A new intrinsic optic fiber evanescent wave sensor is developed.The sensor is fabricated with the 60/125 μm step-index multimode optical fiber wrapped around a scaffold.The scaffold is integrated using plexiglass and large circular arc PVC pipe

the fiber is peeled off a section of length cladding at a certain distance

and a section of fiber by peeled cladding is located among two large circular arc PVC pipe.A new high sensitivity intrinsic optical fiber evanescent wave sensor with the bare core length more than 0.5m can be obtained by application of chemical corrosion method.The experimental results show that the lowest concentration of the methylene blue solution can be detected up to the order of 10-8mol/L

the sensitivity is up to 2.66L/μmol

the sensor has the advantages of high sensitivity

simple structure

easy fabricated

low cost

and it is suitable for the detection of trace amounts of substances in solution or gas.