Gas sensors & Artificial olfactory
In complex environments, it is very hard to detect gases by sensors. However, a human nose, consisting of millions of olfactory receptors and a classifier to process signals generated by the receptors, can sniff out traces of gases. Therefore, sensor arrays, signal acquisition, data processing and pattern recognition systems are required to identify multi-component atmospheres.
We develop arrays of oxide-based gas sensors (Figure 5a) for in-door air quality monitoring; the sensor array is able to detect formaldehyde, benzene, ammonia and TVOC down to ppb level. We also develop sensor arrays for breath analysis, which is very helpful for the early detection of diseases, e.g., asthma, diabetes and lung cancer. Our sensor arrays will be integrated into smart phones. Flexible and transparent sensors working at room temperature under light are another research focus of mine in this field (Figure 5b); such sensors possess following advantages： low energy consumption, no safety concern due to high working temperature, no detrimental effect from inhomogeneous temperature distribution over a sensor. Such sensors are ideal for portable and wearable applications. More importantly, we develop artificial olfactory systems to classify various gases; the artificial olfactory system has a reservoir computing system to extract features from the sensor inputs spatiotemporally, and an artificial neural network to classify the gas features.
We develop arrays of oxide-based gas sensors (Figure 5a) for in-door air quality monitoring; the sensor array is able to detect formaldehyde, benzene, ammonia and TVOC down to ppb level. We also develop sensor arrays for breath analysis, which is very helpful for the early detection of diseases, e.g., asthma, diabetes and lung cancer. Our sensor arrays will be integrated into smart phones. Flexible and transparent sensors working at room temperature under light are another research focus of mine in this field (Figure 5b); such sensors possess following advantages： low energy consumption, no safety concern due to high working temperature, no detrimental effect from inhomogeneous temperature distribution over a sensor. Such sensors are ideal for portable and wearable applications. More importantly, we develop artificial olfactory systems to classify various gases; the artificial olfactory system has a reservoir computing system to extract features from the sensor inputs spatiotemporally, and an artificial neural network to classify the gas features.
Figure 5. (a) Array of thermally-activated sensors (b) Array of sensors activated by light, ~2,600 pics of micron-scaled gas sensors and LED light sources are integrated on a 2-inch sapphire wafer.
