Fuel cell microfluidic

Figure 23 Air-breathing microfluidic fuel cells showing the colaminar flow principle, in combination with oxygen capture via gas diffusion through a porous cathode A three-phase interface is established between gas, electrolyte, and catalyst/solid electrode (reprinted with permission from Jayashree et al., 2005. Copyright 2005 American Chemical Society).

Choban, E.R. Markoski, L.J. Wieckowski, A. Kenis, P.J.A. Microfluidic fuel cell based on laminar flow. J. Power Sources 2004, 128, 54-60. 

Q.29.9 You are asked to experimentally evaluate a new multi-stage microfluidic fuel cell in which a crude solution of cane sugar (sucrose) is first hydrolyzed by and acidic stage and then glucose and fructose diffuse into a second stage where electrochemical oxidation produces power. Propose a microscopic method to measure the rate of sucrose hydrolysis in the first stage. 

Finally, it is worth mentioning the microfluidic fuel cells concept [103] introduced by Whitesides in 2002 [104], based in a membraneless fuel cell design which exploit the laminar flowl that occurs in liquids flowing at low Reynolds number to eliminate convective mixing of fuels. Using this concept on-chip, membraneless, air-breathing monolithic pDAFC has been constmcted by Osaka and coworkers [105, 106] which operate with methanol, ethanol and 2-propanol solution containing sulphuric acid or phosphate buffer. The cell consists of two cathodes at the top of the channel, and the hquid fuel is supphed by capillary force to the anode formed on the bottom of the channel, as indicated in Fig. 1.12a, b. 

Kjeang E, Djilali N, Sinton D (2009) Chapter 3 Advances in microfluidic fuel cells. In Zhao TS (ed) Micro fuel cells. Academic, Burlington, pp 99-139... 

Electrokinetic Liquid Flow in Nanochanneis, Fig. 7 Optical image of the microfluidic fuel cell device proposed by Wadsworth et al. (Reprint with permission frinn [13])... 

Miniaturized fuel cells are an attractive candidate for next-generation portable power sources. A microfluidic fuel cell is defined as a fuel cell with smaU-scale channels, typically submiUimeter in height, in which reactant delivery/removal and electrochemical energy conversion take place. This type of fuel cell can be incorporated with both metalhc and biological catalysts and normally operates without a physical barrier between anode and cathode compartments. Micromachined fuel cells employing ion-conducting membranes are not covered in this entry. 

Microfluidic Fuel Cells, Fig. 1 Basic fuel cell design showing its core components anode and cathode separated by an electrolyte and connected to an external load... 

The present entry describes how microfluidics and fuel cell technologies can be paired to develop alternative, inexpensive microfluidic fuel cell devices employing both metallic and biological catalysts and how practical fuel cell operation can be achieved without ion-conducting membranes. 

Microfluidic fuel cells avoid several common issues encountered in PEM fuel cells, including membrane degradation and durability, water... 

Since its first advent in 2002, the field of microfluidic fuel cells has stimulated many researchers, generating more than 100 scientific publications. Proof-of-concept microfluidic fuel cell devices have been demonstrated with various fuels such as hydrogen, methanol, formic acid. 

Microfluidic Fuel Cells, Fig. 3 Microfluidic fuel cell designs with oxygen-saturated catholyte (a) and air-breathing cathode (b) (Reproduced with permission from Jayashree et al. [5])... 

Microfluidic Fuel Cells, Fig. 5 Chip -embedded thin-film current collector designed to reduce contact resistance (Reproduced with permission from Lee et al. [7], Copyright Elsevier (2012))... 

Lee et al. investigated the overall ohmic resistance of the microfluidic fuel cell with flowthrough porous electrodes [6] and proposed to... 

A wide range of microfluidic fuel cell devices capable of operation without membranes or other physical half-cell separators have been... 

In contrast to the established mass transport limitation of dissolved oxygen-based cells, the performance of recent microfluidic fuel cell technology was typically restricted by a combination of mass transport, electrochemical kinetics, and ohmic resistance. These three limiting factors and possible mitigating actions are discussed below. 

Jayashree RS, Gancs L, Choban ER, Primak A, Natarajan D, Markoski LJ, Kenis PJA (2005) Air-breathing laminar flow-based microfluidic fuel cell. J Am Chem Soc 127 16758-16759... 

Lee JW, Kjeang E (2012) Chip-embedded thin film current collector for microfluidic fuel cells. Int J Hydrogen Energy 37 9359-9367... 

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