We present a fabrication technique to achieve label-free detection of DNA hybridization in microfluidic channel.The label-free detection is based on the electrochemical response of DNA hybridization events on ssDNA doped polypyrrole(PPy)-modified microelectrodes within microfluidic channels.Firstly,the metal microdot(s) as the microelectrodes naked on the inner wall of a microchannle could be made by molding crossed microwires in PDMS via withdrawing and remaining; then a film of PPy and ss-DNA probes is simultaneously electrochemical synthesized on the dot(s) within the microchannle.The label-free detection in thus-formed prototype microchannel device is demonstrated by carrying out hybridization experiments.The described fabrication route enables a fully electronic readout of DNA hybridization events being closely integrated with microfluidic manipulation,rather conveniently and cost-effective.