentration is therefore a powerful method for monitoring and controlling the ripening process. However, current ethylene detection equipment is bulky and expensive or lacking sufficient sensitivity and selectivity. At Holst Centre, a novel electrochemical ethylene sensor has been developed, in which a thin ionic liquid film is used as the electrolyte. This enables the development of a small, low power and low cost ethylene sensor. Currently, the detection limit of the sensor is less than 1 ppm. This is close to the specification needed for monitoring the ripening process during transport and storage of fruits and vegetables. Moreover, fabrication of the sensor on a flexible substrate is demonstrated. This opens up possibilities for integrating the sensor in packaging materials, so-called smart packaging. In this contribution, the sensor technology will be explained and recent developments will be presented.