EAGER SitS: Photonic Sensor Platform for Point of Interest Soil Sensing

尽管土壤对粮食生产、植物学、水循环和环境科学都很重要，但大多数关于土壤的信息仍然不足。更详细地了解地下环境的一个主要制约因素是，目前的工具，如收集和分析土壤岩心样本，成本高、侵入性强、速度慢。这项建议描述了一种小型、低成本、高灵敏度的基于光子学的传感器平台的开发，该平台最初的目标是检测土壤中的关键营养物质，如硝酸盐。这些传感器将能够非侵入性地工作，埋在地下，具有实时传感能力。发展低成本和高灵敏度的地下探测将使人们能够可视化以前神秘的土壤过程，这些过程仍然支撑着地球上生命的关键方面。土壤经历的动态物理、化学和生物变化今天还没有得到很好的了解，这反过来又对植物科学、环境科学和粮食安全产生了影响。发展对这些领域的理解和建立准确的预测模型需要对土壤(在包气带中)在空间和时间上的细粒度知识。目前的土壤传感能力不能满足这些需求。特别是，缺乏可现场部署、准确和廉价的适当传感技术。这项建议描述了基于微型制造的光子结构的地下分析物通用传感平台的开发，这种结构对当地环境折射率的变化非常敏感，特别侧重于测量对土壤和植物科学重要的微量营养素。这些光刻制作的光子结构是使用光刻或电子束光刻在硅/硅氧化物上制造的，因此与广泛的表面功能化化学物质兼容。光刻或电子束光刻的使用确保了传感器设计既具有高度的重复性，又可立即扩展。为了将高亲和力和特异性结合到这个通用的检测平台上，将设计小肽来结合具有高特异性的无机分析物，如硝酸盐和磷酸盐。无机分析物的仿生传感可以通过设计模拟自然观察到的蛋白质结合位置的小肽链来实现高灵敏度和高特异性。到目前为止，这一策略已经用于金属传感和修复，但它还没有扩展到对弱相互作用无机离子的更具挑战性的传感，也没有与土壤传感兼容的检测平台。所提出的传感平台对多种分析物具有通用性。在拟议的工作中，我们将以硝酸盐检测为例来演示其传感能力，因为硝酸盐是土壤中最重要的微量营养素。但与此同时，我们也将应用相同的多肽设计方法来开发对其他分析物(如磷酸盐)敏感的多肽。这一奖项反映了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。

Despite the importance of soil for food production, botany, water cycles, and environmental science, most information about soils remains inadequate. A leading constraint for better understanding of the subterranean environment in more detail is that current tools like collecting and analyzing soil core samples are costly, invasive, and slow. This proposal describes the development of a small, low-cost, high-sensitivity photonics based sensor platform which will be initially targeted to the detection of critical nutrients in the soil such as nitrate. These sensors will be able to operate noninvasively, buried underground with real-time sensing capabilities. Developing low-cost and high-sensitivity underground detection will enable visualization of previously mysterious processes in soil which nonetheless underpin critical aspects of life on Earth.The dynamic physical, chemical, biological changes that soil undergoes are not well understood today and this, in turn has implications for plant science, environmental science and food security. Developing understanding in these areas and building accurate predictive models require fine-grained knowledge of soils (in the vadose zone) in space and time. Present soil sensing capabilities do not meet these needs. In particular there is a lack of adequate sensing technologies that are field deployable, accurate and cheap. This proposal describes the development of a general sensing platform for subterranean analytes based upon micro-fabricated photonic structures which are exquisitely sensitive to changes in the local environmental refractive index with a particular focus on measuring micronutrients important for soil and plant science. These lithographically-fabricated photonic structures are made on silicon/silicon oxide using photo- or electron beam-lithography and therefore compatible with a wide array of surface functionalization chemistries. The use of photo- or electron beam-lithography ensures that the sensor design is both highly-reproducible and imminently scalable. To couple high affinity and specificity to this generalized detection platform, small peptides will be designed to bind inorganic analytes such as nitrate and phosphate with high specificity. Biomimetic sensing of inorganic analytes can achieve both high sensitivity and high specificity by engineering small peptide chains which mimic the binding sites of naturally-observed proteins. Thus far, this strategy has been used in metal sensing and remediation, but it has not been extended to more challenging sensing of weakly-interacting inorganic ions, nor has it been coupled with a detection platform compatible with soil sensing. The proposed sensing platform is general to a wide range of analytes. In the proposed work we will use nitrate detection as an example to demonstrate its sensing capability because nitrate is the most important micronutrient in soil. But in the meantime we will also apply the same peptide designing approach to develop peptides that are sensitive to other analytes such as phosphates.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.