Reducing food waste with a tiny CMOS-MEMS gas sensor, dubbed GMOS

The global food losses is one of the most urgent issues for international community today. The fruits and vegetables waste and losses may reach up to 50% of the initial production quantity. Beside the natural waste, the lost food also represents the waste in resources for its production such as water and energy that leads to unnecessary CO₂ emissions. The immediate question that arises is, what can be done to reduce such high food losses? And the possible solution is by monitoring of food storage environment. Fruits and vegetables produce ethylene gas during the ripening process, therefore monitoring of ethylene level allows us to determine when the food is edible or ready for marketing before it is spoiled. It seems to be an easy solution, but the problem lies in the ethylene low concentration that should be monitored (0.05 – 10 ppm). Nowadays ethylene can be detected mostly by large, expensive and non-selective detection systems.

In this work, we present a tiny combustion type gas sensor (named GMOS) that is fabricated in standard CMOS-SOI-MEMS technology. It is a low-cost thermal sensor with embedded heater, catalytic layer and suspended transistor as sensing element. The sensor principle relies on a combustion reaction that takes place on the catalytic layer. The heat of chemical reaction releases and leads to sensor temperature increase, which modifies transistor current-voltage characteristics. The sensor performance shows an excellent sensitivity of 40 mV/ppm and selective ethylene detection using nanoparticle catalytic layers of Pt as well as TiO₂. Together with low energy consumption, it makes GMOS a promising technology towards low-cost ethylene detection systems for different stages in food supply chain that may reduce the global fruits and vegetables loss and waste.