Improvements

We applied some methods to improve our VOC device and designed the future plan for further optimization.

We have constructed a low-cost thermal enrichment unit.

The thermal enrichment unit consists of a Tenax filled tube, a heating device and its associated controlled gas path. Tenax®TA is a commonly used adsorbent for biological VOC detection, which is a porous polymer that can adsorb gases. It adsorbs VOCs at room temperature, and quickly release the gases at about 280℃, which is exactly the way we can achieve the enrichment.

The picture and schematic diagram of the device we designed are shown in the following figure: During the adsorption process, the air pump and valve are opened and the outside atmosphere is drawn into the Tenax tube. In the desorption process, another air pump and valve open, pumped with the air cleaned by molecular sieve. In the meanwhile the heating device is activated. This device is equipped with a thermostatic control system and can be heated to 280 degrees during heating. It can also displays the current temperature of the device in real time. The desorbed gas then is taken out with the clean air and fed into the detector.

Fig.1 A photo of our thermal enrichment unit

Our thermal enrichment unit can cooperate with our VOC device, to enhance its response value by enriching the VOCs. What’s more, the adsorption time of VOCs can be adjusted to accommodate different detection environments. At the same time, we can use different fillers to shield the interference of background VOCs.

装置的使用视频如下图所示

We combine the weather condition with our disease estimation model.

The weather situation is highly related to the outbreak of tobacco black shank. According to our HP activities in Hunan Tobacco Bureau of the field study, we learned that in the continuous high temperature and humidity, the temperature of 28 ~ 32 ℃ conditions, is most common for tobacco black shank outbreak. Therefore, we measure the weather information on the main equipment and take it into consideration when performing disease diagnosis. In the event of sustained high temperature and humidity weather, it gives a higher probability of disease judgments.

Future work

We'll introduce specific gas sensing pathways into our device.

A specific cell-dependent gas sensor is a more reliable than broad-spectrum detecting electronic VOC sensor. Therefore, we will try a new method of adding genes that can generate gas markers behind the Trichoderma hyperparasitic promoters. When our Trichoderma atroviride encounters pathogens activates this promoter, these gas tags will be released and detected by our specific cell sensors. According to the concentration of gas and duration, it can be more accurate to determine the health situation of plants.

We'll miniaturize our device and reduce the cost.

Because of the major limitation, we can still not integrate all the circuit. In the future, we will work with more parties to make the equipment more miniaturized, and further reduce the cost of equipment, for a wider range of applications. We’ll make all efforts to achieve this goal.