Significantly Enhanced Microchannel and/or Microfluidic Fuel Cell Performance (Case 1870)

Principal Investigator:

 

Tayhas Palmore, PhD, Professor

School of Engineering

Brown University

Providence, RI

 

Brief Description:

 

Laminar flow of fluids within microchannels has been studied for use in microfluidic fuel cells, which consist of an anode and cathode configured as a galvanic cell with a microchannel.  Parallel streams of fuel and oxidant flow across the anode and cathode, respectively, where the electrochemical reactions occur when the potential difference between fuel and oxidant is thermodynamically favorable.  In general, microchannel reactors comprised of substantial constant cross-sectional areas exhibit flows or fluid streams with the concentration of reactant decreasing in the direction of the flow as the reaction progresses, which may lead to a decrease in the reaction rate along the length of the channel - undesirable in some instances.  Indeed, in many conventional reactive microfluidic channels, e.g., fuel cells, a decline in current and power density results due to the this inefficient system. 

 

Rapid changes in the concentration of oxidized/reduced species occur during an electrochemical reaction in a thin [diffusion] layer of liquid near the electrode (anode/cathode) surface.  Under certain conditions of convective flow, this thin diffusion layer is confined near the electrode surface, and as the electrochemical reaction proceeds, electroactive species are depleted cumulatively.  As such, the leading edge of the electrode experiences a higher concentration of electroactive species relative to the trailing edge, because the thickness of the diffusion layer is increasing along the length of the electrode.  As the thickness of the diffusion layer increases, the average mass flux toward the electrode decreases along with the corresponding current and power density.  Therefore, improved compositions and methods are needed to create optimal microchannel formats for higher performing microfluidic fuel cells and any other miniaturized [bio] chemical reactive/analytical device based on microchannels/fluidics.

 

Most simply, this invention delivers a reactant(s) to a reactive surface in a microchannel that has optimized geometry for improved performance - providing both intrinsic and extrinsic advantages over current state-of-the-art.  The invention is a novel fabrication method to improve the geometric arrangement for channels, in which liquids/fluids can be made to flow, for enhanced fuel cell performance or a variety of other chemical/biochemical reactors/analyzers/devices.  In this way, relatively more reactant(s) in a flowing liquid, conforming to a predetermined distribution, may be supplied to the channel wall at various positions relative to the amount that would be supplied in a system without an optimized geometry.  The microchannels may be formed from a variety of materials – silicon, elastomeric or other polymer, etc. –, and methods such as via micromachining, film deposition (spin coating, CVD), laser, photolithography, and etching, and the like.  Moreover, an optimal design that takes into account microchannel height, also important in overall performance, pumping power, pressure, and reactant concentrations, in a microfluidic fuel cell, can be predicted prior to device fabrication, as a part of this invention.

 

This invention may be used with a variety of chemical or biological reactions, and in any system in which it is desirable to control the amount of a reactant supplied to a reactive surface portion.   Applicable scenarios include for use in microfluidic or methanol fuel cells to control the reaction rate at one or more electrodes.  Also, this invention may be used in select biological microreactors, for example, in the control of the amount of a biological molecule (e.g. protein, DNA, carbohydrates) supplied to a wall/support membrane/substrate on which a binding partner/ligand is immobilized in detection and diagnostic methods/devices for use in medicine, environmental testing, and scientific experiments.  Biological reaction types may include: antibody/antigen, enzyme/substrate, receptor/hormone, repressor/inducer, or complementary strands of nucleic acid, among a plethora of other affinity or binding reactions.

Several markets are indicated: pharmaceutical R&D – therapeutic and diagnostic/testing; energy – alternative; environmental testing devices – water, air, soil; and scientific R&D to advance the fields of MEMS (microfluidics/microchannels/microelectronics), medicine, biology, engineering and sensors, and many other research endeavors.

 

Information:

 

US Patent 9,112,192 is issued (08/18/2015)

Patent Information:
For Information, Contact:
Margaret Shabashevich,
Manager of Operations
Technology Ventures Office
Brown University
401-863-7499 TVO_Patents@brown.edu
Inventors:
Tayhas Palmore
Keywords:
© 2017. All Rights Reserved. Powered by Inteum