Optical fiber device for non-destructive detection of water concentration in ethanol

• Optical fiber device for non-destructive detection of water concentration in ethanol • The low-cost device is made of an LED, a USB power meter, and a fiber reflection probe • Water in ethanol is monitored by the reflected light at 1300nm • Contactless detection of water in ethanol in the range 0% to 100% (v/v) rapidly • The device use is repeatable with a measurement accuracy of 1% (v/v) The widespread use of ethanol in various industries requires low-cost, handheld devices to identify the purity standard of ethanol rapidly, especially its water concentration, in a non-destructive way. A portable and low-cost optical device is demonstrated in this paper to detect different concentrations of water in ethanol. The results of the near-infrared (NIR) spectral study of the ethanol-water samples show a significant change in reflectivity at around 1300 nm wavelength. Therefore, the demonstrated device consists of a 1300 nm light emitting diode (LED), a USB optical power meter, and a fiber reflection probe. The performance of the device is tested by preparing samples of different volume percentages of water in ethanol. The sensitivity of the device is found to be 0.0021 µw per 1% (v/v) water in ethanol. The device can resolve a change of 1% (v/v) water in ethanol accurately by monitoring the reflected light at 1300nm from the samples. It detects water concentration ranging from 0% to 100% (v/v) non-destructively, and the measurement speed of the demonstrated device is 4 ms. The repeatability of the measurements and long-term stability of the sensor device are verified through repeated and reversed tests. The cost of the device is 3.5k USD, and it can be used for continuous and remote measurements without destroying the sample or the fiber device. The advantages of the demonstrated device, such as low cost, eco-friendliness, good sensitivity, repeatability, wide concentration range of operation, non-destructive testing, and rapid measurement, make it suitable for commercialization.