As one of the most important tumor-associated antigens of colorectal adenocarcinoma,the carcinoembryonic antigen (CEA) threatens human health seriously all over the globe.Fast electrical and highly sensitive detection of the CEA with AlGaN/GaN high electron mobility transistor is demonstrated experimentally.To achieve a low detection limit,the Au-gated sensing area of the sensor is functionalized with a CEA aptamer instead of the corresponding antibody.The proposed aptasensor has successfully detected different concentrations (ranging from 50 picogram/milliliter (pg/ml) to 50nanogram/milliliter (ng/ml)) of CEA and achieved a detection limit as low as 50pg/ml at Vds =0.5 V.The drain-source current shows a clear increase of 11.5 μA under this bias.