SitS: Wireless, sustainable, and automated sensory system for in-situ monitoring of soil heavy metals

该奖项是通过“土壤中的信号(SITS)”征集，这是美国国家科学基金会和美国农业部国家粮食和农业研究所(USDA NIFA)之间的合作伙伴关系。随着工业化和城市化的快速发展，土壤和灌溉水中非必需重金属的毒性、生物累积性和环境持久性对生态系统健康、食品安全和人畜健康构成了严重威胁。为了密切监测和管理重金属污染的土壤，以确保食品安全和人类健康，密歇根州立大学和弗劳恩霍夫美国中西部中心的研究人员正在合作开发一种新型的无线传感器平台，用于连续现场测量土壤中的重金属浓度。此外，研究团队将把研究课题整合到多样化的教育和外展活动中，包括教师培训机会、通过暑期项目提供的中等教育机会，以及通过各种社交媒体平台和YouTube渠道进行交流。如果研究成果成功，将对土壤传感科学技术、土壤质量、食品安全和公共健康产生重大积极影响。该项目的总体目标是开发一个环境友好、可持续、无线、自动化的微流控传感器平台，能够对土壤pH值和主要重金属元素的浓度进行现场检测、连续监测和远程报告。感兴趣的金属元素包括但不限于铅、汞、镉、镍和锂。该平台将在一个密封紧凑的封装中协同集成几个多功能模块，包括：1)可自我更新的微电极传感器阵列；2)集成了多孔陶瓷过滤器、有源混合器和并行流体通道的高效微流体；3)高性能、环保的太阳能采集器；4)用于电源管理、微流体控制和多通道电化学传感的低功耗电子电路；5)能够进行地上和地下无线数据通信的零能量物联网网络模块；以及6)为终端用户提供的实时信号处理和量化。该原型平台将用于研究由土壤水分波动和优先分布驱动的土壤微站点中金属的阶段性释放，从而深入了解重金属在非均质土壤基质中的动态行为。与现有的土壤重金属传感方法相比，拟议的平台将提供明显的优势。特别是，材料选择、土壤样品处理、电源管理和设备/系统封装是系统设计的一部分，以实现最佳的传感性能，同时将对土壤环境的干扰降至最低。掺硼聚晶金刚石作为一种新型传感材料，可以实现高灵敏度、高选择性、长期稳定的电化学测量。将微电极传感器与自动并行微流控技术相结合，可以高通量地同时检测多个分析物，样品量最少。精心设计的多步骤样品处理可以降低样品基质的复杂性，提供一致的测试条件，并防止废水渗入土壤环境。零能物联网通信可在大型网络中实现安全、节能的无线数据传输，同时消除传感器和数据聚集器之间的束缚配置和视线。使用太阳能收割机作为能源是环保的、自我可持续的，并且具有成本效益。除了对土壤传感科学和技术的重大贡献外，该项目预计将通过将研究与各种教育和推广活动相结合，对与工程和农业相关的STEM教育产生重大影响，例如年度研讨会、外展出版物、教师培训、K-12暑期项目、新的SIT课程、社交媒体和YouTube频道。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award was made through the "Signals in the Soil (SitS)" solicitation, a collaborative partnership between the National Science Foundation and the United States Department of Agriculture National Institute of Food and Agriculture (USDA NIFA). With the rapid growth of industrialization and urbanization, elevated levels of non-essential heavy metals in soils and irrigation water pose major threats to ecosystem health, food safety, and human and animal health, due to their toxicity, bioaccumulation, and environmental persistence. To closely monitor and manage heavy metal contaminated soils for ensuring food safety and human health, researchers at Michigan State University and Fraunhofer USA Center Midwest are collaborating to develop a novel wireless sensor platform for continuous field measurement of heavy metal concentrations in soils. In addition, the research team will integrate the research topics into diverse educational and outreach activities, including teacher training opportunities, secondary education opportunities through summer programs, and communications through various social media platforms and YouTube channels. If successful research outcomes will have a significant positive impact on soil sensing science and technology, soil quality, food safety, and public health. The overarching goal of this project is to develop an environmentally friendly, sustainable, wireless, automated microfluidic-sensor platform, capable of in-situ detection, continuous monitoring, and remote reporting of soil pH and concentrations of major heavy metal elements. Metal elements of interest include, but are not limited to, lead, mercury, cadmium, nickel, and lithium. The proposed platform will synergistically integrate several multifunctional modules in a hermetically sealed and compact package, including: 1) a self-renewable microelectrode sensor array; 2) highly-efficient microfluidics with an integrated porous ceramic filter, active mixers, and parallel fluidic channels; 3) a high-performance, eco-friendly solar energy harvester; 4) low power electronic circuitry for power management, microfluidic control, and multichannel electrochemical sensing; 5) a zero-energy Internet of Things (IoT) networking module capable of both above- and underground wireless data communication; and 6) real-time signal processing and quantification for the end-user. The prototype platform will be demonstrated in a pilot study to investigate the episodic release of metals from soil microsites that are driven by fluctuating and preferential distribution of soil water content, leading to an in-depth understanding of the dynamic behaviors of heavy metals in heterogeneous soil matrixes. The proposed platform will provide distinct advantages over existing approaches for heavy metal sensing in soils. In particular, material selection, soil sample processing, power management, and device/system packaging are carefully considered as part of the system design to achieve the best sensing performance while minimizing disturbance to soil environments. Boron-doped polycrystalline diamond as a new sensing material allows for highly sensitive and selective, long-term stable electrochemical measurements. Integration of microelectrode sensors with automated parallel microfluidics enables high-throughput, simultaneous detection of multiple analytes with minimal sample volume. Deliberately designed multi-step sample processing can reduce sample matrix complexity, provide consistent test conditions, and prevent leaching of wastewater into the soil environment. The zero-energy IoT communication enables secure and energy-efficient wireless data transmission within a large network while eliminating tethered configuration and line of sight between sensors and data aggregators. The use of a solar energy harvester as a power source is environmentally-friendly, self-sustainable, and cost-effective. Besides the significant contributions to soil sensing science and technology, this project is expected to have a great impact on engineering- and agriculture-related STEM education through integration of research with diverse educational and outreach activities, such as annual workshops, outreach publication, teacher training, K-12 summer programs, new SitS courses, social media and YouTube channels.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.