Single-mode polymer optical fibre Bragg gratings (POFBGs) are etched to different diameters and their potential for the development of high-sensitivity sensors are presented. The material properties of the fibre can be changed by etching and thus the etching procedure can have an impact on the performance of POFBGs. To confirm that the material properties of etched polymer fibre can be modified and its sensitivity enhanced, sensing characteristics of different etched POFBGs for pressure, strain and temperature are investigated. From the experimental results, we show that the sensors based on etched polymer fibres exhibit a higher sensitivity and they are more desirable than the un-etched ones for biomedical applications. Two examples of low pressure sensor such as blood pressure sensor and foot pressure sensor are demonstrated. With etching, enhanced sensitivity and bio-compatible polymer fibre sensors could be very useful for biomedical applications.