Hydrogen Test Sensor

Utilizing an electrical current, palladium nanofilm and mechanical bending to test for hydrogen

  1. Concept
  2. Solution
  3. Result
  • Concept

    Hydrogen Sensing Mechanism

    Hydrogen Sensing Mechanism

    Hydrogen is an odorless, colorless, low density gas that is highly combustible. The flammability range of hydrogen varies from a minimum of 4% to a maximum of 75% with an auto ignition temperature is 500 °C. Due to the wide range of flammability and hydrogens clear burning flame, it is difficult to ensure safety from combustion and must, therefore, be monitored at all times with sensors. The combustibility of hydrogen has made it a desirable, but difficult to manage energy source that is used in a variety of applications.

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  • Solution

    Handheld Hydrogen Sensor

    Handheld Hydrogen Sensor

    The proposed solution to the problem is to utilize an electrical current, palladium nanofilm and mechanical bending to test for hydrogen. A simple circuit provides current through the palladium nanofilm (60nm) while a microprocessor measures the resistance of the circuit. A power screw is used to bend the palladium which causes an increase in resistance in the circuit due to cracks. Hydrogen is then passed over the palladium and spontaneously absorbs into the nanofilm which causes the cracks to connect due to volume expansion. The resistance reduces indicating increased current and detection of hydrogen. The final design of this sensor is about the same length as a Galaxy S5 but slightly thicker. The sensor also has a protective rubber casing around the housing that protects against damage from being dropped.

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  • Result

    Accurate Readings

    Accurate Readings

    The results show that this sensor can accurately detect hydrogen. The plot shows the states of the microprocessor plotted in real-time as the test was conducted. There is a very short initial state followed by the bending state. Once the power screw makes contact with the beam, a sharp rise in resistance is noticed. After a greater than 20% change in resistance is measured by the microprocessor, the state changes to wait. This is when the hydrogen is released into the system. It is important to note that throughout the wait and processing states the power screw is maintaining a constant force on the palladium layer and only after the hydrogen is released does the resistance drop. This exponential decay in resistance is due to the diffusion of hydrogen into palladium connecting the cracks formed by bending. The final initial state is when the power screw is removed from the beam, which results in another drop of resistance, this is the resistance of palladium hydride. Research indicates that hydrogen diffuses in an exponential rate which is consistent with our results. Another interesting observation is that palladium hydride has a higher resistance than pure palladium which is also evident in the plot.

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