Multifunctional Micro-Scale Sensors for Water Safety Monitoring with Only Bare Platinum Electrodes

water monitoring;MEMS;sensor;Chemical Engineering;Engineering;Chemical Engineering

Lin, Wen-ChiThompson, Levi Theodore ;

University of Michigan

关键词: water monitoring;    MEMS;    sensor;    Chemical Engineering;    Engineering;    Chemical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/138497/wclin_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

End-point monitoring at home is crucial to secure water safety because water can be contaminated in the drinking water distribution system (DWDS), like the Flint water crisis in 2014. The contamination can come from overgrown algae, pipe corrosion, or even pipe leakage from construction vibration. Though end-point monitoring is crucial, it is still not practical for most users to have home water monitoring device. Water safety analysis involves a number of variables, and a single variable can not represent the quality of water. Thus water monitoring typically performed using multiple sensors, which cost $100 each and the total cost is around thousands. The total size, cost, and the maintenance difficulties of the water sensors are still barriers for most families to secure water safety.This dissertation develops an integrated practical micro-scale sensor for water monitoring. The sensor can measure seven important variables: flow-rate, temperature, ionic conductivity, pH, oxidation-reduction-potential (ORP), lead ions, and other heavy metal ions. The flow-rate, temperature and ionic conductivity sensors are optimized from previous technology. These sensors are simplified for low fabrication cost and easy integration. The flow rate and temperature sensors are capable of measuring 0.5-2.0 GPM in 10-50 ºC. The conductivity sensor can measure 0-8000 µS/cm in 10-50 ºC water. The pH, ORP, lead, and other heavy metal ions sensors are developed with original methods. These sensors require no reference electrodes, sample pre-treatment, surface labeling through chemical reactions, or membrane coating. The sensors measure the targeted ions by controlling the surface reactions on simple platinum electrodes. The pH and ORP sensor can measure pH 4 to 10 and ORP 200 to 800 mV simultaneously with only bare platinum electrodes. The four-electrode heavy metal sensor can distinguish lead from other heavy metals. The sensor is capable of being embedded in the DWDS and detecting Pb at action level (15 ppb). All of the seven sensors presented in this dissertation are composed of only a single layer PVD Ti/Pt. Due to the simple structure and fabrication, the sensors can be easily integrated, and the entire device costs only about 10 cents. This dissertation demonstrates a method to achieve end-point water monitoring at home. The simple structure of these sensors make them promising for long-term applications under strong hydraulic force. The lead and other heavy metal sensors are also operated two months to validate the possibility of long-term monitoring. Though these sensors are not optimized for energy consumption and response time yet, this dissertation presents promising, unique, and practical sensors designed for residential water monitoring.