Sensors for flammable gas detection are essential in occupational health and safety to prevent fire or explosion in gas facilities and underground mining. Three things are needed to support a fire or explosion: a source of fuel (e.g. flammable gas or vapor), air (oxygen) and a source of ignition (e.g. spark, open flame, or high temperature surface). As a result, a sensor for flammable gas detection requires it functioning over a broad temperature range. Room-temperature Ionic Liquids (ILs) represent potential new materials for use in the detection of flammable gases. They have negligible vapor pressure at ambient pressure and possess high thermal stability in air. The nonvolatile nature of ionic liquids and their remarkable thermal stability make them well suited for use as coatings for the detection of flammable gases since they reduce hazards, associated with flash points and flammability. Ionic liquids are also particularly promising because they have the potential to be incredibly stable whereas many polymer or organic coating materials eventually deteriorate leading to their loss of activity. The synthetic flexibility of ILs allows them to be tailored with broad chemical diversity. One ion can be used to provide one function and the second ion can provide a different, completely independent function. Additionally, many ILs are proven to be excellent non-aqueous electrolytes due to their large intrinsic conductivity and wide electrochemical potential windows. Literature study shows that gases (i.e.CH4, C2H4, C2H6, CO2, O2) have widely varying gas solubility in ILs. Electrochemical oxidation of NH3 and SO2 and electrochemical reduction of O2 and CO2 in ILs have been reported. Therefore, we propose to integrate ILs unique solvation and electrochemical properties with real-time, portable, low cost characters of orthogonal Electrochemical and Quartz Crystal Microbalance (QCM) transducers to develop an integrated flammable gas detector widely applicable as a standalone/hand-held gas detector at gas facilities or underground mining. Based substantially on prior achievements, this proposal outlines a research plan to understand, design and control molecular character of ionic liquids on electrode surfaces for their applications in detection of flammable gases. Methane will be the initial target analyte. Several innovations would be realized through the following project Aims. First, develop, characterize and optimize ionic liquid chemical interface immobilization in order to form robust, thin rigid films;Second, evaluate and validate the IL QCM sensor array for methane detection;Third, develop IL electrochemical sensors for methane detection and finally refine the electrochemical IL sensors as well as the QCM IL sensor array to Increase stability, heighten sensitivity and selectivity for real world applications. Our entire research plan is an integrated effort which if successful will have substantial scientific and practical impact in sensor technology for occupational safety and health that could enable personnel in gas facilities and mines to prevent explosions or fires, save lives, avoid injuries, and protect billions of dollars worth of assets. Gas sensors are of increasing interest due to their potential applications in ambient air monitoring, occupational health and safety, biomedical diagnostics, industrial process control, and military and civilian counter-terrorism. The tragedies of human loss in mine explosions in recent years reinforce the importance of recognizing the potential hazards in underground coal mining, and the need for systematic safety and health vigilance. In this proposal, we aim to develop new technology that explore ionic liquids'application as sensing materials and non-aqueous electrolytes for detection of flammable gases at workplace to prevent explosions or fires, save lives, avoid injuries, and protect billions of dollars worth of assets.

National Institute of Health (NIH)
National Institute for Occupational Safety and Health (NIOSH)
Exploratory/Developmental Grants (R21)
Project #
Application #
Study Section
Safety and Occupational Health Study Section (SOH)
Program Officer
Frederick, Linda J
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Oakland University
Schools of Arts and Sciences
United States
Zip Code
Wang, Zhe; Guo, Min; Mu, Xiaoyi et al. (2016) Highly Sensitive Capacitive Gas Sensing at Ionic Liquid-Electrode Interfaces. Anal Chem 88:1959-64
Rehman, Abdul; Zeng, Xiangqun (2015) Methods and approaches of utilizing ionic liquids as gas sensing materials. RSC Adv 5:58371-58392
Wang, Zhe; Guo, Min; Baker, Gary A et al. (2014) Methane-oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification. Analyst 139:5140-7
Rehman, Abdul; Zeng, Xiangqun (2012) Ionic liquids as green solvents and electrolytes for robust chemical sensor development. Acc Chem Res 45:1667-77
Wang, Zhe; Lin, Peiling; Baker, Gary A et al. (2011) Ionic liquids as electrolytes for the development of a robust amperometric oxygen sensor. Anal Chem 83:7066-73
Hou, Kuang-Yu; Rehman, Abdul; Zeng, Xiangqun (2011) Study of ionic liquid immobilization on polyvinyl ferrocene substrates for gas sensor arrays. Langmuir 27:5136-46