Carbon Monoxide Sensing for a Low-Cost Mobile Health Device

We explore the use of electrochemical sensors toward the creation of a personal carbon monoxide monitoring device. Our ultimate goal is the development of an inexpensive, highly integrated mobile health (mHealth) device for improving the outcomes, and decreasing the treatment costs, for smoking cessation therapy among low socioeconomic status (SES) patients. We will combine a number of proven modalities into a single device, which we call the T-COM. This hand-held personal device will integrate a breath carbon monoxide sensor, multilingual motivational text and audio messaging, gamification features and built-in wireless network connectivity. The requirements relating to measuring the concentration of CO in exhaled breath are especially challenging. They include the following – low cost, minimal thickness, robust to a range of ambient temperatures and humidity, as well as being minimally affected by the high humidity in breath. Concentrations as low as a few ppm of CO must be measurable, with an accuracy of a few ppm. The device must not require field calibration. The sensor must be ready for use at virtually any time with no warm-up period, and must register an accurate measurement in under ten seconds. The required support circuitry must be available with similar constraints on cost, size and accuracy. We experimented with several commercially available CO sensors and circuit topologies, and we report on our findings. In addition we have looked into methods for controlling the level of humidity that reaches the sensor, without otherwise affecting the measurement accuracy. Our results to date suggest that a practical solution is achievable, although further improvements would be valuable. Figure 1