Indiana University-Purdue University Indianapolis

IUPUI School of Engineering and Technology

Microfluidic gas generator

project 1

Efficient management and utilization of multiphase flow in microreactors have a broad range of applications in process and reaction engineering. The main objective of this project is to understand the process control and dynamics of an integrated microfluidic gas generator/separator and access its potential applications in portable fuel cells. The mechanism is based on a recently demonstrated self-circulated and self-regulated reactive multiphase flow in a microfluidic network with neither electrical power input nor control circuit. The knowledge gained in the proposed research is expected to facilitate the development and commercialization of highly-efficient and autonomous gas generation systems for a variety of applications in renewable energy and bio-engineering, when gaseous species are generated from or injected into liquid reactants. For instance, the successful implementation of this research would directly facilitate the development of high-energy-density power generation devices based on fuel cells, where hydrogen storage and delivery remain major technical challenges. The proposed approach can help to overcome this problem by achieving autonomously pumping and control for on-demand hydrogen generation with little burden on system complexity and packaging. The advancement in this direction is expected to benefit a series of portable applications, such as portable electronics, implanted biomedical devices, and distributed microsystems with wireless communication capability.

a

The self-circulation mechanism is based on a micro-pumping mechanism of liquid by directional growth and selective venting of gas bubbles. Gas generation is regulated by virtue of the reactant solution being allowed into or forced out of the catalyst channel. The prototype devices have been fabricated from a 375-µm-thick, double-side-polished, 4-inch silicon wafer using MEMS fabrication processes. The figure on the top-left corner shows the (a) optical and (b, c) SEM images of the fabricated silicon chip with V-shaped virtual check valves, reaction channels, venting windows, and Pt black catalyst (c). The animation shows the hydrogen generation and self-circulation processes in a self-circulating and self-regulating microfluidic device.