Nondispersive Infrared Ethylene Oxide Sensor With Temperature Compensation for Medical Sterilization

Abstract

Ethylene oxide (ETO) gas is extensively used in medical sterilization, but it poses environmental and health risks if not properly managed. Therefore, it is crucial to monitor the concentration of ETO in the medical sterilization cabinet in real time. Herein, a dual-channel nondispersive infrared (NDIR) ETO sensor based on a direct optical path with explosion-proof performance was designed. Given ETO’s flammability, the sensor was employed an aluminum alloy explosion-proof structure to ensure safety. The effective optical path of the gas chamber was 1 cm, and the effective utilization of luminous flux was 86%. The sensor has an average relative error of 2% in measuring ETO concentration (0–927 mg/L) in the temperature range of 25 °C–65 °C, which was 3% lower than the industry standard. The response time (T90) was <10 s. To address temperature sensitivity, a chaotic particle swarm optimization back propagation network (CPSO_BPNN) algorithm was proposed for temperature compensation, resulting in improving the measurement accuracy (2%–3%) compared with the traditional linear temperature compensation. In addition, the sensor demonstrated good repeatability with the relative standard deviation (RSD) of less than 2.2% and good stability over a two-month testing period with the standard deviation (SD) of less than 3.4%. All these results demonstrate that the fabricated sensor has excellent stability and repeatability, meeting the required standards.