Structure Design And Performance Optimization Of Microfluidic Microbial Fuel Cell Devices

Microfluidic microbial fuel cell?MMFC?is a new energy technology which uses microorganism as catalyst,converts organic matter directly into electric energy and combines microfluidic technology.It has become one of the research hotspots of microfluidic energy technology for the characteristics of less consumption,fast reaction and small volume.In the reported MMFC,some factors affect the improvement of the electrical performance of devices.For example,some devices have large internal resistance due to the use of proton exchange membrane.The Y-type,and T-type devices have relative low bacterial load due to the small contact area between the channel and electrode.In view of problems above,this paper started from the device channel design and innovative substrate material application,carried out the following research and obtained the corresponding research results.?1?In order to increase the contact area between the electrode and the channel,S-MMFC is designed to increase the growth space of the electro-active bio membrane,and the design optimized through configuration,electrode position,flow rate and bio membrane.When the ratio of anode and cathode channels is 1:1,the shearing force is appropriate and the electrode is completely covered on the channel,the maximum current density of S-MMFC achieves 350 mA m^-22 with a flow rate of 5 mL/h by using putrefaciens CN32 strain as a biocatalyst.?2?The membrane-free S-MMFC was designed to replace the proton exchange membrane by using diffusion-mixing region.The channel structure of membrane-free S-MMFC was optimized and four different kinds of configurations of S-MMFC were obtained:?a?The right-angle S-type cathode and anode channels with 5 mm short side and 10mm long side are connected with T-shape mixing zone;?b?changing the mixing zone of?a?from T-type to Y-type;?c?doubling the length of cathode and anode channels of?a?.?d?The length of the short side of the S channel is shortened to 3 mm.By comparing the current density,power density,impedance,biofilm and other characteristics of the four groups,it is found that S-MMFC of?d?type has the minimum internal resistance.The maximum power density of device?d?is 46 mW m^-2,which is superior to Y-MMFC.?3?A membrane-free cotton thread-based microfluidic microbial fuel cell was designed by means braided winding.Two cotton wires were used as electrolyte channel of cathode and anode respectively.Ion exchange is achieved by winding cathodic cotton thread with anodic one.The siphon capacity of cotton thread is changed by different hydrophilic treatment,so as to regulate the liquid flow rate.Though a series of optimizations,the prepared cotton wire-based MMFC can reach the maximum power density of 268 mW m^-22 with a lift time up to 20 hours.This research provides a way to solve the problem of traditional MMFC which need external pump energy,and makes MMFC have the prospect of developing into wearable device.