Calorimetric Sensor for ${\rm H}_{2}{\rm O}_{2}/{\rm H}_{2}{\rm O}$ Mist Streams

Mist streams comprised of H₂O₂/H₂O droplets are a recent innovation for disinfecting medical equipment, but the availability of a sensor that could monitor the concentration of H₂O₂ applied during the treatment would be desirable. Here we describe a means to obtain a rapid estimation of H₂O₂ concentration in this environment. The proposed sensor is based on a platinum resistance thermometer coated with a layer of MnO₂ catalyst. It may be calibrated to operate either during the mist delivery step of a disinfection cycle, or during the evacuation (drying) phase. Cooling of the sensor surface due to evaporation of H₂O and effervescence of decomposing H₂O₂ operates against heat generated by the decomposition reaction to produce a well-defined minimum in the temperature. The time and temperature at which this minimum occurs are well correlated, with the H₂O₂ content of the solution used to produce the mist droplets.