Miniaturization of Mediatorless Microbial Fuel Cells for High-Throughput Studies of Bacteria-Electrode Interactions

该奖项支持明尼苏达大学微型微生物燃料电池的开发。这些燃料电池将使用最近发现的厌氧细菌，如Geobacter，它可以直接将电子传输到电极表面。目标是开发电子设备，利用这些细菌作为催化剂和传感器。将展示一种新的方法，使用硅基微加工技术和直接印刷在膜上的电极。计划中的活动将制造和测试一系列设计，旨在适应多井板格式，适用于其他高通量平台。另一个目标是制造微型流动反应器，该反应器将创造一种机制，使电极表面上的非常小的细菌群体暴露于恒定层流的条件下，以进行连续传感。这些设备将使仪器尺寸比典型系统缩小两个数量级，并将为研究人员提供工具，以进行与细胞外电子传递、细菌将有机化合物转化为电信号以及与腐蚀和金属还原有关的过程相关的敏感、平行观察。这些被提议的仪器将在一种装置中测量细菌产生的电力，这种装置被设计成利用膜基电极，类似于那些最先进的化学燃料电池。他们还将提供一种微加工界面，允许利用发电生物将有机化合物直接转化为电信号。任何将化学物质转化为电信号的装置的核心都是催化剂。例子包括燃料电池，它将氢或液体甲醇燃料直接转化为电能，或者使用催化剂将酒精转化为电能以进行传感的“呼吸测试仪”。通常，铂等贵金属被用作催化剂，它们将简单的气体或化学物质转化为电能。最近发现，地下含水层和其他缺氧栖息地中的一些细菌通过将电子转移到沉积物中的铁矿物中来产生能量。这个“铁还原”过程本质上包括将沉积物中的有机化合物转化为电信号。当这些铁还原细菌在电极上生长时，各种各样的糖、脂肪酸和芳香族化合物都可以转化为电，这表明有多种可能的发电或传感装置。由于缺乏研究这一独特过程的设备，对这一现象的研究受到了阻碍，我们建议使用微加工和膜打印技术来构建由硅和导电材料制成的小型微生物“燃料电池”。通过将我们对这一过程的微生物学的新理解与电气工程和材料科学的进步相结合，我们将开发出能够同时研究多种培养和条件的仪器，并为研究这些细菌在微型传感器和其他设备中的催化剂提供第一个工具。

This award supports the development of miniaturized microbial fuel cells at the University of Minnesota. These fuel cells will use recently discovered anaerobic bacteria such as Geobacter that can directly transmit electrons to electrode surfaces. The goal is to develop electrical devices that can utilize these bacteria as catalysts and sensors. A new approach will be demonstrated using silicon-based microfabrication techniques and electrodes directly printed on membranes. The planned activity will fabricate and test a series of designs intended to fit in a multiwell plate format, adaptable to other high-throughput platforms. An additional goal is to fabricate microscale flow-through reactors that will create a mechanism for exposing very small populations of bacteria on electrode surfaces to conditions of constant laminar flow for continuous sensing. These devices will reduce instrument size by two orders of magnitude over typical systems, and they will provide researchers with tools to make sensitive, parallel observations related to extracellular electron transport, conversion of organic compounds into electrical signals by bacteria, and processes related to corrosion and metal reduction. These proposed instruments will measure electricity production by bacteria in a device designed to utilize membrane-based electrodes similar to those optimized for state-of-the-art chemical fuel cells. They will also provide a microfabricated interface allowing direct conversion of an organic compound into an electrical signal using electricity producing organisms. The heart of any device converting a chemical into an electrical signal is the catalyst. Examples include fuel cells, which convert hydrogen or liquid methanol fuels directly into electricity, or 'breathalyzers' which use catalysts to convert alcohol into electricity for sensing. Typically, precious metals such as platinum are used as catalysts, and they convert simple gasses or chemicals into electricity. It has recently been discovered that some bacteria in underground aquifers and other oxygen-poor habitats produce energy by transferring electrons to iron minerals present in the sediment. This process of 'iron reduction' essentially involves conversion of organic chemical compounds in the sediment into electrical signals. When these iron-reducing bacteria are grown on electrodes, a full range of sugars, fatty acids, and aromatic compounds can be converted into electricity, suggesting a variety of possible electrical power-generating or sensing devices. Research into this phenomenon is hampered by a lack of devices for studying this unique process, and we propose to use microfabrication and membrane printing techniques to build small microbial "fuel cells" from silicon and conductive materials. By combining our new understanding of the microbiology of this process with advances in electrical engineering and materials science, we will develop instruments to allow simultaneous study of multiple cultures and conditions, and make available the first tools for study of these bacteria as catalysts in miniaturized sensors and other devices.