Breakthrough Sensor in Berkeley Detects Allergens and Spoilage
A novel artificial nose developed at the University of Berkeley relies on an array of 16 gas sensors to identify common food allergens—including walnuts and peanuts—and assess how fresh a product is. Built with carbon nanotubes and operating at room temperature, the device learns to recognize seven different foods and determine the condition of three types of perishable items.
Doctoral candidate Carla Bassil, a member of the Javey research group, led the study. The artificial nose has been trained to detect the following foods:
- strawberry
- blueberry
- banana
- walnut
- hazelnut
- cashew
- peanut
The system can also distinguish the smell of raw chicken, milk, and eggs when fresh, as well as after 24 and 48 hours at room temperature. Its sensitivity is so high that it can detect the aroma of just 0.05 grams of isolated walnut—roughly one-hundredth of an average shelled walnut.
It should be noted, however, that the sensor’s performance has not yet been tested in environments containing other gases, such as those from lettuce or cake. The concept of an electronic nose dates back to the 1980s, but this new version uses carbon nanotubes as the conductive material. These nanotubes form layers only a few nanometers thick, and the sensor chip itself is manufactured using injection molding.
Carla Bassil noted that “smart” refrigerators—equipped with sensors controllable from a phone—would make an excellent application for this kind of technology.
She further explained, “You can think of it as a set of digital taste receptors, where each sensor on this chip reacts uniquely to the different gas molecules it is exposed to.” According to her, “Each of these 16 sensors has a different sensing film, and it works by converting chemical reactions between the sensor surface and the gas molecule into electrical signals.”
Where This Technology Could Lead
The core idea is that “we can use the relative selectivity of gas sensors combined with machine learning pattern recognition to determine which gas fingerprint corresponds to each food.” The result is a sensor chip that, in Bassil’s words, “is far more sensitive and far more objective than any human nose.”
This artificial nose developed at Berkeley has the potential to greatly enhance food safety and reduce risks tied to food allergies. Integrating the technology into “smart” refrigerators could give consumers extra information about product freshness, which in turn might cut down on food waste. Continued research and refinement could unlock new possibilities in health-related and food-safety fields.