This study presents the effects of different carbon sources on the electricity generation ability of microorganisms investigated by the membraneless μMFC developed in our previous report [1] (Fig.1).Although lab-scale MFCs are able to identify the microbial for electricity generation,they require several days for the detection [2].The membranelessμ MFC can accomplish the analysis in as short as 30 min.In this study,several carbon sources such as sodium acetate,glucose and sucrose were applied to investigate their effects on the electricity generation ability of mixed-culture microorganisms.The membranelessμMFC includes the a Y-shaped channel and two flat gold microelectrodes on the glass slide.The flow channel was made by PDMS via soft lithography and the flat gold electrode was fabricated by E-beam evaporation and wet etching.The PDMS sheet and the slide were bonded by O2 plasma treatments.Alive/active cells generate electrons during metabolic process but inactivated cells are not able to carry out the above reactions.Therefore,the difference between active and inactivated samples can be applied to verify the amount of electrons generated by metabolism.Sucrose as a carbon source generated the highest open circuit voltage,which was about 190 mV (Fig.2).Acetate and glucose as carbon sources generated about 50 and 60 mV,respectively.Therefore,sucrose is a more suitable carbon source for the current mixed-culture microorganisms to produce electricity.Using similar principles,this membranelessμMFC can be applied to screening suitable carbon sources for specific microorganism strain or screening cultivation parameters for improving the performance of lab-scale or commercial-scale MFCs.