Since landmine was invented, it has been extensively used in wars and caused millions of deaths and injuries so far. As a huge threat to human lives, the problem of landmines needs to be addressed.
Presence of Landmines:
From the ancient times to present, various of landmines have been used in the battlefields of many Europe countries and other developing countries, and about 1 million of landmines are still being used due to continuous regional wars every year. As of December 2018, according to nonofficial statistics, there are still about 50-100 million anti-personnel landmines distributed worldwide in more than 80 countries .
Traditional Landmine Detection Methods and Their Limitations:
Metal, acoustic and radar detectors are often used in modern detection to locate landmines with the judgement of demining personnel. In most cases, these workers need to get into the minefield with a high risk of their lives. What is even worse is that the landmines made of nonmetallic materials, such as ceramics and plastics, cannot be easily identified. Currently, the detection methods of nonmetallic landmines favored by the international community mainly include: pulse radar, infrared imaging and neutron landmine detection approaches. However, all these methods have obvious weaknesses and limitations, including substantial cost, high misdetection rates, susceptibility to electromagnetic interference, etc. . In addition, animals have also been used in landmine detection based on their highly sensory ability to smells. However, due to their uncontrollable nature, landmine detection by animals has large uncertainty. Overall, there is an urgent and growing demand for a safe, sensitive, accurate and low-cost landmine detection method.
The multi-functional engineering unit of the peacekeeping force of the China's Liberation Army officially performed its duties in May 2018. As of February 25, 2019, our minesweeping officers and soldiers had cleared a total of 6,078 square meters of minefields, and safely located and destroyed 1,213 landmines and an unexploded bomb. On July 20, the commander of the force signed a mission instruction, requiring the peacekeeping force to provide explosives to the Cambodian peacekeeping force for demining purpose, and instructed them how to blast the landmines controllably. As of August 23, 2019, the Cambodian peacekeeping force had been supported to carry out landmine clearance tasks for one month, and 285 Israeli No.4 anti-infantry mines had been destroyed. Chinese officers and soldiers frequently visited Cambodian minefields to check Cambodia's demining progress, lay detonating lines, and assist in final destruction of detected landmines .
According to several research reports of landmines, it will take about 120 years for a plastic landmine to naturally decay in the soil. The minefields left by large-scale military contests between China and Vietnam still cause hundreds of casualties in the local areas each year. Some minefields in mountainous forest areas are characterized by craggy rocks, crisscross gullies and clumps of trees, which makes it impossible for large-scale landmine sweeping machines to enter, and small-scale landmine sweeping robots are also difficult to operate in some areas. Therefore, to effectively avoid the impact of individual’s subjective misjudgement and improve objective accuracy in landmine detection, we want to develop a novel landmine detection technology to complement the traditional methods.
This year, we are committed to developing a new and highly sensitive approach in landmine detection based on synthetic biology. Up to now, a device has been produced with engineered bacteria inside to achieve landmine detection.
Our optical biological landmine detection sensor combines digital signal, optical and biological sensing system into one device. Engineered bacteria inside the device can sense 2,4-dinitrotoluene (DNT) and its metabolite 2,4,5-trihydroxytoluene (THT), trigger the synthesis of green fluorescent protein and then emit green fluorescence. The fluorescent light can be captured by a photoresistor that will transmit the signal to a smartphone. A designated app in the smartphone will calculate the probability of landmine presence using an algorithm, determine their locations, and logically propose the best demining route.
 Robledo, L., Carrasco, M., & Mery, D. (2009). A survey of land mine detection technology. International Journal of Remote Sensing, 30(9), 2399-2410.
 Frische T. (2002). Screening for soil toxicity and mutagenicity using luminescent bacteria——a case study of the explosive 2,4,6-trirfitrotoluene (TNY). Ecotoxicol Environ Saf, 51(2): 133-144.
 Yagur-Kroll, S., Lalush, C., Rosen, R., Bachar, N., Moskovitz, Y., & Belkin, S. (2014). Escherichia coli bioreporters for the detection of 2,4-dinitrotoluene and 2,4,6-trinitrotoluene. Applied microbiology and biotechnology, 98(2), 885–895.
 Shemer, B., Yagur-Kroll, S., Hazan, C., & Belkin, S. (2018). Aerobic Transformation of 2,4-Dinitrotoluene by Escherichia coli and Its Implications for the Detection of Trace Explosives. Applied and environmental microbiology, 84(4), e01729-17.
 Jenkins, T. F., Leggett, D. C., Miyares, P. H., Walsh, M. E., Ranney, T. A., Cragin, J. H., & George, V. (2001). Chemical signatures of TNT-filled land mines. Talanta, 54(3), 501-513.
 Palevsky, N., Shemer, B., Connolly, J. P., & Belkin, S. (2016). The Highly Conserved Escherichia coli Transcription Factor YhaJ Regulates Aromatic Compound Degradation. Frontiers in microbiology, 7, 1490.