The criteria to select the best sensor were combination of the amount of Pt loading, linearity, sensitivity and magnitude of the current density generation of the sensor. Table 4 indicates that the best sensor is the one with 40% Pt/C—0.30 mg/cm2 anode and 20% Pt/C—0.03 mg/cm2 cathode, since it has the highest linearity response, the lowest Pt loading and high Pt mass-based sensitivity. The amount of Pt used in the commercial sensor is more than 130 times higher than thatin this sensor. In addition,this sensor has 67% less Pt catalyst compared to a PEMFC sensor fabricated and tested by Kim, et al. [38]. The advantages of the commercial sensor over fabricated sensors are its higher current and charge density generation plus probably its stability. The latter is not the scope of this study and it is an ongoing study in our lab. Thus, a more accurate current reading electronic circuit may be required for the low catalyst loading sensor fabricated in lab. Fig. 8 illustrates a preliminary study for durability and repeatability of the best developed sensor. The durability runs were completed after 2 months of the sensor sitting idle in a lab environment. Getting almost similar results from the sensor after 2 months shows thatthe sensor was durable and its Nafion membrane was still active and could preserve its moisture. Rerunning the sensor for 2 extra times indicated that results are repeatable, and the sensor could keep its accuracy for all repeated runs.