A Microscale Power Generator Driven by Tethered Bacterial Flagellar Motors

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The advancement of micro- and nanotechnology has enabled the rapid development of compact electronic devices for a wide range of commercial and military applications. However, even though almost every component in an electronic device such as a cell phone or laptop is getting smaller, the batteries used to power them are still relatively large with a low power density. Several alternative power generators including the direct methanol fuel cells, the micro internal combustion engines, and the biological solar cells are currently being developed in an attempt to overcome the constraints of the battery technology. While achieving different degrees of success, all three designs still require significant improvement in a number of technical areas in order to outperform the existing batteries. The present project will develop a new microscale power generator that is designed to meet the demand of both power density and system size. It is also environmentally friendly with no harmful byproducts. Essentially, the proposed power generator is a microscale dynamo except it is driven by rotating biological cells instead of rotating magnets. The project will utilize novel biological and engineering techniques to create a hybrid system that converts the rotational power of the highly efficient molecular motors in the biological cells into electrical power. Due to the forward-looking nature of the proposed works, the project is expected to generate a wealth of new knowledges that will impact the design of future electronic devices and also significantly enhance our fundamental understanding of the molecular motors. The project will provide significant educational opportunities for students at both the undergraduate and graduate levels through cross-training in multidisciplinary areas including microbiology and nanotechnology. Such experience will provide them with a solid foundation to face the future job market that increasingly requires multidisciplinary skills.The proposed biological dynamo will integrate bacterial flagellar motors with ferromagnetic beads and micro/nano coils in a microfluidic system. Flagellar motor is a nanoscale molecular motor capable of a large rotary torque and highpower output. When the motor is tethered to a substrate through a shortened flagellar filament, it turns the bacterial cell body at a stable rotational rate of 10 Hz, providing a natural source of rotational power. Manipulation and tethering of the flagellar motors in the microfluidic system will be accomplished by optically induced dielectrophoresis (ODEP). The proposed project will fabricate a microscale hybrid system that combines an ODEP chip with the flagellar motors of a non-pathogenic, genetically engineered strain of Escherichia coli. Based on the result of a preliminary numerical simulation, the power density of the flagellar motor dynamo is similar to that of other biological based microscale power generators. Fabrication of the flagellar motor dynamo will be based on the core flagellar motor assembly technologies developed by the PIs' research groups over the last decade. Specific objectives of the project include the development of an effective cell tethering protocol, the development of an effective bead attachment strategy, the design and fabrication of an ODEP chip, the application of the ODEP chip to capture and enable local tethering of free swimming cells, and finally a thorough performance testing of the flagellar motor dynamo.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.