Experimental investigation of a strain gauge sensor based on Fiber Bragg Grating for diameter measurement

•Use of a taper as an elastic element to increase the sensor dynamic range.•The strain sensitivity is a function of the taper diameter and total length of the sensor.•Diameter variation monitoring by use of optical strain gauge based on an FBG only or an FBG with fused a taper.•Possibility of diameter monitoring of trees.•Strain-sensitive sensor to monitor displacement.