Manipulation of Surface Tension and Wettability for Microfluidic Devices

Friday, February 26, 2010 3:00 – 4:00 pm
Room 610, M&M Building

Dr. Dennis Desheng Meng
Multi-Scale Energy System (MuSES) Laboratory
Department of Mechanical Engineering – Engineering Mechanics
Michigan Technological University

Abstract

Microfluidic technology has inspired significant scientific interest and shown promising applications in health care,energy, and national security. Manipulation of surface tension and wettability is regard as a core technology ofmicrofluidics. The unique interfacial phenomena at microscale both formed a foundation of this emerging researchfield and offered many powerful tools to implement microfluidic devices. This seminar will discuss the followingthree examples:

  • Self-regulated microfluidic management for microfuel cells are achieved by hydrophobic venting andbubble-driven micropumping, which are based on nanoporous membrane and microchannels with designedwetting/nonwetting patterns respectively. An embedded self-pumping mechanism is demonstrated to deliverthe liquid fuel of micro direct methanol fuel cells (μDMFCs) by employing the CO2 gas bubbles generated bythe fuel cell reactions without any power consumption. On-demand gas generators are also developed tosupply hydrogen and oxygen to a micro polymer electrolyte membrane (PEM) fuel cell, which is automaticallyregulated according to the need of the fuel cell current output.
  • Superhydrophilic surfaces are obtained and tested to investigate their antifogging, antifoulingproperties for microfluidic devices. After hydrophilic treatments, both polyester film and ITO glassdemonstrated reduced adhesion with florescent particles. The superhydrophilicity and its degradation areattributed to the surface functional groups.
  • Self-assembly of bubble/droplet arrays is introduced as a promising microfabrication method. Theaffinity of bubbles/droplets to surfaces in liquid environments is quantified by bubble capturing potential “Fbc”.Self-assembly of low melting-point alloy droplets is employed to fabricate self-adaptive thermal switch array forthermal management of micro power sources.The presentation will also give brief introductions on other on-going projects in the speaker’s group (MuSES lab),including high voltage electrophoretic deposition of nanoforests and microfluidic fabrication of self-healingmaterials.

Biography

Dennis Desheng Meng is currently an Assistant Professor at the Department of MechanicalEngineering – Engineering Mechanics of Michigan Tech. He obtained his Ph.D. degree in Mechanical Engineeringfrom the University of California at Los Angeles (UCLA) in 2005 along with the Outstanding Ph.D. Award. After hejoined Michigan Tech in August 2007, Dr. Meng started the Multi-Scale Energy Systems (MuSES) Laboratory towork on micro- and nanotechnology for energy applications. The research of MuSES lab is based upon micro- andnanofabrication, such as novel electrochemical methods, microfluidic fabrication and surface treatment. Particularattentions are given to the design and fabrication of micro power sources, such as micro fuel cells, micro batteries,micro supercapacitors, as well as their thermal management.

Metallurgical Investigation of Medical Device Titanium Alloy Wire Fracture During Forming

Thursday, February 18, 2010 10:00 – 11:00 am
Room 610, M&M Building

Jon Stinson
Boston Scientific
Interventional Cardiology Division
Maple Grove, MN

Abstract

Beta III titanium wires are subjected to a 180 degree bend operation duringmedical device manufacturing. After years of successful processing,Manufacturing started to find cracked or broken wires. An investigation waslaunched to identify the root cause of the failures. Processing and material wereevaluated. This presentation will serve as an example of industrial failure analysisand problem solving, which often has limitations of schedule and funding.

Biography

Jon Stinson is a manager at R&D Materials Analytical Lab, Boston ScientificInterventional Cardiology Division. He received a B.S. degree in Metallurgical Engineering atMTU in 1982 and MBA Management degree at the University of St. Thomas in 1992.  Jon firstworked for 12 years in aerospace and defense (Williams International, Howmet, Honeywell,Alliant Techsystems) as a metallurgical engineer on R&D projects for gas turbine engines andordnance. Then he worked for 14 years in the medical device industry as a metallurgicalengineer and materials lab manager on R&D projects for intraluminal catheter, guidewire, andimplant products.

Capillary Phenomena in Fuel Cells

Friday, February 12, 2010 3:00 – 4:00 pm
Room 610, M&M Building

Dr. Jeffrey S. Allen
Advanced Power Systems Research Center
Department of Mechanical Engineering – Engineering Mechanics
Michigan Technological University

Abstract

Effective water management is critical to deployment of durable, low-temperature fuel cells forautomotive applications. The inability to manage the product water directly affect the durability ofa fuel cell stack; currently limiting the stack lifetime well below commercialization targets.  Itturns out that capillary phenomena is largely responsible for the ineffective water managment.Most engineering efforts directed at fuel cell water management attempt to over powercapillarity.  Much of our research is directed towards utilizing the natural presence of capillarityin order to more effectively manage the product water in low-temperature fuel cells.  Theresearch is a combination of experimental and numerical methods. Recent research results oncharacterizing water transport in the Porous Transport Layer (PTL), also known as the gasdiffusion layer (GDL), and predicting that transport will be discussed.  In addition, recent findingson capillary phenomena which dictates water motion in the reactant flow channels will be presented.

Biography

Dr. Jeffrey Allen is an Associate Professor in the Department of MechanicalEngineering – Engineering Mechanics at Michigan Technological University.  He graduated fromthe University of Dayton in Mechanical and Aerospace Engineering (BME 1988, MSME 1990,Ph.D. 1998).  From 1992 to 2004, Dr. Allen conducted experimental research at the NASAGlenn Research Center in the areas of capillary flow and interfacial transport phenomena asboth a principle investigator and as a project scientist for experiments conducted on the MirSpace Station and the NASA Space Shuttles.  In 2004, he joined Michigan Tech where he hasestablished the Microfluidic & Interfacial Transport Laboratories and is the Associate Director ofthe Advanced Power Systems Research Center.  Current research activities include the study oftwo-phase flow in anisotropic porous layers and microchannels directed towards watermanagement in PEM fuel cells, capillary-driven flows, stability of evaporating/condensing liquidfilms, fluidic flow control, microfluidics and microfluidic measurement techniques.