We have proposed an inexpensive and sensitive DNA sensor to detect biomarkers related to personalized medicine with a low cost.All of the steps can be automatically finished in a single tube without the opening of the tube,so the risk of crosscontamination due to amplicons is much low.The detection process includes three steps.At first,PCR amplification of the target sequence was carried out to produce amplicons; and then Afu flap endonuclease-induced invader reaction was performed on the amplicons with two target-specific probes.Finally the flaps yielded from the invader reaction trigger the sensor,which is made from a hairpin-probe and two kinds of gold nanoparticle probes,to develop a red color by cutting the hairpin-probe.A positive result is expressed as a red color of the tube.While if no target exists in the tube,flaps would not be produced,and the sensor would not be triggered.All gold nanoparticle probes would be captured by hairpin-probes to form an aggregation.The keys of the method include the temperature control at each step,and the modification of gold nanoparticles to avoid a high temperature and enzyme absorption.As the tube is closed during the test,the risk of cross-contamination is greatly reduced.By this “TubeLab”-based DNA biosensor,we have successfully detected biomarkers of both SNPs and somatic mutations with a sensitivity of 150 copies and a specificity of 0.1% of mutants in a large amount of backgrounds.Successful detection of real biological samples indicates that the proposed method could be a convenient and inexpensive tool for personalized medicine in hospitals.